Interactive effects of drought and weeds on greengram: Impacts on physiological, biochemical and yield traits

Global agricultural productivity is increasingly threatened by the combined effects of biotic and abiotic stresses, particularly weed interference and drought, which pose significant challenges to achieving Sustainable Development Goal 2 (Zero Hunger). Weeds alone contribute to an estimated global economic loss of USD 32 billion annual. To ensure food security and develop climate-resilient strategies (SDG 13), this study aimed to investigate the interactive effects of weed competition and drought stress on the physiological, biochemical, and yield responses of greengram. An experiment conducted over two consecutive years (2022 and 2023) evaluated the impact of two key weeds, Echinochloa colona and Trianthema portulacastrum, at the greengram critical competitive phase under both well-watered (WW) and drought-stressed (DS) conditions. The results revealed that E. colona exerted significantly greater adverse effects on greengram than T. portulacastrum, particularly under drought stress. This was evidenced by reduced relative water content (WW: 65.26%; DS: 62.31%), membrane stability index (WW: 66.58%; DS: 62.54%), and gas exchange parameters, along with markedly increased oxidative stress markers malondialdehyde (WW: 1.60-fold; DS: 2.08-fold), superoxide ion (WW: 4.04-fold; DS: 5.63-fold), and hydrogen peroxide (WW: 1.41-fold; DS: 2.23-fold). The findings underscore the greater competitive impact of E. colona on greengram, particularly under water-deficit scenarios, and highlight the urgent need for integrated weed and drought management strategies to safeguard food security and sustainability.