Journal of Advances in Biology & Biotechnology

Weather variability strongly influences chickpea phenology, yield formation, and the incidence of major pests and diseases. A comprehensive investigation was conducted using long-term meteorological data (1992–2022) to develop a crop–weather–pest calendar for chickpea in Gaya district, Bihar, within Agro-climatic Zone III-B. Long-term daily weather records from the Gaya station were used to compute weekly and monthly averages of meteorological parameters and establish climatic normals. These normals were then used to evaluate actual weather conditions and their influence on chickpea yield. Phenological calendars for chickpea were prepared using data obtained from field experiments conducted at Gaya. By integrating weekly climatic normals with the crop’s phenological data, crop–weather calendars were constructed to represent optimal climatic requirements at different growth stages. The crop–weather–pest calendars identified climatic conditions that favour the incidence of specific pests during each developmental stage. The analysis indicated that cool and moderately humid conditions during sowing and germination (Tmax 16–29°C; Tmin 9–19°C; RHmax ≈92%) favoured uniform crop establishment, whereas moderate temperatures (17–28°C) with occasional light rainfall (5–6 mm week⁻¹) promoted vigorous vegetative growth and nodulation. Flowering and pod formation occurred under optimum temperatures (25–33°C) and moderate relative humidity (73–81%), whereas temperatures exceeding 32°C adversely affected pollen viability, resulting in flower drop and yield reduction. Peak incidence of Helicoverpa armigera was observed from the 48th to the 8th Standard Meteorological Week under moderate temperatures (Tmax 25–28°C; Tmin 10–13°C), RHmax of 75–79%, RHmin of 52–55%, and low rainfall (0.5–2.7 mm week⁻¹). Cutworm and termite infestations were associated with relatively warm and dry weather conditions during the vegetative stage. Fusarium wilt was favoured by temperatures of 27–28°C and high humidity (>85%), whereas Ascochyta blight and rust developed under cooler (Tmax 20–22°C; Tmin 8–12°C), humid conditions accompanied by intermittent rainfall during flowering and pod formation. The developed crop–weather–pest calendar provides a practical agrometeorological decision-support tool for forecasting pest and disease incidence, optimising sowing time and crop management, scheduling timely plant protection measures, and issuing weather-based agrometeorological advisories.