Optimizing biomass yield of three herbaceous forage legumes through dual inoculation of Arbuscular Mycorrhizal Fungi and Rhizobia

Abstract

The production of forage legumes under Sub-Saharan region of Eastern Cape Province (South Africa) had been limited by several factors which includes low levels of soil nitrogen and phosphorus. The current study aimed at investigating the effects of Arbuscular Mycorrhizal Fungi (AMF) and Rhizobium inoculation on growth and yield of three forage legumes, namely, Vigna unguiculata, Lablab purpureus and Mucuna pruriens. The field trials were established over two growing seasons (2017/2018 and 2018/2019) to measure growth parameters such as seedling survival, plant height, stem diameter and plant vigor as well as mycorrhizal dependency, nodulation and forage yield. The results showed that the dual inoculation of AMF and Rhizobia bacteria significantly increased (P ≤ 0.05) seedling survival, plant height, stem diameter, plant vigor, nodule numbers, active nodulation rate and dry matter yield. However, nodule dry weight and dry matter content of forage legumes were significantly reduced by the dual inoculation of AMF and Rhizobia. In conclusion, the dual inoculation resulted in high forage production compared to single inoculation and un-inoculated forages in both seasons. Therefore, the dual inoculation could be an ideal alternative in attempts to reduce the overreliance of chemical fertilizer application on forage production under semi-arid regions.