基于干热风危害指数的黄淮海地区冬小麦干热风灾损评估

全球气候变化背景下,农业气象灾害呈上升态势。干热风灾害发生区域、次数和强度都发生了明显的变化。研究干热风灾害对农作物的影响对于我国农业可持续发展、保障粮食安全等均具有重要的现实意义。利用黄淮海地区68个气象台站1961—2010年的逐日气象资料,和54个农业气象试验站1981—2006年小麦的发育期、产量、干热风灾害等数据,采用公认的中国气象局2007年发布的气象行业标准《小麦干热风灾害等级》中冬小麦干热风灾害指标,计算干热风危害指数,进一步细化发育期,确定冬小麦抽穗前气象条件对气象产量影响的关键气象因子,分离干热风年冬小麦气象产量,构建重度干热风影响下干热风危害指数与冬小麦抽穗—成熟阶段气象条件对气象产量影响的统计模型,进行1981—2006年黄淮海地区冬小麦干热风灾损的评估。结果表明:(1)重度干热风危害下,1981—2006年期间黄淮海各地区冬小麦不同发育时段的干热风危害指数平均在抽穗—开花时段最大,乳熟—成熟时段居中,开花—乳熟时段最小,分别为0.17、0.15和0.14,平均0.15;(2)冬小麦抽穗前气象条件对气象产量影响的关键气象因子为:播种—出苗期间的最低气温、拔节—孕穗期间的平均气温和孕穗—抽穗期间的平均气温,各个单因子相关系数分别为0.64、0.86和0.99,均达到极显著水平。其中播种—出苗的最低气温可决定小麦出苗的迟早和苗情;拔节—孕穗期间,在小花原基形成期—四分体形成期气温偏低可延长小穗、小花分化时间,防止退化,提高结实率;孕穗—抽穗的平均气温偏高有利于提早抽穗,延长后期灌浆时间,且晴天有利于开花授粉;(3)分离干热风年冬小麦气象产量后,构建了重度干热风影响下干热风危害指数与冬小麦抽穗—成熟3个阶段气象条件对气象产量影响的统计模型,验证结果表明该模型客观上能够综合地反映干热风在不同发育阶段对小麦产量的影响。进一步灾损评估表明:重度干热风危害下,黄淮海地区冬小麦减产率在21.52%—39.80%之间,平均为27.83%。

Assessment of the yield loss of winter wheat caused by dry-hot wind in Huanghuaihai Plain based on the hazard index of dry-hot wind

Under global climate change, agricultural meteorological disasters are increasing. The affected area, frequency, and intensity of dry-hot wind have significantly changed. Therefore, researching the impacts of dry-hot wind on crops will have great practical significance for sustainable agriculture development and food security. In this study, the following were used to evaluate the yield loss of winter wheat caused by dry-hot wind in Huanghuaihai Plain: (1) the daily climate variables gathered from 68 meteorological stations in Huanghuaihai Plain from 1961 to 2010; (2) the observations (growth stages, yield, hot wind disasters of winter wheat, etc.) from 54 agro-meteorological experimental stations in Huanghuaihai Plain from 1981 to 2006; (3) recognized hazard indicators about disaster grades of dry-hot wind for winter wheat from the meteorological industry standard which was released by China Meteorological Administration in 2007; (4) detailed developmental stages in which dry-hot wind occurred: from tasseling to flowering, from flowering to milky maturity, and from milky maturity to maturity. The hazard index of dry-hot wind was further calculated. The key meteorological factors affecting the meteorological yield of winter wheat before tasseling were determined. The meteorological yields of winter wheat during the year of dry-hot wind were separated. Next, in order to evaluate the yield loss of winter wheat caused by dry-hot wind, the model was constructed between the hazard index of severe dry-hot wind and the effect of meteorological conditions on meteorological yield before heading. The results showed that: (1) under severe dry-hot wind, the average hazard index of dry-hot wind from 1981 to 2006 in Huanghuaihai Plain was the highest during the stage from tasseling to flowering (0.17), medium during the stage from milky maturity to maturity (0.15), and the lowest during the stage from flowering to milky maturity (0.14), with an average of 0.15; (2) the key meteorological factors determining the effect of meteorological conditions on meteorological yield before tasseling were the minimum temperature during the stage from sowing to emergence, the average temperature during the stage from jointing to booting, and the average temperature during the stage from booting to tasseling. Among them, the minimum temperature during the stage from sowing to emergence can determine the seeding time of wheat and the detailed growth of the seedlings. As for the stage from jointing to booting, the low temperature in the flower primordia -tetrad formation period can prolong the spike and floret time, prevent degradation, and improve the seed maturation rate. The high average temperature during the stage from booting to tasseling is conducive to early heading, to extend the late filling time. Furthermore, it is favorable for pollination to occur during sunny days. (3) After clarifying the meteorological yields of winter wheat during the year in which dry-hot wind occurred, the statistical models describing the relationships between the hazard index of severe dry-hot wind and the effect of meteorological conditions on meteorological yield were constructed. These models could synthetically reflect the impact of dry-hot wind on wheat yield at different developmental stages. The assessment showed that the yield losses of winter wheat caused by severe dry-hot wind disaster in Huanghuaihai Plain were between 21.58% and 39.96%, with an average of 27.91%.