eChapters

Onion is an economically significant bulb crop cultivated across diverse agroecological environments. Its cultivars vary considerably in bulb size, shape, colour, pungency, maturity, storage behaviour and photoperiod response. Understanding its vegetative and reproductive morphology, growth habit, physiology and taxonomic relationships is fundamental to crop improvement and germplasm conservation. This chapter examines the botanical features and taxonomic position of onion within the genus Allium. It explains relationships among cultivated types, landraces and allied species and discusses varietal classification according to climatic adaptation and consumer preference. Classical characterization and molecular taxonomy are considered important tools for developing productive, resilient and market-preferred onion cultivars.

The reproductive physiology of finfish and shellfish involves the complex biological systems that regulate their breeding and spawning cycles. In aquaculture, a sound understanding of these systems is critical for effective hatchery operations, seed production, and broodstock management. Reproductive success in both groups is influenced by hormonal signals, environmental cues, and genetic traits. In finfish, reproduction is typically seasonal and sensitive to external factors such as light cycles (photoperiod), water temperature, diet, and overall water quality. Central to their reproductive regulation is the hypothalamus-pituitarygonadal (HPG) axis. The hypothalamus secretes Gonadotropin-Releasing Hormone (GnRH), which prompts the pituitary gland to release follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These hormones drive the formation of gametes—oocytes in females and sperm in males. Oogenesis involves yolk formation and final maturation of eggs, while spermatogenesis includes sperm cell development and release. Spawning can be natural or artificially induced using hormonal treatments like human chorionic gonadotropin (hCG), Ovaprim, or carp pituitary extract.
In shellfish, including mollusks and crustaceans, reproductive strategies vary widely. Mollusks may have separate sexes or be hermaphrodites, and they typically respond to environmental changes such as shifts in temperature or salinity. For instance, in oysters, gametes develop within the gonads and spawning can be initiated using methods like thermal changes or chemical stimuli such as serotonin. Crustaceans, like shrimp and crabs, rely on the brain-eyestalkgonad axis. Here, the X-organ–sinus gland complex in the eyestalk secretes gonad-inhibiting hormone (GIH), which slows down reproductive development. To promote spawning in shrimp like Penaeus monodon and Penaeus vannamei, eyestalk ablation is often used to remove this inhibition. Technological advancements have allowed for greater control over the reproductive cycles of aquatic species. Techniques such as hormonal manipulation

Introduction

Carrot (Daucus carota L., 2n=2x=18) is a cool-season root vegetable grown all over the world in temperate as well as sub-tropical climates. In India, it is cultivated over an area of 24,000 hectares with an annual production of 3,50,000 metric tones with a productivity much lower (14.58 t/ha) than the world average (22.17 t/ha) as per FAO, 2004. Carrots are used for human consumption as well as for animal feed. Carrot can thus be used for augmenting fresh fodder supply to milch animals during the lean winter in Kashmir (Hussan and Ahmed, 1999). Carrot has a significant place as an ingredient in soups and sauces and in dietary composition and also as a salad. A sweet preparation called Gajar Halwa is very famous dish in North India. Besides canning, it is also used in preparation of pickles. It is also exported in the form of fresh roots to the countries like Kuwait and Sharjah. Carrot is a rich source of á and â- carotene. The total carotenoid content in the edible portion of carrot roots ranges from 6.00 to 54.80 mg/100g. The yellow and orange coloured roots contain relatively more carotenoid. Carrot roots contain protein, fat, carbohydrate, minerals (especially Ca, Mg, Na, K, Cu, S etc.) besides vitamin A, B₁, B₂, nicotinic acid and vitamin C. In carrot roots, sucrose is the most abundant with endogenous sugar contents 10 times than those of glucose and fructose.

Asia minor, Afghanistan, North West India, Iran and Turkey are the centers of origin of carrot. As per Encyclopedia Britannica, carrots have originated from Afghanistan, Punjab and Kashmir with secondary centers in Ethiopia and North America. The European carotene carrot (syn. Western carotene carrot, temperate carrot) has been derived from the Asiatic anthocyanin containing forms of carrot (syn. Eastern anthocyanin carrot, tropical carrot). Afghanistan is the centre of diversity of the purple coloured carrot (anthocyanin carrot) and as such this country is suggested as the primary centre for origin. Integration between the Asiatic and European carrots has given the present day forms which are fleshy, smoother, less forked and better coloured.

Punjab and Kashmir are also considered as primary centre of origin with secondary centers in Ethopia and North America. It is still found in its wild form in Himachal Pradesh and Kashmir valley where wild animals especially brown bear feed on its roots. People still eat the wild carrots in some parts of Kashmir (Yawalkar, 1980). In north India highly coloured types of carrots are found which are not available in Europe. The colour of carrot ranges from absolute colourless to light lemon, light orange, orange and deep orange, light purple, deep purple and almost black. It is also an indication of this region being a primary centre of origin of carrot.

Objective synonym: An absolute or nomenclatural synonym resulting from the proposal either of a replacement name for a supposedly preoccupied name or of names based on the same specimen, illustration, or taxonomic entity (cf. Synonym, Subjective synonym).

Obligate parasite: A parasite that requires a living host to survive and reproduce and which cannot exist in any other way.

Obligatory: Compulsory, or exclusive; e.g. obligatory diapause is a resting stage that occurs in every individual of each individual of each generation of a univoltine insect.

Oblique sternals: Lateral abdominal muscles in other than longitudinal or dorsal-ventral orientation

Conventional fertilizers often exhibit low nutrient-use efficiency, resulting in nutrient losses, soil degradation, water contamination and unnecessary production costs. Nano-fertilizers offer controlled and targeted nutrient delivery through formulations engineered at the nanoscale. Their high surface-area-to-volume ratio can improve nutrient availability, plant uptake, growth, bulb quality and storage performance while reducing conventional fertilizer requirements. This chapter explains the nature, modes of action and potential benefits of nano-fertilizers in onion production. It also considers nano-biofertilizers, smart nutrient-delivery systems and nano-sensors. Particular attention is given to manufacturing cost, nanotoxicity, effects on soil microorganisms, farmer accessibility and the need for standardized safety and regulatory frameworks.

Two principal hatchery systems are widely adopted in aquaculture: the large-tank hatchery system and the small-tank hatchery system. Recently, hybrid systems have emerged that integrate advantageous features from both approaches, particularly addressing constraints related to spawner availability.
KEY DETERMINANTS IN HATCHERY DESIGN
Three major factors govern the design of an aquaculture hatchery:
1. Target Species: The specific biological and ecological requirements of the species to be cultured are critical. Hatchery infrastructure must accommodate these needs, and as such, a clearly defined target species is essential before initiating the design process.
2. Production Target: The hatchery’s output goal is determined by market demand and available financial investment. For species such as Penaeus monodon, where fry production is reliant on wild spawner collection, output is naturally capped by spawner availability. In contrast, species like P. japonicus and white shrimp, which have abundant spawner supply, allow for scalable production targets.
3. Financial Inputs: Investment capacity influences not only the scale of operations but also the complexity and automation of the hatchery. In Japan, for example, large-scale hatcheries culturing P. japonicus feature tanks with capacities reaching up to 2,500 cubic meters. In Southeast Asia, where P. monodon is the primary hatchery species and wild spawner availability is limited, smaller tank capacities are the norm.

Precision farming manages spatial and temporal variability within fields through targeted, data-driven interventions. Onion is particularly suited to precision management because its productivity and quality are sensitive to moisture, nutrients, environmental stress, pests and diseases. This chapter describes applications of GIS, GPS, variable-rate technology, IoT, cloud platforms, drones, remote sensing, multispectral imaging, smart sensors, artificial intelligence, automated systems and crop-response models. These technologies support soil assessment, field preparation, irrigation, fertilization, crop monitoring, stress detection, protection, yield estimation, harvesting and storage. Their potential to reduce input waste and improve profitability is considered alongside constraints involving investment costs, technical knowledge, connectivity, accessibility and data privacy.

In Indian aquaculture, live feed plays a critical role, especially in nurturing the larvae of fish and shrimp. Commonly used live feeds include rotifers, copepods, and Artemia nauplii, which are vital for the early survival and growth of larvae. The process of producing these feeds typically begins with microalgae cultivation, which serves as a foundation for developing high-quality larval feed and successful hatchery seed output.
Live feeds provide essential nutrients and help stimulate the feeding instincts of larvae—especially crucial when the larvae are transitioning from utilizing their yolk reserves to external feeding.
LARVAL CHALLENGES
Marine fish species such as bass, bream, meagre, and sole have very small larvae with limited yolk reserves that last just 2–3 days at 20°C. Their small mouths limit the size of food particles they can consume. While shrimp larvae also face food size issues, their appendages aid in capturing and breaking down food, making it less restrictive.
Species like penaeid shrimp go through developmental stages where their feeding habits shift—from herbivorous filter-feeding on microalgae to becoming carnivorous, feeding on organisms like Artemia. Mollusks, including oysters, clams, mussels, and abalone, feed on microalgae throughout their lives using filter-feeding mechanisms.
Natural and Cultured Diets
In the wild, these larvae feed on a wide range of phytoplankton (like diatoms, flagellates, and green algae) and zooplankton (such as copepods and small crustacean larvae). This diversity in plankton sizes and nutritional profiles is essential for meeting their dietary needs. However, collecting such natural plankton on a large scale isn’t practical for commercial aquaculture

Ginger is used extensively as a spice in cuisines throughout the world. Ginger belongs to Zingiberaceae family and an English botanist William Roscoe (1753-1831) gave this plant the name Zingiber officinale in the year 1807. The name of the genus Zingiber derives from a Sanskrit word denoting “horn shaped” in reference to the protusions on the rhizomes (Ghosh et al., 2011). It is an oldest rhizome widely domesticated as a spice where the edible part is the swollen underground stem or rhizome. The Zingiberaceous plants have strong aromatic and medicinal properties and are characterized by their tuberous or non-tuberous rhizomes (Chen et al., 2008). Ginger is a medicinal plant that has been widely used all over the world, since antiquity, for a wide array of unrelated ailments including arthritis, cramps, rheumatism, sprains, sore throats, muscular aches, pains, constipation, vomiting, hypertension, indigestion, dementia, fever and infectious diseases (Ali et al., 2008). Ginger has direct anti-microbial activity and thus can be used in treatment of bacterial infections (Tan and Vanitha, 2004).

6.1 INTRODUCTION

The Climate and soil play important role in growth and development of the plant. Growers in general and fruit growers in particular should have adequate knowledge of the effect of various soil and climatic conditions on raising horticultural crops. Horticultural crops cannot be grown in all types of soil and climate. Hence zone- wise cultivation is made. Climate includes a number of parameters like temperature, rainfall, atmospheric humidity, wind, hail and light whereas soil covers factors like moisture content, texture, soil reaction, nutrient content, chemical composition and soil temperature.

6.2 SOIL

Soil is a thin outer covering of the earth surface. It is the natural resource directly developed by different natural forces acting on natural materials. Soil serves as a base and support for plant growth. It is a basic medium for plant growth and supplies nutrients for growing plants. Soil is the home of the plant root and the reservoir for essential nutrients and water for growth and development of crop plants.

19.1 Introduction

Fish are the most common aquatic vertebrates. Fishes’ primary aquatic adaptation is the presence of gills. They use the oxygen that remains dissolved within the water via their gills. The gills use up to 80% of the oxygen dissolved in the water that passes over them. In addition to the gills, skin, the air bladder and accessory respiratory organs perform gas exchange functions in some fishes.

Fish gills are essentially the same. The gills have been specially modified to use up to 80% of the oxygen dissolved in the water that passes over them. Cyprinus and Carassius gills excrete six to ten times more nitrogenous waste than kidneys.

Fungal and parasitic infections represent major health challenges in Indian aquaculture, impacting both freshwater and marine systems across diverse climatic regions. These pathogens significantly affect fish health and productivity, often causing substantial losses in high-density farming systems. Their complex life cycles and often nonspecific clinical symptoms make diagnosis and control particularly difficult. Effective detection, timely treatment, and preventive biosecurity are essential to maintaining sustainable aquaculture practices in India.
Fungal pathogens such as Saprolegnia, Achlya, and Branchiomyces are commonly encountered in Indian aquaculture. These opportunistic fungi typically infect fish weakened by environmental stress, physical injury, or concurrent bacterial infections. Among these, Saprolegnia spp. are most frequently implicated, especially in carps, catfishes, and ornamental fish. Infected fish often display white or greyish cotton-like growths on the skin, gills, or eggs.
Field-level identification relies on observation of external lesions, erratic behavior, and increased mortality. Microscopic examination of skin scrapes or gill biopsies mounted in saline or potassium hydroxide (KOH) can reveal fungal hyphae, which are long, filamentous, and typically non-septate or sparsely septate.
Fungal cultures are grown on Sabouraud Dextrose Agar (SDA) or Potato Dextrose Agar (PDA), often supplemented with antibiotics to suppress bacterial contamination. Incubation at 25–30°C allows colonies to develop, which can be characterized by morphological and microscopic traits. Molecular diagnostics, including PCR targeting fungal ITS regions, are increasingly utilized in advanced laboratories such as ICAR institutes and state fisheries departments.

10.1 INTRODUCTION

Most botanists identify trees by their leaves, f lowers and fruit. However, the plant architecture specialist is interested in trunks, branches and twigs. All types of fruit tree do not require pruning, e.g., mango, sapota, while some fruit trees can grow well naturally, e.g., pineapple, papaya as they do not require pruning. Most deciduous trees like apple, pear, almond etc. and grapes, ber, fig, citrus, pomegranate, guava etc. require pruning to train them for desired shape.

10.2 TRAINING

Training is an operation by which the plant is made to develop an orderly structure or frame work. This is done by staking, tying, supporting, propping, trailing or spreading on certain structure with or without pruning of plant. Training is usually done when plants are young. Bending, twisting, decapitations are done by using springs of hard wire, where it is required. It is a physical technique which controls the shape, size and direction of plant growth known as training or in other words, training in effect is orientation of plant in space through techniques like tying, fastening, staking, supporting over a trellis or pergola in a certain fashion or pruning of some parts.

21.1 Introduction

The air (=gas or swim) bladder, also known as the fish maw, is a tough sac-like structure with an overlying capillary network. It develops as an outgrowth from the oesophageal region and is found in bony fish. It demonstrates a wide range of development, structure, and function in various fish. It is usually a hydrostatic organ that controls buoyancy, allowing the body to remain at the current water depth without having to expend energy swimming. It is similar to a diver’s buoyancy compensation device (BCD). It also serves as a resonating chamber for producing or receiving sound and is used as an air-breathing organ.

Histopathology is a critical diagnostic method used to examine tissue structure and detect pathological changes caused by infectious agents in fish. In India’s rapidly growing aquaculture sector—encompassing economically significant species such as rohu, catla, tilapia, pangasius, and ornamental fish— histopathology plays a pivotal role in disease surveillance, diagnosis, and research.
As fish farming intensifies across major aquaculture states like Andhra Pradesh, West Bengal, Tamil Nadu, and Kerala, advanced diagnostic techniques like histopathology are becoming increasingly important. These techniques enable early detection of diseases and support efforts in biosecurity and sustainable fish farming.
The process begins with the careful collection of tissues from fish suspected of disease. Key organs examined include gills, liver, kidney, spleen, heart, intestine, and muscle, which are commonly affected in systemic infections of bacterial, viral, parasitic, or fungal origin. Fish samples are collected from ponds, tanks, cages, or RAS units and transported under chilled conditions—preferably on ice—to laboratories such as ICAR-CIFE, state fisheries universities, or certified private centers.
Tissue dissection is conducted under aseptic conditions. Samples are immediately fixed in 10% neutral buffered formalin, the most commonly used fixative in India, to prevent autolysis and maintain cellular architecture. Fixation typically takes 24–48 hours, depending on tissue size and thickness.
After fixation, tissues are processed through graded alcohol dehydration, clearing in xylene (or substitutes), and embedding in paraffin wax. These steps are often performed using automated tissue processors available in regional laboratories. Once embedded, tissues are sectioned at 4–6 microns using a rotary microtome and mounted on clean slides.

Cytological and wet mount techniques are essential diagnostic tools in Indian aquaculture, especially in regions with limited access to advanced laboratory infrastructure. These methods offer rapid, cost-effective, and straightforward approaches for identifying fish pathogens, making them highly suitable for both field and laboratory use.
Cytology involves the collection of cells from various fish tissues—such as gills, skin, fins, kidney, liver, and other internal organs—which are then smeared onto clean glass slides. The smears are air-dried, stained, and examined under a microscope to detect cellular abnormalities, inflammatory responses, or the presence of infectious agents.
• Common stains used in Indian labs include Giemsa, Leishman, and Wright’s, which effectively highlight the morphology of erythrocytes, leukocytes, and abnormal cells.
• Cytology can reveal conditions such as anemia, inflammation, and bacterial or fungal infections, particularly those caused by pathogens like Aeromonas or Edwardsiella.
• Swabs from liver or kidney are frequently used to observe inclusion bodies and aberrant cell structures that suggest systemic infections.
Wet mounts involve placing fresh samples—such as mucus, gill biopsies, skin scrapings, or fecal material—on a slide with a drop of saline or water, covered by a coverslip. These are examined under light microscopy to detect motile parasites and other abnormalities in real time.

Principle

Good documentation constitutes an essential part of the quality assurance system. Clearly written documentation prevents errors from spoken communication and permits tracing of batch history. Specifications, Manufacturing Formulae and instructions, procedures, and records must be free from errors and available in writing. The legibility of documents is of paramount importance.

General

Specifications describe in detail the requirements with which the products or materials used or obtained during manufacture have to conform. They serve as a basis for quality evaluation. Manufacturing Formulae, Processing and Packaging Instructions state all the starting materials used and lay down all processing and packaging operations.

Procedures give directions for performing certain operations e.g. cleaning, clothing, environmental control, sampling, testing, and equipment operations.

Records provide a history of each batch of product, including its distribution, and also of all other relevant circumstances pertinent for the quality of the final product.

Agricultural scientists and policy makers have understood that continuation of modern agriculture might lead to severe ecological and economic problems. We are also convinced that modern agriculture may not be able to meet the requirements of the ever increasing population in the future. So, we are searching for alternative technologies. Several alternatives have been proposed such as low external input agriculture, sustainable agriculture, organic farming, biodynamic farming etc. However, they require, some times little or considerable external inputs whose availability may be uncertain in future.

Hence for the developing countries, the other alternative viz., traditional methods have special advantages over modern agricultural techniques. Also the capital and technological skill requirements in the use of traditional technologies are generally low and their adoption often requires little restructure of the traditional societies. The traditional technologies are nothing but indigenous technical knowledge. By adopting such indigenous knowledge, our ancestors did not face any problem of large-scale pest out break or economic crisis unlike the today’s farmers.

5.1 Definitions

The erodibility of soil is its vulnerability or susceptibility to erosion, that is the reciprocal of its resistance to erosion. A soil with a high erodibility will suffer more erosion than a soil with low erodibility if both are exposed to the same rainfall. Whereas the erosivity of rainfall was shown in chapter 4 to be a fairly straightforward measure of the rain’s physical properties, the assessment of erodibility is more complicated because it depends upon many variables. There are alternative uses of the term erodibility. In the widest sense it can be used to include all the variables which effect erosion except the erosivity of rain, as in the first line of figure 2.2. It is also used in the narrower sense as a measure only of the effect of physical characteristics of the soil, as in the erodibility index K of the Universal Soil Loss Equation, where the effects of land management and crop management are assessed separately, as shown in the last line of figure 2.2.

5.2 Factors influencing erodibility

In this chapter we will look at the three broad groups of factors which affect erodibility. First, there are the physical features of the soil, including the chemical and physical composition. Second, there are the topographic features, such as the slope of the land. Third, there is the management of the land, i.e. how it is used.

1. Chlorophylls

Chlorophyll can be regarded as a true representation of health of green plants. This presumption is based on the fact that chlorophyll is most commonly and immensely influenced by biotic and abiotic stress conditions in addition to events like pathogenic invasion, pollution, mineral deficiencies as well as mineral toxicity. This is the reason that estimation of chlorophyll is considered to be one of the most important parameters in plant physiological studies.

Eukaryotic plant cells possess many types of ‘reserves’, one of them is plastid. A plastid, that contains green colour is known as chloroplast and the green colouration of a chloroplast is mainly due to the presence of a pigment to which we call as chlorophyll. Normally, chlorophyll constitutes about 4% of chloroplast dry weight.

Chlorophyll ‘a’ and ‘b’ are the most abundantly found in all autotrophic higher plants. However, there are other chlorophylls also such as ‘c’, ‘d’, ‘e’, bacteriochlorophyll and bacterioviridin which have restricted presence in blue-green, brown and red algae.

A chlorophyll molecule contains ‘Tetrapyrrole’ skeleton formed into a ring with an atom of magnesium (Mg⁺⁺) in the centre. A so-called ‘Pyrrole’ molecule contains four carbon and one nitrogen atoms arranged in a ring. Four such pyrrols arranged in a ring form the ‘Head’ of chlorophyll molecule. Attached to this is ‘porphyrin ring’, at one point, is a ‘phytol’ tail- a long chain of linked carbon.