Associative effect of Rhizobium and Phosphate- solubilisng bacteria on growth and Nutrient uptake of Faba Bean (Vicia faba L.).

A greenhouse pot experiment was conducted to study the effect of inoculation of efficient phosphate-solubilising bacteria (PSB) isolate and rhizobium on the growth and yield of faba bean on soils collected from two yield-depleted and two yield-sustained areas. The two yield-depleted and two yield-sustained areas. The two yield-deplleted areas were Mehal meda and Molale while the two yield-sustained areas were Ankober and Keyit. The treatments included one SPB isolae (Meh-101), one Egyptian rock-phosphate as phosphorus sources (ERp) and one rhizobia, Rhizobium sp. (EAL-103). There were seven treatments (T1, T2, T3, T4, T5, T6, and T7,) laid out in randomized complete blocks design (RCBD) in three replicates in the greenhouse. The result showed that after inoculation, the PSB isolate established well in the rhizosphere of faba bean with the highest population count occurring on the 7th week of growth. The Rhizobium sp. (EAL-103) was not able to from effective nitrogen-fixing nodules in the yield-sustained areas. Inoculation of PSB isolate along with the application of rock-phosphate significantly improved (P0.01) the dry-matter yield of faba bean compared to the control with and without rhizobium. The dual inoculation of the micro-organisms together with the rock-phosphate increased the dry-matter yield by 75% in Molale and 62% in Mehal Meda. When compared with the control except inoculation of PSB alone on Ankober and Keyit soils the nitrogen content of faba bean showed highly significant variation (P0.01). the inoculation of the micro-organisms significantly improved the phosphorus uptake of the faba bean as compared to the control. Dual inoculation of the micro-organisms (rhizobium and PSB) together with the rock-phosphate highly increased all the growth parameter measured both in yield-sustained (Ankober and Keyit) and yield-depleted (Mehal Meda and Molale) areas. The overall result showed that inoculation of rhizobium and PSB together with rock-phosphate improved faba been yield, enabling large-scale manipulation of these biofertilizers for the purpose of supplementing or replacing chemical fertilizer in agricultural input.