Climate change impact assessment of growing degree days and thermal growing period of cotton in north-west India

ABSTRACT Temperature is an indispensable necessity of plant growth, which explains the 95% variability in plant development. Accumulated temperature, i.e. growing degree day (GDD) is a useful agro-climatic indicator that translates raw climatic data into meaningful decisions. In this study, the GDD concept is used to analyze spatio-temporal variability of accumulated growing degree days (AGDD) and thermal growing period of cotton for the past and future climates in the three different zones (north-east, central and south-west) of Punjab. During the baseline period, higher AGDD were accumulated in the south-western (2,441 °C day), followed by central (2,276.8 °C day) and north-eastern (2,073.8 °C day) zones. During the end of mid-century, AGDD of the central zone was increased by 4–11%, 3–27% for north-eastern, and 3–7% for south-western zones in contrast to the baseline period. This increase in AGDD of cotton might decrease the thermal growing period by 6–14%, 8–25%, and 4–8% for central, north-east and south-western zones, clearly indicating the thermal stress over the cotton crop. This study provides quantitative information for crop breeders and cotton scientists to develop new genetically modified cultivars and improved agronomic practices to mitigate the adverse effect of climate change.