Responses of Calyx Phytochemical Characteristic, Yield and Yield Components of Roselle (Hibiscus sabdariffa L.) to Different Sowing Dates and Densities

In order to evaluate the effects of sowing date and intra rows spacing on yield, yield components and some phytochemical characteristics in Roselle, a field experiment was conducted as a split plot layout based on randomized complete block design with three replications in 2013 and 2014 growing seasons. Five sowing dates were considered as the main plots (11th and 30th of March, 14th of April, 5th and 22th of May) and three intra rows spacing were considered as the subplots (50, 75 and 100 cm). The results indicated that delayed sowing date significantly reduced plant height, number of bolls, number of branches per plant, calyx dry weight, calyx yield, seed yield and biomass yield. Plant height, calyx yield, seed yield and biomass yield were increased by reducing intra rows spacing. Reducing the intra rows spacing caused decrease in number of branches, number of bolls, seed weight, calyx and plant dry weights. Anthocyanin and vitamin C were significantly reduced by delaying in sowing date. Although sowing dates had no significant effect on total phenol but antioxidants were influenced by sowing date. Furthermore, intra rows spacing did not caused any significant effect on phytochemical traits of Roselle. Based on the obtained results, it seems sowing hibiscus tea in the late of March to mid-May and 50 cm intra rows spacing, under hot and dry climate condition would be suitable for increase the final yield of Roselle.