Quantification of the impacts of climate warming and crop management on canola phenology in Punjab, Pakistan

摘要

Yield is influenced by the length of the growing season, which is affected by weather conditions and management practices of a crop, including sowing dates and shifting of cultivars. It is necessary to understand the effects of agronomic management practices and weather variables on phenological stages and crop phases in order to develop strategies for adaptation of agricultural systems to changes in climatic conditions. The goal of this study was to determine the impact of warming trends on phenology of canola from 1980 to 2014 for central and southern Punjab, Pakistan. Sowing, emergence, anthesis and physiological maturity dates were delayed by an average of 6.02, 3.14, 3.31 and 1.89days per decade, respectively. The duration of sowing to anthesis, sowing to physiological maturity and anthesis to physiological maturity phases decreased an average 2.71, 4.13 and 1.42days per decade, respectively, for all 10 locations that were analysed in this study. The sowing, emergence, anthesis and physiological maturity dates were positively correlated with an increase in temperature by an average 2.71, 1.41, 1.49 and 0.85days per degrees C, respectively. However, the phenological phases such as sowing to anthesis, anthesis to maturity and sowing to maturity were negatively correlated with an increase in temperature by an average of 1.22, 0.64 and 1.86days per degrees C, respectively, for all 10 locations. Applying a process-based CSM-CROPGRO-Canola model using a standard cultivar (field tested) for all locations and years indicated that the simulated phenological stages occurred earlier due to the warming trend compared to the observed phenological stages. One-quarter of the negative effects of this thermal trend was compensated by growing new cultivars that had higher thermal time requirements. Therefore, new canola genotypes with a higher number of growing degree day requirement and high temperature tolerance should be a priority for evolving new cultivars.