International Journal of Environment and Climate Change

Background: Green gram (Vigna radiata L.), locally called moong, is a high-protein pulse crop that improves soil fertility through nitrogen fixation and serves as food, cattle feed, and green manure. Its growth and yield are strongly influenced by weather, sowing time, and variety, with optimal planting enhancing productivity and resource-use efficiency.

Aim: To assess the impact of the thermal indices, phenological development, and canopy temperature depression (CTD) under different sowing windows and varieties to optimize sowing strategies for enhanced crop resilience and yield stability in green gram.

Study Design: Factorial Randomized Block Design (FRBD).

Place and Duration of Study: AICRP on Agrometeorology farm, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola, during the 2023-24 kharif season.

Methodology: Nine treatments including three sowing windows, viz., D₁- 28^th MW (10^th July), D₂- 29^th MW (17^th July) and D₃- 30^th MW (24^th July) as main plots, and three varieties, viz., V₁- PKV Green Gold, V₂- PKV AKM-4 and V₃- Utkarsha as sub-plots replicated thrice.

Results: Crops sown in the 28^th MW (1108 °C day) window accumulated the highest GDD, which decreased by 7.5% in 29^th MW, and 10.5% in 30^th MW. Similarly, the highest PTU were observed in 28^th MW (14993 °C day hrs), followed by 29^th and 30^th MW with a decrease of 7.5% and 10.7%, respectively. These trend was continued for TUE with the maximum achieved under 28^th MW (2.5 kg ha^-1°C^-1 day^-1), succeeded by 29^th and 30^th MW with a decline of 8.4% and 16.0%, respectively. On the other hand, late sowing (30^th MW) achieved the highest HTU (3932 °C day hrs), followed by 28^th and 29^th MW with a reduction of 4.3% and 9.4%, respectively. Maximum CTD was found in 28^th MW (1.23 °C), which reduced with delayed sowing in 29^th (40.7%) and 30^th MW (42.3%). Among the varieties, PKV Green Gold exhibited the highest GDD, PTU, HTU, and CTD, ensued by PKV AKM-4 while Utkarsha recorded the lowest. Soil moisture content was the highest in 28^th MW sowing, except at the pod initiation stage. Correlation analysis revealed that the optimal crop development was influenced by certain weather conditions, such as cooler temperatures that favoured emergence and maturity, while higher minimum temperatures supported flowering.

Conclusion: Sowing in 28^th MW optimized thermal indices and yield efficiency, while delayed sowing (29^th and 30^th MW) showed reduction, as late sowing lead to the forced maturity of crop. PKV Green Gold exhibited the highest GDD, PTU, and CTD, whereas PKV AKM-4 demonstrated the better efficiency to utilize available thermal units. This study will prove an important step towards deciding appropriate sowing time for maximizing growth and yield of crop under varying weather conditions.