Quantification the impacts of climate change and crop management on phenology of maize-based cropping system in Punjab, Pakistan

Crop production is greatly impacted by growing season duration, which is driven by prevailing environmental conditions (mainly temperature) and agronomic management practices (particularly changes in cultivars and shifts in sowing dates). It is imperative to evaluate the impact of climate change and crop husbandry practices on phenology to devise future management strategies to prepare for climate change. Historical changes in spring and autumn maize phenology were observed in Punjab, Pakistan during 1980-2014. Sowing (S) of spring maize was earlier by an average of 4.6 days decade(-1), while autumn maize 'S' and emergence (E) were delayed on average 3.0and 1.9 days decade(-1). Observed anthesis (A) plus maturity (M) dates were earlier by 7.1 and 9.2 days decade(-1) and 2.8 and 4.4 days decade(-1) for spring and autumn maize, respectively. Similarly, S-A, S-M and A-Mphases were shortened on average by 2.4, 4.6 and 1.9 days decade(-1) and 5.5, 7.8 and 2.2 days decade(-1) for spring and autumn maize, respectively. The variability in phenological phases of spring and autumn maize had significant correlation,with the increase in temperature during 1980-2014. Employing the CSM-CERES-Maize model using standard hybrid for all locations and years illustrated that model-predicted phenology has accelerated with climate change more than infield-observed phenology. These findings suggest that earlier late sowing and shifts of cultivars requiring high total growing degree day during 1980-2014, have partially mitigated the negative impact of climate change on phenology of both spring and autumn grown maize.