Effect of Nutritional Management on Yield and Yield Components of Roselle (Hibiscus sabdariffa) as a Medicinal Plant in Mashhad Condition

Roselle (Hibiscus sabdariffa) is an annual plant with a height of about 64 to 429 cm belongs to Malvaceae family. Roselle is self-pollinated and sensitive to cold. Sepals of Roselle are used in food and pharmaceutical industries. It has been reported that Roselle is not native to Iran but it is cultivated extensively in Sistan and Baluchistan province, Iran. In order to achieve high quality and quantity yield of Roselle sepal it is necessary to improve nutritional systems of plant. Proper management of soil fertility and plant nutrition can preserve environment, improve biodiversity and also increase inputs efficiency. Results showed that use of nutritional resources will improve plant growth. Organic fertilizers such as compost can improve soil fertility as an important source of food that increase yield of plants. Nabila and Aly (2002) observed that use of hen and cow manure increased plant height, number of lateral branches, numbers of fruit and sepal yield of Roselle. Each plant species has the maximum potential in favorable conditions. Therefore, evaluation the effect of climatic and agronomic factors and nutritional management for plants is essential. This experiment was conducted to evaluate the yield and yield components of Roselle in response to use of single and combined nutritional resources.
Materials and Methods : In order to study the effects of single and combined organic, biological and chemical fertilizers on yield and yield components of Roselle (Hibiscus sabdariffa), a field experiment was conducted with 12 treatments based on a Randomized Complete Block Design with three replications at Research Station, Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, in 2013-2014. Treatments included: 1- mycorrhiza (Glomus intraradices), 2- cow manure, 3- chemical fertilizer, 4- vermicompost, 5- chemical fertilizer cow manure, 6- chemical fertilizer vermicompost, 7- chemical fertilizer mycorrhiza, 8- cow manure mycorrhiza, 9- vermicompost mycorrhiza, 10- cow manure vermicompost mycorrhiza, 11- control. Roselle seeds were planted in seedling trays at greenhouse in mid-March 2014. Then seedlings transferred to field in last April 2014. The distance between rows and plants were 75 and 25 cm, respectively. Chemical fertilizer (200 kg ha-1), vermicompost (8 ton ha-1) and cow manure (32 ton ha-1) were put at the depth of 30 cm soil. Along with the cultivation Glomusintraradice was used 30 g per seedling. Roselle was harvested in mid-October before the arrival of the first winter cold in Mashhad. Statistical analysis of the data was performed by using of Minitab Ver.16. Also, means comparison were compared by Duncan multiple range test at 5% probability level.
The results indicated significant effect of treatments on most of the traits of Roselle. The maximum plant height (138 cm) was obtained in chemical fertilizer cow manure. The combined use of fertilizers increased plant height by 9% compared with using of single it. Results showed that the maximum height was observed by combined using of organic and chemical fertilizers. The highest sepal yield was observed in mycorrhiza (854.1 kg ha-1) and then chemical fertilizer cow manure (791.6 kg ha-1) and the lowest sepal fresh weight and yield (3202.1 and 420.8 kg ha-1, respectively) were obtained in cow manure treatment. Combined use of fertilizer improved sepal yield 11% compared with using of single it. Researchers concluded that combined use of fertilizers by creating a stimulatory effect on the balance of elements in the soil can be improved growth of plants. Also, the maximum amount of biological yield was obtained in vermicompost mycorrhiza (10482.9 kg ha-1) and then chemical fertilizer cow manure (9887.2 kg ha-1). Several studies showed that the combined application of manure and chemical fertilizers by improving soil physical properties and increasing the availability of nutrients, improve the efficiency of nutrient uptake and yield of plants.
Generally, combined application of organic and chemical fertilizers through improvement of growth indices, increased quantity yield of Roselle compared with single application. As well as, transplanting of this plant had a positive effect on sepal and biological yield. Therefore, with the advent of early winter cold in Mashhad, recommended that Roselle cultivated three month earlier as transplanting in the greenhouse.