Effect Of Low Temperature Stress On Spike Development In Different Genotype Wheat At Booting Stage

The experiment was conducted in the Agricultural Experimental Center of Anhui Agricultural University from 2015 to 2017.Two wheat varieties with different low-temperature sensitivity（spring wheat variety Yangmai 18 and semi-winter variety Yannong 19）were selected as experimental materials.Simulated low-temperature stress in the artificial climate chamber to study the effect of low temperature stress on the spike development and yield formation in different genotype wheat.The main findings are as follows:1 Effect of low temperature stress on the morphology of spikelet and floret in different genotype wheat at booting stageThe spikelet of Yangmai 18 and Yannong 19 suffered from varying degrees of damage after 4°C low temperature stress at the booting stage.The spikelet spiked after the damage were all smaller than the normal growing control group;the second,third and fourth of Yangmai 18 were damaged.The florets were seriously affected.The 3rd and 4th florets of Yannong 19 were seriously affected.The growth of the florets was slower and the color became lighter than the normal growth control group.The young spikelet of spring wheat Yangmai 18 with poor cold resistance at booting stage was seriously affected and was more sensitive to low temperature stress.2 Effects of low temperature stress on photosynthetic parameters and endogenous protective enzyme activities of different genotype wheat flag leaves at booting stage After low temperature stress,the photosynthetic rate（P_n）,stomatal conductance（G_s）,intercellular CO₂concentration（C_i）,transpiration rate（T_r）and SPAD values of wheat flag leaves all showed a downward trend in Yangmai 18 and Yannong 19 at booting stage.With the strengthening of low temperature stress,the more significant the impact of flag leaf photosynthetic performance.Among the varieties,it was found that the photosynthetic performance of the semi-winter soybean variety Yannong 19was less affected by the low temperature,and the photosynthetic performance of the spring variety Yangmai 18 was greatly affected by the low temperature.The activities of superoxide dismutase（SOD）,peroxidase（POD）,and malondialdehyde（MDA）contents in flag leaves of Yangmai 18 and Yannong 19 were significantly affected by low temperature at 4°C for 3 days at the booting stage,and the activities of SOD and POD were significantly affected.Both showed an upward trend and decreased MDA content.Among the cultivars,the increase of SOD activity in flag leaves of Yangmai 18 was higher than that of Yannong 19 after low temperature stress,and the decrease of MDA content was greater than that of Yannong19,and the increase of POD content in Yannong 19 was greater than that of Yangmai18.3 Effects of low temperature stress on the content of sucrose and sucrose metabolism related enzyme activities in spikelets of different genotypes at booting stageThe sucrose content in the spike of wheat increased at the booting stage under low temperature stress,increased with the increase of cold stress,and increased the activity of sucrose phosphate synthase（SPS）,and the activities of sucrose synthase（SS）and invertase（Inv）decreased.Among the cultivars,the increase of sucrose content in the panicle of Yannong 19 was greater than that of Yangmai 18,especially the content of sucrose in the middle and lower parts of the panicle;the Inv activity in the upper and lower parts of Yangmai 18 decreased more than that of Yannong 19,and the Inv activity in the middle of the ear of Yannong 19 was found.The extent of decline was greater than that of Yangmai 18;the decline in SS activity of Yannong 19was greater than that of Yangmai 18;the SPS activity of Yannong 19 spike was greater than that of Yangmai 18.4 Effects of low temperature stress on the content of endogenous hormone in spikelet of different genotypic wheats at booting stageLow temperature stress at booting stage had significant effects on abscisic acid（ABA）,auxin（IAA）and gibberellin（GA）contents in Yangmai 18 and Yannong 19panicles,and the ABA content in different parts of wheat panicle increased,IAA and GA.The content decreased,and the IAA content in the lower part of the panicle,the upper ABA content,and the GA content in the upper and middle parts had a great influence.Comparing the two varieties,the lower extent of IAA content in the lower ear of Yanmai 18 was greater than that of Yannong 19;the increase of ABA content in the upper part of Yangmai 18 was greater than that of Yannong 19;the decrease of GA content in the upper and middle parts of the panicle was greater than that of Yannong19.5 Effects of low temperature stress on the activity of ADPG and SSS enzyme and the yield of different wheat genotypes in different parts of grain filling stage at booting stageThe low temperature stress at booting stage had a significant effect on the activities of ADPG and SSS enzymes in different parts of Yangmai 18 and Yannong 19 at the grain filling stage.The activities of ADPG enzyme and SSS enzyme in grains at different parts of the wheat panicle during filling stage showed a downward trend.Among the varieties,it was found that the activities of ADPG in the middle and lower parts of Yangmai 18 had a greater decrease than that of Yannong 19,while that of ADPG in the middle part of Yannong 19 was greater than that of Yangmai 18;the decrease in the activity of SSS in the middle part of Yangmai 18 was greater than that of Yannong 19,the tobacco farmers.The activity of SSS activity in the upper and middle parts of the ear decreased more than Yangmai 18.The number of panicles per plant,grain number per panicle and 1000-grain weight of wheat genotypes with different genotypes showed a downward trend after low temperature stress at the booting stage,and the differences were significant before and after low temperature treatment.