Effect of defoliation and late-season stress on yield, yield components and dry matter partitioning of grain corn in Kermanshah region, Iran

Abstract

In order to examine the effect of defoliation and late-season stress on yield, yield components and dry matter partitioning of grain corn cv. Single-cross 704 in Kermanshah, Iran, an experiment was conducted in June 2011 as a split-plot experiment based on a Randomized Complete Block Design with three replications. The main plot was devoted to defoliation at seven levels of control, tassel removal, cab leaf removal, upper leaves removal (upper than the position of cab formation), lower leaves removal (lower than the position of cab formation), removal of three lower leaves and removal of three upper leaves. In addition, the sub-plot was devoted to water stress including no irrigation and irrigation intervals of 6, 12 and 18 days. The treatments were imposed on 50% of plants at tasseling stage. It was found that the highest grain yield (1377.23 g m-2) was produced by control and the lowest one (1014.49 g m-2) by the treatment of lower leaves removal. Also, the effect of irrigation interval was significant on this trait, so that the highest yield (1404.41 g m-2) was produced by the irrigation interval of 6 days and the lowest one (805.36 g m-2) by no-irrigation treatment. The highest 1000-grain weight (302.04 g) was obtained under control treatment and the lowest one (245.13 g) under the treatment of lower leaves removal. The highest dry biomass (3450.40 g m-2) was produced by control and the lowest one (2570 g m-2) by the treatment of upper leaves removal. In addition, the effect of irrigation interval was significant for dry biomass. The highest dry biomass (3464.39 g m-2) was produced under 6-day irrigation interval and the lowest one (2118.64 g m-2) under no irrigation treatment. The highest leaf dry weight (465.98 g m-2) was observed in control and the lowest one (296.38 g m-2) in the treatment of upper leaves removal. The effect of irrigation interval, too, was significant on this trait, so that the highest leaf dry weight (460.55 g m-2) was observed in 6-day irrigation interval and the lowest one (267.07 g m-2) in no-irrigation treatment. The highest leaf area index (4.27) was related to control and the lowest one (2.91) to the treatment of lower leaves removal. Additionally, the effect of irrigation interval was significant for this trait, so that the highest and lowest leaf area indices (4.16 and 2.42) were obtained under 6-day irrigation interval and no irrigation treatment, respectively. Results revealed that defoliation did not significantly influence stem dry weight, but the effect of irrigation interval was significant for it, so that the highest and lowest stem dry weight (1152.14 and 740.66 g m-2) were produced under 6-day irrigation interval and no-irrigation treatment. The effect of defoliation and water stress was not significant on harvest index. The interaction between defoliation and water stress was not significant for the studied traits.