Study On Low Temperature Disaster Impact And Diagnosis Method Of Winter Wheat

In order to explore low temperature diagnosis method of winter wheat, sowing date-varietyinteraction experiment was conducted at National Precise Agriculture Demonstration Base in Beijing,while sowing date-variety-plant density interactive experiment and controlled experiment with artificialfrost chamber were conducted at Shangqiu Agriculture Technology Research Institute in Henanprovince in2009and2010, respectively. The effect of winter freezing damage and frost damage ongrowth and development and yield formation of winter wheat was analysed during these experiment.Based on the experiment research, explore low temperature diagnosis method of winter wheatappropriate to agriculture wireless remote monitoring system and give advices on suitable variety,optimal sowing date and plant density. The results showed that:1. The winter freezing damage of wheat was related to seedling situation and weather conditionsbefore winter. Wheat seedling situation before winter depended on weather conditions of growth stagebefore winter, especially from seedling to over-winter stage. There was no severe freezing injury whenaccumulated temperature before winter is less than310.19℃·d and cumulative sunshine hours is lessthan258h. Dead seedling rate was related to negative accumulative temperature, extreme lowtemperature and precipitation which were the key indicators of winter freezing damage warning. Mainindicators of over-winter seedling situation of winter wheat were group tiller, main stem leaf age,secondary radical root and tiller number per plant. In further, build seedling situation index (I) toquantitatively evaluate over-winter seedling situation. Winter freezing injury caused leaves dry up, insevere cases death of seedling or tiller, so over-winter loss is significant. Winter freezing injury mainlyaffected the number and percentage of ears.2. The stage from late differentiation of stamen and pistil to early another connective stage wasfrost sensitive. The results of controlled experiment with artificial frost chamber showed that-5℃is thecritical temperature when frost damage happened at another connective stage, and the lower thetemperature, the higher dead seedling percentage. When winter wheat developed into young panicledifferentiation stage, frost resistance become weaker. At this time, frost injury did harm to young ear,and then affected final production. Define days after jointing stage and minimum temperature as frostindicators, and then construct frost injury index (F) to precisely estimate the degree of frost injury whichcan be showed on website or mobile phone.3. Varieties with strong cold resistance and appropriate sowing date and pant density were the mosteffective measures to prevent winter freezing damage and frost damage of winter wheat. In Beijing,winter variety 'Jing9843' and semi winter variety 'Zhongyou206' could gain higher production affectedby winter freezing damage, and the suitable sowing date was between September28thand October3th.Weak spring variety 'Yunong949' was not recommended in Beijing for it was severely affected bywinter freezing injury and its product could not remain stable. In Shangqiu of Henan Province, underweak frost injury semi winter variety 'Aikang58' had higher production than 'Yunong949'. Through the analysis of the combination of density and seedtime, the reasonable sowing dates were during the firstand second ten days of October. And planting density of60to120kg per hm2was more appropriate.