Interactional Impacts of Drought and Weed Stresses on Nutritional Status of Seeds and Water Use Efficiency of Peanut Plants Grown in Arid Conditions

Globally, rationalizing and converting each drop of irrigation water into food is a crucial act in agricultural production, particularly with climatic change concerns. Thus, the current study seeks to find an integral practice between irrigation pattern and weed control for saving the irrigation water in peanut fields with improving the nutritional value of the seeds. In sandy loam soil, under two irrigation regimes (75 and 100% of crop evapotranspiration—ETc₇₅ and ETc₁₀₀, respectively), the responses of peanut pod yield and quality (seed oil, N, P, and K contents) and water use efficiency to six weed control treatments (bentazon, clethodim, bentazon + hoeing once,clethodim + hoeing once, hoeing twice and unweeded) were evaluated. The obtained data of 2016 and 2017 seasons illustrated that whether using ETc₇₅ or ETc₁₀₀, hoeing twice showed the highest efficiency of weed control in peanut. Reduction in yield was diminished from 15.1–16.9% in unweeded plots to 9.0–9.7% in weeded ones. Controlling weeds led to a decrease in their efficiency for exploiting the applied water. That decrease amounted to 64.4 and 64.3% reductions with ETc₁₀₀ as well as 66.9 and 64.4% reductions with ETc₇₅ in the 1st and 2nd seasons, respectively. Peanut plants consumed less water under ETc₇₅ than ETc₁₀₀ to produce one kilogram of pods by about 17.9% in weeded plots (mean of applied weeded treatments) as well as 10.1% in weedy conditions. Also, ETc₇₅ plus weeded practices raised the benefit/cost by 52.3% compared to unweeded one. In conclusion, the interactional impact of irrigation and weed control proved that peanut plants can be irrigated as much as 75% of evapotranspiration under water shortage conditions with hoeing twice or herbicide use. Selecting the appropriate weed control practice is a vital act for water saving and keeping productivity, quality and returns of peanut cultivation in arid regions.