Assessment of yield gaps in timely and late sown wheat varieties in low fertility loamy sand soil

The performance of timely and late sown 13 wheat (bread and durum) varieties was assessed during rabi 2015–16 under irrigated and rainfed conditions in a low fertile loamy sand soil. Grain yield of timely sown bread wheat varieties varied between 4.89–5.74 t/ha, compared with 4.35–4.53 t/ha for late sown varieties. Grain yield of timely sown bread wheat varieties under rainfed conditions varied between 3.74 and 4.05 t/ha. In contrast, grain yield of timely sown durum wheat under irrigated conditions varied between 2.76–3.96 t/ha. Data revealed that an average grain yield of timely sown bread wheat varieties under irrigated conditions was 35.7% higher as compared to wheat varieties sown as rainfed. Timely sown bread wheat varieties sown under irrigated conditions yielded ∼57 per cent higher grain yield, compared with durum wheat varieties. The production efficiency (PE) of timely sown bread wheat varieties under irrigated conditions was 4.5kg/ha/d (∼15%) higher than sown as rainfed. It was higher by 12.9 kg kg/ha/d (61.7%) for timely sown bread wheat varieties, compared with durum wheat varieties under irrigated conditions. The PE was 5.2kg/ha/d (15.4%) lower for late sown bread wheat varieties, compared with timely sown varieties. Yield gap estimated over yield potential varied between 0.04–0.31 t/ha for bread wheat varieties sown under irrigated condition, compared to between 0.32–1.34 t/ha under rainfed condition. However, a yield gap estimated over yield potential for late sown bread wheat varieties under irrigated conditions varied between 0.35–0.36 t/ha, about 56 per cent higher than for timely sown wheat varieties.