高温胁迫─小麦超高产的主要障碍

小麦是冷季作物，最适生长温度为１５～２０℃。我国由于受季风的影响，夏季是同纬度除少数沙漠干旱地区以外最热的国家，淮河一秦岭以北冬小麦集中产区，小麦抽穗～成熟的日平均气温大于３０℃的高温天气占到该生育期的１／３，大约７０％的时间突破了临界温度。北方受高温干热风影响的小麦面积占到小麦播种面积的７１％，为害频率为十年七遇，小麦年减产１８．５～３５亿ｋｇ，热胁迫危害成为我国北方小麦高产的主要生理障碍。小麦耐热基因型与热敏感基因型存在广泛的变异，耐热品种的干物质积累显著高于热敏感品种，为小麦抗热筛选提供了依据。提高小麦的抗热性水平，缓解胁迫为害，是今后小麦超高产育种的重要方向。

High Temperature Stress-Main Barrier of High Productivity on Wheat

Wheat is a type of cold crop and its most suitable growth temperature is about 15-20℃.Under this ecologic condition,the output of dry matter,the 1000-seed weight,the harvest index and the seed yeild are all of the best.High yeild districts of wheat in the world gatheraround the broadleaf forest climate area of and mid-low latitude district of the Qingzan and theYunnan plateau.in China,which the average temperature of hottest month is about 12￣20℃.Because of the monsoon effect,China is one of the hottest countries at shine latitude area exceptseveral arid desert district in summer.Day-average temperature above 30C sustains one thirdof the time during seed maturation in the north from the Huai River to the Qin Mountain and thetime above critical temperature occurs about 70% Of the time.During high temperature,thephotorespiration consumes 33.3% of the photosynthetic substance.High temperature reducesphotosynthetic rate and acelerates the decrepitude of wheat.Wheat area suffered high temperature in China are 70% of total wheat area.The losses decrease 1.85￣3.5 billion kg of wheat peryear.So heat stress is main barrier of wheat high yeild in the north of China.The researchproves that high temperature induces synthesis of heat shock protein, which is heat protectant ofplant;chlorophyll content and dry matter accumulation of heat-tolerance wheat cultivars arehigher than heatsusceptible cultivars,which supplies substantial proof for antiheat screen ofwheat.In order to raise heat-tolerance of wheat and revive heat stress harm,as well as fullybring high yeild potentiality of wheat,introducing species resource of wheat from low latitudedesert arid district for anti-heat screen and hereditary transfer are future direction of high yieldbreeding in wheat.