| In this experiment,high sugar tomato"181"and common quality tomato"Mao Fen 802"were used as test materials,and the irrigation amount of 75%-90%maximum field capacity of substrate was set as control(CK).The two tomato varieties were treated with mild(80%CK),moderate(60%CK)and severe(40%CK)water deficit treatment,respectively.The growth of tomato plant,yield,appearance quality,flavor quality and nutritional quality of tomato were measured and the flavor components of sugar,sugar metabolism related enzyme activity and related gene expression were analyzed to explore the effects of water deficit degrees on quality and sugar metabolism of tomatoes cultivated with substrate in greenhouse.The results of the study will provide theoretical support for high quality cultivation of tomato in greenhouse.The main results are as follows:1.Water deficit inhibited the growth of tomato plants,and the greater the degree of water deficit,the more obvious the inhibition effect on plant height,stem diameter and leaf area of the two varieties.After treating with different water deficit degrees for 42 days,the plant height,stem diameter and leaf area of 181 under severe water deficit condition were significantly reduced by 25.92%,7.03%and 15.04%,respectively,while those of Mao Fen802 were significantly decreased by 31.61%,3.24%and 11.23%,respectively.There was no significant difference in the number of leaves among different treatments.At the same time,water deficit also reduced transpiration rate,net photosynthetic rate and stomatal conductance.The transpiration rate,net photosynthetic rate and stomatal conductance of181 were significantly decreased by 20.34%,39.36%and 13.08%,respectively,while those of Mao Fen 802 were significantly decreased by 14.17%,47.29%and 13.71%,respectively.2.Water deficit reduced the weight per fruit,yield per plant and yield per 667 m~2 of tomato,and the less irrigation water,the more obvious the yield reduction effect.The yield per 667 m~2 of 181 was 5332.51 kg in control treatment,and the yield per 667 m~2 of 181tomato treated with severe water deficit was 3495.64 kg,which decreased by 34.44%.The yield per 667 m~2 of Mao Fen 802 was 8511.89 kg in control treatment,and the yield per 667m~2 of Mao Fen 802 tomato treated with severe water deficit was 6779.68 kg,which decreased by 20.35%.Although the yield of the two varieties treated with mild water deficit was lower than that of the control treatment,there was no significant difference between them.Although water deficit reduced the yield,the water use efficiency(WUE)increased significantly.The WUE of 181 treated with mild,moderate and severe water deficit treatment was increased by 14.69%,25.80%and 40.00%,respectively,and that of Mao Fen802 was increased by 14.69%,35.28%and 70.09%,respectively.3.Water deficiency could improve the quality of tomato in different degrees,The sugar content of 181 increased first and then decreased with the decrease of irrigation amount,and the sugar content of moderate water deficit treatment was the highest.The sugar content of Mao Fen 802 increased gradually with the decrease of irrigation amount,and the sugar content of severe water deficit treatment was the highest.Volatile matter content of 181 of tomato fruits increased firstly and then decreased with the aggravation of water deficit.The total contents of volatile substances in 181 of tomato fruits were 2235.47μg/kg,3096.57μg/kg,3729.57μg/kg and 2221.70μg/kg,respectively,and the total number of volatile substances in 181 of tomato fruits were 60,65,78 and 62 kinds,respectively.The contents of volatile substances in Mao Fen 802 increased with the decrease of irrigation amount.The total contents of volatile substances in each treatment were 1750.78μg/kg,1896.13μg/kg,2030.32μg/kg and 2269.57μg/kg,and the total number of species were 46,50,50 and 53,respectively.Water deficit also increased the contents of lycopene,lutein andβ-carotene in tomato fruits,and decreased the content of chlorophyll in tomato fruits.The more serious the water deficit was,the more the pigment decreases or increases.Compared with the control treatment,the contents of lycopene,lutein and carotene of 181 under severe water deficit increased by 16.96%,9.01%and 3.72%,respectively.However,the Mao Fen 802increased by 33.15%,5.47%and 7.27%,respectively.4.Effects of water deficit on different varieties and different developed periods of tomato are different.In tomato maturation,the moderate water deficit of 181 and the severe water deficit of Mao Fen 802 could up-regulateα-AYM,β-AYM,SS,SPS,AI genes,and down-regulate NI genes.The activity ofα-amylase,β-amylase,SS enzyme,SPS enzyme and AI enzyme was increased,and the activity of NI enzyme was decreased..Furthermore,the decomposition of starch and sucrose and the synthesis of glucose and fructose were enhanced,and finally the soluble sugar content of tomato fruit was increased.In conclusion,although water deficit reduced the growth of tomato plants and the yield of tomato,it improved water use efficiency and fruit quality.Compared with the control treatment,the yield of 181 treated with mild water deficit was 5029.6 kg/667m~2,which decreased by 5.68%and had no significant difference.The treatment save 20%water,and the water use efficiency was 14.69%higher.Compared with the control treatment,the contents of soluble sugar,organic acid and total volatile matter were increased by 20.60%,10.34%and 38.52%,respectively.Compared with the control treatment,the yield of Mao Fen 802 under mild water deficit treatment was 8028.94 kg/m~2,which decreased by 5.68%and had no significant difference.The water use efficiency was increased by 14.69%,and the contents of soluble sugar,organic acid and total volatile matter were increased by 8.58%,50.00%and 7.08%,respectively.By regulating the expression ofα-AYM,β-AYM,SS,SPS,AI and NI genes,water deficit affected the activities ofα-AYM,β-AYM,SS,SPS,AI and NI enzymes,leading to the change of sugar composition in tomato fruits.Moreover,the two varieties of tomato had different responses to water deficit.For soluble solids,volatiles and sugars,water deficit always promoted the quality of Mao Fen 802.However,severe water deficit can inhibit the quality of 181. |
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