土壤基质势调控对温室滴灌番茄土壤水分分布和产量的影响

【目的】指导设施蔬菜生产中科学合理地利用滴灌技术进行灌溉。【方法】采用小区试验的方法,以冬春茬番茄为研究对象,布置了7个不同土壤基质势阈值的试验,在番茄开花坐果期和结果期分别控制滴头正下方20 cm深度土壤基质势在-15和-15 kPa(S1)、-15和-30 kPa(S2)、-15和-45 kPa(S3)、-25和-25 kPa(S4)、-30和-15 kPa(S5)、-30和-30 kPa(S6)以及-30和-45 kPa(S7),研究了日光温室滴灌土壤基质势调控下土壤水分随时间变化及空间分布的规律,以及番茄产量、畸形果率和灌溉水利用效率等。【结果】①控制滴头正下方20 cm深度土壤基质势可以明显影响0～100 cm深度土壤水分状况。②在番茄开花坐果期,当土壤基质势阈值控制在-30 kPa或更高时,番茄根系主要吸收利用0～60 cm深度以上范围的土壤水分,70 cm深度以下土壤水分基本不变,0～60 cm深度土壤体积含水率平均为28.6%,为田间持水率的84%,60～100 cm土壤体积含水率平均为36.2%,为田间持水率的90%。③番茄进入结果期后,当土壤基质势阈值控制在-25～-15 kPa时,整个土体土壤含水率基本保持在田间持水率的77%～91%,根系主要吸收利用0～60 cm深度以上范围的土壤水分,70 cm深度以下土壤水分消耗缓慢;当土壤基质势阈值降低到-45～-30 kPa时,根系吸收利用到80～100 cm深度的土壤水分,整个土体土壤含水率不断降低,降低到田间持水率的60%～66%。④不同处理番茄产量、畸形果率和灌溉水利用效率有明显差异,其中S3和S7处理番茄产量高,S5处理产量低;S1、S3和S4处理的畸形果率大,S6和S7处理的畸形果率低;S1处理的灌溉水利用效率最低,S7处理的灌溉水利用效率最高。【结论】日光温室少量高频滴灌条件下,当滴头正下方20 cm深度土壤基质势阈值开花坐果期控制在-30 kPa、结果期控制在-45 kPa时,整个土体土壤水分状况基本良好,番茄的产量高,畸形果率低,灌溉水利用效率高。

Using Soil Matric Potential Underneath the Drip Emitter to Regulate Soil Moisture Distribution and Improve Greenhouse Tomato Production

【Objective】Soil moisture controls crop growth. In this paper, we investigated how to regulate soil moisture distribution by drip irrigation using the matric potential measured underneath the drip emitter in attempts to improve greenhouse tomato production.【Method】The experiment was for winter-spring season tomato grown in a solar greenhouse. The treatments were to maintain soil matric potential 20 cm underneath the drip emitter at seven levels:-15 kPa(S1), between-15 kPa and-30 kPa(S2), between-15 kPa and-45 kPa(S3), between-25 kPa and-25 kPa(S4), between-30 kPa and-15 kPa(S5), between-30 kPa and-30 kPa(S6), and between-30 kPa and-45 kPa(S7), during flowering-fruit setting and fruiting stage. In each treatment, we measured spatiotemporal soil moisture distribution, yield and visual defects of the fruits, as well as use efficiency of the irrigation water.【Result】The matric potentials had a significant impact on moisture distribution in 0～100 cm soil. ① When the matric potential was controlled at-30 kPa or above during flowering-fruit setting stage, most water in 0～60 cm soil was taken up by roots while the water in soil below 70 cm remained almost unchanged; the average volumetric water content in 0～60 cm soil was 28.6%, approximately 84% of the field water capacity. In 60～100 cm, the average soil moisture was 36.2%, about 90% of the field water capacity. ②When soil matric potential was controlled between-15 kPa and-25 kPa during the fruiting stage, the soil water content was approximately 77% to 91% of the field water capacity, and most water in 0～60 cm was used by the crop, compared to water below 70 cm. ③When the soil matric potential was between-30 kPa and-45 kPa, crop could take water from 80～100 cm soil and the soil water content reduced to 66% of the field water capacity. There was a significant difference in tomato yield, fruit defects, and use efficiency of irrigation water between the treatments. The yield was comparatively high in S3 and S7, and low in S5 treatment; visual fruit defect rate was high in S1, S3 and S4, and low in S6 and S7; the irrigation water use was least efficient in S1 and most efficient in S7.【Conclusion】Controlling soil matric potential at 20 cm below the emitter at-30 kPa during the flowering-fruit setting stage,-45 kPa during fruiting stage,improved tomato yield and irrigation water use efficiency; it also reduced visual fruit defects.