Agricultural Research Journal

Maize is a vital cereal crop primarily grown during the kharif season. Although it is a short-duration crop (approximately 90 days), it is highly sensitive to abrupt changes in weather conditions. To better understand this, a study was conducted to determine the critical thresholds of temperature, relative humidity, and rainfall by analyzing meteorological data (collected from meteorological observatories) and crop data (2004-2018) from three locations in Punjab (collected from statistical abstracts). Over the 15-year period, three high-yield years were identified for Ludhiana (>5000 kg/ha), Ballowal Saunkhari (>4200 kg/ha), and Amritsar (>4000 kg/ha), and meteorological data for crop growth stages were tabulated accordingly. Weekly deviations of each meteorological parameter from normal data were computed. The stage-specific critical limits of these parameters were then validated using actual yield data from the crop years 2019 and 2020. In 2019, medium yields were observed, as temperature (T_min) and relative humidity (RH_max) exceeded the upper threshold during the flowering and grain filling stages. In contrast, a high yield of 4376 kg/ha was recorded at Ballowal Saunkhari in 2020, as temperatures remained consistently within the optimum range, accompanied by well-distributed rainfall. The results indicated that for higher maize productivity, the optimal ranges for temperature and relative humidity at various crop stages are as follows: during germination, 36-40°C (max) / 21 27°C (min) and 30-55% RH; during vegetative growth, 31-41°C (max) / 24-30°C (min) and 55-75% RH; and during flowering to grain filling, 31-37°C (max) / 21-27°C (min) and 60-85% RH. Additionally, a well distributed rainfall between 500-600 mm is ideal for maize growth in Punjab.