What is allelopathy? Discuss its role in major cropping systems of irrigated agriculture. (Not more than 200 words)

Agriculture is best assessed through its developmental, institutional and implementation dimensions, with equity and resilience as the governing tests.

Allelopathy is the beneficial or harmful biochemical influence of one plant on another through released compounds. Chemicals may enter soil through root exudates, leached leaves, volatilisation or decomposition of residues.

In irrigated systems, crop residues and living plants can suppress weeds, alter germination and influence nutrient cycling. Examples include rice residues affecting succeeding crops, sorghum and wheat producing inhibitory phenolics, and legume or cover-crop residues modifying weed emergence.

Its positive role is natural weed suppression, lower herbicide dependence, conservation of soil moisture and possible pest management. But compounds may also inhibit the next crop, reduce germination or interact with soil microbes; continuous monocropping can intensify autotoxicity.

Use requires crop- and cultivar-specific evidence, residue timing, rotation design and appropriate decomposition management. Integrate allelopathic varieties and cover crops with mechanical and chemical control, while testing field concentrations, irrigation effects and impacts on beneficial organisms before recommendation.

Keywords: agriculture; crop ecology; plant interactions; allelopathy