Elucidating the interactive effects of drought, weeds, and herbicides on the physiological, biochemical, and yield characteristics of rice

Rice yields are significantly influenced by both biotic and abiotic factors, like drought stress and weed infestation being prominent contributors to substantial crop losses. Environmental conditions, including drought stress, can impact the effectiveness of herbicides. This study aims to investigate the impact of drought stress on the efficacy of the herbicide (cyhalofop + penoxsulam) against the weed species, Echinochloa colona (L.) Link, and Alternanthera paronychioides A. St.-Hil. Additionally, the study aims to assess the potential consequences of improper weed control, including the survival of weeds and their subsequent adverse effects on rice.

The herbicide was applied to rice plants under two distinct conditions: well-watered (WW) and drought-stressed (DS) at 8 days following the suspension of irrigation. The herbicide’s effectiveness against two weed species, E. colona and A. paronychioides, was assessed by quantifying weed growth and biomass.

The findings elucidate a reduction in the herbicide efficacy against both the weeds under DS conditions. However, under DS the decline in herbicide effectiveness was more significant against E. colona than A. paronychioides, leading to inadequate weed control. As a result, the survival of these weeds further exacerbates oxidative stress in rice plants. The magnitude of oxidative stress was excess in rice with E. colona than A. paronychioides, and it significantly reduced the yield under both WW and DS.

The study highlighted that under drought conditions rice is more susceptible to E. colona infestation than to A. paronychioides with increased oxidative stress and reduced yield. The study underscores the critical importance of understanding complex interactions between multiple environmental factors in developing adaptive, climate-resilient weed management strategies, essential for safeguarding rice yields against the combined impacts of drought stress and weed interference, and addressing climate change-related challenges to food security.