Effects Of Low Temperature Stress On Root Physiology And Pathogen Content Of Stem Base Rot Of Wheat

Winter wheat is one of the important food crops in Hebei Province.In recent years,the low quality of corn straw returning to the field,too shallow rotary tillage,and substandard suppression operation and other agricultural management problems have led to the deterioration of winter wheat root zone environment.Abrupt temperature decrease in winter and early spring,caused low temperature freezing injury or chilling injury,reducing the resistance of root system and accelerating the infection of soil borne pathogens.The effect of low temperature on Fusarium crown rot(FCR)caused by Fusarium pseudogr amine arum was obvious,and the yield of wheat was seriously affected..Therefore,the study on the effects of soil temperature drop on wheat resistance and pathogen infection is of positive significance to clarify the relationship among pathogen,environmental conditions and host wheat.At the same time,it also has great reference value for the construction of green and efficient prevention and control technology system of winter wheat FCR.In this study,"Shulan 02-1"(not resistant to low temperature)and"Jimai 738"(resistant to low temperature)were used as experimental materials.Low temperature treatments were set in overwintering,rising and jointing stages of Wheat by pot inoculation.The physiological characteristics of root stress resistance and the incidence of FCR were measured.The changes in the content of pathogen and severity of disease were analyzed.The main results are as follows:(1)Compared with different low temperature treatment periods,low temperature treatment at overwintering stage could increase SOD enzyme activity and soluble protein content of wheat roots,but also increase EC Value and MDA content;low temperature treatment at rising stage could improve the activities of pod and cat,and the increase of soluble sugar was the largest,and the low temperature resistant variety showed more obvious performance.Compared with different varieties,low temperature treatment in the early stage had an significant effect on cat enzyme activity,soluble sugar content,MDA content and EC value of low temperature resistant varieties.While the effects of low temperature treatment in early stage on SOD and POD activities of low temperature resistant varieties were more significant.(2)Compared with the control,the CT value of the two varieties increased by 40.3%on average.At the milk ripening stage,the effect of low temperature treatment on the CT value still existed.The three low temperature treatments increased 230.2%(Shiluan)and 54.2%(Jimai)respectively.Compared with different varieties,the effect of low temperature treatment on root CT value of low temperature resistant varieties lasted longer.The effect of low temperature treatment on the incidence rate and disease index of wheat stem and base rot was the most obvious,the two varieties showed the same performance,and the incidence of low temperature resistant varieties was more serious.(3)After low temperature stress,the cortical cells of wheat roots were broken,abscission,deformation and irregular arrangement caused by large intercellular space,and the performance of low temperature resistant varieties was more significant.At the same time,the infection speed and depth of root pathogens of low temperature resistant varieties were significantly higher than those of low temperature resistant varieties.(4)there was a significant positive correlation between the Ct value of the main pathogens and the disease index and incidence rate of wheat stem basal rot.The correlation coefficient of "Shulan 02-1" was r=0.80**to 0.92**,and the correlation coefficient between Jimai 738 was r=0.90**to 0.95**.In stress resistance physiology,MDA content and EC value were significantly or extremely significantly positively correlated with fluorescence quantitative value and disease characteristics,with correlation coefficients ranging from 0.79**to 0.87**.There was no significant positive correlation between SOD,POD and CAT activity and disease index and incidence rate(r=0.51-0.69).The relationship between the content of SS and SP,CT value and disease characteristics of the two varieties were different.