Effect of nano-potassium fertilizer on some morpho-physiological characters of peppermint (Mentha piperita L.) under drought stress

In order to investigate the effects of low water stress and nano potassium fertilizer on some vegetative and physiological characteristics of peppermint ,an experiment was conducted in greenhouse condition in 2014 as factorial based on randomized complete block design with three replications. Different levels of water deficit include: 100% field capacity (FC), 80% of field capacity (80% FC) and 60% of field capacity (60% FC) and four nano-potassium foliar application (control (no sprayed (T1), spray (T2:2/1000), (T3:4/1000), (T4:6/1000)) was applied. Plant height, number of tillers per plant, fresh and dry yield, weight percent of essential oil and oil yield, chlorophyll a, chlorophyll b , RWC, prolin and total soluble carbohydrates were measured. The results showed that with increase in application of nano-potassium fertilizer ,the plant height, number of tillers per plant, fresh and dry weight, yield and percent of essential oil , chlorophyll a, chlorophyll b , RWC, prolin and the total soluble carbohydrates increased. The effect of drought stress showed that control treatment (FC) was significant and account for the highest means without chlorophyll b, prolin and percent of essential oil. In general, with increasing drought stress, the essential oil percentage was added. The highest dry weight (4.81 g per pot), oils yield (7.52 g per pot) and total soluble carbohydrates (2.13 µg per g fersh weight) were obtained in foliar application in control, moderate stress and severe stress treatments, respectively. In total, nano-potassium spray application reduced the effect of dehydration stress.