Abstract: The accumulation rate of dry matter and leaf growth rate reached their biggest value at 30℃ root temperature.Plant growth became slower at lower or higher root temperature. Higher root temperature harmed plant more seriously, and harmed root more seriously than shoot. Root temperature, lower or higher than 30℃, affected leaf growth through the increase of leaf elastic modulus rather than through the decrease of leaf pressure potential. The increasement rate of total absorption area of root system was the biggest at 30℃ root temperature; that of active absorption area was biggest at 25℃ root temperature.The increasement of total and active absorption area of root system became the slowest at 40℃ root temperature. Absorption area of unit weight root was the smallest at 25℃ root temperature, and reached its biggest value at 40℃ root temperature. At lower root temperature, the percentage of active absorption area and root/shoot ratio became bigger, and the influence of root temperature on root growth was amaller relatively.Tomato did adaptation reaction to harmful root temperature through function compensation.

Key words: Tomato, Root-temperature, Growth, Adaptation