Growth analysis, agronomic and physiological characteristics of three hybrid varieties of maize under deficit irrigation conditions

Determining appropriate deficit irrigation regimes and varieties under these conditions is necessary to optimize the use of available water in arid and semi-arid regions. In this regard, field experiments were carried out for two years (2014-2015) at the Moghan plain, Iran. The experimental design in each year was split plot based on randomized complete blocks with three replications. The main plots consisted of four irrigation levels: normal irrigation, 80% of maximum daily crop evapotranspiration (ETc), 70% ETc and 50% ETc. Three maize hybrids (SC704, SC703, SC705) were arranged in the sub-plots. Mean comparisons showed that deficit irrigation caused a significant decrease in grain yield and other agronomic traits, physiological characteristics (chlorophyll a, b and relative water content) and growth parameters (leaf area index, crop growth rate, relative growth rate). On the other hand, leaf rolling percentage increased due to the water deficit stress. By increasing deficit irrigation intensity (especially at 50% ETc), chlorophyll a, b and relative water content decreased in SC705 more than the other two hybrids (SC703, SC704) and the leaf rolling percentage at the severe stress condition reached to 60% in SC705. The highest grain yield (8.51 t/ha) and biomass (19.36 t/ha), averaged over two years, were observed under normal irrigation for the SC705 hybrid. However, this hybrid had minimum grain yield and biomass at 50% ETc. By increasing water deficit from normal irrigation to 50% ETc, significant decrease was observed for leaf area index, plant growth rate, relative growth rate and net photosynthesis rate of SC705. Due to the sensitivity of physiological characteristics and growth parameters to the deficit irrigation and the influence of grain yield from these traits, it seems necessary to prevent the occurrence of water deficit at critical stages of maize growth. In conclusion, due to the sensitivity of the SC705 to water shortage, this hybrid is not recommended to water deficit conditions and it would rather be planted when enough irrigation water is available. On the other hand, SC704 seems suitable for the water deficit environments, especially at the severe water stress condition (50% ETc).