Preface   Plants encounter a wide range of environmental insults during a typical life cycle and have evolved mechanisms by which to increase their tolerance of these through both physical adaptations, biochemical changes molecular and cellular changes that begin after the onset of stress. Environmental rudeness faces by the plants in the form of abiotic and biotic stress that seriously reduces their production and productivity. Approximately 70% of crops could have been lost due to both abiotic and biotic factors. Variety of distinct abiotic stresses, such as availability of water (drought, flooding), extreme temperature (chilling, freezing, heat), salinity, heavy metals (ion toxicity), photon irradiance (UV-B), nutrients availability, and soil structure  are the most important features of and has a huge impact on growth and development and it is responsible for severe losses in the field and the biotic stress is an additional challenge inducing a negative pressure on plants and adding to the damage through herbivore attack or pathogen. Multiple stress exposure gives a possible outcome that Plant system develops tolerance to one environmental stress may affects the tolerance to another stress, for example, after exposure of plants to abiotic stress leading to enhanced biotic stress tolerance, wounding increases salt tolerance in tomato plants.  In tomato plants, localized infection by Pseudomonas syringae pv. tomato (Pst) induces systemic resistance to the herbivore insect Helicoverpa zea.

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.

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).

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.

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).

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).

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. 

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).

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.

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). 

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).

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.