The Effect Of Different Water Flow In Root-cooled Pipe Of Water-cooled Seeding Bed On Growth Of Tomato Seedling

High temperature stress is one of the main factors of intensive seedling in summer and low temperature can be used as an effective cooling method in the nursery. In order to explore whether water-cooled seedbed is useful in summer seedling, this paper studied the influences of different flow rates(0.03 m3/h, 0.06m3/h, 0.09m3/h) and different pipe length(each 2m in a plot, totally 5 plots) at the same rate on tomato seedlings. The conventional seedbed seedling was used as control. Suitable flow rate and the length of facilities were determined by measuring various physiological indexes in different development phases. Results showed that:1、T he different growth tendencies of tomato seedlings were observed at different flow rates. AW2(at 0.09m3/h、2-4m) was suitable by comparing hypocotyls length and seedling index. Hypocotyls length and plant height of seedlings on water-cooled seedbeds decreased obviously compared with CK. So water-cooled seedbeds could alleviate the high temperature stress.2. Root activity, chlorophyll content showed a rising trend at an increasing flow rate while a decreasing trend was observed as the distance of water at the same flow rate. 3、As seedling age rose, the advantages of water-cooled seedbeds gradually displayed. The seedlings had a significantly lower plant height, an increased stem diameter and a higher seedling index compared with CK.3. As seedling age rose, the advantages of water-cooled seedbeds gradually displayed.There were a significantly lower plant height, an increased stem diameter and a higher seedling index compared with CK.4. Temperature of water-cooled seedbed s was controlled between20~25℃in sunny days and the accumulated temperature was obviously lower than CK, even in cloudy days. The minimum temperatures of water-cooled seedbeds were AW1 at the highest flow rate(at 90m3/ h, 0 to 2 m).5. Accumulated temperature of tomato roots on water-cooled seedbeds increased obviously with the decreasing flow rate while rose when distance to water increased.