(a) What do you understand by agroecology? How does agroecology help in crop distribution and sustainable food production? (20…

(a) Agroecology: crop distribution and sustainable food production

Agroecology applies ecological principles to design and manage food systems, treating a farm as an agroecosystem of nutrient cycles, energy flows and biological interactions rather than an input–output factory. Its scientific base is in the work of Gliessman and Altieri, and the FAO's ten elements cover diversity, synergies, recycling, resilience, co-creation of knowledge and responsible governance.

Crop distribution. It matches crops to agro-climatic zones, soils, rainfall and local niches instead of forcing monocultures with chemicals. Diversified spatial and temporal arrangements, such as intercropping, strip cropping, agroforestry, crop rotation and mixed farming, place crops with complementary rooting depths, canopies and durations together and spread risk across the landscape. In India this supports zone-wise cropping under the agro-climatic regional planning approach and revival of millets and pulses in rainfed regions.

Sustainable production. Legumes fix nitrogen, organic matter builds soil structure and carbon, habitat for predators and parasitoids regulates pests, and on-farm recycling of residues and manure cuts external inputs and cost. The system is more resilient to drought, heat and pest outbreaks and supports nutrition through diverse crops. Indian expressions include natural farming (Bharatiya Prakritik Krishi Paddhati under PKVY, scaled through the National Mission on Natural Farming, 2024), organic farming in Sikkim and Andhra Pradesh's community-managed natural farming. Its constraints are lower yields in transition, need for knowledge and certification, and marketing, so scaling should be evidence-based and site-specific.

(b) Parasitic weeds and Orobanche management

Parasitic weeds attach to host plants through haustoria, which draw water, food and minerals. On the basis of parasitism they are classified as:

Holoparasites (total parasites) lack chlorophyll and depend wholly on the host; examples are Cuscuta (dodder, a stem parasite) and Orobanche (broomrape, a root parasite). Hemiparasites (partial parasites) have chlorophyll and take only water and minerals; examples are Striga (witchweed, a root parasite on sorghum, maize and sugarcane) and Loranthus (a stem parasite on trees).

Orobanche (O. aegyptiaca) attacks mustard, tomato, brinjal and tobacco, especially mustard in Rajasthan, Haryana, Gujarat, Uttar Pradesh and Madhya Pradesh.

Preventive measures: use clean, certified seed free of weed seed; clean implements and avoid moving infested soil or farmyard manure; quarantine; and prevent seed set by removing plants before flowering.

Integrated management: deep summer ploughing and soil solarisation with clear polythene in summer; crop rotation with non-hosts such as wheat, barley, gram or berseem, and trap crops that cause suicidal germination; delayed sowing of mustard and adequate fertility; hand pulling before seed set; early low-dose glyphosate (about 25 g a.i./ha) sprayed on mustard at about 25–30 and 50–60 days after sowing, as mustard tolerates it; pre-emergence pendimethalin; biocontrol with Fusarium oxysporum f. sp. orthoceras (host-specific fungus); and tolerant varieties.

(c) Microbial consortia in crop residue management

A microbial consortium is a designed mixture of two or more compatible, non-antagonistic microbial strains (bacteria, fungi, actinomycetes) that work together and do jointly what single strains cannot.

In residue management, such consortia decompose cellulose, hemicellulose and lignin of paddy and wheat straw. Fungi such as Trichoderma, Aspergillus and Phanerochaete and actinomycetes release cellulase, xylanase and ligninolytic enzymes, while bacteria take up the products, hastening composting. Residues break down in situ in about 20–25 days, which lets farmers sow the next crop without burning, and they return nutrients and organic carbon and improve moisture retention. ICAR-IARI's Pusa Decomposer, a fungal consortium in capsules, is used against stubble burning in the rice–wheat belt of Punjab, Haryana, Uttar Pradesh and Delhi.