Answer the following questions in about 150 words each : 10×5=50 (a) Define seed viability. Describe in brief the metabolic…

(a) Seed Viability and Metabolic Aspects of Seed Germination

Seed viability denotes the capacity of a seed to remain alive, metabolically active, and capable of producing a normal seedling under favorable environmental conditions of moisture, temperature, and aeration.

The metabolic sequence of germination begins with imbibition, where dry seeds physically absorb water, causing cellular rehydration, membrane reorganization, and structural repair. This triggers basal metabolism, transitioning cellular respiration from an initial anaerobic pathway to aerobic respiration via the Krebs cycle and oxidative phosphorylation for sustained ATP generation. In cereals, endogenous gibberellins secreted by the embryo diffuse to the aleurone layer, initiating the de novo synthesis of hydrolytic enzymes, principally α-amylase, alongside proteases and lipases. These enzymes hydrolyze insoluble stored starches, proteins, and lipids into soluble sugars, amino acids, and fatty acids. These mobilized nutrients are translocated to the embryonic growing axis, providing the requisite energy and metabolic precursors for rapid cell division, elongation, and radicle emergence through the seed coat.

(b) Pests, Pesticides, and Pesticide Formulations

In pest management, a pest is defined as any living organism—such as insects, pathogens, weeds, or vertebrates—whose population exceeds the Economic Threshold Level (ETL), causing measurable economic injury and qualitative or quantitative crop loss. A pesticide is any chemical or biological agent, substance, or mixture formulated to prevent, destroy, repel, attract, or mitigate pest populations.

Technical active ingredients are rarely applied in their pure form due to extreme concentration, high toxicity, low water solubility, or chemical instability. Therefore, they are mixed with inert carriers, surfactants, solvents, and adjuvants to create formulations. Major formulation types include Emulsifiable Concentrates (EC), Wettable Powders (WP), Suspension Concentrates (SC), Granules (GR), and Ultra Low Volume (ULV) liquids. Pesticide formulations are essential to improve shelf-life stability, ensure uniform field dilution and spray coverage, facilitate targeted delivery to the pest, reduce phytotoxicity to host plants, improve operator handling safety, and maximize bio-efficacy in a cost-effective manner.

(c) Role of Post-Harvest Technology in Minimising Losses in Fruits and Vegetables

Fruits and vegetables are highly perishable, exhibiting post-harvest losses up to 25–30% due to continuous respiration, transpiration, and microbial decay. Post-harvest technology (PHT) establishes an integrated handling chain to minimize these quantitative and qualitative losses.

The process begins with rapid pre-cooling to remove field heat immediately after harvest. Subsequent washing, sorting, and grading standardize produce quality. Applying surface waxes creates a protective barrier that reduces transpirational water loss and fruit shriveling. Modern packaging, including Modified Atmosphere Packaging (MAP) and Controlled Atmosphere (CA) cold storage, regulates atmospheric oxygen and carbon dioxide levels. This suppresses respiration rates, inhibits ethylene biosynthesis and action, delays tissue senescence, and controls microbial pathogens causing fungal or bacterial rot. Furthermore, temperature-managed cold chain logistics maintain produce integrity, while minimal processing and value addition convert non-table-grade surplus into shelf-stable processed goods, substantially extending commercial viability and eliminating farm-gate losses.

(d) Plant Quarantine Measures and the Indian Context

Plant quarantine represents the legal, regulatory restriction imposed on the movement of plants, planting materials, seeds, and soil to prevent the introduction, establishment, and geographical spread of foreign exotic pests, weeds, and diseases. In India, these operations are governed by the Directorate of Plant Protection, Quarantine & Storage (DPPQS) under the Destructive Insects and Pests Act (DIPA), 1914 and the Plant Quarantine (Regulation of Import into India) Order, 2003.

Key regulatory measures encompass absolute prohibitions on high-risk plant materials, mandatory requirement of Phytosanitary Certificates from the exporting country, port-of-entry visual and laboratory inspections, post-entry quarantine (PEQ) isolation, and disinfestation treatments including methyl bromide fumigation and vapor heat treatment. In the Indian context, notable measures include the complete ban on cocoa planting material from Ghana to prevent the introduction of Cocoa Swollen Shoot Virus (CSSV), stringent restrictions on coconut germplasm from Sri Lanka to exclude Lethal Yellowing disease, and strict quarantine heat treatment protocols on fruit imports from Southeast Asia to intercept exotic fruit flies (Bactrocera spp.).

(e) Importance of Greenhouse in Agriculture

Greenhouses represent an advanced system of protected cultivation where the internal microclimate—temperature, solar radiation, humidity, and carbon dioxide levels—is manipulated to optimize plant growth and photosynthetic efficiency regardless of external climatic extremes.

Greenhouses allow year-round and off-season crop production, enabling growers to harvest produce during supply deficits and secure premium market prices. They maximize resource efficiency, cutting water and fertilizer consumption by up to 80% through automated micro-irrigation and fertigation systems. Enclosed structures provide a physical barrier against insect vectors, drastically reducing pest incidence and chemical pesticide dependence. Greenhouses enhance yields 5 to 10 times compared to open-field systems and are critical for raising disease-free commercial nurseries, micropropagation acclimatization, and high-purity hybrid seed production. Supported by schemes like the Mission for Integrated Development of Horticulture (MIDH), greenhouses have become indispensable for the intensive, high-value commercial cultivation of exotic vegetables like colored capsicum and parthenocarpic cucumbers, alongside cut flowers such as roses, gerberas, and carnations.