Effect of date of sowing, irrigation, tillage and residue management on productivity of wheat in sub-tropical environment

A field study was conducted for two rabi seasons of 2012–13 and 2013–14 at Punjab Agricultural University, Ludhiana (Punjab) to study the combined effects of sowing time, irrigation and tillage & residue management on yield and water productivity of wheat. The treatments included two dates of sowing (1^st week of November and December) in main plots, two irrigation regimes [based on IW/PAN-E ratio of 1.2 (I1.2) and 0.9 (I0.9)] in sub plots, and three tillage and residue management (no tillage with residue-NT; conventional tillage with residue mulch-CTm and conventional tillage without residue-CTm0) in sub-sub plots. Mean grain yield was at par in D2 (5.73 t ha⁻¹) with early sown D1 (5.67 t ha⁻¹). Similarly yield in irrigation regimes i.e. I1.2 and I0.9 were also at par (5.68–5.72 t ha⁻¹). Grain yield of wheat was 12% lower in NT over the average yield of CTm and CTm0 which yielded at par. Average plant height was more by 5.1 cm when crop was sown in 1^st week of November. The treatments CTm and CTm0 recorded larger number of effective tillers, ear length, and straw yield than NT. Mean gain in straw yield was more when crop was frequently irrigated and sown in 1^st week of November. Water productivity (WP) of wheat was significantly affected by time of sowing, irrigation regimes and tillage & residue management. Interactions between date of sowing and irrigation showed that improvement in WP was 27% when crop was sown in 1^st week of December with I0.9 over I1.2 while in 1^st week of November it was 12% only. The mean water productivity was the lowest in NT (11.11 kg ha⁻¹ mm⁻¹) compared to CTm (12.46 kg ha⁻¹ mm⁻¹) and CTm0 (12.50 kg ha⁻¹ mm⁻¹).