Evaluate the Effect of Green Fertilizer and Two Sources of Potassium on Growth , Yield , some Chemical Constituents of Roselle Plants (Cv. Sabaheia 17) and the Availability of Macronutrients in Soil after Harvest

Abstract

A field experiment was carried at El-Gemmeiza Agric. Res. Station, El-Gharbihya Governorate, Egypt during the two successive summer seasons of 2017 and 2018 to evaluate the effect of green fertilizer (faba bean) and two sources of potassium (mineral potassium sulphate (KS) 48 % K 2 O) or natural feldspar (KF) 10.6 % K 2 O with three levels 50, 75 and 100 % of the recommended rate (RR) beside untreated (control treatment) on growth, yield, sepals chemical constituents and the availability of macronutrients in soil after harvest of Roselle plants (cv. Sabaheia 17) under clay soil conditions. Fourteen treatments were carried out including the combinations of two levels of green fertilizers and six potassium fertilizes, while control treatments contain no fertilizers. A RCBD using a split plot was applied. Results revealed that growth and yield traits of Roselle plants including plant height, number of branches/plant, total dry weight/plant, fruit weight/plant, number of fruit/plant, seed weight/plant, sepals fresh and dry weight per plant and fed. and total yield of seeds/fed., leaf total chlorophyll and carotenoides, anthocyanin concentration, total carbohydrates, total acidity and P percentage in sepals were markedly improved when the green fertilizer combined with fertilizing with 75 % of the recommended Potassium rate (RR) in the form of feldspar (KF) (10.6 % K 2 O) equal 530.65 kg /fed., was applied.The interaction between green fertilizer and fertilizing with 100 % RR in the form of KF possessed the greatest availability of N, P, K, pH and EC in the soil after harvest. K2O at 50 , 75 and 100 % of RR in the form of KS equal 78.12, 117.18 and 156.24 kg/fad, respectively K2O at 50 , 75 and 100 % of RR in the form of KF equal 353.77, 530.65 and 707.54 kg /fad. respectively