Quantifying the effect of temporal variability of agro-meteorological disasters on winter oilseed rape yield: a case study in Jiangsu province, southeast China

To address the increasing hazards of climate change to winter oilseed rape production in Jiangsu province, southeast China, a total of 12 agro-meteorological disaster indices (MDI) during 1961–2012 was applied to quantify the disaster impacts of spring precipitation extremes, autumn droughts, winter freezing injuries, and spring chilling injuries. The main findings were as follows: (1) due to the obvious north-south gradient of MDI, this province was classified as four climactic sub-regions: north, central-north, central-south, and south Jiangsu, respectively; (2) in central-north, central-south, and south Jiangsu, the maximum length of dry spell during autumn (DI3), the maximum duration of consecutive rainfalls during spring (PI3), and number of rainy days during spring (PI1) were selected as the leading MDI affecting oilseed rape yield, respectively; (3) each 1d of DI3, PI3, and PI1 increase would result in yield losses of 0.7%, 3.6%, and 1.7% in central-north, central-south, and south Jiangsu, respectively; (4) compared to the weak changes in spring rainfall and autumn drought, the significant weakening of winter-spring cold extremes across Jiangsu had more notable yield increasing effects, especially the strong decrease of freezing events during winter had increased yield by up to 1.4–3.0%.