JWSS - Journal of Water and Soil Science

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As increasing of disaster such as drought and pest invasion in recent decades, it is essential to find out practical approaches in optimizing water use and water management for reduce the adverse effects of this disaster in agriculture. In order to study the effects of water stress and pest stress on corn yield, an experiment was conducted in the research farm of Isfahan University of Technology. In sprayed and non sprayed of the field, a factorial design, based on the completely randomized block, was carried out with three treatments of irrigation regimes including intensive stress (50% water requirement), moderate stress (75% water requirement) and no water stress in four stages of corn growth from seed germination until tasseling, from tasseling until milky, from milky until harvest and the whole period of corn growth, in four replications for one year (2005). The results showed that applying water stress on corn reduced seed yield between 6-62% and also decreased other agronomic characters except protein percentage. Water stress in non sprayed condition, reduced significantly more physiological characteristics of corn compared to the sprayed condition. Intensive water stress and pests stresses increasd 3 and 13% of percentage protein, respectively. In sprayed condition applying moderate stress in first stages of corn until the first of third stage is suggested in drought condition.

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In order to investigate the effect of pest and water stresses on different growing stages of cowpea (Vigna sinensis) and pest occurrence, an experiment was conducted in Khazaneh Research station of Isfahan University of Technology. The experiment was carried out in a factorial complete randomized block design, in two different farms, with and without insecticide application. The treatments included severe water stress (50% water requirement), moderate water stress (75% water requirement) in four stages of cowpea growth, the first stage (from seed germination until flower in, second stage (from flowering until pod-filling), third stage (from pod-filling until harvesting) and the whole period of cowpea growth, in three replications. There was a control treatment in each farm with no stress in the whole period of cowpea growth, in three replications. The results showed that water stress had no significant effect on percentage of protein and mineral material. Result also showed that water stress had a significant effect (P≤ 0.01) on population of insects. Water stress significantly (P≤ 0.01) reduced the population of nymphs and adults of Empoasca decipiens Paoli and leaf minor damages, but water stress increased population of Thrips tabaci Lind. Considering the duration of first stage of growth (63 days), it is concluded that this stage had less sensitivity to water stress than the other stages. In regions, where farmers encounter water shortage for cowpea planting, the best performance can be obtained when moderate water stress (75% water requirement) is applied at the first stage of growth.