Growth of Water Yam (Dioscorea alata L.) as Affected by Bacterial Inoculation under Growth Chamber Conditions

Abstract

Soil fertility is one of the most important limitations in yam (Dioscorea spp.) growth and yield. This study evaluated the effect of bacterial inoculation on the growth and source of nitrogen in water yam (D. alata L.) cv. A-19 under growth chamber conditions. The plants were inoculated with two different inoculant concentrations (10⁺⁴ and 10⁺⁶ CFU.ml^-1) of Agrobacterium sp. strain 343, which was previously isolated from the root of water yam cv. A-19, along with a non-inoculated as the control treatment. Sterilized vermiculite was used as a growing substrate and data were collected at 30, 60 and 90 days after inoculation. The inoculation significantly improved most of all growth parameters (i.e., the number of leaves, leaf area, plant dry weight and chlorophyll content) and nitrogen content in leaves of inoculated plants compared with the control. The δ¹⁵N results suggest that 33 to 51% N in inoculated plants could be derived from the atmosphere. To the best of our knowledge, this is the first work reporting the effects of its root endophytic bacterial inoculation on yam.