Effect of Zinc and Copper Loaded Alginate Beads on Growth, Yield and Nutrient Use Efficiency of Black Gram (Vigna mungo L.)

Background: Black gram (Vigna mungo L.) is a major pulse crop valued for its protein content, but its productivity is often
constrained by micronutrient deficiencies, particularly zinc (Zn) and copper (Cu). These nutrients are essential for enzyme activity,
photosynthesis and reproductive development. Conventional fertilizers show low efficiency due to leaching and fixation losses,
necessitating improved delivery systems. The study aimed to evaluate alginate-based micronutrient delivery for improving black
gram performance.
Methods: A pot experiment was conducted during winter 2024-25 and summer 2025 at VISTAS, Chennai. Zinc- and copper-loaded
alginate beads were synthesized using the ionotropic gelation technique and characterized by Atomic Absorption Spectroscopy.
Seven treatments, including soil, foliar and combined applications along with control, were evaluated in a Completely Randomized
Design with three replications. Growth, yield and physiological parameters were recorded.
Result: Soil + foliar application of Zn (T4) recorded the highest plant height (27.30 and 28.38 cm), dry matter (20.35 and 22.65 g plant-1),
pods per plant (20.39 and 22.42) and yield (13.68 and 14.29 g plant-1) during winter and summer, respectively. This treatment also
improved reproductive efficiency and growth vigour index compared to other treatments. Foliar Zn (T 6) showed comparable
performance, while Cu treatments exhibited moderate improvements over the control.
Key words: Alginate beads, Black gram, Controlled-release, Micronutrients, Nutrient use efficiency, Sustainability