Investigating of zeolite role in modifying the effect of drought stress in hemp: Antioxidant enzymes and oil content

Abstract

Hemp is one of the industrial plants so that its oil is extracted from its grains and its quality and quantity are affected by abiotic stresses, especially water deficit. In order to study the physiological and biochemical responses of hemp to drought stress and zeolite application, a two-year experiment was performed in the experimental field of Shahrekord University (Shahrekord, Iran). Four levels of irrigation including severe stress, moderate stress, mild stress and well-watered (40 %, 60 %, 80 % and 100 % of crop water requirement, respectively) and 3 rates of zeolite clinoptilolite application including 0, 5 and 10 t ha−1 during growth season in 2014 and 2015 were studied as split plot.Water deficit reduced the morphological characteristics, chlorophyll content, dry matter and oil yield, and increased carotenoids content, antioxidant enzymes and oil content. The percentage of dry matter and oil yield reduction was improved with zeolite application, and the lowest percentage of dry matter and oil yield reduction compared to control was obtained from 10 t ha−1 zeolite under mild stress. Zeolite also greatly kept the process of antioxidant enzymes close to suitable conditions and reduced their activity, especially under mild stress. Thus, zeolite application reduced the negative impact of water deficit on these traits in hemp. It seems that 10 t ha−1 zeolite under mild stress conditions increases the threshold of hemp perception of water deficit and the activity of its defense systems has been reduced dramatically.