[Effects of day and night temperature difference on growth, development, yield and fruit quality of tomatoes].

Abstract: The effects of day and night temperature difference (DIF) on tomato's growth were studied in three precisely controlled units in phytotron. Set DIF as 6 °C (25/19 C), 8 °C (26/18 °C), 10 °C (27/17 °C) respectively, with the same diurnal mean temperature as 22 °C. The results showed that, different tomato varieties needed different suitable DIF at different growth stages. Before flouring, compared with DIF 6 °C , DIF 8 °C could significantly improve the growth and development of the wild currant tomato LA1781, increasing the plant height by 23.1%, fastening leaf development by 1-2 leaves, advancing flowers by 7 d. DIF 10 °C had similar effects with DIF 8 °C on LA1781. As to the cultured ordinary tomatoes LA2397 and LA0490, DIF 6 °C made the seedlings grow well, DIF 8 °C had no significant improved effects on seedlings, DIF 10 °C depressed the seedling's growth and flouring, decreasing the plant height by 12.0%-18.3%, lowering the leaf development by 2-3 leaves, delaying flouring by 2-4 d. But DIF 10 °C increased the dry aboveground mass of these three varieties by 25.2%-44.2%. After flouring, compared with DIF 6 °C, DIF 10 °C could significantly improve the yield and fruit quality of LA1781, increasing fruit number by 34.7%, yield per plant by 92.1%, single fruit mass by 40.0%, soluble sugar content by 16.3%, lycopene content by 95.6%. Compared with DIF 6 °C, LA2397 and LA0490 had higher yields and better fruit quality under DIF 8 °C, and lycopene content increased more than twice as that under DIF 6 °C. Under DIF 10 °C, yields of LA2397 and LA0490 slightly decreased (5.0%), soluble sugar contents of fruit decreased, but fruit size and lycopene content increased. The results showed that, DIF should not be very great in the seedling period of tomatoes, and a moderate DIF in flower and fruit periods could improve the yield and fruit quality, but a too high DIF would result in poor growth and yield reduction.