Nahed, M. Rashed* and E.A. Moursi( 2016). Effect of skipping one irrigation during different growth stages and foliar application of micronutrients on roselle (Hibiscus Sabdariffa, L.) plants and some water relations in heavy clay soils, EgyptJ. Agric. Res. Kafr El-Sheikh Univ., 42 (1), 83-108
Abstract: Water considers the most important component of life, it is rapidly becoming a critically short commodity for humans and crop production. Drought is one of the major a biotic stresses in agriculture worldwide. In order to study the effect of water stress (skipping one irrigation at vegetative, flowering and fruits formation growth stages) in comparison with traditional irrigation in addition to foliar application of chelated iron , zinc , manganese and their combination on growth , productivity of dark roselle (Hibiscus sabdariffa, L.) plants and some water relations under surface irrigation system. Two field experiments were conducted at the Experimental Farm of Sakha Horticulture Research Station, Kafr El-Sheikh Governorate during the summer seasons of 2014 and 2015. The results revealed that skipping one irrigation at any of the three studied stages significantly reduced all the tested growth parameters and yield production as compared with unstressed plants (control). However, subjecting roselle plants to water stress at flowering stage had the most negative effect on growth parameters and yield production. On the other hand, water stress had a stimulating effect on chemical composition (total anthocyanin, T.S.S, acidity%, pH and T.S.S acidity ratio). The present study also indicated that foliar application of chelated Fe ,Zn, Mn and combination among them had a positive effect on growth parameters, yield and chemical composition but chelated Zn application surpassed the other nutrients in counteracted the deleterious effects of stress on chemical composition. Application of chelated Fe+ Zn + Mn showed the significant increasing in calyxes yield/fed, fibers yield/fed and seeds yield/fed. Also, the highest overall mean values for seasonal amount of water applied, consumptive use, water productivity and productivity of irrigation water for all plant organs were recorded under traditional irrigation. Meanwhile, the lowest overall mean values were recorded under water stress treatments and the amount of water saving is 8.89%. Concerning, micronutrients as foliar application, the highest overall mean values were recorded under application of chelated (Fe+Zn+Mn) in comparison with non-application and application every nutrient as alone. Regarding, consumptive use efficiency, the highest mean values were recorded under skipping one irrigation at vegetative growth stage, but the lowest were recorded under traditional irrigation. Also, the highest values were recorded under foliar application treatment (Fe+Zn+Mn) comparing with non- application and application every nutrient as alone .This study can be concluded that skipping one irrigation at vegetative growth stage when cultivated roselle plants under studying region with chelated ( Fe+ Zn+ Mn) foliar application which counteracted the deleterious effects of stress and chelated Zn foliar application only to increase chemical component .Nevertheless, reduction in yield offset saving nearly 9% of water applied.
Keywords: (roselle , water stress, iron, zinc , manganese , foliar application)
