Abstract

Corn production management including irrigation and planting pattern might be different under various conditions. This research was conducted to study the effects of different levels of irrigation and planting pattern on grain and biological yield, yield components, and water use efficiency of grain corn (hybrid SC.704) in 2010 cropping season at Natural Resources and Agricultural Researches Center of Khuzestan, south-west Iran. The study was split-plot experiment, using Randomized Complete Block Design (RCBD) with three replicates. Three irrigation levels consisting of optimum irrigation (I₁), drought moderate stress (I₂) and drought severe stress (I₃), (irrigation based on 100, 80 and 60% water requirement, respectively) were considered as main plots and subplots consisted of two planting pattern, planting in furrow (P₁) and planting on raised bed (P₂). The amount of water applied was determined by Class-A Pan evaporation every day. Required irrigation water was applied as 70 mm of evaporation of Class-A Pan. The total evaporation from Class-A Pan was measured with a manual limnimeter that has 0.1 mm accuracy. These measurements were checked with the readings from the water flow meters mounted in every plot. The results indicated that the effect of drought stress and planting pattern on grain and biological yields was significant at 1% probability level. The maximum grain yield of about 998 gm^-2 was obtained from optimum irrigation treatment. Drought severe stress reduced the grain yield by 30% compared to the optimum irrigation condition. This reduction was mainly due to reduction in grain number per ear and average of grain weight. Step-wise regression analysis indicated that about 88% of grain yield variation was related to the grain number per ear. Increasing amount of water applied, while planting in furrow improved economical and biological water use efficiency mainly due to increased grain and biological yields. The results also indicated that selecting suitable treatments )optimum irrigation with planting in furrow system( and change in leaf area index would be optimal for corn grown in semi-arid regions with saline soil similar to the area in south west of Iran where this study was conducted and can cause plant growth increase and high yield access.

Key words: Corn, irrigation, planting pattern, water use efficiency.