Impact of Zinc on Growth of Soybean (Glycine max L.)

This study investigated the impact of five different concentrations of Zinc Sulphate (ZnSO4 .7H2O), ranging from 0 (control), 250, 500, 750, 1000, 1250 mg/kg., on soybean (Glycine max (L.) Merr.) plant growth attributes like root and shoot length, as well as dry weight at pre, peak, and post-flowering stages. The experiments were set up in pots with three replications in green house of Department of Botany of University of Rajasthan, Jaipur during the month of April in natural outdoor conditions, where the photoperiod was 12 h and the average temperature was 30°C. The effect of Zinc on almost all the growth parameters under study was found to be statistically significant. The study revealed that at 500 mg/kg had maximum root length (56.04 cm), shoot length (74.06 cm), root dry weight (1.321 g) and shoot dry weight (5.106 g) at post flowering stage. In contrast, at 1250 mg/kg application resulted substantial reduction in root length (31.10 cm), shoot length (46.22 cm), root dry weight (0.519 g) and shoot dry weight (2.923 g) at post flowering stage as compared to control. The experiment finding showed that at low levels of zinc (250 and 500 mg/kg) showed a significant increase in growth parameter, with maximal growth observed at 500 mg/kg soil concentration. Considering this, a recommended zinc application rate of 0.75 kg/ha is suggested to optimize plant growth and nutrient uptake in agricultural fields. Furthermore, caution should be exercised to avoid soil concentrations surpassing 750 mg/kg to mitigate potential phytotoxicity or nutrient imbalances, particularly in soybean cultivation areas. These findings suggest that urgent measures are warranted to mitigate zinc pollution and ensure the productivity of food crops.