Effect of antitranspirants substances and drought stress ameliorator on leaf area duration, water use efficiency and grain yield of chickpea (Cicer arietinum L.) under different irrigation regimes

Terminal drought depending on the geographical area and climatic conditions during the growing season reduces 30 to 60 percent of the chickpea grain yield (Kanouni et al., 2003). By developing new crop management practices and irrigation methods and also using drought stress tolerant varieties, we can compensate the reduction in chickpea yield due to drought stress (Saman et al., 2006). One of the agricultural management is the use of antitranspirate substances such as chitosan (Jan- Mohammadi et al., 2014) and drought stress ameliorators in plants that can tolerate plant stress through physiological activities and intensification of defence mechanisms. The main purpose of this study was to investigate the effects of antitranspirants substances and drought stress ameliorators on grain yield of chickpea under different irrigation regimes. This experiment was conducted in Ekbatan Research Station in Hamedan during the 2014-2015 growing season. A factorial split plot experiment based on CRD design with three replications was used. Four irrigation regimes including non-irrigation, irrigation at flowering stage, irrigation at podding stage and two irrigation flowering + podding stages in main plots and anti- transpiration substances (kaolin 5%, chitosan 200 ml-1) and stress ameliorators (chloride calcium 5 mM, sodium selenate 40 mgL-1) with non spray (control) treatments were placed as factorial in subplots. Seeds were planted with 30 cm row spacings and 31 plants per m2 density at 5 cm depth of soil on March 5th. Weed control was done by hand. Application of stress ameliorators was performed in two stages before and after flowering. Spraying of anti-transpiration substances in the middle of the podding stage was done by hand sprayer on the leaves. In this investigation, the traits related to yield were studied. The results of analysis of variance showed that in addition to the effects of two-way interaction factors, the three-way effects of studied factors on pod length, diameter of grain, and leaf area duration at l% level and the number of pods per plant, number of seeds per plant, grain protein, grain yield, biological yield and water use efficiency traits were significant at 5% level. Twice irrigation regime with chitosan and calcium chloride applications had the highest leaf area duration, and then the once irrigation in podding or flowering stages with chitosan and calcium chloride applications had the maximum leaf area duration. Also, the highest grain diameter, number of pods per plant and number of seeds per plant were obtained in two irrigation regimes with the use of chitosan and calcium chloride. The maximum percentage of grain protein in non-irrigation (dryland) regime was obtained by chitosan and calcium chloride consumption, and then by sodium selenate treatment. The grain protein content of seeds in once irrigation at flowering or podding and two irrigation regimes in flowering + podding stages with spraying chitosan and calcium chloride had 4, 8 and 12 percentage reduction, compared to non-irrigated conditions, respectively. In general, in different irrigation regimes, the spray of chitosan and calcium chloride was more effective than kaolin and sodium selenate on most of the studied traits. The chitosan along with calcium chloride protects the leaf water content and has a positive effect on the development of leaf area which prevents the earlier senescence of the leaves during reproductive stages under drought. Also, their application improves the leaf area duration at the end of the growing season and increases the water use efficiency of the plant. In addition leaf area duration, the highest grain yield and water use efficiency were obtained by irrigation regimes during flowering + podding stages and chitosan spray with calcium chloride. The podding stage irrigation to amount 1910 m3 with chitosan spray and calcium chloride application increased the grain yield by 192% and water use efficiency by 65% compared to the non-irrigation regime. As a result, due to the shortage of atmospheric precipitation during the growing season of chickpea, especially the occurrence of drought at the end of the season, once irrigation regime in the podding stage and spray of chitosan and calcium chloride with mentioned concentrations can be beneficial to increasing the grain yield of chickpea, although in the case of water supply, two irrigation is recommended during flowering and podding stages.