The effect of irrigation levels and foliar application (zinc, humic acid and salicylic acid) on growth characteristics, yield and yield components of roselle (Hibiscus sabdariffa L.)

Introduction Hibiscus tea (Hibiscus sabdariffa) with the scientific name of the Mallow family (Malvaceae) is native to Africa, and in all tropical and warm cultivation. Roselle annual plants, short days and is self-pollinated. This plant is very sensitive to cold and frost, plant, and two different components to be used. Prohibiting the environmental factors on the growth and yield of crops and machinery, land the most important factor, especially in arid and semi-arid reduce the production goes. Salicylic acid can increase plant tolerance to drought stress and moderate water deficiency, as well as some of the growth has increased. Humic acid by increasing the activity of the enzyme Rubisco, increasing the photosynthetic activity of the plant. On the micronutrients that are essential for normal growth and reproduction of plants. Since the sprayed material to the plant in drought conditions helps to maintain or enhance performance, the purpose of this test is to determine the effects of irrigation levels and is sprayed on the plant Hibiscus tea. Material and method In order to investigate the effects of irrigation and foliar application levels (zinc sulfate, humic acid and salicylic acid) on Roselle in 2013, at Sarableh Research Station of Sirvan city in Ilam province, in a randomized complete block design with Split plot with three replications. The experimental factors were included three levels of irrigation with 100, 130 and 160 mm evaporation from class A pan and four substrate contamination factors including humic acid, zinc sulfate, salicylic acid and control. Land preparation operations (plow, disc, Leveler) was conducted in late April and then ground using a tractor to bed with a width of 60 cm and map implementation plan was prepared. Fertilizers triple superphosphate (100 kg/h), potassium sulfate (150 kg/h) for pre-planting and urea (200 kg/h) at 2 times the first week of August and first week of October as top dressing in conjunction with irrigation farms were added. To determine the percent oil by weight was used. Result and discussion Analysis of variance showed that the main effect of irrigation and spraying on all traits Except shoot fresh weight, dry weight and fresh weight sepals that had no significant effect. The results showed interaction of irrigation and spraying the length and diameter of fruits and vegetables had a significant effect there was no significant difference on other traits. The results of irrigation levels showed that the highest number of fruits per plant in 100 mm evaporation treatment was 56.34 and the lowest number of fruits per plant in 160 mm evaporation treatment was 45.27. The highest amount of anthocyanin with 0.26 (μg / ml) was obtained with salicylic acid foliar application while the lowest ones was recorded in the non-soluble state (control) with 0.2 (μg / ml). The result of irrigation showed that the highest (% 2.21) and loweast (% 1.98) essential oil were recorded in the treatment of 160 and 100 mm evaporation treatment, respectively. Conclusion In general, the results of this study showed that drought stress reduced the yield of Rosell in quantitative and qualitative terms. Also, the foliar application (salicylic acid, zinc sulfate and humic iodine) had a significant role in improving the quality and quantity performance of medicinal herbs. Foliar application of zinc sulfate was identified as the best treatment for increasing the essential oil. However, salicylic acid had the greatest effect on fruit weight gain, but its effect was not significant compare to zinc sulfate. Therefore zinc sulfate foliar application was identified as the best treatment.