EFFECTS OF WATERING REGIME AND RHIZOBIAL INOCULATION ON NITROGEN FIXATION CAPACITIES, YIELD AND YIELD COMPONENTS OF SOME LEGUME SPECIES.

Abstract

The experiment was conducted in the screen house of the Department of Crop, Soil and Pest and Management, Federal University of Technology, Akure, to evaluate the effects of watering regime and rhizobium inoculation on nitrogen fixation capacities, yield and yield components of some legume species, using pure river sand as growth medium. Treatments were 5 x 3 x 2 factorial scheme consisting of legume species (Phaseolus lunatus, Soy bean (TGX 199057f and198057), Stylozanthes and Desmodium species), watering regimes were 4, 8, and 12days watering intervals and with or without rhizobium inoculation. At each watering regime, 900 ml of water was applied per plant. The rhizobium (AMF) spore was applied to legume seedlings at 5 days after planting. The experiment was laid out in a Completely Randomized Design with 3 replications. Data were collected on growth parameters of legume seedlings from January to August, 2015. Growth variables measured included plant height, number of leaves and branches, number of nodules, seed weight, number of pod, pod weight, root length, nodule diameter and number of seed per pod. The variables of the leaf chemical and proximate composition measured were nitrogen, soluble carbohydrate, crude protein, crude fibre, chlorophyll concentration, ash content, and elemental composition. Treatment effect was significant (P<0.05) on some of the measured growth, yield, leaf and chemical properties of legume seedlings. These variables were enhanced by the 4 and 8 days watering intervals. Legumes species that were watered at 4 and 8 days interval were consistently taller and produced higher number of leaves and branches compared to those watered at 12 days interval. Legume species that were watered 4 and 8 days interval and inoculated with rhizobium were consistently taller and produced higher number of pods, seeds, seeds weight and yield compared with those watered at 12 days interval. Phasoelus lunatus that was watered 4 days interval and inoculated with rhizobium were consistently taller and produced higher number of nodules, nodule weight, root length and root weight compared to non- inoculated species. Stylozanthes watered at 4 and 8 days interval produced higher number of leaves, plant height and branches compared with those watered at 12 days. Desmodium watered 4 and 8 days interval and inoculated with rhizobium produces higher number of root compared with non- inoculated species. The interaction between watering regime and rhizobium inoculation was significant on some growth and yield parameters of legume species such as root length, root weight, number of nodules, number of seeds and seeds weight. The response of legume seedlings to rhizobium inoculation was not consistent. However inoculated seedlings were taller and have high number of nodules and root length than the non- inoculated seedlings. Rhizobium inoculation influenced the nitrogen content of the soil and the chlorophyll, crude protein, crude fibre and soluble carbohydrates content of leaf of legume species. For a good vigour, growth and development of legume seedlings, seedlings of legume species Soy bean (TGX 199057f and TGX 198057) should be inoculated with rhizobium and watered at 4 and 8 days interval, these treatments are recommended for optimal growth and yield of soy bean.