Seasonal Variation in Photosynthetically Active Radiation Interception and Radiation Use Efficiency in Green Gram [Vigna radiata (L.)Wilczek] in Lower Gangetic Plain of India

Aim: The present study was conducted for identifying sowing windows and cultivars of green gram in spring – summer and rainy seasons depending on light interception pattern and photo synthetically active radiation use efficiency (PARUE) in the lower Gangetic Plains of Eastern India.

Methodology: Five green gram varieties (V1, V2, V3, V4 and V5) were sown on four dates (D1, D2, D3 and D4) in the spring –summer season starting from 15th February and on three dates (D1, D2 and D3) in the rainy season, starting from 20th August at interval of 10 days. Cumulative intercepted PAR (CIPAR), PARUE for above ground biomass and green gram seed and the seed yield were measured. The experiments were conducted under strip –plot design.

Results: Results showed that CIPAR increased gradually in both the seasons under different dates of sowing. The mean PARUE for above ground biomass were 3.97, 4.58, 3.18 and 2.64 gMJ-1 for D1, D2, D3 and D4 sowings during spring – summer season. In rainy season the same was declined from 8.67 to 3.73 g MJ-1 with the delay in sowing. Maximum seed yield was obtained under D2 and V3 in the spring –summer and under D1 and V5 in the rainy season. The mean PARUE for seed yield were 0.65 and 0.64 g MJ-1 and 0.40 and 0.42 g MJ-1 in the spring summer seasons of 2011 and 2012 respectively. In the rainy season the maximum PARUE were 0.91 and 0.55 g MJ-1 under D1 for two experimental years.

Conclusion: Depending on PARUE Pant Mung – 5 and Mehashould be sown during 3rd week of February and August in this zone.