Abstract:

The objective of this study was to evaluate the effect of temperature stress on Lactuca sativa var. ramosa in prefabricated solar greenhouse, with a view to laying the foundation for the high quality cultivation of facility vegetables and improving the level of environmental regulation and management. L. sativa var. ramosa was used as the test material, and four temperature treatment groups (5, 10, 15, 23℃) were set up during the seedling stage. Each temperature treatment group was treated for 3, 6 and 9 d respectively. The effects of different treatments on plant height, fresh weight, water content, leaf number and leaf area during the growth were analyzed. The results showed that: (1) the longer the treatment days, the more significant the difference on plant height and fresh weight caused by different temperatures. Among them, T₉₂₃ (23℃ treatment for 9 days) showed the most significant growth in culture, with plant height 127%, 86.98%, 72.60%, and fresh weight 104%, 79.25%, 60.16% higher than T₉₅ (5℃ treatment for 9 days), T₉₁₀ (10℃ treatment for 9 days), T₉₁₅(15℃ treatment for 9 days) at maturity, respectively. (2) Under the condition of 3 d treatment, the difference of water content at four temperature levels was not obvious, but under the condition of 6 and 9 d treatments, 5, 10, 15℃ treatments had different degrees of inhibition. (3) The leaf number at four temperature levels was not significantly different under the conditions of 3 and 6 d treatments, and increased by 3 to 4 times in the mature stage. Under the condition of 9 d treatment, the leaf number at lower temperatures (5, 10, 15℃) was significantly less than 23℃. The mature stage only increased by 2.3-2.6 times compared to the initial stage of cultivation. (4) For leaf area, there was no significant difference among the four temperature levels under 3 d treatment conditions. While under 6 and 9 d treatments conditions, the leaf area at 23℃ was significantly higher than that at lower temperatures (5, 10, 15℃). Among them, the maturity period under the 6 d treatment was 119%, 86.25%, 71.46% higher than that under the 5, 10, 15℃ treatments. While under the condition of 9 d treatment, it was 174%, 143%, 113% higher, respectively. Research has shown that the plant height, fresh weight, water content, leaf number and leaf area could be significantly improved by pretreatment at 23℃ for 9 d during the seedling stage. Temperature below 15℃ for more than 3 d is not conducive to the growth and development of L. sativa var. ramosa.

Key words: prefabricated solar greenhouse, Lactuca sativa var. ramosa, seedling stage, temperature stress, growth index, facility vegetables