Effects Of High Temperature And High Humidity On Tomato Fruit Growth?Sugar And Nitrogen Metabolism In Greenhouse

To study the effects of high temperature and high humidity combined stress on tomato,a three-factor orthogonal test of temperature,relative humidity and durations was carried out using " Fen Luo Lan " as material.There were four levels of temperature: 32?/22??35?/25??38?/28??41?/31?(the daily maximum temperature /lowest temperature),three levels of air relative humidity: 50%±5%,70%±5%,90%±5%,and four durations(3,6,9,12d),with 26?/16? and 50?55% humidity as control(CK).High-temperature and high-humidity tests were performed during the flowering and fruit expansion periods.Through systematically studying the dynamic changes of tomato fruit growth and the changes of sugar and nitrogen metabolism during fruit expansion,turning and maturity periods,the metabolic mechanism of high temperature and humidity affecting tomato fruit growth and quality formation was explored.The results of the study are as follows:(1)High temperature stress obviously inhibited the growth of tomato fruit in both horizontal and vertical diameters.The higher the degree of high temperature stress,the lower the maximum value of the fruit's horizontal and vertical diameters,the smaller the peak of the growth rate,the rapid growth time prolonged,and the peak point and the end of the growth rate delayed to varying degrees.The maximum value and peak growth rate of fruits treated at high temperature in fruit stage were significantly lower than those at flower stage.Under high temperature conditions,the maximum value of RH70% treatment and the peak growth rate were higher than those of the other two treatments.(2)High temperature stress significantly affected the index of nitrogen metabolism in tomato fruits,With the increase of temperature stress,the soluble protein content,NR and GS of fruit in each growth period increased first and then decreased after the high humidity stress during flowering period,and the soluble protein,NR and GS content of each fruit period gradually decreased after high temperature stress in fruit period.Free amino acids showed a significant increase,GOGAT showed a significant decrease.Under high temperature environment,the soluble protein and NR of fruit were highest at RH70%.GS and GOGAT increased with the increase of humidity,and free amino acids were not sensitive to changes in humidity.After high temperature treatment,the soluble protein content was significantly positively correlated with NR,GS and GOGAT.(3)With the increase of temperature stress,the total sugar,sucrose,SSc and SPS of tomato fruits showed a gradual decrease,while AI,NI and SSs all showed an increase.In different humidity treatments,the total sugar content of tomato fruits at various growth stages in the flowering period was the highest at RH70%,and the highest at the fruiting period.The sucrose content increased with increasing humidity.From the mean value of humidity treatment,AI,NI and SSs decreased with increasing humidity,and SSc and SPS had higher activity at RH70%.After high temperature stress,total sugar and sucrose showed positive correlation with SSc and SPS,but negative correlation with AI,NI and SSs.In summary,high temperature is the main factor affecting tomato fruit growth and sugar and nitrogen metabolism.Increasing humidity in a high-temperature environment can alleviate high-temperature stress to a certain extent and promote fruit growth,but little effect on the metabolism of sugar and nitrogen.