基于作物生长模型的玉米生殖期冷害致灾因子研究

Chilling Disaster Factors in Maize Reproductive Stage Based on Crop Growth Model

利用东北玉米生长模型(NEC_MaGM)结合历史冷害数据分析了东北玉米灌浆期低温和初霜冻的发生规律,探讨了两者对玉米生长发育过程的影响与实际冷害年份之间的对应关系。结果表明,东北地区玉米灌浆期间较易出现15～16℃以下的急剧降温天气,对籽粒灌浆影响很大;出现在发育指数(DVS)为1.9之前且日平均温度连续5d低于16℃的低温将对玉米贮存器官干重(WSO)积累造成重大影响,其出现年份与实际冷害发生年份符合度较高,是发生大面积冷害的致灾因子之一;随着气候变暖,东北各地初霜冻日和新玉米品种的成熟期均在推迟,但初霜冻日的年际波动不断增大。模拟显示,初霜冻发生在玉米成熟前的频率也在增加,初霜冻对玉米的影响仍不容忽视;初霜冻对WSO积累影响严重的年份与历史上出现冷害的一些典型年份比较一致,也是重要的冷害致灾因子之一。灌浆期低温和初霜冻出现时间以及由此导致WSO的损失程度可以作为基于作物生长模型进行玉米冷害监测预测的重要指标。同时,作物生长模型可以成为研究农业气象灾害致灾因子的有力工具。

In recent years,temperature in the northeast of China has been significantly increasing with global warming.However,since planting areas of relatively late-maturing varieties of maize are shifting towards north,the frequency and intensity of maize chilling disaster are increased in some areas and some years.The prevention and mitigation of chilling disaster of maize in the Northeast depend on our understanding about chilling disaster factors and the degrees of impacts.In this paper,using North East China Maize Growth Model（NEC_MaGM） and historical chilling disaster data,we analyzed temporal and spatial variations of low temperature during the grain filling period and the first frost day,and discussed the match relations between chilling years based on the two disaster factors and actual chilling years.The results indicated that NEC_MaGM had a satisfied outcome in simulating maize growth and development.The absolute deviation at simulated tasseling and maturity stages calculated by NEC_MaGM was 3.6 d and 5.9 d,respectively.The root mean square error of simulated weight of storage organ（WSO） was 839.5 kg ha^-1.The average temperature in grain filling stage of maize in the Northeast was 16.7-23.5℃.However,the rapid decrease of temperature（〈16℃） that usually occurred in the late period of maize development stage had a great impact on grain filling.The average temperature on the first frost day in the northeast was 7.4-9.2℃,which was below the threshold for maize growth.In addition,the first frost day in the Northeast had a trend of delay with time.However,maturity of new maize variety also delayed with global warming,so the first frost frequently occurred before maturity.When the average daily temperature of five successive days lower than 16℃ occurred before DVS =1.9（development stage）,there was a severe impact on WSO.The years with above situation were consistent with those actually occurred in historical record.The partial early first frost occurred mainly in the period of 1.8〈 DVS≤1.9 in the Northeast. The numbers of sites where WSO reduced owing to the first frost were more than 11% in the Northeast for 44% of years. The years that the first frost occurred before maize maturity resulted in halt of WSO accumulation were consistent with historical record. It is concluded that low temperature in the grain filling period and the earlier first frost are the key factors of maize chilling disaster in the Northeast, which could be used as the indicators in earlier warning and prediction of chilling disaster based on the crop growth model output. Meanwhile, the crop growth model can be a powerful tool to analyze agro-meteorological disasters factors.