Demystifying the wheat (Triticum aestivum) yield penalty due to delay in sowing: Empirical evidence from eastern India

Wheat (Triticum aestivum L.) yield in Indo-Gangetic plain of eastern India is much less than its actual potential. Apart from several yield deterministic factors, late sowing of wheat is one of the major reasons for sub-optimal wheat yield. The persistent yield gap poses a threat to future food security of this region with a vast population that is growing rapidly. In the present research, an attempt was made to quantify and classify the yield losses in wheat due to late sowing which is prevalent in this part of India. On-farm participatory agronomic trial was conducted at 1073 plots in 3 districts of eastern India, 2 from Uttar Pradesh and 1 from the state of Bihar. The trial was conducted during four consecutive winter season from 2016–17 to 2019–20. Following a split-plot design, main plots were categorized based on wheat sowing time and sub-plots were classified depending on the wheat varietal class. A sample survey of randomly selected 629 wheat farmers was conducted in 2017–18 wheat season in these 3 districts. Results from the agronomic trial showed that wheat yield decreased by 58 kg/ha for every one-day delay in sowing. Moreover, the yield of long-duration improved wheat variety (HD-2967) was statistically same (P=0.479) compared to the most preferred short-duration variety (PBW-373) in a very late-sown scenario (late December). Farmers’ survey data reconfirmed that the wheat yield has a very strong negative correlation with the sowing dates, but the yield decline was statistically insignificant until mid-November. Wheat yield in this part of India can be adequately boosted if sowing time of wheat advances and adoption of long-duration improved wheat varieties improves.