Effect of zeolite on growth and physiological parameters of proso millet (Panicum miliaceum L.) under deficit irrigation management

The production of crops especially cereals in Iran is a challenge due to the presence of arid and semi-arid climates. Zeolite application is one of approach to ameliorate the effect of water deficit on crops. High water absorption zeolite is able to absorb water in the soil to a maximum level and maintain it for a long time within its network. Regarding the problem of water deficit and the necessity of managing agricultural production in conditions of water deficit and the possibility of using millet as a premature and compatible plant with most regions of Iran, this experiment was conducted out to evaluation of the effect of deficit irrigation and zeolite application on Proso millet. In order to study the influence of deficit irrigation and zeolite application on Proso millet, an experiment was conducted as strip block in randomized complete block design base, at Shahrekord University, in 2015. Irrigation regime gad four levels (supply of 100, 75, 50 and 25 percent of field capacity) and zeolite had three levels (0, 0.5 and 1 kg m-2). Plant water requirement was calculated by FAO Penman-Monteith equation. Irrigation regimes were applied at V4 stage (4th three foliate leaf has unfolded) and continued until the end of the growing season. Plant water requirement was calculated by FAO Penman-Monteith equation. Results showed that leaf area index (LAI) had sigmoidal pattern. The highest LAI (3.3) was recorded in 100%FC and one kg m-2 zeolite interaction. Also lowest LAI (1.1) was observed in 25% FC and 0 kg m-2 zeolite interaction. Results also showed that water deficit reduced dry matter accumulation but in each irrigation treatment increase of zeolite amount resulted in ameliorated the effect of deficit irrigation. Maximum and minimum of dry matter were recorded in 100% FC*1 kg m-2 zeolite and 25 % FC* 0 kg m-2 zeolite interactions respectively. The crop growth rate in all of the treatments increased until mid-growing season and then reduced. The deficit irrigation reduced membrane stability but zeolite application increased it. Membrane stability in 75, 50 and 25 percent of FC reduced by 23%, 66% and 57% respectively. Water deficit also reduced relative water content. RWC were reduced by 13%, 26% and 41% in 75, 50 and 25 percent of FC respectively. Stomatal conductance reduced by deficit irrigation but in each level of irrigation treatment the highest stomatal conductance was observed in 1 kg m-2 zeolite application condition. The grain yield of Proso millet was higher under 1 kg.m-2 zeolite application condition in all deficit irrigation treatments. The highest grain yield reduction compared to control treatment (100% FC and no zeolite application) was observed in 25% FC and no zeolite application condition. Finally results showed that however zeolite application under 100% FC condition had little effect but under deficit irrigation condition, zeolite reduced the harmful effects of deficit irrigation on studied traits and in this context uses of 1 kg.m-2 zeolite is recommended.