Effects Of Nocturnal Low Temperature On Growth And Physicochemical Indexes Of Two Types Of Tomato Seedlings

In this study,in order to screen out the accuracy of nocturnal low temperature indicators of tomato,the effects of nocturnal low temperature were studied on morphological indexes,physiological and biochemical indexes and photosynthetic characteristics of different genotypes of tomato,and response mechanism of different seedling age of tomato were researcheed under nocturnal low temperature stress.The cold resistance of tomato and cherry tomato was compareed.The effect of nocturnal low temperature on the tomato production was provided,which could provide reference for the environmental control of the tomato.The conclusions of this study are as follows:1.The low temperature stress at night has a significant inhibitory effect on the growth of two different genotypes of tomato。The plant height,stem diameter,fresh weight,dry weight,dry weight and fresh weight of tomato seedling were affected by different degrees,especially the plant height,underground dry and fresh weight。The low temperature stress at night reduced the root activity of tomato.With the extension of processing time,the lower the temperature at night,the lower the root vigor of tomato seedling seedlings.The contents of soluble sugar,proline,SOD activity and CAT activity in tomato leaves increased first and then decreased.The content of MDA and the activity of POD in tomato leaves showed an increasing trend,and the lower the temperature at night,the greater the increase.2.Nocturnal low temperature stress had a great influence on the photosynthetic pigments and photosynthetic characteristics of two different genotypes of tomato.The low temperature at night hindered the synthesis of chlorophyll a,increased the content of chlorophyll b and fluctuated the total chlorophyll content.And nocturnal low temperature decreased the photosynthetic rate of the plants.The low temperature stress at 5 at night was the most serious damage to tomato photosynthesis.℃3.There was no significant difference in the contents of MDA,soluble protein,SOD activity and photosynthetic pigments in leaves of two different genotypes.The results showed that the plant height,seedling index,root activity and POD activity of tomato "ZhaoYan 5" were significantly higher than those of cherry tomato "Devil".The soluble sugar content and proline content in cherry tomato "Devil" leaves were higher than those of Tomato "ZhaoYan 5".4.For the same kind of tomato seedlings that were forced in the same nocturnal low temperature,the longer the seedling age,the stronger the cold resistance.In summary,the different levels of low nocturnal temperature stress caused varying degrees of damage for different genotypes of tomatoes.The lower the temperature and the longer the treatment time,the more serious the damage to tomato seedlings.The longer the seedling the tomato seedlings have,the stronger the cold resistance.Plant height,underground dry weight,fresh weight,root activity,POD activity,soluble sugar content,photosynthetic characteristics,chlorophyll b and so on can be used as indicators of tomato varieties at night.