Abstract: Based on soil ridged substrate-embedded cultivated method (SRSC), the authors further alleviate the problem of high temperature stress in the process of substrate cultivation and further promote the growth of tomato seedlings in summer in Chinese solar greenhouse by studying on the effect of heat insulation and cooling effect of different plastic films. A pot experiment was carried out to test changes of temperature and heat flux and record growth of tomato plants. In this study, five treatments were set, including soil ridge covered by transparent film as control (CK), SRSC ridge covered by transparent film (TM), SRSC ridge covered by black film (HM), SRSC ridge covered by ordinary reflective film (PF), SRSC ridge covered by highly reflective film (QF). Results showed that SRSC method could decrease temperatures under plastic film and in root zone compared with CK before planting, and temperatures under plastic film and in root zone of QF were the lowest. Average maximum temperatures under plastic film and in root zone of QF were 12.78 and 9.73℃ cooler than CK, and the average daytime temperatures under plastic film and in the root zone of QF were 7.88 and 6.16℃ cooler than CK, and QF had the best effects on the decrease of temperatures. After planting, changes of temperature under plastic film and in the root zone of each treatment were consistent with the former, and QF had?the best effects on the decrease of temperatures in this stage, and average maximum temperatures under plastic film and in root zone of QF were 8.96 and 8.97℃ cooler than CK, and average daytime temperatures under plastic film and in root zone of QF were 6.02 and 5.47℃ cooler than CK. But the cooling effect of QF was worse than the previous period caused by high environmental temperature. On the root zone cooling effect, cooling capacity followed by QF>PF>HM>TM>CK, respectively. At night, temperatures under plastic film and in root zone decreased to a suitable level. Root zone temperature and heat number has no direct relationship, and root zone heat transfer and root zone temperature of QF were the most slow in all treatments, and that suggested that slower of heat transfer, cooler the root zone temperature. Plant height and stem diameter of tomatoes cultivated on PF and QF were both higher than that of CK, and the effect of QF was the most significant. The biomass of tomato seedlings was gradually increased with effect of heat insulation and cooling increasing, and the fresh and dry shoot and root weight of QF was the best, and the growth of tomato seedlings was the best. In a word, SRSC covered highly reflective film can improve the ridge root zone heat effect and conducive to the growth of tomato seedlings compared with SRSC with other types of plastic film covering.

Key words: Heat preservation, High root zone temperature, Film, Changes of heat and temperature, Tomato