Effects Of Exogenous NO On Different Eggplant Seedlings Under Low Temperature Stress

In this experiment,eggplant was used as the test material.Througu the physiological and biochemical analysis and comprehensive evaluation of cold tolerance of six different varieties under low temperature stress were studied.And sprayed with different concentrations(0,0.1,0.3,0.5,1.0 mmol/L)exogenous NO donor SNP solution to study the effects of eggplant seedlings on the growth,physiological characteristics,photosynthetic pigment content,photosynthetic parameters,and chlorophyll fluorescence parameters of different eggplant seedlings under low temperature stress,with a view to alleviating the low temperature stress environment on eggplant.In order to provide some effective methods and theoretical basis for alleviating the adverse effects of low temperature stress environment on the growth of eggplant.The main findings are as follows:1.The physiological effects and comprehensive evaluation of cold tolerance of different eggplant seedlings were studied.The results showed that the relative conductivity and MDA,proline,soluble protein contents and SOD,POD,CAT activities of six eggplant seedlings increased compared with the normal temperature control under low temperature stress,while the chlorophyll content was lower than the normal temperature control.Different varieties of eggplant seedlings had different physiological and biochemical reactions under low temperature stress.Principal component analysis and membership function analysis showed that the contents of proline and MDA could be used as indicators for rapid screening of eggplant seedling cold tolerance varieties.The cold resistance from strong to weak was’xiuniang’>’round purple eggplant’>’xiangmizi purple red long eggplant’>’funong green eggplant’>’round green eggplan’>’No.7 white eggplant’.2.Effects of exogenous NO on the growth and physiological characteristics of eggplant seedlings under low temperature stress.The results showed that the plant height,stem thickness,dry weight,seedling growth index and relative growth amount of the eggplant seedlings in the T0 and A0 treatments of’xiuniang’and’No.7 white eggplant’varieties were lower than the normal temperature control under low temperature stress.However,all indexes in spraying different concentrations of exogenous NO donor SNP solution were improved.However,the relative conductivity,and MDA,proline,soluble protein,soluble sugar contents,and SOD,POD,CAT activities were higher than the normal temperature control in the T0 and A0 treatments,the relative conductivity and MDA content of each treatment by spraying different concentrations of exogenous NO donor SNP solution decreased,proline,soluble protein,soluble sugar contents and SOD,POD,CAT activities increased,and the change time was earlier.Both varieties were treated with 0.3mmol/L exogenous NO donor SNP solution for the best relief effect,while exogenous NO donor SNP solution was too high and the relief effect was poor.Among them,the seedling growth index,relative growth amount and SOD activity of’xiuniang’variety increased greatly,the MDA content and relative conductivity decreased greatly,while the content of osmotic adjustment substance and POD and CAT activities of’No.7 white eggplant’variety increased greatly.3.Effects of exogenous NO on pigment content and parameters of photosynthetic of eggplant seedlings under low temperature stress.The results showed that under low temperature stress,the chlorophyll a,chlorophyll b and chlorophyll a+b contents,intercellular carbon dioxide concentration Ci,transpiration rate Tr and stomatal conductance Gs of eggplant seedlings treated with T0 and A0 were significantly lower than normal temperature control.The indexes of spraying different concentrations of exogenous NO donor SNP solution were higher than T0 and A0 treatments.Both varieties were treated with 0.3mmol/L exogenous NO donor SNP solution for the best relief effect,followed by0.1mmol/L exogenous NO donor SNP solution treatment,but the performance of the indicators of the two varieties was different.The photosynthesis rate Pn of the’xiuniang’variety with T1-T3 treatments reached the control level,and the Ci and Gs of each treatment increased higher compared with the T0 treatment.The photosynthetic pigment content of A2 treatment reached the control level on the 2nd and 8th days of the’No.7 white eggplant’variety,and the Tr of each treatment increased higher compared with the A0 treatment.4.Effects of exogenous NO on chlorophyll fluorescence parameters of eggplant seedlings under low temperature stress.The results show that the maximum fluorescence Fm,maximum fluorescence under light Fm’,the photorealistic chemical quantum efficiency Y_Ⅱ,the apparent electronic efficiency ETR,and the photochemical quenching QL of eggplant seedlings treated in T0 and A0were all lower than the normal temperature control under low temperature stress,while the non-photochemical quenching NPQ was higher than the normal temperature control.However,Fm,Fm’,NPQ,Y_Ⅱ,and ETR of different treatments by spraying different concentrations of SNP solutions were significantly increased,while NPQ was significantly reduced.Among them,the overall performance of the’No.7white eggplant’variety was better.Both varieties were treated with0.3mmol/L exogenous NO donor SNP solution to improve the effect was best,while 1.0mmol/L exogenous NO donor SNP solution treatment was the worst.