Effect of Micronutrient Loaded Alginate Beads on the Growth and Yield of Black Gram (Vigna mungo L.)

Black gram (Vigna mungo L.) is an important pulse crop and a major source of protein in many tropical countries. However, its productivity is often constrained by micronutrient deficiencies such as iron (Fe), zinc (Zn) and copper (Cu). These micronutrients are essential for plant growth, photosynthesis and enzyme activity. Conventional fertilizers often show low efficiency due to nutrient losses in soil. Therefore, controlled-release nutrient delivery systems like alginate-based beads may improve micronutrient availability and crop productivity.

A pot culture experiment was conducted during Winter and Summer 2025 at Vels Institute of Science, Technology and Advanced Studies (VISTAS), Chennai. Micronutrient-loaded alginate beads containing Fe, Zn and Cu were synthesized using the ionotropic gelation method and analyzed using Atomic Absorption Spectroscopy. The experiment consisted of ten treatments including soil, foliar and combined applications along with a control. The treatments were arranged in a randomized block design with three replications. Growth and yield parameters were recorded at different stages of crop growth.

Foliar application of Fe (T₇) recorded the highest plant height (28.40 and 29.38 cm), dry matter (20.86 and 23.46 g plant^-1), pods per plant (21.82 and 24.31) and yield (14.22 and 14.83 g) during Winter and Summer (2025). It also produced higher seeds per pod (6.99 and 7.67), pod length (6.68 and 6.62 cm) and test weight (7.61 and 8.10 g). Soil + foliar application of Fe (T₄) and Zn (T₆) also improved growth and yield compared to the control. These results indicate that alginate-based micronutrient delivery enhanced nutrient uptake and crop productivity.