Effects of hydrogel on drought resistance of medicinal plant roselle (Hibiscus sabdariffa L.)

To investigate the effects of hydrogel on growth, yield, and some secondary metabolites of roselle (Hibiscus sabdariffa L.) under drought stress conditions, an experiment was conducted in a farm located in the south of Dalgan city, Sistan and Baluchestan province in the 2017-2018 crop year. This research was carried out as a split plot experiment in a randomized complete block design with three replications. The experimental treatments included drought stress as main plot at four levels (irrigation at FC (field capacity), 85% of FC, 70% of FC, and 55% of FC), and hydrogel consumption as sub plot at three levels (A200 hydrogel consumption, silicate hydrogel consumption, and no hydrogel consumption). The quantitative traits including plant height, number of sub-branches per plant, number of flower per plant, plant fresh and dry weight, sepal fresh and dry yield, and harvest index and qualitative traits including content of anthocyanin and sepal phenolic compounds were measured. The results showed that the highest amount of quantitative traits was obtained from full irrigation treatment with the consumption of A200 hydrogel. But there was no significant difference between this treatment and the treatments of full irrigation with silicate hydrogel consumption and full irrigation without hydrogel. Also, no significant difference was observed between the above three treatments and the treatments of both types of hydrogels application in 85% and 70% of FC. The qualitative traits increased with increasing the stress intensity. The hydrogel consumption in comparison with not consuming it led to a decrease in the amount of anthocyanin and sepal phenolic compounds due to the modification of stress conditions by hydrogel.