Morphological and Biochemical Responses of Vigna unguiculata ssp. sesquipedalis in Different Zinc Concentrations

Zinc is an essential trace element required by plants. However, high zinc concentrations can lead to environmental pollution and plant toxicity. This research aimed to investigate how plants respond to different concentrations of zinc (0, 100, 200 and 300 ppm) in soil, using Vigna unguiculata ssp. sesquipedalis (Yard long bean) as a model plant. A total of 12 parameters were collected including plant morphological characteristics such as plant height, leaf number, yield, root length, pod length and fresh weight. Furthermore, key biochemical properties including chlorophyll content, total protein content, total phenolic and flavonoid content in plants were analyzed, in addition to soil pH and electrical conductivity. These parameters were used to determine the morphological and biochemical responses of plants under zinc-stress conditions. The results indicated that different concentrations of zinc significantly decreased the leaf number and pod length V. unguiculata. Soil electrical conductivity was significantly high at 200 ppm zinc. Significant changes in total protein were observed in stems and pods. Moreover, the total phenolic content in leaves showed a significant increase with higher zinc concentrations, while the opposite trend was observed for total phenolic content in V. unguiculata pods. In summary, varying concentrations of zinc had a significant impact on various morphological and biochemical properties of V. unguiculata, exhibiting a distinct pattern specific to each organ. This suggests that V. unguiculata is responsive, adaptive and capable of tolerating abiotic stress induced by a broad range of zinc concentrations.