Cold Tolerance Evaluation Of Twelve Wheat Varieties In Henan Based On Their Physiological Responses To Low Temperature Stress In Spring

Agriculture is the most sensitive department to climate change and is the largest field restricted by climate.Climate change will affect the food security and sustainable development directly.The emerging possibility of late spring coldness is increasing year by year.To explore the response of wheat cultivars to low temperature in spring,12 wheat cultivars widely planted in Henan were used to study the effects of low temperature during jointing and booting stage on spike number,grain number per spike,1000-grain weight,yield and physiological indices of leaves and tillering nodes and the correlation of the cold damage level with the physiological indices increment.We used the principal component analysis and clustering analysis to evaluate the cold resistance of different wheat cultivars and screened the physiological indices closely related with the cold resistance in spring.And we studied the influences of low temperature on grain protein and starch content.It is vital important to study the wheat spring cold response mechanism.In this paper,the main results were as follow:Analysis on the relationship between the wheat spike differentiation and the change of physiological indices showed that the contents of soluble sugar,soluble protein and soluble proline and the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)had a larger increment in strong cold resistant cultivars compared with weak cold resistant cultivars.Besides,the MDA content in leaves and tillering nodes showed the opposite trend and the slower of the process of wheat spike differentiation,the stronger of the wheat cold resistance.The spike number,grain number per spike,1000-grain weight and crop yield of 12 cultivars decreased under low temperature stress during jointing and booting stage.Cold had a more serious influence on the1000-grain weight at jointing stage but on the grain number per spike at booting stage.Low temperature had no significant effect on the spike number and yield at jointing and booting stage.All wheat cultivars dry matter decreased at the same time and jointing stage low temperature had a more serious influence on dry matter.Using the principal component analysis we obtained D value of lead and tillering node and the cluster analysis on evaluating the wheat cultivas cold resistance was based on D value.Thenthe 12 wheat cultivars were classified into three types under jointing stage low temperature,the first type was high cold resistance(H)type that included Zhengmai 366,Aikang 58 and Yunong211;the second type was medium cold resistance(M)type that included Zhoumai 26,Yumai49-198 and Xinong 979;the third type was low cold resistance(L)type that included Zhengmai7698,Zhoumai 22,Zhoumai 27,Pingan 8,Kaimai 21 and Hengguan 35.These results above were based on D value of leaf.The cluster analysis based on D value of tillering node results showed that H type included Zhengmai 366,Aikang 58 and Zhoumai 27;M type included Zhoumai 22,Zhoumai 26,Yunong 211 and Yumai 49-198;L type included Zhengmai 7698,Pingan 8,Kaimai21,Hengguan 35 and Xinong 979.The cluster analysis based on the decrement of yield during jointing stage showed that H type included Zhengmai 366,Aikang 58 and Zhoumai 27;M type included Zhengmai 7698,Zhoumai 22,Zhoumai 26 and Pingan 8;L type included Yunong 211,Yumai 49-198,Kaimai 21,Hengguan 35 and Xinong 979.Under the booting stage low temperature,the results of cluster analysis based on D value of leaf showed that H type included Aikang 58 and Yunong 211;M type included Zhengmai 366,Zhoumai 27 and Yumai 49-198;L type included Zhengmai 7698,Zhoumai 22,Zhoumai 26,Pingan 8,Kaimai 21,Hengguan 35 and Xinong 979.The cluster analysis based on D value of tillering node results showed that H type included Aikang 58;M type included Zhengmai 366,Zhoumai 26,Zhoumai 27,Yunong 211 and Yumai 49-198;L type included Zhengmai 7698,Zhoumai 22,Pingan 8,Kaimai 21 and Xinong979.The cluster analysis based on the decrement of yield showed that H type included Aikang 58,Yunong 211,Hengguan 35 and Xinong 979;M type included Zhengmai 366,Zhoumai 22,Zhoumai 26,Zhoumai 27 and Kaimai 21;L type included Zhengmai 7698,Yumai 49-198 and Pingan 8.Results about analysis on screening the physiological indices closely related with the cold resistance in spring showed that under low temperature during jointing stage,the cold damage level was significantly or very significantly correlated with the increment of soluble protein,soluble proline and MDA content,SOD and CAT activity in leaf;the cold damage level was significantly or very significantly correlated with the increment of soluble sugar,soluble proline and MDA content and CAT activity in tillering node.Under low temperature during booting stage,the cold damage level was significantly or very significantly correlated with the increment of soluble sugar,soluble protein and MDA content,SOD,POD,CAT activity in leaf;the cold damage level was significantly or very significantly correlated with the increment of soluble sugar,soluble protein and MDA content and CAT activity in tillering node.The effect of jointing and booting stage low temperature on grain protein and starch content of different wheat cultivars indicated that all grain protein content increased otherwise grain starchcontent decreased.Tweleve wheat cultivars were divided into 3 groups under cluster analysis based on the protein increment and starch decrement.The first group was that cultivars grain protein and starch responsed to the low temperature most sensitively;the seconed group was in which cultivars grain protein and starch responsed to the low temperature most insensitively;the third group was that cultivars grain protein and starch responsed to the low temperature generally.The wheat cultivars grain protein average increment in group 1,2,3 were 88.76% and 97.70%,6.86% and 8.54%,44.70% and 50.52% respectively under jointing and booting stage low temperature.The grain starch average decrement in group 1,2,3 were 27.51% and 25.27%,12.25% and 7.75%,19.79% and 15.19% respectively.So cold had a more serious influence on starch content at jointing stage but on the protein content at booting stage.