Defining and validating limits of meteorological parameters for high yield of wheat in Punjab, India

<p>Wheat is a rabi season crop and is highly susceptible to abrupt increases/decreases in weather parameters. So, a study was conducted to compute the critical limits of temperature, relative humidity, and rainfall by analyzing meteorological and crop data (1999–00 to 2018–19) for six locations (Ballowal Saunkhari, Ludhiana, Patiala, Amritsar, Bathinda, and Faridkot) in Punjab. Amongst the 20 years, high, medium, and low yield years for each location were identified, and then meteorological data for crop growth stages, i.e., sowing-emergence (43–47 Standard Meteorological Week (SMW)), vegetative (48–02 SMW), anthesis (03–06 SMW), grain filling (07–11 SMW), and physiological maturity (12–15 SMW), were tabulated. The week-wise deviations of maximum/minimum temperature, maximum/minimum relative humidity, and rainfall from normal data of those 20 years under study were computed to derive their critical limits. Then these stage-wise critical limits were validated using the actual yields achieved during crop years 2019–20, 2020–21, and 2021–22. During a good crop year 2019–20, the upper and lower limits of the ranges accounted for high yields obtained at 03 locations and medium yields at the remaining 03 locations. During the crop year 2020–21, when the medium yield was obtained at all six locations, the major reason was the deviation of temperature above the upper range during the later grain-filling stage. On the other hand, during 2021–22, when low yield was reported at 03 locations and medium yield at remaining 03 locations, in addition to temperature deviations, heavy rainfall during SMW 1 and 2 (late vegetative stage) and hot and dry weather during SMW 10 and 11 (late grain development stage) were the major reasons. Hence it may be concluded that to get higher wheat productivity during vegetative growth, flowering, and grain filling, the maximum/minimum temperature ranges should be 16–22/4–9 ℃, 21–28/7–13 ℃ and 25–32/11–16 ℃, respectively; the maximum/minimum relative humidity ranges should be 85%–99%/39%–77%, 80%–92%/32%–66% and 75%–86%/31%–59%, respectively.</p>