Effects Of Low Temperature And Drought Stress On Physiological And Biochemical Indexes Of Male And Female Plants In Ilex Centrochinensis

This thesis is based on 6-year-old male and female seedlings as low temperature stress test materials,respectively in the natural winter(October to March the following year)and artificial low temperature(5?,0?,-5?,-10?,-15? and-20?),The effects of relative conductivity(Rec),malondialdehyde(MDA),free proline(Pro),soluble protein(SP),soluble sugar(SS)and Superoxidedismutase(SOD)Peroxidase(POD),chlorophyll(Chl)and carotenoid(Car)content were measured;At the same time,the I.Centrochinensis of one-year-old male and female were used as drought stress test materials.Respectively,in the natural drought(not watering after a watering)and artificial drought(CK:35%-40%of the soil moisture content;mild drought:25%-30%of the soil moisture r content;moderate drought:15%-20%of the soil moisture content;High drought:5%-10%of the soil moisture content),The physiological indexes of WSD,Rec,MDA,Pro,SP,SS,SOD,POD and Chl were measured,and the correlation analysis and principal component selection of these nine physiological indexes were carried out.Comprehensive evaluation of cold resistance and drought resistance of male and female plants with semi lethal temperature(LT50).The results are as follows:1.During the natural winter,the relative electrical conductivity of the male and female plants were positively correlated with the natural temperature.The contents of MDA,SS and Pro increased with the decrease of natural temperature,and then decreased gradually after the temperature rising;SOD activity and SP content were consistent,showing the trend of rising first and then rising again,The activity of POD,Chl and Car decreased with the decrease of natural temperature,and the temperature increased gradually.2.Under the stress of artificial temperature,the content of Rec and MDA in male and female plants showed "S" type increase with the decrease of temperature.The change of SS content was"first rise then fall then rise".Pro,SP and SOD of the change was "first rise and fall" trend,and the activity of POD was "decreasing first and then rising".The change of chlorophyll content decreased with the decrease of stress temperature,and the change of carotenoid content was basically unchanged.3.The contents of SOD,SS,SP and Pro in the leaves of the middle mongolica were lower than those under the low temperature stress,and the contents of the physiological indexes were lower than those under the low temperature stress.SOD and SS content is about 2 times higher than normal,Pro content for normal circumstances 3 to 5 times.The results showed that the accumulation of SOD,SS,SP and Pro could improve the cold resistance of I.Centrochinensis.4.Under natural drought stress,the WSD,Rec and MDA of male and female were increased with the number of days of stress,and positively correlated with the number of stress days.The changes of SS,SP,Pro and POD were "rising first and then decreasing" with the increase of the number of days.SOD activity and Chl content decreased with the number of days of stress,and negatively correlated with the number of stress days.5.Under the artificial drought stress,the drought growth rate of the soft soil was the fastest.The changes of WSD,MDA,Pro and SS contents were not significantly different from CK under mild drought stress.Under moderate drought and severe drought stress,there was a sudden increase in WSD,the content of Pro increased with the increase of the number of days.The change of SS content increased first and then decreased.The change of SP content increased with the increase of the number of days of stress,which was positively correlated with the number of days of stress.The decrease of SOD activity with the increase of stress days was negatively correlated with the number of stress days.Under mild drought and moderate drought stress,POD activity increased with the increase of stress days,and there was no significant difference between them.The activity of POD was "rising first and then decreasing"under severe drought.The chlorophyll content of different drought gradients was not consistent.In the mild drought,the chlorophyll content of the male and female plants was increased with the increase of the number of stress days.The chlorophyll content under the moderate drought stress was the trend of increasing first and then decreasing.The chlorophyll content increased with the increase of the stress days and down.6.There was a significant negative correlation between low temperature stress and Rec and MDA.Low temperature stress had significant positive correlation with SP and Chl.The number of days of drought stress was positively correlated with Rec,which was positively correlated with WSD,and negatively correlated with SOD.The contents of Rec,MDA,WSD,SP,Pro,SOD,POD and Chl were closely related to the cold resistance and drought resistance of the male and female plants in I.Centrochinensis,and could be used as a physiological index to evaluate their cold resistance and drought resistance.The cold resistance and drought resistance of the female and male plants were not significantly different.The Male and female strains in January the semi-lethal temperature were:female-4.84? and male-4.40?,cold hardiness.The natural drought stress for 30?45 days was the longest drought stress time,mild drought was beneficial to the growth of I.Centrochinensis,strong drought resistance.