maize hybrids performance under varying irrigation regimes: i. chlorophyll fluorescence, growth and grain yield

iran is mainly situated in a dry climate part of the world. due to the limiting and scarce water resources, crop production in the country is increasingly facing water shortages. a field experiment was conducted to investigate the impact of irrigation regimes on growth, chlorophyll fluorescence and grain yield of maize in 2006 at the research farm, college of agriculture, isfahan university of technology, employing a 3-replicate split-plot rcbd. four irrigation regimes (i1, i2, i3 & i4) constituted the main plots while four corn hybrids (sc 704, sc700, sc500 and tc647) served as subplots. such chlorophyll fluorescence parameters as f0, fm and fv/fm in addition to growth and grain yield attributes were studied. while hybrids differed in their f0 at leaf10 stage, they differed with regard to fm at tasseling stage. plant height and lai decreased with drought. grain yield and yield components differed among hybrids and among irrigation regimes, with i4 yielding the lowest grain, as compared to other irrigation regimes. sc700 outperformed other hybrids in terms of grain yield. it seems that, at least according to the present study, a decreased photosynthetic area leaves a more pronounced impact on plant productivity, compared to a decreased efficiency of psii under drought conditions. since the fv/fm for different levels of irrigation applied, in this experiment, were not significantly different, using the latter ratio doesn't seem suitable for a determination of irrigation timing in the field.