The Impact of Different Levels of Irrigation, Planting Date and Fertilizer Management on Yield and Yield Components of Roselle (Hibiscus sabdariffa L.) in Minab

  Roselle (Hibiscus sabdariffa ) is considered as a member of Malvaceae family which is cultivated across all tropical and warm areas. More than 300 species of Hibiscus are found in tropical and subtropical regions across the world. Roselle is annual and self-pollinated plant. This plant is very sensitive to cold and glacial, it is multipurpose plant and its various components are used. Severe water restrictions and the high water costs cause in some areas, the optimal level of water to become lower than the required level for maximum production. Nowadays, appropriate irrigation management and the cultivation of drought-resistant plants are regarded as strategies to deal with drought stress. Roselle is one of the few drought resistant plants. To study the effect of different levels of irrigation, planting date and fertilizer management on yield and yield components of Roselle, an experiment was contacted in Agricultural Research Station, 105 kilometers East of Bandar Abbas, Minab city, Iran. An experiment was conducted as split-split-plot based on a randomized complete blocks design with three replications. Treatments included irrigation levels in three levels (100,80 and 60 percent evapotranspiration from reference crop) as main plots, planting date in three levels (June 15, September 10 and October 1th) as subplots and three levels of fertilizer (Cow manure, chemical fertilizer 50% and 50% cow manure and chemical fertilizers) are allocated as sub-sub plots. The results showed that the highest plant height (127.7 cm) and stem diameter (1.97 cm) were obtained in irrigation after 60 percent evapotranspiration from reference crop. The highest number of growing stems (3.20 stems) and sepal dry weight (18.48 g) were shown in 100 percent evapotranspiration from reference crop. The total number of stems, the number of generate stems, flower dry weight and plant dry weight were decreased by increasing the percent evapotranspiration from reference crop. Thus, the lowest total number of stems (7.70), the number of generate stems (4.52), flower dry weight (4.28 g. per plant) and plant dry weight (377.1 g. per plant) were shown in 100% evapotranspiration of the reference treatment. Most of the studied criteria were decreased by delaying sowing date. The lowest stem height (108.2 cm), stem diameter (1.32 cm), total number of stems per plant (7.3), the number of generate stems per plant (3.94), sepals dry weight per plant (16.15 g), flower dry weight per plant (3.65 g), total dry weight per plant (212 g), were obtained on 1th October sowing date. The highest stem diameter (1.85 cm), total number of stems per plant (10.78), the number of growing stems per plant (7.22), sepals dry weight per plant (21.02 g), flower dry weight per plant (6.59 g), total dry weight per plant (420.02 g), were obtained under 100% chemical fertilizer treatment. The highest plant height (125.1 cm) and the number of growing stems per plant (3.61) were obtained under 100% chemical fertilizer treatment+100 percent evapotranspiration from reference crop under 1th of October treatment. The lowest stem diameter, the number of generate stems, the number of growing stems, sepals dry weight and total dry weight in each plant were obtained under 100% chemical fertilizer treatment+100 percent evapotranspiration from reference crop under 1th of October treatment. The highest stem diameter, the number of generate stems per plant and flower dry weight per plant were observed under 100% cow manure+60 percent evapotranspiration from reference crop. The highest number of stems per plant, the number of generate stems per plant, sepals dry weight per plant and dry weight of flower per plant were obtained under 100% cow manure on 15 July sowing date treatment. The results showed that most of the studied criteria were decreased by delaying sowing date from June to October. The highest dry weight of flower per plant and sepals yield were obtained under 100% animal manure+ June 15 sowing date treatment. The lowest dry weight of sepals per plant was shown under 100% of evapotranspiration irrigation of the reference crop.