eChapters

Crop improvement is essential for developing horticultural varieties with superior yield, quality, resistance, and adaptation. This chapter introduces conventional breeding methods such as selection, hybridization, backcrossing, and mutation breeding, along with modern approaches involving molecular markers and biotechnology. Important breeding objectives include disease and pest resistance, abiotic stress tolerance, improved nutritional quality, shelf life, fruit characteristics, and market preference. Modern techniques such as marker-assisted selection, genomic approaches, and genome editing can accelerate the development of improved cultivars. The chapter connects traditional genetic principles with contemporary breeding technologies and explains how integrated breeding strategies can address changing production environments, consumer requirements, and emerging horticultural challenges.

Horticultural crops comprise a diverse group of plants differing in botanical characteristics, growth habits, climatic requirements, economic uses, and production systems. This chapter presents systematic approaches for classifying horticultural crops into fruits, vegetables, flowers, plantation crops, spices, medicinal and aromatic plants, and other specialized groups. Classification based on botanical relationships, life cycle, climate, growth habit, edible parts, and commercial utilization is discussed to provide a practical understanding of crop diversity. Knowledge of classification helps students identify crops, understand their biological relationships, select appropriate production practices, and organize horticultural resources. The chapter establishes an essential foundation for crop-specific management and improvement

Floriculture and landscape architecture combine plant production with aesthetics, environmental improvement, recreation, and urban development. This chapter introduces the production, management, post-harvest handling, and marketing of flowers and ornamental plants. It also explains principles of landscape design, including balance, rhythm, harmony, colour, texture, form, space, and focal points. Softscape and hardscape components are considered in the planning of gardens, parks, institutional landscapes, roadsides, and urban green spaces. The chapter highlights the increasing importance of floriculture and landscape plants for urban biodiversity, pollution reduction, temperature moderation, recreation, and human well-being. Modern applications include turf management, green infrastructure, indoor plants, and peri-urban floriculture.

Horticultural crops are vulnerable to numerous insect pests, diseases, nematodes, weeds, and other biological stresses that can reduce yield and quality. This chapter presents integrated pest and disease management as a coordinated approach combining prevention, monitoring, cultural practices, biological control, mechanical methods, resistant varieties, and need-based chemical intervention. Accurate diagnosis and regular scouting are emphasized as foundations of effective management. Biorational products, pheromones, microbial pesticides, and natural enemies can reduce dependence on conventional pesticides. Responsible chemical use requires correct product selection, dose, timing, coverage, safety measures, and resistance management. The chapter promotes economically effective and environmentally responsible crop protection while safeguarding beneficial organisms, workers, consumers, and ecosystems.

Horticultural commodities are highly perishable because they remain physiologically active after harvest and are susceptible to moisture loss, respiration, microbial deterioration, mechanical injury, and physiological disorders. This chapter introduces principles of harvesting maturity, handling, grading, sorting, packaging, storage, transportation, and cold-chain management. Appropriate post-harvest practices help preserve freshness, nutritional quality, appearance, and market value while reducing losses. The chapter also examines value addition through processing, drying, preservation, packaging, and development of new horticultural products. Efficient post-harvest systems connect production with consumers and markets and are particularly important for high-value fruits, vegetables, flowers, spices, and other perishable commodities. Together, improved technology, quality management, and value addition can significantly increase farmer income and strengthen horticultural value chains.

Precision agriculture uses spatially and temporally variable information to improve crop management, resource efficiency and agricultural productivity. This chapter examines the integration of artificial intelligence throughout the precision agriculture workflow. It introduces variable-rate technologies, georeferenced data collection and decision-support systems, followed by machine learning, deep learning, computer vision, reinforcement learning, fuzzy logic and expert systems. Applications include crop yield prediction, plant disease monitoring, soil property estimation, irrigation planning and autonomous agricultural operations. Remote sensing, satellite imagery, IoT sensor networks and edge computing are considered for real-time decision-making. The chapter also discusses agricultural robots and autonomous machinery, practical field applications, data limitations, hardware costs, connectivity and model interpretability.

Artificial Intelligence (AI) is becoming an important tool for addressing complex challenges in plant science and agriculture. This chapter introduces the fundamental concepts, methodologies and emerging paradigms of AI applied to plant research. It discusses machine learning, deep learning, convolutional and recurrent neural networks, and transformer architectures, with applications in plant phenotyping, disease diagnosis, genomics and precision agriculture. Different data modalities, including imaging, LiDAR, remote sensing, genomic sequences and metabolomics, are examined. The chapter also considers transfer learning, data augmentation, explainable AI, graph neural networks, federated learning and multimodal AI, together with challenges, ethical issues and future research directions

A. Bhattacharya

6.1.    Macronutrients (Primary)
    
6.2.    Macronutrients (Secondary and Tertiary)
    
6.3.    Micronutrients
    
6.4.    Inter-relationships Between Nutrient Elements
    
    6.4.1.    Synergism
    6.4.2.    Antagonism
    
6.5.    Potassium Inter-relationships with Macronutrients
    
    6.5.1.    Potassium Inter-relationships with Secondary Nutrients
    6.5.2.    Potassium Inter-relationships with Micronutrients
    
6.6.    Nutrient Deficiency
    
6.7.    Role of Mineral Nutrition Against Environmental Stress
    
6.8.    Role of Mineral Nutrition Against Drought Stress
    
6.9.    Role of Potassium in Abiotic Stress Resistance
    
    6.9.1.    Potassium and Drought Stress
    6.9.2.    Cell Elongation and Cell Membrane Stability
    6.9.3.    Aquaporins and Water Uptake
    6.9.4.    Osmotic Adjustment
    6.9.5.    Stomatal Regulation
    6.9.6.    Detoxification of Reactive Oxygen Species
    6.9.7.    Potassium and Salt Stress
    6.9.8.    Potassium and Low-Temperature Stress
    6.9.9.    Potassium and Waterlogging Stress
    
6.10.    Partition of Photosynthates under Nutrient Deficiency
        
References

Pulses belongs to the family Fabaceae (earlier known as leguminosae) comprises more than 600 genera and about 18,000 species of cultivated plants. It is the second largest family after Poaceae (earlier known as Gramineae), in terms of food and vegetable protein source and of fodder. The sub-family Papilionoideae consist of 480 genera and about 12,000 species, of which only a few species are cultivated for human nutrition. Endowed with excellent food and fodder qualities, these crops also restore soil fertility by scavenging atmospheric nitrogen, adding organic matter, enhancing phosphorous availability and improving physical, chemical and biological properties of soil (Graham and Vance, 2003; Dita et al., 2006).

The word ‘pulse’ is derived from latin word ‘puls’ meaning pottage i.e. seeds used to make porridge or thick soup. Pulses or grain legumes in general are indispensible source of supplementary proteins to daily vegetarian diets (Table 1) these are regarded as “poor man’s meat”. Pulse proteins are chiefly globulins and contain low concentrations of sulphur containing amino acids such as methionine and cysteine, but higher concentration of lysine than cereals, pulses provide a perfect mix of essential amino acids with high biological value and also contain higher calcium and iron than cereals.

A. Bhattacharya
1.1.    Specific and Unspecific Reactions to Stress

Plants are exposed to a wide range of environmental stresses and have to adapt physiologically to these as the local environment changes. Unfavorable soil properties, fertility imbalances, moisture extremes, temperature extremes, chemical toxicity, physical injuries, and other problems are some of the most discussed examples of abiotic disorders that can hamper plant growth which ultimately lead to death of the plants under extreme conditions. Furthermore, many of these abiotic stresses can predispose plants to diseases caused by infectious microbes. These stresses in plants also lead to a series of physiological, biochemical and molecular changes. Impact of biotic stresses on agricultural plants such as wheat, rice, maize, groundnut and many others have been top listed area of interest for researchers but until now, ornamental plants have not been a major object of such studies even though these plants constitute a major part of horticultural production and play an important role in everyday human life.
 
Ornamental plants are an integral part of the urban public places and private gardens. However, these plants are highly sensitive to abiotic stresses, which are known as the most harmful factor concerning the growth and development of these plants. Plant stress implies some adverse effect on the physiology of a plant induced upon a sudden transition from some optimal environmental condition.

A. Bhattacharya
    
8.1.    Glycolysis in Plants
    
    8.1.1.    Oxidative Decarboxylation of Pyruvate
    
8.2.    Citric Acid Cycle
    
8.3.    Oxidative Phosphorylation
    
    8.3.1.    Efficiency of ATP Production
    
8.4.    Photorespiration
    
8.5.    Effect of Abiotic Stresses 
    
8.6.    Effect of Drought on Respiration
    
8.7.    Effect of Waterlogging on Respiration
    
    8.7.1.    Plant Metabolism and Energetic Alteration Under 
        Waterlogging
    
8.8.    Effect of Low Oxygen on Respiration
    
8.9.    Effect of Higher Day and Night Temperature on Respiration
    
8.10.    Respiration Under Low Temperature Stress
    
8.11.    Effect of Salt Stress on Respiration
    
    8.11.1.    Reactive Oxygen Species
    8.11.2.    Physiological and Biochemical Processes
    
8.12.    Effect of High CO2 Concentration on Respiration
        
References

A large number of insect pests are associated with stored grains which are directly related to geographical and climatic conditions. There are different estimates on post harvest losses in food. During storage both quantitative and qualitative losses occur due to insects, rodents, and microorganisms. Almost all the insect species may destroy 10.0 - 15.0 % of grain and contaminate with undesirable odour. These pests also helps in transportation of fungi. Some insect pests initiate damage at the ripening stage of crops and continue during storage. Major sources of infestations are old gunny bags, storage structure and old containers (Pruthi and Singh, 1950). The spread and distribution of stored product pests are facilitated by movement of grains from one area to another and by flight of insect pests as some of the adult insects are strong fliers. The cracks and crevices are probable sites for cross infestation. Nearly one thousand species of insects have been associated with stored products in different part of the world. Majority of insect pests belong to the orders Coleoptera and Lepidoptera (Khare, 1994).

Crop yields are affected by a combination of abiotic stresses, biotic stresses, and nutritional factors but abiotic stresses (drought, heat, cold or salinity) are the major factors that prevent crops from realizing their full yield potential (Edmeades, 2009). In traditional approach, breeders grow and cross varieties and then evaluate how the progenies vary in their ability to deal with stresses. The best-adapted plants are then selected for growing in fields exposed to stresses. Biotechnologists have taken advantage of recent advances in biotechnology and functional genomics to genetically engineer crops which can give better yield in adverse conditions than the unmodified ones (Manavalan et al., 2009; Umezawa et al., 2006). Drought, extreme temperatures (high or low), high salinity and cold are the major abiotic stresses that affect plant growth and result in significant yield losses. Although plants have evolved a wide spectrum of programs for adaptation to changing environment, the current understanding of the mechanisms associated with the ability of crops to maintain yield under abiotic stress are poorly understood (Witcombe et al., 2008; Munns et al., 2008; Bartels et al., 2005). New advances in ‘omic’ technologies are providing opportunities for identification of transcriptional, translational and post-translational mechanisms and signaling pathways that regulate the plant response. This chapter describers several examples of how modern crop technologies may be applied to broaden crop tolerance of various abiotic stresses and to increase total biomass.

Environmental constraints that include abiotic stress factors such as salt, drought, cold, extreme temperatures and heavy metalsalready a major limitingfactor for crop productivity and will soon become even more severe due to climate change conditions.Together, these stresses constitute the primary causes of crop losses worldwide, reducing average yields of most major crop plants by more than 50% (Boyer, 1982; Bray et al., 2000; Wang et al., 2003). Current climate change scenarios predict an increase in mean surface temperatures and drought that will drastically affect global agriculture in the near future (Le Treut et al., 2007).
 
Abiotic stresses trigger many biochemical, molecular and physiological changes and responses that influence various cellular and wholeplant processes (Wang et al., 2001, 2003). For example, drought, salinityand low temperature stress lead to reduced availability of water (alsoknown as dehydration/osmotic stress) characterized by a decreasedturgor pressure and water loss (Dhariwal et al., 1998; Boudsocq and Lauriere, 2005). Osmotic stress promotes the synthesis of the phytohormoneabscisic acid (ABA)which then triggers a major change in gene expressionand adaptive physiological responses (Seki et al., 2002; Yamaguchi and Shinozaki, 2006; Shinozaki andYamaguchi-Shinozaki, 2007).

India is the largest producer and consumer of pulses in the world, accounting for 33 per cent area and 25 percent production. Pulses are mostly grown under rainfed conditions in marginal to sub-marginal lands. Once a net exporter it is presently one of the largest importer of pulses as our demand outstrips domestic production. While the traditional cropping pattern almost always included a pulse crop either as a mixed crop or in rotation, the commercialization of agriculture has encouraged the practice of sole-cropping. As a result, the annual import has increased from 0.50 million tonnes to 1.80 million tonnes during the last five years and contribution of pulses in the national food basket reduced from 17% to 7%. Pulses are generally grown on marginal and sub-marginal lands under rainfed conditions with low inputs and suffer heavily due to biotic and abiotic stresses, resulting into low productivity. Challenges for pulses in India are decline in area of pulses, low genetic yield potential, low realized yield, instability in production, climate change, biotic and abiotic stresses, poor seed replacement rate, post harvest losses, wide fluctuation in price, no regular MSP/procurement policy, poor availability of critical inputs in productivity zone and poor transfer of technology.

Vegetable is an important constituent of Indian diet. India is the second largest producer of vegetables which contributes 16.7% to global vegetable area with a production of 156.33 million tons (15.4%) (Table 1). The level of productivity of vegetable17.4 tons/ha is quite low (Rai et al., 2014). Majority of Indians are vegetarian, with a per capita consumption 135 g per day as against the recommended 300 g per day. It is still very less than recommended diet level. In near future, there is a need of around 5-6 million tons of food to feed our 1.3 billion Indian population expected by the year 2020 (Paroda 1999). The major biotic stress in vegetable production is due to increased insect pest. In many cases, there is 100 per cent yield loss due to viral diseases vectored by insects. Vegetables are more prone to insect pests and diseases mainly due to their tenderness and softness as compared to other crops and virtual absence of resistance characters because of intensive hybrid cultivation. The insect pests inflict crop losses to the tune of 10-30 per cent in vegetable production (Table 2). To overcome these losses farmers used indiscriminate doses of toxic chemical on vegetable. It accounts for 13-14 per cent of total pesticides consumption, as against 2.6 per cent of cropped area (Sardana, 2005). For the benefit of the farmer and other, application of BIPM is must. Bio intensive pest management involves every part of management that keeps pest below economic injury level so that pest does not cause any economic loss to the farmers or growers.

Plants are often exposed to various abiotic and biotic stresses and have developed specific mechanisms to adapt, survive and reproduce under these stresses (Pieterse et al., 2009). Abiotic stresses include drought, water logging, high temperature, cold(low temperature), salinity, chemical pollution (xenobiotics), uv radiation, heavy metal and oxidative and plants are also challenged by biotic stresses through microbial pathogens such as myco-plasma, nematodes, fungi bacteria (Tippmann et al., 2006). The biology of plant cell is more complicated with any foreign stimulus from the environment; multiple pathways of cellular signaling and their interactions are activated. These interactions mainly evolved as mechanism to enable the plant systems to respond to stress with minimum and appropriate physio- biochemical processes. Abiotic and biotic stress induces signals and theses signals are recognized by receptors, followed by generation of secondary messengers e.g. activation of ion channels, production of reactive oxygen species (ROS) Xiong et al., 2002, accumulation of hormones (Bari and Jones, 2009; Peleg and Blumwald, 2011) such as salicylic acid (SA), ethylene (ET), jasmonic acid (JA) and abscisic acid (ABA). Secondary messengers are responsible for modulating intracellular level of calcium, often initiating protein phosphorylation cascade, which may leads to the activation of various proteins directly involved in cellular protection (Tippmann et al., 2006) Fig.1.

A systems approach to pest management based on an understanding of pest ecology is referred to as Biointensive Integrated Pest Management (BIPM). It is more dynamic and ecologically informed as compared to IPM that considers the farm as part of an agro ecosystem. Accurate diagnosis of the pest problem is the first step, which then relies on a range of preventive tactics and biological controls to keep pest populations within acceptable limits. It also considers ecological and economic factors into agricultural system design and decision - making and addresses public concern about environmental quality and food safety. As a last resort, the reduced – risk pesticides are used if other tactics have not been adequately effective.

The earlier concept of IPM has failed because of ease of applicability to easy availability of chemical pesticides. Hence, the present concept of BIPM, with more intensive use of biological and other biorational means has emerged. The flexibility and environmental compatibility of BIPM strategies make it useful in all types of cropping system. BIPM would likely decrease chemical use and costs entailing them. BIPM ultimately provides resistance / immunity to the entire system so that no foreign elements (insect pests or disease causing organisms) survive or gain upper hand. BIPM if followed for years shall enhance the natural control system, thus suppressing pest populations below those causing economic injury.

A. Bhattacharya    
    
4.1.    Factors of Abiotic Stress
    
4.2.    Light
    
4.3.    Temperature
    
    4.3.1.    Heat-stress Threshold
    4.3.2.    Low Temperature Stress
    4.3.3.    Plant Responses to Heat Stress
    
4.4.    Water
    
    4.4.1.    Drought
    4.4.2.    Flooding
    
4.5.    Soil
    
    4.5.1.    Soil Type
    4.5.2.    Soil pH
    4.5.3.    Soil Fertility
    4.5.4.    Soil Salinity
    
4.6.    Growth and Development
    
    4.6.1.    Phases of Development Sensitive to Temperature or Photoperiod
    
4.7.    Phenology
    
    4.7.1.    Changes in Phenology of Cropping Systems
    4.7.2.    Effect of CO2 on Flowering
    4.7.3.    Temperature and Effects on Phenology
    4.7.4.    Effect of Salinity
    
4.8.    Molecular/Genetic Aspects of Flowering Response to Climate Change
    
4.9.    Simulation of Phenology for Future Climate
        
    References

Growth and development of plants are dependent upon the temperature surrounding the plant and each species has a specific temperature range represented by a minimum, maximum, and optimum. These values were summarized by Hatfield et al. (2008, 2011) for a number of different species typical of grain and fruit production. The expected changes in temperature over the next 30 to 50 years are predicted to be in the range of 2 to 3°C Intergovernmental Panel Climate Change (IPCC) (2007). Heat waves or extreme temperature events are projected to become more intense, more frequent, and last longer than what is being currently been observed in recent years (Meehl et al., 2007). Extreme temperature events may have short-term durations of a few days with temperature increases of over 5°C above the normal temperatures. A recent review by Barlow et al. (2015) on the effect of temperature extremes, frost and heat, in wheat (Triticum aestivum L.) revealed that frost caused sterility and abortion of formed grains while excessive heat caused reduction in grain number and reduced duration of the grain- filling period. Analysis by Meehl et al. (2007) revealed that daily minimum temperatures will increase more rapidly than daily maximum temperatures leading to the increase in the daily mean temperatures and a greater likelihood of extreme events and these changes could have detrimental effects on grain yield. If these changes in temperature are expected to occur over the next 30 years then understanding the potential impacts on plant growth and development will help develop adaptation strategies to offset these impacts.

India is the second largest producer of vegetables after China with 14 % contribution in total World vegetable production (1160 million tonnes). After the advent of green revolution, more emphasis is laid on the quality of the agricultural product along with the quantity to meet the ever-growing food and nutritional requirements. Both these demands can be met when the environment for the plant growth is suitably controlled. Olericulture a vital component of Indian Horticulture, which includes science and management of vegetables, has made a rapid stride during the last decade, recording appreciable growth in production (162.90 million tonnes against 81.89 million tonnes in 2000-01) and productivity (17.4 t/ha against 12.2 t/ha in 2000-01), availability (210 g/capita/day against recommendations of 300 g/capita/day) and export (36,94,860 tonnes worth Rs. 14,36,487 lakhs.) during 2013-14. Vegetables play a major role in Indian agriculture by providing food, nutritional and economic security and more importantly, producing higher returns per unit area and time (Srivastava et al. 2013). In addition, vegetables have higher productivity, shorter maturity cycle, high value and provide greater income leading to improved livelihoods. The total production of vegetables during 2013-14 was 162.90 million tonnes compared to 21.19 million tonnes in 1960-61, 81.89 million tonnes in 2000-01 and 146.55 million tonnes in 2010-11. Although, olericulture has exhibited leadership role but challenges are much greater. Looking to the requirement, which is estimated to be 225 million tonnes by 2020 and 350 million tonnes by 2030, which has to be produced from declining land and water resources and in the scenario of climate change, the task to meet the needs of growing population would be difficult but not impossible (Singh et al. 2014).

Vegetables constitute a substantial part of human diet supplying vitamins and minerals, in which other food materials are deficient. India has emerged out as the second largest producer of vegetables in the world. More than 25% of fruits and vegetables are damaged by the attack of insect-pests (Pradhan, 1964).Vegetable crop is damaged by both sucking as well as chewing insect-pests. Sucking pests are aphids, whitefly, jassids and bugs attacking in initial stage whereas chewing pests like borers, infesting in flowering and fruiting stage. Sucking pests may transmit the viral diseases which cause severe loss in yield in tomato and okra crops. About 13-14 % of total pesticides used in the country are applied on vegetables. Average pesticide consumption in vegetables in India around 0.678 a.i. kg/ha. Maximum pesticide usage in chilli followed by brinjal, cole crops and okra. Global agro-chemical consumption dominated by fruits and vegetables, accounting 25 % of total pesticide market. Major insect-pests of different vegetable crops and their management are as follows:
 
Cole crops

Cabbage (Brassica oleracea var capitata) and Cauliflower (Brassica olercea var botrytis L) are grown in cold and moist climate. It is rich in minerals namely iron, magnesium, phosphorous and sodium. Cole crops were attacked by number of insect pests and cause heavy economic loss. The major insect pests are described below along with their management:

Okra Abelmoschus esculentus L.

Cotton Jassid Amrasca biguttula Ishida (Hemiptera: Cicadellidae)

Economic importance: Sucking pest cause damage during May to September. Adults are also found on plants such as potato, brinjal, tomato, etc.

Mark of identification and life cycle: Adults are about 3 mm long and greenish yellow during the summer, acquiring a reddish tinge in the winter. The winged adults jump or fly away at the slightest disturbance and are also attracted to light at night. Females lay about 15-38 yellowish eggs on the underside of the leaves, embedding them into the leaf veins. The eggs hatch in 4-5 days. Nymphs are wedge-shaped and are very active and complete five instars with 3-5 days in each instars. Adult live for 11days.

Nature of damage: Damage to the crop is caused by the adults as well as by the nymphs, both of which are very agile and move briskly, forward and sideways. They suck cell-sap from the underside of the leaves and pass through six stages of growth in 7-21 days. They feed constantly on the plant juice. The pest completes seven generations in a year. Damage symptoms: Injury to plants is due to the loss of sap and probably also due to the injection of toxins. The attacked leaves turn pale and then rust-red. With change in appearance, the leaves also turn downwards, dry up and fall to the ground.

Solanaceous Vegetables

Solanaceous vegetables are also infested heavily by several major insect pests.

Brinjal Solanum melongena L.
 
Fruit and shoot borer Leucinodes orbonalis Gunnee (Lepidoptera: Pyraustidae)

Economic importance: Most destructive pest of brinjal, found throughout the country. Besides brinjal, the pest is also known to infest potato, bitter gourd, pea pods, cucurbits and other solanaceous etc. The infestation on brinjal can be as high as 70 per cent. The pest is active throughout the year, except in severe cold weather in North India.
 
Mark of identification and life cycle: Moths wings are white with pinkish or black tings and are ringed with small hair along the apical and anal margins. The fore wings are ornamented with a number of black, pale and light brown spots. Female lays 80-120 creamy white eggs, singly or in batches of 2-4 on the underside of leaves, on green stems, flower buds or the calyces of fruits. Caterpillars are creamy when young, but light pink when full-grown in 9-28 days. Pupate in tough silken cocoons among the fallen leaves with period of 6-17days and adult survive for 2-5days of its life cycle. A single life-cycle takes 22 - 25 days extending up to 74 days during winter and there may be 8 - 12 generations in a year.

The oilseeds crop occupies an important position in agriculture economy in the world. Indian agriculture has made considerable progress, particularly in respect of food crops such as wheat and rice in irrigated areas; however, performance has not been so good in case of other crops particularly oilseeds, pulses, and coarse cereals. Therefore, after achieving self sufficiency in food grains the government is focusing attention on these agricultural commodities. On the oilseeds map of the world, India occupies a prominent position, both in regard to acreage and production. India is the 4th largest edible oil economy in the world and contributes about 10 percent of the world oilseeds production, 6-7% of the global production of vegetable oil, and nearly 7 percent of protein meal. This sector also has an important place in the Indian agricultural sector covering an area of about 26.5 million hectares, with total production of over 25.3 million tonnes in the triennium ending 2015-16 (GOI, 2016). This constitutes about 14.8 per cent of the gross cropped area in the country. A wide range of oilseed crops is produced in different agro-climatic regions of the country. Insects-pests are one of the limiting factors in the production of oilseed crops. Management of these pest problems by using possible control techniques could increase the quality and quantity of the products. These crops are damaged by a more number of insect pests, of which some are more serious. These pests can be effectively controlled by the integration of different techniques such as use of various safe insecticides/biopesticides, some modification in cultural practices and use of pest tolerant varieties. Integrated pest management approaches will help to increase the production and productivity of oilseed crops by reducing the pest damage without any adverse effect on the agro- system and erosion in the environment. 

Pest wise information of oilseed crop and management of major pests are described below.

Food productivity is decreasing due to detrimental effects of various biotic and abiotic stresses; therefore minimizing these losses is a major area of concern to ensure food security under changing climate. Environmental abiotic stresses, such as drought, extreme temperature, cold, heavy metals, or high salinity, severely impair plant growth and productivity worldwide. Drought, being the most important environmental stress, severely impairs plant growth and development, limits plant production and the performance of crop plants, more than any other environmental factor (Shao et al., 2009). Plant experiences drought stress either when the water supply to roots becomes difficult or when the transpiration rate becomes very high. Available water resources for successful crop production have been decreasing in recent years. Furthermore, in view of various climatic change models scientists suggested that in many regions of world, crop losses due to increasing water shortage will further aggravate its impacts. Drought impacts include growth, yield, membrane integrity, pigment content, osmotic adjustment water relations, and photosynthetic activity (Praba et al., 2009). Drought stress is affected by climatic, edaphic and agronomic factors. The susceptibility of plants to drought stress varies in dependence of stress degree, different accompanying stress factors, plant species, and their developmental stages. Acclimation of plants to water deficit is the result of different events, which lead to adaptive changes in plant growth and physio-biochemical processes, such as changes in plant structure, growth rate, tissue osmotic potential and antioxidant defenses (Duan et al., 2007 and Shakeel et al., 2011).

Cereal crops are interchangeably called grain crops. In many publications and correspondence, they are simply called grains or cereals. As of 2012, the top 5 cereals in the world ranked on the basis of production tonnage are rice (paddy), wheat, maize (corn), barley and sorghum. These crops are also among the top 50 agricultural commodities in the world with maize ranking second next to sugarcane. Rice (paddy) ranks third, wheat - 4th, barley - 12^th, and sorghum - 30^th. Another cereal, millet, ranks no. 42 (FAO Stat 2014, updated Aug. 18, 2014). According to Chapman and Carter (1976), “a cereal is generally defined as a grass grown for its small, edible seed.” They also explained that all cereals are angiosperms, monocots, and members of the grass family Gramineae. Similarly, Lantican (2001) defines cereal or grain crops as agronomic crops belonging to the grass family Gramineae or Poaceae which are utilized as staples; the word “cereal” is derived from the most important grain deity, the Roman Goddess Ceres. Among the food grains cereals occupies for most status in human food requirements. Cereals are grown under different agro-climatic (Upland, Low land & Rainfed) conditions and it is most important staple food of about 65% of Indian population. Cereals crop is attacked by a large number of insect pests right from initial to till the harvest of the crops. Brief descriptions of the major crops, major insect pest and appropriate control measures are given below:

Fruit Flies and Economic Importance

Fruit flies belong to order Diptera (true flies) with one of the largest, most diversified and fascinating acalypterate family Tephritidae. These are commonly called as fruit flies due to their close association with fruits and vegetables and are also known as peacock flies because of their habit of strutting about and vibrating spotted and striped wings. Of the 4500 known species of fruit flies worldwide, nearly 200 are considered as pests but 70 species are regarded as agriculturally important throughout the world (Clarke et al., 2005, Schutz et al., 2012). David and Ramani (2011) reported 325 species in the Indian subcontinent of which 243 in 79 genera are from India alone. Important fruits flies damaging fruit crops in India include Oriental fruit fly or mango fruit fly, Bactrocera dorsalis (Hendel); peach fruit fly, B. zonata (Saunders); guava fruit fly, 
B. correcta (Bezzi); melon fly, B. cucurbitae (Coquillett) and ber fruit fly, Carpomyia vesuviana Costa, whereas important fruit flies in Punjab include B. dorsalis and B. zonata. Important host plants of B. dorsalis are mango, guava, peach, citrus, pear, ber and loquat but most preferred host of B. dorsalis is guava while that of B. zonata are guava, peach, mango, pear, ber, citrus and loquat but C. vesuviana infests only ber (Mann 1990, Sharma et al., 2005, Singh 2008b, Singh 2012, Singh et al., 2014a,b and Singh et al., 2015). Bactrocera dorsalis is considered to be the most damaging and aggressive fruit flies in the world (Leblance and Putao 2000). They are strong fliers and can fly upto two kilometers in search of food (Butani 1979).

Stress, is usually defined as an external factor that exerts disadvantageous influence on the plant. In most cases, stress is measured in relation to plant survival, crop yield, growth (biomass accumulation), or the primary assimilation processes (CO2 and mineral uptake), which are related to overall growth. Some environmental factors (such as air temperature) can become stressful in just a few minutes; other may take days to become stressful or even months (some mineral nutrients) to become stressful. Different types of abiotic stresses that affect fruit production are; water stress, heat stress, chilling and freezing stress, salinity stress, flooding stress. Although, it is convenient to examine each of these factors separately, many are interrelated. For example, water deficit is often associated with salinity in the root zone/ or with heat stress in the leaves. Plants often display cross resistance, or resistance to one stress induced by acclimatization to another. This behaviour implies that mechanism of resistance to various stresses share many common features.

Plants encounter adverse environmental stresses during their life cycle, which have negative impacts on growth and greatly affect crop productivity. As perennial crops, fruit trees are exposed to an array of stresses for a long time once they are planted. If the trees are severely injured by environmental stresses, it would be hard for them to recuperate, leading to retarded growth and reduced fruit production. Furthermore, the negative effects of the stresses are not limited to the fruit production in the current year but can also extend to the next year(s). Therefore, it is of critical importance to develop techniques for reducing stress injury and/or improving stress tolerance in fruit trees for sustainable cropping, which can be fulfilled by the cultivation method or genetic engineering (Holmberg and Bulow, 1998). 

Nematodes are the most numerous metazoa on earth. They are either free living or parasites of plants and animals. Although currently only about 4100 species of plant parasitic nematodes have been described (i.e. 15 % of the total number of nematode species known), their impact on humans by inflicting heavy losses in agriculture is substantial. Most of the developing countries including India lie in tropical or sub tropical regions where climate is suitable for activity and multiplication of nematodes almost throughout the year. Sandy and warm soils such as found in India other developing countries in the arid zone are very favorable for nematode infection, especially in irrigated areas which are used for crop production continuously. The percentage of crop losses caused by plant pathogens, insect pests and weeds world wide has been estimated to 42% according for $500 billion worth of damage. The estimated overall annual yield loss of world’s major crops due to damage by plant parasitic nematodes has been reported to the extent of 12.3% (Sasser & Freckman, 1987). Estimated losses due to nematodes attack on different cultivated crops all over the world by FAO are around 400 million dollars. Annual crop losses in India is Rs. 242.1 billion. A large number of plant parasitic nematodes have been found associated with pulse crops in allover India but pathogenicity has not been proved for all. Plant parasitic nematodes are one of the most unwanted organisms in agricultural soils. They parasitize the roots of our carefully nurtured crops, reduce their ability to produce yields, make them weak and perhaps vulnerable to many pests and diseases. They reduce the crop yields that may equal those associated with more severe and easily identifiable plant diseases and we do not even realize their presence. Damage to crops by nematodes often goes unnoticed or attributed to other causes such as lack of fertility, deficient soil moisture. Sandy and warm soils such as found in India other developing countries in the arid zone are very favourable for nematode infection, especially in irrigated areas which are used for crop production continuously (Taylor, 1967).

Raj Bahadur
    
3.1.    Nitrogen Fixation in Saline Soil
    
3.2.    Legumes and Nitrogen Fixation
    
    3.2.1.    Legumes in Saline Agriculture; Nitrogen Fixation Capabilities
    3.2.2.    Legumes in Saline Agriculture; Salinity Tolerance of Legumes
    3.2.3.    Improvement of Salinity Tolerance of Legumes
    3.2.4.    Legumes of the HALOPH Database
    
3.3.    Perspective for Saline Agriculture
    
3.4.    Impacts of Agriculture and Global Climate Change Terrestrial Biogeochemical Cycle of Nitrogen
    
    3.4.1.    Nitrogen Chemistry and Terrestrial Life
    
3.5.    Nitrogen Fixation
    
    3.5.1.    Decomposition
    3.5.2.    Nitrification
    3.5.3.    Denitrification
    3.5.4.    Bio-geochemical Linkage of Nitrogen and Carbon
    3.5.5.    Soil Organic Matter
    3.5.6.    Perturbations and N and C Biogeochemistry
    3.5.7.    Organic Nitrogen
    3.5.8.    Mineralization
    
3.6.    Factors Influencing Biological Nitrogen Fixation in Legumes
    
    3.6.1.    Temperature
    3.6.2.    Soil Water Status
    3.6.3.    Nitrogen Concentration in the Root Zone
    3.6.4.    Carbon Demand for Fixation
    3.6.5.    Seasonal Regulation of Legume Biological Nitrogen Fixation
    
3.7.    Quantification of Biological Nitrogen Fixation
    
    3.7.1.    Estimation with Empirical Models
    3.7.2.    Potential N Fixation Rate
    3.7.3.    Impact of Soil Temperature
    3.7.4.    Impact of Soil Water Status
    3.7.5.    Effect of Soil Mineral N or Internal Substrate N
    3.7.6.    Influence of Plant Substrate C or C supply
    3.7.7.    Changes in N Fixation with Plant Growth Stage
        
    References

Agricultural research has been primarily focused to assure food self-sufficiency and security, and little concern on nutritional value “nutritional security” or health promoting qualities of food being produced. Food security has three dimensions, namely: (1) endemic hunger caused by poverty-induced under-nutrition and malnutrition; (2) hidden hunger caused by the deficiency of micronutrients like iron, iodine, zinc and vitamin A in the diet; and (3) transient hunger caused by natural calamities or civilian conflicts. Micronutrient malnutrition is recognized as a massive and rapidly growing public health issue especially among poor people living on an unbalanced diet.
 
Although great progress has been made in reducing the prevalence of hunger, over 805 million people are undernourished in 2012-14, still unable to meet their daily calorie needs for living healthy lives. This number has fallen by 100 million over the last decade (Table: 1 & Table: 2; Source: FAO, 2014). Undernourishment refers to food intake that is insufficient to meet dietary energy requirements for an active and healthy life. About one in nine people go to bed daily on an empty stomach. In cases where food is available, often the quality of the food does not meet micronutrient (vitamin and mineral) needs. More than two billion people continue to suffer from nutritional deficiencies such as vitamin A, iron, zinc and iodine. Despite progress, the number is still high, and marked differences across regions persist. 

Inorganic pest management systems using external inputs such as chemical fertilizers, pesticides, high yielding varieties have resulted in increased yields in certain areas, but resulted in ecological degradation hence a decrease in productivity. Under organic farming systems, the fundamental components and natural processes of ecosystems, such as soil organism activities, nutrient cycling, and species distribution and competition are used to work directly and indirectly as farm management tools. For example, crops are rotated, planting and harvesting dates are carefully planned, and habitat that supplies resources for beneficial organisms are provided. Soil fertility and crop nutrients are managed through tillage and cultivation practices, crop rotations, cover crops, and supplemented with manure, composts, crop waste material and allowed substances.
 
Bio intensive IPM incorporates ecological and economic factors into agricultural system design and decision making and addresses public concerns about environmental quality and food safety. The benefits of implementing bio intensive IPM can include reduced chemical input costs, reduced on-farm and off-farm environmental impacts, and more effective and sustainable pest management. An ecology-based IPM has the potential of decreasing inputs of fuel, machinery, and synthetic chemicals—all of which are energy intensive and increasingly costly in terms of financial and environmental impact. Such reductions will benefit the grower and society.

A. Bhattacharya
    
5.1.    Chlorophyll
    
5.2.    Response to Drought Stress
    
5.3.    CO2 Fixation Under Drought
    
5.4.    Response to High Temperature Stress
    
5.5.    Response to Low Temperature Stress
    
5.6.    Effect of Cold Stress on CO2 Fixation
    
5.7.    Cold Acclimation and its Role in Providing Freeze-tolerance
    
5.8.    Response to Salinity Stress
    
5.9.    CO2 Fixation Under Salinity Stress
    
5.10.    Response to High Light Intensity Stress
    
5.11.    Stress-induced Changes
         
    5.11.1.    Effects on Photosynthetic Pigments
    5.11.2.    Effects on Photosystems
    5.11.3.    Effects on Gas-exchange Characteristics        
    5.11.4.    Effects on Activities of key Photosynthetic Enzymes
    
5.12.    Improvement in Photosynthetic Capacity Under Stress by Engineering Photosynthesis-related Genes or Transcription Factors
    
    5.12.1.    Transfer of C4 genes/traits to C3 plants
    5.12.2.    Role of Transcription Factors in Regulation of Genes Involved in Photosynthesis
    
5.13    Role of Mitogen-activated Protein Kinases (MAPKs) in Photosynthesis
    
5.14    Conclusion and Future Prospects
        
References

Globally, agriculture productivity is challenged by abiotic and biotic stresses, but abiotic stresses in particular (Gong et al., 2013) affect spreading of plant species across different environmental zones (Chaves et al., 2003). The changing climate is expected to worsen abiotic factors globally and adaptation strategies need to be established for target crops to specific environments (Beebe et al., 2011). Connect between different stress factors will likely surge harm to crop yields (Beebe, 2012). Soil salinity is a major environmental constraint to agricultural productivity (Greenway and Munns, 1980; Rhoades and Loveday, 1990). High concentrations of different types of salts, including chlorides, carbonates, and sulfates of magnesium, calcium, potassium, and sodium, characterize different saline soil areas around the world. Moreover, for each type of naturally occurring salinity, constantly changing environmental conditions, such as temperature and precipitation, as well as agricultural practices cause rapid modifications in levels of salinity and salt distribution patterns. Sodium and chloride are the predominant ions in the vast majority of saline areas.

During evolution, various species of plants, known as halophytes, readapted to life in high-salinity environments, but a large majority of plant species grown in non-saline areas are salt-sensitive (referred to as glycophytes). These glycophytic plants, including the majority of crop species, differ greatly in their tolerance to salt stress (Greenway and Munns, 1980; Flowers and Colmer, 2008).

A. Bhattacharya

2.1.    Seed Germination
    
    2.1.1.        Drought Tolerance in Plants
    2.1.2.        Osmotic Adjustment
    2.1.3.        Cell membrane Stability
    2.1.4.        Epicuticular Wax
    2.1.5.        Partitioning and Stem Reserve Mobilization
    2.1.6.        Salt Stress and Seed Germination
    
2.2.    Seedling Drought Traits
    
2.3.    Seed Germination Under Abiotic Stress

2.4.    Salt Stress and Seed Germination

2.5.    Seedling Growth

2.6.    Stress Effects on Seedling Growth
    
    2.6.1.        Temperature
    2.6.2.        Nutrition, Salinity, and pH
    2.6.3.        Water
    2.6.4.        Under Flooding Condition
    
2.7.    Drought Stress and Abscisic acid (ABA)
    
2.8.    Salt Stress on Seedling Length
    
    2.8.1.        Salt Stress on Seedling Dry Weight
    2.8.2.        Mechanism of Salt Stress on Germination
    2.8.3.        Root Establishment Methods
    
2.9.    Root Development
    
    2.9.1.        Root System Development and Abiotic Stress
    
2.10.    Root Development Under Abiotic Stress
    
    2.10.1.        Drought Stress
    2.10.2.        Regulation of Root System Architecture by Water Availability and Salinity Stress
    2.10.3.        Regulation of Root System Architecture by Nutrients
    2.10.4.        Phosphate Starvation
    2.10.5.        Nitrogen
    2.10.6.        Potasium and Iron
    2.10.7.        Meristematic Activity Regulation by Abiotic Stress
    2.10.8.        Waterlogging Stress
    2.10.9.        Salt Stress
    2.10.10.    Temperature Stress
    2.10.11.    Illumination Stress
    2.10.12.    Nutrient Deficiency or Excess
    2.10.13.    Heavy Metal Stress
    2.10.14.    Elevated Atmospheric Levels of CO2
    2.10.15.    Mechanical Stress
    
2.11.    Biochemical Regulation of Root
        
References

Soils are the basis of food production. Ninety five percent of our food is directly or indirectly produced on our soil. A healthy soil maintain a diverse community of organisms that helps in controlling pests (insects, weeds, and fungus) but also form beneficial symbiotic association with plant roots, recycle essential plant nutrients and improve soil structure. A healthy soil can also be a strategic ally in mitigating and adapting to climate change, as soil sequesters CO₂ and prevent to escape into the atmosphere. Beside this, it contributes to mitigate climate change by maintaining or increasing its carbon content. This can be said that the proportion of organic carbon is available more in the soil than combining both atmosphere and ground vegetation. Most of the soil organic carbon (SOC) stored in the first metre of the soil in the form of organic matter. However, organic matter degrades due to deforestation; deplete soil biodiversity, loss of nutrients as consumed by crop plants, soil compaction due to excessive use of agricultural machineries, soil erosion, water logging conditions, and urbanization, which release greenhouse gases like CO₂, CH₄, and N₂O into the atmosphere causing global warming and climate change. One third of all CO₂ emissions come from changes in land use (deforestation, shifting cultivation, and intensification of agriculture) whereas two-thirds of CH₄ and majority of N₂O emitted through agricultural practices (Kotschi and Müller-Sämann, 2004).

7.1.    Single Action Gene
    
    7.1.1.    Osmoprotectants
    7.1.2.    Detoxifying Genes
    7.1.3.    Late Embryogenesis Abundant (LEA) Protein
    7.1.4.    Transporter Genes
    7.1.5.    Multifunctional Genes for Lipid Biosynthesis
    7.1.6.    Heat -shock Protein Genes
    
7.2.    Regulatory Gene
    
    7.2.1.    Transcription Factors
    7.2.2.    Signal Transduction Genes
    
7.3.    Choice of Promoters
    
7.4.    Physiological Evaluation of Stress Effect
    
7.5.    Conclusions
        
References

1. Introduction

The scientific naming of plants is called botanical nomenclature. Although, nomenclature is included in taxonomy, but it distinctly differs from taxonomy. Plant taxonomy is concerned with grouping and classifying plants, however, the botanical nomenclature provides names for the results of this process. Names are a means of reference to all living and non-living things. The common names of pants and animals vary from place to place and language to language. But, scientific names of plants and animals are universal. For uniformity and consistency, the scientific names are given to plants according to certain internationally accepted rules provided in International Code of Nomenclature. It was Linnaeus who for the first time proposed some rules for generic names of plants in his Fundamenta Botanica, 1736 and Critica Botanica, 1737. However, the first proper set of rules of plant nomenclature was drafted by A. P. de Candolle and passed by the International Botanical Congress at Paris in 1867. The present Botanical nomenclature is governed by the International Code of Nomenclature for algae, fungi, and plants (ICN), which replaces the International Code of Botanical Nomenclature (ICBN) in 2012.

Botanical nomenclature has a long history, going back to the period when Latin was the scientific language throughout Europe, and perhaps further back to Theophrastus. The starting point for modern botanical nomenclature is Linnaeus’ Species Plantarum (1753). In the nineteenth century it became increasingly clear that there was a need for rules to govern scientific nomenclature and initiatives were taken to produce a body of laws. These rules were published in successively more sophisticated editions after every six years. The most recent is the Melbourne Code, adopted in 2012.

All formal botanical names are governed by the ICN, and within the limits set by that code there is another set of rules, the International Code of Nomenclature for Cultivated Plants (ICNCP). The latter Code applies to plant cultivars that have been deliberately altered or selected by humans and require separate recognition

Abiotic stress: Unfavourable situation created by non-living factors to the growth and development of plants. Factors include water, temperature, soluble salts, heavy metals, etc.

Abscissic acid (ABA): A plant hormone belongs to isoprenoid compounds. It is also known as stress hormone since it has relevance in stress tolerance in plants. Some of the physiological effects of ABA are closing of stomata, synthesis of osmolytes and seed dormancy.

Abscission layer: Distinct layer of cells with weakened cell walls in abscission zone.

Abscission zone: A region near the base of petiole of leaf which contain abscission layer.

The extreme temperatures those are consequences of present-day global climate changes are considered as major abiotic stresses for crop plants. Different studies clearly show that temperatures exceeding the limits of adaptation substantially influence the metabolism, viability, physiology, and yield of many plants. Plants exposed to extreme temperatures often show a common response in the form of oxidative stress. However, the extent of damage caused by extreme temperatures depends greatly on the duration of the adverse temperature, the genotypes of the exposed plants, and their stage of growth. There is ample need to develop temperature tolerance in crop plants by exploring suitable strategies. Numerous research findings support the notion that induction and regulation of antioxidant defenses are necessary for obtaining substantial tolerance against environmental stress. The development of genetically engineered plants, by the introduction and/or overexpression of selected genes, would to be one feasible strategy. However, plant adaptation to either high temperature or low temperature is a multigenic response which is very complex in nature. Thus the task of identifying the traits those correlate with stress tolerance is incredibly difficult for researchers. Plant response to continuous light depends on plant tolerance and can be modified by alteration in temperature, light intensity, CO2 level, and other environmental factors.

The stresses, drought, salinity, chemicals, cold and hot temperatures, have interconnected effects on plants, resulting in the disruption of protein homeostasis. Maintenance of proteins in their functional native conformations and preventing aggregation of non-native proteins are important for cell survival under stress. The heat shock proteins buffer this environmental variation and are therefore important factors for the maintenance of homeostasis across environmental regimes. Heat shock proteins are known to be expressed in plants experiencing high-temperature stress. Heat shock proteins are important in relation to stress resistance and adaptation to the environment. Their molecular function might be membrane or protein stabilization, but, for now, for most heat shock proteins the molecular function remains to be elucidated. The general observation of the response and induction of heat shock proteins following heat stress suggests that they play a fundamental role in cellular homeostasis. It is possible that heat shock proteins may be involved with the phenomenon of acquired thermotolerance. Heat stress disturbs cellular homeostasis and can lead to severe retardation in growth and development, and even death. Temperature stress can have also a devastating effect on both the plant anabolism and catabolism, initially acting on protein complexes, being the quaternary structure the first folding that is lost during heat stress or heating. Understanding the role of HSPs in relation to stress resistance in a more applied perspective as a potential indicator of stress is important. New technological developments make it possible to investigate the role of genes coding for heat shock proteins in greater detail. A combination of genomics and proteonomics will further elucidate the effects of stress on expression patterns at the DNA, RNA and protein level.

Environmental stress can disrupt cellular structures and impair key physiological functions. Drought, salinity, and low temperature stress impose an osmotic stress that can lead to turgor loss. Membranes may become disorganized, proteins may undergo loss of activity or be denatured, and often excess levels of reactive oxygen species are produced leading to oxidative damage. As a consequence, inhibition of photosynthesis, metabolic dysfunction, and damage of cellular structures contribute to growth perturbances, reduced fertility, and premature senescence. Responses to environmental stresses occur at all levels of organization. Cellular responses to stress include adjustments of the membrane system, modifications of the cell wall architecture, and changes in cell cycle and cell division. In addition, plants alter metabolism in various ways, including production of compatible solutes that are able to stabilize proteins and cellular structures and/or to maintain cell turgor by osmotic adjustment, and redox metabolism to remove excess levels of ROS and re-establish the cellular redox balance. At the molecular level, gene expression is modified upon stress and epigenetic regulation plays an important role in the regulation of gene expression in response to environmental stress.

Plants that are affected by various abiotic stresses react differently as a result such as the reduction in organ size or a change in the antioxidant enzyme system, and while drought and heat are often studied separately, in nature they often occur together, meaning it is essential to carry out joint studies. Furthermore, and related to the above when we consider high temperature stress, one must always consider the use of water and nutrients by the plant and other physiological functions. The effects of heat stress can also be analyzed by the technique that measures lipid peroxidation in polyunsaturated acids of the plasma membrane. The accumulation of metals in plants, affects the normal processes of plant metabolism. The study shows that there is a relationship between high metal contents in plants and their modified morphology: strong reduction of leaf thickness, modified parenchyma structure, and decreased mitochondria organization were ascertained, although toxic symptoms were apparently absent. Water-deficit stress has a significant effect on plants growth and development, with primary affects on plant structure, leaf morphology and cell ultrastructure. Physiological processes such as stomatal conductance, photosynthesis and respiration are consequently impaired with further implications on the metabolic functions such as carbohydrate and energy production as well as carbohydrate translocation and utilization.

Climate change drastically influence water availability, salinity and several adverse soil conditions which will have direct bearing on original yields. Abiotic stress factors influence growth and secondary metabolite production in higher plants. The influences are well marked. In fact, productivities depend on the changed ecosystem also. Secondary metabolites play a major role in the adaptation of plants to the changing environment and in overcoming stress constraints. This flows from the large complexity of chemical types and interactions underlying various functions: structure stabilizing, determined by polymerisation and condensation of phenols and quinones, or by electrostatic interactions of polyamines with negatively charged loci in cell components, photoprotective, related to absorbance of visible light and UV radiation due to the presence of conjugated double bonds, antioxidant and antiradical, governed by the availability of –OH, –NH2, and –SH groupings, as well as aromatic nuclei and unsaturated aliphatic chains, signal transducing. Several plant-abiotic stress stimuli systems evidenced the multiplicity of biochemical mechanisms involved in the protective role of secondary metabolites:

As homogeneity is a basic criterion, it is important to know the solubility of solutes, which is a temperature dependent property. Besides temperature, solubility is influenced by the acidity (pH) of the solvent due to the acid-base character of the solute. Bases tend to dissolve better in acidic solutions, whereas acids do in basic solutions. Therefore, one often needs to change the pH of solutions accordingly. As the most widely used concentration units (molarity, w/v% and v/v%) refer the amount of solute in a given volume of the solution, it is the volume of the complete solution that must be set to the desired (calculated) value thus, one must consider not only the solvent but the solute(s) as well. Another reason why one must add the solute(s) to an amount of solvent which is less than the final volume might be that one will need to set the pH subsequently in order to enhance solubility and/or to reach a desired pH value. The volume of acid or base solutions used for pH setting is usually not known in advance and is not negligible. If the solute was initially dissolved in the final desired volume, one would exceed this volume during pH setting (even if the volume of the solute is negligible) and, thus, the solution would not have the desired (calculated) concentration but a smaller (and mostly unknown) one. Thus, according to the correct procedure, one must take into consideration the fact that the final volume will contain the volume of the buffering component. value particularly in the case of dissolving proteins, which have a tendency to stick to the bottom of the dish, thereby making dissolution substantially slower.

Units/measures are used to specify quantities. Every unit has a well-defined standard basic value, which is used as a reference in measurements. The units used in scientific practice constitute a scientifically established system, SI (Système International). Although only SI units are official , numerous non-SI units are still widely used (calorie, Ångström, Celsius etc.). We distinguish two types of quantities with two corresponding types of SI units. The base quantities cannot be derived from other quantities. Many of these are used in biochemistry (names of units and their symbols are given in brackets) to quantify the mass (gram, g), the length (meter, m), the time (second, s), the temperature (kelvin, K) and the charge (coulomb, C). Much larger is the group of derived quantities. Of these, the various units of concentration (to characterise the abundance of materials in solutions and other mixtures), volume and energy are the ones most frequently used in biochemistry. It is important to note that the terms mass and weight are often used interchangeably as alternatives. Technically, however, they have different meanings. The mass is the total quantity of matter in an object, which comes from the mass of all of its protons and neutrons, although not simply additively. Weight is a measure of the gravitational force exerted on an object. As the mass of protons and neutrons is the unit mass, their total mass in an object (e.g. the mass of a molecule, the molar mass) is a unitless number (e.g. the molar mass of water is 18). In other words, the molar mass is a relative number that would reflect the number of protons and neutrons in an atom or molecule, if the masses of protons and neutrons were additive. We make mass measurable by expressing it in grams because this way we can handle it as weight and measure it with a balance, the device developed for this purpose. 

Acids are chemical substances that are sour in taste and highly corrosive. The term ‘Acid’ was derived from a Latin word ‘acidus’, meaning ‘sour’. They emit sharp odour and transform litmus colour from blue to red. They lose their properties when alkalis are added to them. However, in this process, alkalis also lose their alkaline properties.

Introduction

It is an established fact that water in terms of direct deficit (drought) as well as water surfeits (flooding and water logging) and poor irrigation water quality (salinity)- are major constraints on the use of solar energy for food, feed and fiber production in almost all the agricultural regions of the world. The various biophysical, physiological, genetic, agronomic and ecological aspects of plant water relations have been thoroughly reviewed in recent years with the objective aimed at water availability as a constraint on crop production. This review will attempt a limited synthesis of these aspects, drawing mainly from research on drought resistance in grain crops, rice in particular, and emphasizing the progress- theoretical and practical- that could result from collaboration between physiologists, geneticists and plant breeders. A central theme will be research and development aimed at fitting crop plants to fluctuating drought prone environments. It is noteworthy that shortage of water restricts crop productivity all over the world-not just in those areas classified as arid or semiarid, but in any area in which the evaporative demand exceeds rainfall during the growing season. As such, the interaction between genotype and environment in situations has an important bearing affecting the physiology and also biochemistry at cellular level vis-à-vis the crop phenology. Cultivars with better ability to access soil water and improved water use efficiency could increase yields in an economic and environmentally sustainable way.