Effects of nano and bio-nano fertilizer on physiological, biochemical characteristics and yield of roselle (Hibisicus sabdariffa L.) under drought stress

The replacement of chemical inputs with ecological compatible inputs (organic amendments) seems necessary as a step towards transition from common to sustainable agriculture. In this regard, an experiment was conducted at the experimental farm, University of Zabol, in split plot based on randomized complete block design with three replications, during 2015. Four drought stress levels of 30, 50, 70 and 90 percent of available water were considered as main plots and four levels of nano and nano bio-fertilizers were considered as sub plots. Main effects of fertilizer, drought stress and their interaction were significant for all studied traits. Maximum of photosynthetic pigments, fresh and dry weight of sepals were obtained under treatment of 70% of available water irrigation and foliar application of nano-iron fertilizer. The highest amount of anthocyanin, proline and carbohydrate osmolytes belonged to 30% of available water irrigation and the highest relative water content of leaves belonged to 90% of available water irrigation and foliar application of nano-iron fertilizer. The results of cluster analysis and principal component analysis showed that the best studied treatment was 70% of available water irrigation including with foliar application of nano-iron fertilizer. Spraying nano-iron fertilizer mitigated the effects of drought stress and increased the quantity and quality of roselle sepals