The Effect of Water Deficit Stress and Foliar Application of Zinc Oxide Nano Particles on Morphophysiological Characteristics of Landraces Withania coagulans L.

In order to evaluate the effect of water deficit stress and foliar application of zinc oxide nano particles on morphophysiological characteristics in Withania coagulans L. landraces, a factorial experiment in a completely randomized design with 3 replications was setup. The experiment included various irrigation regimes (control), (medium stress), (severe stress), four landraces (Fanuj, Khash, Saravan and Sarbaz), with and without foliar application of zinc oxide nano particles. The experiment was conducted in green house of the faculty of Agriculture, Tarbiat Modares University, during 2018-2019. The highest leaf area (538.92 cm2) was related to Sarbaz in control irrigation and the lowest leaf area (245.88 cm2) was related to Khash in severe water deficit stress. Based on the comparison results, the mean of maximum plant dry weight (1.76 g) was related to Sarbaz and control irrigation and the lowest plant dry weight (0.63 g) was related to Fanuj and severe water deficit stress. Also, the highest amount of chlorophyll a (2.55 μmol.g-1) was related to Khash, control irrigation and foliar application of zinc oxide nano particles. The highest amount of chlorophyll b (1.26 μmol.g-1) was related to Fanuj, control irrigation and foliar application of zinc oxide nano particles, which was not significantly different from other landraces. Also, the lowest amount of chlorophyll b (0.62 μmol.g-1) was related to Khash, severe water deficit stress and without foliar application of zinc oxide nano particles. Sarbaz had the highest amount of anthocyanin (0.3 μmol.g-1) in the treatment of severe water deficit stress and lack of foliar application of zinc oxide nano particles, which was not significantly different from Saravan. Also, the lowest amount of anthocyanin (0.146 μmol.g-1) was related to Fanuj in the treatment of severe water deficit stress with foliar application of zinc oxide nano particles. Severe water deficit stress reduced the amount of traits tested. Also, the Sarbaz showed good tolerance to water deficit stress conditions compared to other landraces. The foliar application of zinc oxide nano particles also improved plant growth and increased some of the tested traits under stress conditions.