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.

Gerbera ranks among the leading cut flowers globally and is especially important under protected cultivation in India. This chapter covers its origin, distribution, genetics, botanical characteristics and commercially important varieties. It explains greenhouse requirements, climate, light, soil, growing media, propagation, planting density, irrigation, fertigation and crop management. Important pests and diseases, physiological problems, harvesting, grading, postharvest treatment and yield are discussed in relation to commercial quality. The chapter highlights Gerbera's suitability for progressive farmers and its production in Maharashtra, Karnataka, Tamil Nadu and other Indian regions.

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.

Climate change is altering insect-pest development, reproduction, feeding, survival, distribution, host preference and interactions with natural enemies. These shifts may make conventional control measures and existing integrated pest-management programmes less reliable. Climate-resilient IPM must therefore combine continuous pest surveillance, forecasting, biological control, resistant cultivars, cultural practices, habitat management and the careful use of pesticides. Management decisions should account for changing pest phenology, emerging invasive species and regional climate risks. This chapter examines how climate change affects established IPM components and proposes adaptive, knowledge-based approaches for sustainable pest suppression, reduced pesticide dependence, ecosystem protection and long-term food security.

Metabolites are small molecules generated or utilized during cellular metabolism and include amino acids, carbohydrates, lipids, organic acids, nucleotides, vitamins, hormones, and secondary metabolites. This chapter introduces the major classes of metabolites and their biological significance. It explains metabolic architecture as the organization and interaction of interconnected biochemical pathways that regulate cellular energy production, biosynthesis, degradation, signaling, and adaptation. The chapter describes primary and secondary metabolites and examines central metabolic pathways and their interrelationships. Understanding metabolic architecture provides the foundation for interpreting metabolomic profiles and identifying changes associated with physiological conditions, environmental stresses, disease processes, and alterations in cellular metabolic regulation.

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.