eChapters

1. Introduction

Organic farming is gaining a lot of importance in recent years owing to raising awareness among the consumers of the agricultural commodities about the health concerns of the indiscriminate use of chemical fertilizers and pesticides (Anonymous 2015; Lakhsman et al., 2024). The increasing demand for organically produced agricultural commodities and the premier prices have attracted the farmers’ interest and motivated them to switch over to organic production systems. The shifting to organic farming by the farmers needs careful consideration of several issues starting from the suitability of soils, selection of crops, adoption of package of practices, processing, storage and marketing. There are several finer aspects which the farmers have to gloss over before they decide to change their production system to organic farming. Although the broad contours are known to all the farmers, there is a need to look into the research findings in the areas of farmers’ interest for changing over to organic farming. The research evidence on the practical viability in a newer area will boost the confidence of the farming community for undertaking the organic farming. It further helps in systematic planning by the policy makers. The traditional research carried out with the modern agricultural practices may not be appropriate for organic farming. There are fundamental differences in the approaches followed in the organic farming research where the emphasis is on using all the natural resources in a complementary way so that there is hardly any need for synthetic inputs in the form of fertilizers and pesticides. It calls for systematic inventorization of resources available and additional organic inputs needed to make organic farming successful. It begins with assessing the suitability of soils, agro-climatic conditions, selection of crops, adoption of management practices, harvesting, processing, storage and marketing of organically-produced food commodities. The practical feasibility, economic viability and social acceptability of organic farming in newer areas need to be established through sound organic farming research before it is taken to the farming community.

Organic food sales increased steadily from the late 20th century. Greater environmental awareness, coupled with concerns over the health impacts of pesticide residues and consumption of genetically modified (GMO) crops, fostered the growth of the organic sector. Realizing the benefits of organic food, especially after COVID-19, consumers are also demanding organically grown food and fiber and are willing to pay premium price. But to tap the market, there is an inevitable need for certification. Recently launched Food Safety and Standards (Organic Food) Regulation, 2017 mandates that all food products sold as organic must be certified and comply the basic requirements of the Act. The organic food offered or promoted for sale shall also comply with all the applicable provisions of either National Programme for Organic Production (NPOP) or Participatory Guarantee System for India (PGS India). Organic certification is a process certification. The requirement to confirm that the product is organic include labelling on the package and traceability for both domestic and export needs to be understood. For import and export of organic produce, transaction certificate issued by an Accredited Certification Body is required. These requirements are essential for fresh and processed food items. In this chapter, we tried to eloborate the process and procedures for organic certification.

Agricultural sector, with the technological advancements, is also contributing to global climate change, loss of biodiversity and degradation of resources. Further, there is a serious global concern about chemical residues, healthy food and healthy planet earth. Organic and natural farming are acclaimed to be the best alternative non-chemical production pathways to reverse the ill effects of modern agriculture. However, these systems are not contemplated to meet the food security and other requirements of ever-growing human population, particularly in developing countries. In this chapter, based on the available and documented protocols and production practices of these systems, the additional research, extension and policy needs to strengthen these production pathways to attain economic, ecological and social sustainability are discussed while considering the Sustainable Developmental Goals (SDGs) of United Nations.

1. Introduction

In India, though organic crop production and certification system is reasonably well established in India, the organic livestock and poultry sector is in its budding stage. Organizations such as APEDA, FSSAI and BIS along with research establishments like ICAR- National Meat Research Institute are now putting serious efforts to establish the protocols and promote organic livestock production and certification in India. As a result, in the last few years, livestock farmers are gradually getting encouraged to take up organic production and around 3000 farmers mostly from Uttar Pradesh, Madhya Pradesh and Himachal Pradesh have taken up organic dairy, sheep and poultry farming. Export of organic milk and ghee from India to different countries has just begun and is expected to grow very fast in volumes and revenues in the years to come.

The unsustainable, faulty, environmentally detrimental modern agricultural practices and their plausible deleterious effects on one side and challenges like global climate change, ever shrinking land and water resources and loss of biodiversity on the other hand are the main problems that Agriculture is facing. Hence, there is a need to adopt a set of ecofriendly and climate smart practices to achieve sustainable development goals (SDGs). Agroforestry and organic farming (farming without chemicals) are the two important concepts projected to mitigate the effects of climate change, enhance soil health, encourage crop diversification, promoting biodiversity and achieving climate resilience. We made an attempt to synthesize the available information on the role of agroforestry in promotion of organic farming.

1. Introduction

Agroforestry is a land use system that integrates trees, crops and animals in a way that is scientifically sound, ecologically desirable, practically feasible and socially acceptable to the farmers (Nair, 1979). It is a collective name for land use systems and technologies, where woody perennials (trees, shrubs, palms, bamboos, etc.) are deliberately used on the same piece of land management units as agriculture crops and/or animals in some form of spatial arrangement or temporal sequence. It includes both ecological and economical interactions among the different components. Nearly 43% of world’s agricultural land has at least 10% tree cover, which suggests that agroforestry is widespread and infact, it is present in all continents. Agroforestry accounts for nearly 45.4 m-ha globally and 23.25 m-ha of land in India (Rizvi et al., 2019; Anonymous, 2020).

Organic farming in groundnut cultivation is gaining global recognition as an environmentally sustainable and socially responsible approach. Groundnut is a versatile crop with high nutritional value and economic importance. This chapter explores the principles and practices involved in organic groundnut farming. It focussed on soil management, organic fertilization, pest, disease and weed management without using synthetic chemicals. This approach minimizes impact on the environment and reduces the presence of pesticide residues in the final produce. Moreover, organic practices help maintain soil health, conserve biodiversity and reduce environmental pollution. Thus, farmers can produce high quality groundnuts and fetch higher price and profits.

1. Introduction

The groundnut (Arachis hypogaea L.) is known by different names such as monkey nut, goober, earth nut etc., and belongs to leguminosae family. It produces flowers above ground but the fruits/pods underground (Sanders, 2003). It can be grown successfully in tropical and sub-tropical regions of the world. Globally, groundnut covers 32.7 M ha with a production of 53.9 MT with a productivity of 1648 kg ha-1 (FAOSTAT, 2021). Among the developing countries, Egypt has the highest productivity of groundnut with 2.70 t ha-1 (Nautiyal, 2001). Globally, India ranks first in groundnut area (5.42 m-ha) and is the second largest producer in the world with 10.1 MT with a productivity of 1863 ha-1 in 2021-22 (agricoop.nic.in). India ranks second next to China (34%) with 19% of world groundnut production in 2021. Gujarat is the largest producer contributing 36% of the total production of groundnut followed by Rajasthan (17%) and Tamil Nadu (7.5%). Groundnut accounts for 18% area and 26.8% production of the total oilseeds in India (CARP, 2022).

Globally, organic oilseeds constitute an important element in organic production. Their products are important feedstuffs (oilcake) and also relevant for human consumption (soya products, oils), and demand for these is continually growing. Almost half of the global organic oilseed area is occupied by soybeans, and another almost 20% is for sunflower seeds and sesame. Rape and turnip rape constitute about 6% of the organic oilseed area. Oilseeds are of pivotal significance in the Indian agricultural economy supporting income of millions of farmers practicing mainly rainfed cultivation. Nine annual oilseed crops are cultivated in India that includes groundnut, rapeseed-mustard, soybean, sunflower, sesame, niger and safflower that are edible and non-edible oilseed crops include castor and linseed. Organic agriculture is one among the broad spectrum of production methods that are supportive of the environment. The principal method of organic farming includes crop rotation, green manures and composts, biological pest control and reduced tillage. The performance of annual edible oilseed crops and development of package in relation to organic management for sustainable agriculture are discussed in this chapter.

1. Introduction

In India, both annual and perennial edible oilseed crops are cultivated. Annual edible oilseed crops include groundnut, rapeseed-mustard, soybean, sunflower, sesame, niger and safflower. India, the 4th largest vegetable oil economy in the world, stands first in the production of castor, sesame, safflower, and niger oils, whereas second in groundnut, third in rapeseed mustard, fourth in linseed and fifth in soybean oil. About 14 million farmers are engaged in oilseeds production and another million in their processing. Whereas, the perennial edible oil seed crops include oil palm and coconut. Edible oils are also produced domestically from secondary sources such as rice bran, cotton seed, corn, and other tree-borne oilseeds (TBOs), besides some minor oil producing species of forest origin.

Since many years, there has been an extensive use of synthetic pesticides against which has caused pest resistance, resurgence, residues environmental problems and toxicity to non-target organisms. Therefore, attention is given towards the alternate methods which are ecologically, economically sustainable. Botanical pesticides that control insects by using plant oils and extracts have proven to be the most effective. As they have promising role in organic farming, they help in reduction of pest load and improve crop quality and thereby increase crop yield without disturbing the environment and helps in maintaining the balance of natural ecosystems. This book chapter, discuss about the active functional ingredients of each botanical pesticide and mode of action, its importance in organic farming, their commercial formulations, major insect pests suppressed or controlled, their challenges in usage in agriculture and horticulture and its future prospects.

1. Introduction

Synthetic pesticide use has caused pest resistance, environmental problems and toxicity to non-target organisms. It is essential to follow alternate methods because these synthetic pesticides have led to acute and chronic poisoning in farm workers, applicators, and even customers. Employing botanical pesticides, is the most effective way to replace the widespread use of synthetic pesticides, is one of the important alternative strategies. Among them, plant-based bio pesticides that control insects by using plant oils and extracts have proven to be the most effective. Botanicals being natural and non-toxic to humans, animals, and the environment, have a significant role in organic farming as they help in promoting plant growth, controlling pests and diseases, and enhancing soil health. The use of botanicals is an essential component of organic farming as it helps in maintaining the balance of natural ecosystems, improves crop quality, and increases yield without the negative impacts of synthetic chemicals. As the use of synthetic pesticides and fertilizers is prohibited in organic agriculture. Organic farmers rely on natural methods to protect their crops from pests, diseases, and weeds. The beneficial insects, crop rotation, and natural remedies such as neem oil or garlic sprays are used to protect the crops. The use of natural methods to manage pests and diseases promotes biodiversity, maintains soil health, and minimizes the environmental impact of farming. Thus, plant protection is crucial in organic farming to ensure sustainable and responsible agriculture practices.

The concept of insect pest management and the strategies employed have evolved over the time. With the increased emphasis on safe agricultural practices and elevated demand for safe and healthy food, the various solutions for pest management have shifted more towards use of biocontrol agents. Bio- rational pest management methods have now evolved as important pillar of the integrated pest management to replace the synthetic insecticides and also other associated advantages. They include the use of botanical pesticides, insect growth regulators, pheromones and allelochemicals. The major positive attributes associated with all of them are their low mammalian toxicity, safety to beneficial and non-target organisms, higher specificity, low risk of development of resistance and low environmental persistence. Though bio-rational insecticides are considered to be safe, in an organic ecosystem, it should be done with caution because over reliance on them for longer periods may facilitate the target insect pests to develop some kind of resistance against them. So, proper deliberations on the positive and negative attributes of bio rational pest management strategies should be done so as to facilitate their long term usage in organic farming.

Trichoderma is fungus is well adapted to different ecosystem and identified > 250 species for agricultural use. It is primarily used as a bio-fungicide because of the variety of secondary metabolites produced and applied mainly for biocontrol and bioremediation and growth promotion activities. Bio-control potential of Trichoderma used for the control of soil borne diseases through various mechanisms responsible for broad range of cell wall degrading enzymes, anti-microbial and organic volatile compounds produced by Trichoderma. During abiotic stress, Trichoderma play an important role in plant growth promotion through mobilization of various nutrients. Presently Trichoderma is used as an effective biocontrol agent against plant parasitic nematodes. It is also used for one of the alternate remedy for improving the quality of the soil by removing the heavy metal in agricultural field, makes them suitable for cultivation.

1. Introduction

Trichoderma is one of the genus of fungus species which belongs to Ascomycetes (Order Hypocreales) present in diverse soil ecosystems, colonise under various agro ecological niches and most of the prevalent are culturable microorganism. They are primarily used as efficient biocontrol agents against a variety of soil-borne plant diseases. However, they have also shown potential in processes like bioremediation, promoting plant growth, and managing nematode populations.

Insect pests are responsible for 10.8% of crop losses on an average. Their management is crucial in agriculture to protect crops and boost output. In organic farming systems, preventative measures are taken more often than curative. Understanding the impacts that the local climate, topography, soils, and all other facets of the production system are expected to have on crop performance and potential host/pest complexes is essential for developing successful organic crop protection techniques. Crop rotation, soil health management, host plant resistance, field location, monitoring pests and their natural enemies, vegetation management to enhance natural enemies and exert direct effects on pest populations, releases of bio-control agents and use of approved insecticides of biological origin are highlighted in organic farming in order to reduce pest damage. The safe and environmentally friendly methods for managing the pests in organic farming are discussed in this chapter.

1. Introduction

The fundamental tenet of organic pest management is the use of environmentally sound measures as outlined by worldwide and national organic agricultural standards. The emphasis of organic farming's pest management strategies is on the employment of numerous and diverse strategies integrated into the cropping system, which ultimately lowers the pest incidence. Pest and disease options mainly dependent on preventive measures in organic farming rather than curative and maintaining healthy ecosystems is priority. The farmer should have a better grasp of the pests and beneficial organisms that exist in the specific crop ecology when practising organic farming. The farmers must follow a monitoring mechanism in which they may able to act on the pest before they reach devastating levels.

Crop residues are valuable natural resources that may be managed to maximize various input use efficiencies. These are a great source of organic materials for improving the soil structure, water holding capacity, the soil's ability to withstand pH variations, increasing the cation exchange capacity, reducing the phosphate fixation, as a storehouse for micronutrients and secondary nutrients especially in organic farming. Organic matter serves as a source of energy for soil fauna and microbes, which are the main agents controlling the decomposition and release of mineral nutrients in organic soil ecosystems. Crop leftovers are frequently burned by farmers, especially after harvest, which depletes the soil's nutrient content and microbial population and produces greenhouse gases. Each year, a sizable amount of crop residue is produced and if used efficiently, they may provide partial or full amount of the nutrient budget required under organic farming for the production of annual or perennial crops besides achieving resource conservation and environmental sustainability.

1. Introduction

Crop residues are the non-economic plant parts like straws, stubble, stover etc., that remain in the field after harvesting the economic product. Crop remains from threshing sheds such as groundnut shells, oil cakes, rice husks, corn and sorghum cobs or discarded during crop processing can also be utilized in organic farming. India produces 108.75 MT of wheat, 121.46 MT of rice seed, 30.24 MT of maize seeds, 49.66 MT of millets seeds (jowar, bajra, ragi, and small seed millets), 392.8 MT of sugarcane, 46.11 million bales of fibre crops (jute, mesta, cotton), 25.58 MT of pulses and 36.57 MT of oilseed (Agricultural statistics at a glance, 2021).

Organic liquid formulations (OLFs) are agricultural inputs derived from natural sources, designed for use in organic farming. These formulations, consisting of liquid solutions or suspensions containing organic compounds, nutrients, and beneficial microorganisms, play a crucial role in enhancing soil fertility, plant nutrition, and pest management, while promoting environmental sustainability and ecosystem health. Despite their eco friendly nature, OLFs demand careful consideration for their environmental impact and safety. They biodegrade readily, reducing long-term persistence and are less harmful to non-target organisms. While OLFs offer numerous benefits, they also face limitations in potency and effectiveness compared to synthetic pesticides, often requiring more frequent applications and leading to increased labor costs. Their impact can vary with pest species and environmental conditions, and they generally provide gradual rather than immediate pest control. Availability and accessibility can be limited, posing challenges for some farmers. This chapter explores the role of OLFs in achieving success in organic farming, highlighting their benefits and limitations, and emphasizing the importance of Integrated Pest Management strategies and careful consideration of various factors to optimize their use in promoting sustainable agriculture.

Increased awareness of the importance of quality and nutrient-rich food among the majority of the population created a need for the development of organic production systems and suitable varieties/hybrids for cultivation. The quality of soil, water and air is affected by the overuse of agrochemicals in agriculture. The use of organic varieties helps in reducing the use of various agrochemicals and high-quality pesticides. Organic varieties can address environmental issues and climate change. The world organic seed market is valued at USD 4.2 Bn in 2022 and it is expected to grow at an annual rate of around 8.7% between 2022 and 2031. The demand for organic seeds in the market has created new opportunities for organic farmers. By following standard organic crop production practices and seed certification guidelines, they can produce quality organic seed or planting material on their own farm.

1. Introduction

Worldwide, organic agriculture is a rapidly growing sector. The demand for organic food markets is increasing recently with the fast-growing movement of community support for organic agriculture. A total of 96.4 m-ha were grown organically with 2% of the worldwide agricultural land. The region with the most organic agricultural land is Oceania (53.2 m-ha) followed by Europe (18.5 m-ha), Latin America (9.5 m-ha) Asia (8.8 m-ha), North America (3.6 m-ha) and Africa (2.7 m-ha). Australia stands first in area with 53.0 m-ha followed by India (4.7 m-ha) and Argentina (4.1 m-ha) (FiBL & IFOAM, 2024). The global organic farming market will grow from $169.04 billion in 2022 to $287.83 billion in 2027 at a Compound Annual Growth Rate (CAGR) of 11.3% (Organic Farming Global Market Report, 2023).

All hybrids and varieties perform better under conventional farming in response to excess use of chemical fertilizers and pesticides, which are harmful to humans, animals and environment. Hence, there is a need to develop varieties/hybrids exclusively for organic farming. Breeding aspects of organic farming include breeding tools/methods which are used to breed varieties/hybrids including testing and multiplication under organic conditions duly following the principles of organic farming as defined by IFOAM. These cultivars should have high nutrient use efficiency, resistance to diseases and pests, competitive ability against weeds, higher yield and stability across environments along with enhanced nutritional quality. This book chapter briefly discusses the aspects of breeding that are involved in generating cultivars suitable for organic farming.

1. Introduction

Currently, organic farmers rely heavily on conventionally developed and produced varieties. Nevertheless, in order to optimize their production under organic agriculture, it is necessary to develop cultivars that are more suitable for organic cultivation. According to some studies, the naturalness of organic agriculture should go beyond simply by avoiding chemical inputs and substituting natural and organic components during the transition from conventional to organic farming.

Organic farming necessitates a shift from conventional to non-chemical agricultural methods and practices. For this, it needs creation of facilities for the production of organic inputs, adoption of crop rotation, green manuring and other best management practices for the organic production of crops and livestock. Further, the ‘towards organic approach’ in intensive agricultural areas and ‘scientific organic farming’ in niche areas have to be implemented for development of an organic farm. The synthesized information on how to convert an inorganic farm into an organic farm followed by its sustainable maintenance is the need of the hour. This chapter holistically deals with designing and maintaing the whole ecosystem organic.

1. Introduction

Nowadays, the growers, policymakers and consumers are talking about organic farming (OF) across the globe. For practitioners, it is still a confusion regarding what and how to practice OF. There is a wrong notion that simple addition of organic manures and the use of chemical pesticides for growing different crops is considered as organic farming. In sense real, organic farms are the cultivated fields without addition of chemical fertilizers, pesticides, livestock additives, etc., and only organic and (or) non-chemical methods are practiced, and the concept or practice is known as organic farming. A large number of farms have been converted from conventional into chemical farms during the last more than 50 years by using synthetic chemicals. In view of the increasing demand for organic products and spiraling soil and human health problems, there is need to transform them gradually into organic farms. So that, it can help enhance soil organic carbon status and fertility which in turn can support crop growth and produce healthy foods besides protecting the environment. However, the extent of chemical used might be varying from one farm to another depending on the crops cultivated, nutrient requirement, pest/ disease severity, availability and accessibility to chemical use, socio-economic condition of the farmers, geographical location, etc.

The onion, or Allium cepa var. cepa L., 2n=16, is one of the most important vegetables that are grown and eaten globally (Kiani et al., 2023). It is referred to as the 'queen of the kitchen' because of its wide range of culinary applications (Selvaraj, 1976). It can be eaten raw or prepared in a variety of ways, including as pickles, soups, frying, boiling, and baking (Cattivelli et al., 2021). Apart from being consumed raw, onions also provide excellent raw materials for the processing sector. They can be processed into onion pastes, dehydrated powder, flakes, rings, shreds, and onions in vinegar or brine (Gnanasundari et al., 2023). Additionally, it possesses several health promoting factors such as antihyperlipidemic, anti-diabetic, anti-hypertensive, anti-microbial, immune-protective, anti-obesity properties, and rich in several minerals and vitamins (Pareek et al., 2017). Medicinal value of onion has been known since antiquity; the third or fourth century A.D.'s "Charak Samhita" is one of the medical treatises that mentions it (Ray et al., 1980). Allicin, ajoene, allixin thiosulfinates, sulphites, and other significant biochemical components are found in onion, giving them considerable use and nutraceutical value.

Dolichos bean, [Lablab purpureus (L.) Sweet] var. typicus (2n=22) also known as Indian bean or sem is one of the vital leguminous vegetables grown in India for its tender green pods. Both pole types and bush types are commercially grown. It is predominantly cultivated in Maharashtra, Tamil Nadu, Andhra Pradesh, Uttar Pradesh and North-East India. Protein, minerals, vitamins and f ibers are abundant in Dolichos bean. Bush-type vegetable dolichos unlike the pole-type dolichos (which are generally grown during the winter season as they require short day) are thermosensitive and can be grown year-round.

Dolichos is a versatile and valuable leguminous crop, offering multiple benefits. It boasts a high protein content of 3.6% and fiber content of 1.8%. The dry seed is composed of a protein content ranging from 23.0% to 28.0%. The pods are abundant in phenols, with levels ranging from 1.7 to 9.67 mg/100 g, making them a valuable source of antioxidants. Furthermore, dolichos serves as an excellent source of amino acids, particularly lysine, along with vitamins such as A, C, and riboflavin, and essential minerals (Ca, Fe, Mg, S, Na and P). The seeds of dolichos contain a flavonoid, kievitone, recognized for its potential in combating breast cancer. Additionally, the presence of tyrosinase in the seeds indicates promising possibilities for treating hypertension in humans. Dolichos beans are utilized for various medicinal purposes, acting as stomachic, anthelmintic, diuretic, aphrodisiac, antispasmodic, digestive, febrifuge, and carminative agents. Furthermore, they are rich in bioactive compounds that offer significant benefits in treating specific ailments such as liver problems, diabetes and tumors.

French bean (Phaseolus vulgaris L.) is a nutritious protein-rich legume vegetable crop cultivated in all parts of the world except Antarctica. Immature pods are consumed as vegetables, and matured pods are used as grain legumes (Allem, 2013). French bean is cultivated in 1.65 million hectares of area with a production of 26.98 million tonnes and productivity of 16.36 tonnes per hectare for vegetable purposes. As a grain legume, French bean was cultivated in 33.02 million hectares with a production of 28.90 million tonnes and productivity of 874.1 kg/ha during 2019 globally. In India, French bean is grown in 2.56 lakh hectares for vegetable purposes and 126.91 lakh hectares for grain legume purposes with a production of 7.26 lakh tonnes as immature pods and 53.10 lakh tonnes of grain legumes with a productivity of 2.83 t/ha of green pods and 418.4 kg/ha as grain legumes (area, production and productivity of livestock, Food and Agriculture Organization of United Nations, 2020). However, the area, production and productivity statistics of beans in FAO statistics may also include other beans such as mung bean and others (Sharma et al., 2013). French bean is also known by other names such as common bean, kidney bean, dwarf bean, haricot bean, string bean and garden bean. In India, French bean is also known by different names as Frash bean and Rajmah in Hindi, Shravanghevada in Marathi, Thingalaware in Kannada and Fras bean in Punjab.

Cucumber, both slicing and pickling types, is one of the most popular vegetable crops of the family Cucurbitaceae. Like other cucurbitaceous crops, the cucumber also requires a warm season for commercial cultivation and has little or no tolerance to frost. Temperatures above 20°C are optimal for cucumber growth and development. Currently, its cultivars are generally classified as either pickling or slicing types, each with its own set of quality attributes. Pickling types typically have more prominent warts (tubercles) and lighter-coloured skin. They are harvested more frequently at the immature stage, when their length and diameter (LD) ratios are lower. The LD ratio for pickles typically falls within the range of 2.8 to 3.2. On the other hand, slicing cucumbers are harvested and commonly sold in lengths ranging from 12 to 25 cm, with diameters ranging from 1.5 to nearly 7.5 cm. Most slicing cucumbers have cylindrical-shaped fruit with blocky or slightly rounded ends that taper slightly from the stem to the blossom end. Generally, slicers have an LD ratio greater than 4.0, a smooth surface, and thicker skin compared to pickling types. This difference is accentuated because slicers are harvested at later stages of maturity than pickling cucumbers.

Melons are annual plants that have up to three meters of climbing, creeping, or trailing vines. Several of them are consumed as dessert fruits while a few varieties/types are used for vegetable purposes. Generally, the fruits of commercial varieties are sweet, juicy, delicious with good nutritional and medicinal properties and a daily intake of 120-150 g can help in weight loss, better eye and skin health (Shivapriya et al., 2021).

Currently, muskmelon is being cultivated throughout the world, especially under tropical and subtropical climatic conditions. In India, muskmelon is grown in 54,000 ha with a production of 1.23 million tons (NHB, 2018). The estimated national seed requirement per year is about 27 tons with a value of about Rs. 27 crores. The crop is cultivated mainly in rabi season (November to February sowings), thus limiting its availability in the market during summer. Rarely, melons are cultivated for the off-season market, and those fetch a premium price. The total value of muskmelon fruits in the domestic market is estimated as Rs.1231 crores.

Watermelon (Citrullus lanatus (Thunb.) Matsum and Nakai) is an important cucurbit crop throughout the tropical and subtropical regions of the globe. It is an annual creeping vine and native to the Southern part of Africa, most probably the areas around the Kalahari Desert. Presently, more than 1200 cultivars have been developed and are being grown in nearly 122 countries with tropical and subtropical climates. Watermelon is mainly valued for its ripe ‘pepo’ fruits which are consumed as fresh-cut dessert or as juice. The fruits are a rich source of carotenoids, minerals, phenolic compounds, flavonoids, vitamin C and Citrulline, a non-essential amino acid. The red colour of the watermelon flesh is due to the presence of lycopene, the content of which is 40% more than that of tomato. Besides, there is good variation available for f lesh colour ranging from red, pink, yellow, orange, white and green. Owing to the ability to prevent several chronic diseases due to the presence of pigments like lycopene, anthocyanin, carotene, xanthophyll etc., presently watermelon is also considered as a functional food. The exocarp (rind) is also consumed as stewed, pickled or stir-fried or may be used for the preparation of ‘tooty fruity’. Watermelon seeds are considered a good omen and are gifted during Chinese New Year in East Asia. The seeds are also used in the baking and confectionary industries as these contain a characteristic nutty flavour. The seeds are also rich in protein, vitamins as well as omega-3 and omega-6 fatty acids.

Pumpkin (2n = 40) is an important ‘pepo’ vegetable of the Cucurbitaceae family. Five domesticated species viz., C. maxima, C. moschata, C. pepo, C. argyrosperma and C. ficifolia are included in the Cucurbita genera (Schaffer and Paris, 2003). Owing to the presence of maximum genetic diversity in the neotropical regions and its ability to grow in varied agro-ecological conditions and its tolerance to hotter climatic conditions as compared to the other cultivated Cucurbita species, C. moschata is known as “tropical pumpkin” (Andres 2004). In terms of the average nutritive values, pumpkin (2.8) stands at a higher position when compared to many widely grown vegetables. The fruits are rich in carotenoid pigments. However, the proportion of beta carotene is higher than the others. Beta carotene shows strong anti oxidative and anti-cancer properties. While, it has relatively low content of other carotenoids like alpha-carotene, lutein, zeaxantin and violaxantin (Matus et al., 1993; Fraser and Bramley, 2004). Moreover, pumpkin fruits are also rich in mineral elements viz., potassium, phosphorus, magnesium, iron and selenium. The mature pumpkin seeds contain the essential unsaturated fatty acids and minerals like zinc. Pumpkin-rich diet has also shown to have a pharmacological effect on reducing blood glucose (Xiong and Cao, 2001; Cai et al. 2003). Further, water-extracted pumpkin polysaccharides showed better hypoglycemic (Zhang and Yao, 2002). As a result, pumpkin has emerged as a staple food in many developing countries (Ferriol and Pico, 2008).

Ridge or ribbed gourd (Luffa acutangula (Roxb.)L.) is grown commercially and in homesteads for its immature fruits which are used as cooked vegetable. It is a popular vegetable both as spring-summer and rainy season crops. It is grown in tropical and subtropical countries, especially in Asia and India as an important cucurbitaceous vegetable crop (Jansen et al., 1993). The immature fruit is a rich source of dietary fiber and minerals (Sheshadri, 1990). Apart from culinary properties, it has vast medicinal properties which are traditionally used for the curing of stomach ailments and fever (Burkill, 1985; Chakravarty, 1990). The genus derives its name from the byproduct 'loofah', which is used in bathing sponges, doormats, scrubber pads, mattresses, pillows and in cleaning utensils. The tender fruits are prescribed for people suffering from malaria and other seasonal fevers because it is easy to digest and act as an appetizer. Ridge gourd contains 0.5g protein, 3.4g carbohydrates, 37mg carotene and 18mg vitamin C per 100g of edible portion. Some round varieties of ridge gourd are also used for stuffing purposes.

Ridge gourd is originated from India and is grown throughout the country by many of the small and marginal farmers for their regular income. Uttar Pradesh, Madhya Pradesh, Punjab, Chhattisgarh, Bihar, West Bengal, Maharashtra and all southern states like Andhra Pradesh, Telangana, Karnataka, Kerala and Tamil Nadu are the major states in India where ridge gourd is cultivated. It is grown in an area of 1.00 lakh ha in India with a productivity of about 10 12 t/ha which is very low.

Bitter gourd (Momordica charantia L.) is one of the important commercial cucurbitaceous cash crops grown mainly by small holding farmers in Asia where it is cultivated on more than 340,000 ha annually (McCreight et al., 2013). Eastern Asia, possibly Eastern India, or Southern China is most likely the center of origin for bitter gourd (Walters and Decker-Walters 1988; Miniraj et al., 1993). It is also known as bitter melon, bitter cucumber, balsam pear, bitter apple, or bitter squash (Morton, 1967). Fruits are known for abundant source of vitamins and minerals. Delicious preparations are made from fruits after stuffing and frying. It is also consumed in the form of Juice, Tea and Pills. Bitter gourd fruit abounds in phytonutrients (Dhillon et al., 2017) and often used to manage type 2 diabetes as a folk medicine. Clinical studies confirmed that elevated fasting glucose levels in pre-diabetics can be reduced by supplementing the diet with bitter gourd fruits. (Amirthaveni et al., 2018; Krawinkel et al., 2018). Medicinal properties present in the bitter gourd fruits are used in the curing of diabetes, asthma, blood diseases and rheumatism.

The current seed market of bitter gourd in Asia values ≈ 16 million Euros. The bitter gourd seed market in India alone is 400 metric tonnes having value of 350-400 crores. 70 % area is under hybrids and 30 % is covered by open pollinated varieties.

Okra [(Abelmoschus esculentus (L.) Moench] is one of the traditional vegetable crop cultivated in tropical, subtropical and warmer regions of the world. Okra fruits are rich in calcium (90 mg/100 g fresh weight) and provide valuable supplementary items in the tropical diet which is starchy in nature lacking calcium and iron. The root and stem are used for clearing cane juice in preparation of jaggery or ‘gur’. The high iodine content of fruits helps prevent goiter, while leaves are used in inflammation and dysentery. It has yet multiple uses. The dry seed contains 13-22 % good edible oil and 20-24 % protein. The oil is used in soap, cosmetic industry and as vanaspati, while protein is used for fortified feed preparations. The crushed seed is fed to cattle for increasing the milk production and the fibre is utilized in jute, textile and paper industries. India ranks first in the world with 7.16 million tonnes of production 5.49 lakh hectares of area. Gujarat is the leading okra-producing state which produces around 1147.66 thousand tonnes from an area of 93.95 thousand hectares followed by West Bengal. Fresh fruit of okra is exported to UAE, Sri Lanka, the Netherlands, Bangladesh, Malaysia, Nepal, UK, Saudi Arabia and Qatar. The national average productivity is very low (11.70 t/ha), that the crop is prone to damage by major biotic stresses like fungus, nematodes and viruses like Yellow Vein Mosaic Virus and Enation Leaf Curl Virus. The yield potential of okra is low; however, it could be improved through hybridization. Marked heterosis has been reported in okra for yield and its components.

Chilli (Capsicum annuum L.) and bell pepper (Capsicum annuum var. grossum) are economically significant crops in India, known for their distinct attributes and culinary uses. Despite their shared progenitor, these crops exhibit varietal differences and require specific breeding strategies for hybrid seed production due to small flower size. The development of male sterile systems has revolutionized hybrid seed production, with the exploitation of Genetic Male Sterility (GMS) and Cytoplasmic Male Sterility (CMS) in chilli and bell pepper breeding. The market for chilli seeds in India is substantial, driven by the demand for high-value hybrid seeds. This chapter comprehensively reviews the botanical characteristics, genetic resources, and breeding objectives in Capsicum species, emphasizing traits like disease resistance, high yield, and stress tolerance. It also highlights varietal achievements in public and private sectors, showcasing improved cultivars and hybrids with specific attributes. The integration of molecular markers in male sterile genes facilitates efficient hybrid seed production, ensuring genetic purity and quality. Additionally, the package of practices for seed production in chilli underscores the importance of isolation, field standards, inspection, harvesting, seed processing, and quality standards to maintain seed purity and viability.

Advances in seed production techniques have revolutionized brinjal cultivation, enhancing productivity, quality, and sustainability. Traditional methods, such as manual emasculation and pollination, have been supplemented and in some cases replaced by innovative approaches, contributing to increased efficiency and reduced labor costs. Cytoplasmic male sterility (CMS) and grafting technologies have emerged as valuable tools, offering novel avenues for enhancing breeding efficiency and managing soil-borne pathogens. These advancements have facilitated the development of high-yielding F1 hybrids and improved pure-line varieties with enhanced resilience to pests and diseases. Furthermore, the adoption of precision agriculture techniques, including controlled environment agriculture and hydroponics, has enabled year-round seed production, mitigating the impact of seasonal fluctuations and adverse weather conditions. Integrated pest management (IPM) strategies have been integrated into seed production protocols, minimizing chemical inputs and promoting environmentally sustainable practices. Additionally, innovations in seed extraction methods, such as mechanical extraction and dry extraction techniques, have streamlined the seed processing workflow, resulting in higher seed purity and improved germination rates.

Tomato (Solanum lycopersicum L.) is one of the most commercially important vegetable crops globally, with a significant demand for high-yielding hybrids and improved open-pollinated varieties. Efficient seed production methodologies play a crucial role in ensuring the availability of genetically pure and high-quality seeds for commercial cultivation. Traditional hand emasculation and pollination remain widely used despite being labor intensive, given their economic feasibility due to high seed yield per fruit. Hybrid seed production is further refined through mechanized pollen collection and controlled pollination techniques, enhancing efficiency. Seed quality management, including rigorous isolation protocols, field inspections, and breeder and foundation seed production standards, ensures genetic purity and viability. Advances in molecular breeding and the application of marker-assisted selection (MAS) have enhanced the efficiency of parental line development and hybrid seed production. This chapter provides an in-depth review of tomato seed production methodologies, covering botanical characteristics, genetic resources, and breeding objectives aimed at improving disease resistance, abiotic stress tolerance, and fruit quality traits. It further discusses varietal advancements in the public and private sectors, highlighting elite hybrids and open-pollinated cultivars tailored for different agro-climatic conditions. Additionally, the package of practices for seed production in tomato underscores the importance of isolation, field inspections, seed extraction methods, processing techniques, and quality assurance standards to maintain genetic purity and seed viability.

15.1 Introduction

The genus Castanea, (chestnuts and chinkapins), belongs to the family Fagaceae, which includes other important timber producing genera such as Quercus and Fagus. The chestnuts are native of Western Asia, Europe and Northern America. Chinese chestnut (Castanea mollissima) is a native of China, Japanese chestnut (Castanea crenata) is native of Japan and South Korea and European chestnut is native of Mediterranean countries of South Europe and Asia miner (Conedera et al., 2004; Davis et al., 2006). The Chinese chestnut (Castanea mollissima), Japanese chestnut (Castanea crenata), American chestnut (Castanea dentata), and European chestnut (Castanea sativa) are widely cultivated owing to the economic relevance for their fruits (Larue et al., 2021 and Song et al., 2021). Interspecific hybrids which have emerged from disease resistance work are used for nut, timber and as rootstock.

14.1 Introduction

Hazelnut is also known as Cob nut or Filbert nut. In its natural form the hazelnut is a deciduous, monoecious, multi-stemmed bush, but commercially should be grown as a single trunk tree. Tree sizes are up to 6 m tall in the commercial state. The term ‘Hazel’ was derived from Anglo-Saxon word ‘Haesel’ meaning bonnet, whereas ‘Corylus’ was derived from Greek word ‘Korys’ meaning Hood or helmet. There are nine widely recognized species. five of those are shrubs: C. avellana, C americana, C. cornuta, C. heterophylla, and C. sieboldiana, and four are trees: C.columa, C. jacquemontii, C. chinensis, and C. ferox (Thompson et al., 1996). The nuts of C. avellana are large with superior quality; this species is less hardy and used in breeding programs either exclusively or combination with other species (Thompson et al., 1996). Hazelnuts are deciduous trees or shrubs, grown for their edible nuts. Hazelnuts are large multi-stemmed shrubs or small trees with rounded leaves which possess a doubly serrated margin (each tooth bears another tooth). Hazelnut can reach a height of 3–8 m (10–26 ft) and can live for many years, although its commercial life span is usually about 40 years.

13.1 Introduction

Pecan nut is cultivated for edible fruits (drupaceous nuts) consumed as dried fruit or as processed food, as an ornamental plant, and to promote timber wood production (Wakeling et al., 2001 and Marozzi et al, 2017). In recent years, demand for pecan kernels has increased worldwide, partly because of the good flavour of the kernel, their high nutritional value or as an alternative crop to traditional and widely known nuts (pistachios, almonds, walnuts, etc.). In USA, it is considered as “Queen of nuts” because of its value both as a wild and as a cultivated nut. Poonch district in Jammu & Kashmir holds the reputation of “Pecans Capital of India.” Pecans can be available in the market year around in this region.

12.1 Introduction

Walnut (Juglans regia L.), called “the magic tree” since ancient times, is one of the most economically significant and widely distributed cultivated species for its timber and nutritious nuts all over the world. It is an important source for food, medicines, phytotherapeutic products, raw material in the wood industry and biomass. The nuts are also known as “King of Nuts”. Walnut is known to be trees with a high market potential. Its nutritious nuts and good quality timber are highly valued and the market demand is correspondingly high. It is known for its high-quality nuts and timber. It makes it an economically and nutritionally important tree species. Almost all plant parts and their by products have been used in one or other way. It is the most widespread nut tree in the world (Sharma, 2022). It is relatively fast-growing reaching a total height of 18-30 m and a canopy width of 12-18 m. Roots are sensitive to oxygen depletion which can occur in wet conditions.

11.1 Introduction

The kiwi fruit is native to China, also known as Chinese Gooseberry. It was brought to New Zealand from China by missionaries in the early 20th century with the first commercial planting occurring several decades later. In 1960, it was renamed Chinese Gooseberries. It is a new fruit crop in India which is cultivated on a small scale and people do not know much about its cultivation. In India, it was first planted at Bangalore and after that in Himanchal Pradesh in 1963. In India, Kiwi is mostly grown in Jammu & Kashmir, Himachal Pradesh, Sikkim, Meghalaya, Arunachal Pradesh, Uttar Pradesh and Kerala.

10.1 Introduction

Persimmon is known as the national fruit of Japan. In India, persimmon was introduced by the European settlers somewhere in 1921. At present it is grown on a limited scale in Jammu and Kashmir, Himachal Pradesh, hilly areas of Uttar Pradesh and parts of eastern India. No organized cultivation of this fruit has yet been undertaken in India. The fruit is commonly known as ‘Japaniphal’ which is cherished for its unique flavour and high nutritional content. It is mainly originated from China, Japan and Korea (Lucas-Gonzalez et al., 2017) and is cultivated in warm region of China, Japan, Brazil, Italy and Mediterranean region (Bubba et al., 2009). It was originally cultivated in China and Japan, and it is therefore also known as the ‘Chinese date plum’. Persimmon is good source of various bioactive compounds that possess antioxidant activity which is beneficial for human health, owing to their ability to prevent from various chronic diseases.

9.1 Introduction

Almond is one of the major and oldest tree-nut crops of the world. It is a close relative of peach. It was bought to California in the 17th century by Spanish. In India it was first introduced into Kashmir during 16th century by Persian settlers. The tree bears a fruit called a drupe consisting of an outer hull and a hard shell with the seed inside. Almonds are generally cross-pollinated. Therefore, the common honeybee plays a vital role in the production of the nuts. A compound called ‘Amygdaline’ differentiates the bitter almond from the sweet almond. In the presence of water (i.e., on hydrolysis), amygdaline yields glucose and the chemicals, benzaldehyde and hydrocyanic acid (HCN). The salt of HCN known as cyanide is poisonous. The bitter almond is slightly broader and shorter than the sweet. Bitter almonds yield 4-9 mg of hydrogen cyanide per almond. Almonds are cultivated in many parts of the world, with the five leading countries being the U.S., Spain, Australia, Iran and Morocco.

8.1 Introduction

The garden strawberry (or simply strawberry) is one of the most preferred soft and attractive, tasty and nutritious fruit with a distinct and pleasant aroma, and delicate flavour. The fruit of strawberry is technically known as an accessory fruit and the fleshy part is derived not from the ovaries (achenes) but from receptacle. The common cultivated strawberry (Fragaria ×ananassa Duch.) is a widely grown hybrid plant resulting from the cross between two American species, Fragaria chiloensis of western North and South America and Fragaria virginiana of eastern North America. Its name has been derived from farmers mulching called “Straw”, earlier the strawberries were just planted for medicinal purpose but later on Carlus Linneaus for the first time introduced strawberry as edible fruit (Lieten et al., 1995). Strawberry is herbaceous perennial. It is an aggregate accessory fruit (not a berry indeed), meaning that the fleshy part is derived not from the ovaries of the flower but from the receptacle, that holds the ovaries. Each apparent seed (properly named achene) on the outside of the fruit is actually one of the ovaries of the flower, with a seed inside it. This fruit is widely appreciated for its characteristic aroma, bright red colour, juicy texture, and sweetness. It is consumed in large quantities, either fresh or in prepared foods such as preserves, fruit juice, pies, ice creams, milk shakes, and other desserts (FAO, 2012).

7.1 Introduction

Cherry is one of the important temperate stone fruits of the world. It is widely grown in the cooler climates where the span of winter is wide and very much pronounced. Sweet cherry is tall, attaining a height of 18 m, and pyramidal form. The branches are usually erect, and leaves are large, thin, variable pubescent beneath and coarsely serrated. Sweet (Prunus avium L.) and sour (P. cerasus L.) cherry ripen first among stone fruits followed by apricot, peach and plum. Sweet cherry comes first on the fresh market; hence, it is in high demand during late spring and early summer. Sweet cherry cultivars with red fruit colour lead the market while cultivars of yellow, white, or blush colour are in less demand. Sour cherries have smaller fruit size and are less firm than sweet cherries. The vast majority of the sour cherries are processed. The tree of sour cherry is usually 6-9 m tall, open headed, round topped or spreading and often without a central leader. The leaves are much smaller, dark green in colour and more numerous and trees are hardier than those of sweet cherry. Diameter of sour cherry fruit is about 2 cm.

6.1 Introduction

Plum is one of the important and widely cultivated fruit crops of temperate regions of the world. It occupies a unique position amongst the stone fruits in world fruit production and ranks next to peaches in economic importance. Plums are the most taxonomically diverse stone fruits which belongs to genus Prunus of sub-family Prunoideae and family Rosaceae (Potter et al., 2007). There are about 42 species of plum but the cultivated plums are derived from two species namely Prunus domestica (European plum) and Prunus salicina (Japanese plum). The Japanese plums are widely grown in the country whereas the European plums are grown only on a limited scale. The European plums are most often produced for the dried fruit market particularly in France and California, where it is called prune and dried plum, respectively. In the recent past some prunes have been introduced for fresh market in Himachal Pradesh. These prunes are sold fresh like plums and have become quite popular.

5.1 Introduction

Apricot (Prunus armeniaca L.) is an important fruit crop of temperate regions of India. In India, it is mainly grown in the states of Jammu & Kashmir, Himachal Pradesh and Uttarakhand and on a limited scale in North Eastern states. It is popular worldwide owing to their high nutritional value and delicious flavour, which not only can be used as fresh fruit but also has a high importance as processed product (Moradinezhad and Jahani, 2016). Apricot is drought resistant, salt tolerant, hardy and less susceptible to pests and diseases and can be grown with minimum cultural care in the tracts which are otherwise unfit for cultivating other temperate fruits.

4.1 Introduction

Peach is temperate and economically important fruit species and is in third position among temperate fruits after apple and pear. The peach, and its smooth skinned mutant, the nectarine, are primarily grown in temperate zones of the world. Peach belongs to the family Rosaceae and is native to China (Lurie and Crisosto 2005). Peach was also called as Persian apple and was probably carried from China to Persia (Iran) and, thus, peach quickly spread from there to Europe (Lurie and Crisosto 2005). In India, it is grown in the mid-hill zone of the Himalayas extending from Jammu & Kashmir to Khasi hills up to an elevation of 2000 m above mean sea level (Meitei et al. 2013). It is one of the most important stone fruits grown in Punjab, Haryana and the adjacent areas of Western Uttar Pradesh, Uttarakhand and Himachal Pradesh. Because of its refreshing, health promoting and delicious qualities, peach fruit is popular all over Northern India. There are many types of peaches. The free-stone types, which have melting yellow or white flesh, are usually consumed fresh and the second one, the cling-stone types with rubbery flesh, are used in processing; the nectarine, which is characterized by non-fuzzy skin, resulted from a mutation, and Peento, a flat peach with a saucer shape, is another variant. It is also a rich source of vitamin A, iron and proteins. Peaches are eaten fresh, canned or dried and are excellent sources of fibre, vitamins and antioxidants The peach kernel oil is utilized in manufacturing of a large number of cosmetics and pharmaceutical products. Nectarines, scientifically known as Prunus persica var. nucipersica, are commonly known as stone fruits which bears fruits similar to peaches but is smooth and lacks hairy fuzzy feature of peaches.

3.1 Introduction

Pear (Pyrus spp.) is one of the important fruit crops that belong to the family Rosaceae. It is one of the important fruits of the temperate and sub-temperate zones. In India, among temperate fruits, pear is next to apple in importance, acreage, production and varietal wealth. It is grown from warm humid sub tropical plains to cold dry temperate regions of India. In the world, pear is cultivated in China, USA, Argentina, Italy, Turkey, Spain, India, South Africa, Japan, Belgium etc. It is grown under a wide variety of climatic regimes ranging from cold dry temperate hilly conditions to warm humid sub-tropical conditions on the plains of northern India. In India pear is widely cultivated in Punjab, Himachal Pradesh, Jammu & Kashmir, Uttar Pradesh, Uttarakhand etc. Pear fruits are generally sweeter and of softer texture than apples and are distinguished by the presence of hard cells in the flesh, the so-called grit, or stone cells. In general, pear fruits are elongate, being narrow at the stem end and broader at the opposite end.

2.1 Introduction

Apple is the most widely grown temperate fruit of the world. It is considered as ‘King of Temperate Fruits’. Apple is popular because of its delicious taste and pleasant aroma. It is rich in carbohydrate, calcium, phosphorous, iron, and vitamin B6. Apple is rich in anti-oxidant, flavonoids and dietary fibre. The phytonutrients and anti-oxidants may help reduce the risk of developing cancer, hypertension, diabetes and heart disease. Apple is mainly used for table purpose. The various processed products are prepared from fruits like juice, jelly, candy, preserve, canned slice, wine, concentrated juice and cider.

1.1 Introduction

Temperate fruits are those fruits that are adapted to the temperate climate where the winter is distinctly cold. They can tolerate both diurnal and seasonal wide fluctuation of temperature and are grown only in places where winter is distinctly cold. They require exposure to specific chilling temperature for certain period to break bud dormancy and initiate bud break. These fruit plants are generally deciduous and suitable for higher elevation as they can withstand frost. Their cultivation is confined to Jammu and Kashmir, Punjab, Himachal Pradesh, Assam, Uttaranchal and Uttar Pradesh; they are also grown to a small extent, at suitable elevations in south India as in the Nilgiris of Tamil Nadu. They shed the leaves during winter and remain in dormant condition throughout the winter. The most economically important temperate fruits belong to Rosaceae family and includes peach, pear, cherries, almond, apple, apricot, plums, raspberries and strawberries (Ferree and Warrington, 2003). Among them apple is the dominant temperate fruit with greater than 71 million tonnes of global production. It was perceived as native to Central Asia and now grown in many countries across the world (Janick et al., 1996; FAO, 2009).

The native and applied organic matter play an important role in terms of nutrient adsorption , nutrient mobility and microbial habitat on soil. The dominant ions present in soil under a particular agro-ecological situation may or may not be available to the growing plants due to the presence of organic matter. The binding energy and the stability of the organo-metal complexation would play an important role in availability of nutrients to the plants. The organo-metal complexation reaction depends on the nature of the ionic species (ionic/non ionic) present in soil. The organic fractions (Humic acid/Fulvic acid) react with metal ions present in soil to form complexes which may be stable or unstable depending upon the molecular arrangement and degree of coiling of humic/fulvic substances. The surface charge density on clay and soil pH also play an important role to determine the order of stability of different nutrients (macro/micro) in soil.

Understanding the chemistry of submerged soil in the field of Geology, Pedology, Agriculture and other allied sectors draws attention to the research on characteristic changes in soil under submergence. It has been reported that, about 72% of the earth’s surface is covered by submerged soils or sediments . Rice plants have unique adaptation capability to grow under submerged soil and in any type of soil (acid/alkaline) condition or land situation (upland/lowland). The knowledge on changes of important physical, chemical and biological properties under submergence have important role to play in understanding the mechanisms of availability of nutrients to the plants and sustainability of the crop during its growing period.

9.0 Submerged Soil

The soils which are saturated with water for a longer period of time in a year to make the soil a distinctive gley horizons resulting from oxidation-reduction processes are called submerged soil. About 72% of the earth’s surface is covered with soil –submergence or sediments.

Nutrient adsorption in soil is one of the important phenomena in terms of nutrient availability to plants. Due to the nutrient fixation of the added nutrients supplied through fertilizers or manures may result the increase in cost of production due to the non-availability of the added nutrients at the optimum level to the plants. Hence, management options are required to release the sorbed nutrients from soil for better availability to the plants. The ion-fixation is driven by physico-chemical and biological processes and varies under agro ecological situations. The chemistry of ion fixation in the form of specific or non-specific adsorption on soil colloids will help understanding the bonding and adsorption reactions of ions in the soil.

8.0 What is fixation?

Fixation of plant nutrients in soil may be defined as the process, where readily soluble plant nutrients are transformed into less soluble forms by physical or chemical reaction with organic or inorganic compounds and thus restricting the mobility of ions in soil that leads to the decrease in availability to the plants. There are two kinds of fixation in general, viz; cation (N, K, Fe, Mn, Cu, Zn, Ca,Mg etc.) and anion (P, B, Mo etc.) in soils. The fixation of ions in soil is governed by important physical and chemical parameters of soil based on which the available pools of nutrients for plants may be determined.