Phosphorus Level Affects Brown Blotch Disease, Development and Yield of Cowpea
Application of Phosphorus in adequate concentrations could directly or indirectly reduce disease incidence and severity of cowpea brown blotch and improve the forage and grain yield. A field experiment was conducted to investigate the effects of level of phosphorus application on Brown Blotch disease of cowpea (Vigna unguiculata (L.) Walp), caused by Colletotrichum capsici during 2003, 2004 and 2005 planting seasons. Application of phosphorus was at 30, 60, 90 and 120 kg ha of P O. As P level increased numbers of petioles, 1 25 pods, nodules, seed/pod, leaf area and yield significantly increased. Disease incidence and severity of Brown Blotch were significantly reduced at 90 and 120 kg ha of P O was not affected irrespective of the method of 1 25 application. Application method did not affect yield. Reduction in brown blotch disease at higher levels of P was recorded.
Wheat performance as affected by pre-plant and foliar application of phosphorus under inoculation with arbuscular mycorrhizal (AM) and non-inoculation
Increased cost of chemical phosphate fertilizer in the world and huge reserves of indigenous phosphate rocks reveals the importance of using of these resources. Little information is on the combined effect of mycorrhizal fungi and foliar application of P and the types of phosphate rocks in phosphate uptake. An experiment was conducted in during 2011-2012 growing season to determine the effects of foliar and pre-plant application of P on wheat yield and yield components in wheat inoculated with arbuscular mycorrhizal (AM) fungi and noninoculated plants at Research Fields of University of Tehran (Karaj), Iran. The experiment was laid out as a split plot factorial based on randomized complete block design using four replicates. The first factor was (a) foliar application of phosphorus at four levels (a1=0, a2=6, a3=8 and a4=10 kg ha-1), the second factor (b) was wheat planting in the presence or absence of mycorrhizal fungi and the third factor was (c) pre-plant application of P at three levels (c1=recommended dose, c2=25% lower than recommended dose and c3=50% lower than recommended dose). Results indicated that the highest grain yield was found in plots received foliar P at 8 kg ha -1 (7.89 ton ha-1) and plots with pre-plant P at recommended dose (7.91 ton ha -1 ). The minimum grain yield was related to plots with foliar application of P and without mycorrhizal (6.67 ton ha -1 ). The greatest and lowest biological yield were detected in plots with pre-plant P at recommended dose (17.4 ton ha-1) and 25% less than recommended dose (14.9 ton ha -1 ), respectively.
Host specificity among five species in the cowpea cross-inoculation group
SummaryIn a cross-inoculation experiment using crushed nodules from cowpea (Vigna unguiculata), groundnut (Arachis hypogea), bambara groundnut (Voandzeia subterranea), lima bean (Phaseolus lunatus) and soybean (Glycine max.), it was found that soybean did not nodulate with Rhizobia from any of the other species whilst its Rhizobia nodulated with all species. Cowpea and lima bean, on the other hand, nodulated with Rhizobia from all species, but their Rhizobia nodulated only with each other. Groundnut and bambara groundnut nodulated with Rhizobia from all species except cowpea and lima bean, and their Rhizobia also nodulated with all species except soybean.