塑料大棚渗灌灌水下限对番茄生长和产量的影响

利用土壤水分张力计监测土壤水分吸力的变化，以灌水时30cm土层的土壤水分吸力表示渗灌灌水下限，研究灌水下限为10、16、25、40和63kPa时对塑料大棚番茄生长和产量的影响．结果表明，番茄株高、生物量分别随灌水下限的增大而减小．番茄的产量和水分利用率与灌水下限间的关系曲线为抛物线，而茎粗／株高比与灌水下限间的关系曲线为三次多项式曲线．灌水下限不同，番茄的根／冠比(R／S)动态不同，番茄根系与株冠的生长状况不同．灌水下限在25～33kPa时，番茄植株生长健壮，根冠比例协调，产量大，水分利用率高．此指标作为渗灌灌水下限，灌水时土壤水分的含量比常规灌水低，灌水次数少，有利于提高保护地番茄栽培的水分利用率和劳动生产率．

Effects of lower limit of subsurface drip irrigation on tomato growth and its yield in plastic tunnel

A subsurface drip irrigation experiment was conducted in a plastic tunnel to study the effects of different lower limits of subsurface drip irrigation on tomato growth and its yield. The lower limits of subsurface drip irrigation were expressed by soil water suctions detected by tensiometers placed in 30 cm soil layer. The designed values of soil water suction in this experiment were 10, 16, 25, 40 and 63 kPa, respectively. The results showed that the height and biomass of tomato plant decreased significantly with increasing lower limits of subsurface drip irrigation. Parabolic regression curves were suitable to simulate the relationships of stem diameter of tomato plant, yield, and water use efficiency (WUE) with lower limits of subsurface drip irrigation. The relationship between the ratio of stem diameter to plant height of tomato and lower limit could be simulated by three-dimensional multinomial regression curve. The growth of tomato root and shoot and their ratio R/S) varied under different lowerlimits of subsurface drip irrigation. The tomato plant grew well, RI/S was favorable, and the yield and WUE were higher when soil water suction was in the range of 25- 33 kPa. When this range was served as the criteria for subsurface drip irrigation, the soil water content at the beginning of irrigation should be lower, and the irrigation frequency should be fewer than that of conventional irrigation. This range of soil water suction was in favor of improving the WUE and decreasing labor cost for tomato cultivation in plastic tunnel.