Abstract:

【Objective】 The effects of different water supply tension(WST) that is different soil moisture on the growth and development of greenhouse cucumber (Cucumis sativus L.) were studied. The demand of water at different growth stages of greenhouse cucumber was determined to provide a theoretical basis for the irrigation decision-making. 【Method】 A negative pressure water supplying and controlling pot device was used to control different soil water contents by setting the WST of the device at different values. The differences in photosynthetic rate, yield and water use efficiency(WUE) of cucumber under different WST were analyzed. 【Result】 The results showed that the negative pressure water supplying and controlling pot device can maintain soil water content in a enactment state by setting the WST. The leaf photosynthetic rate, biomass accumulation as well as yield and marketable fruit rate of cucumber were much higher at 3-5 kPa WST treatments, the highest WUE 36.57 appeared in WST of 7 kPa and a significant lower WUE was observed in WST of 1 kPa, differences in WUE for other 6 WST were not significant. The result shows that WUE can only by improved by control water supply at different growth stages of cucumber. The result also indicates that the water demand increase with the growing process. The growth will be restricted and yield will be reduced with the shortage of water supply, increase the yield at terminal fruiting stage can be obtained by increasing soil water content at fruiting stage of cucumber. 【Conclusion】 The above results indicate that the range of WST from 3-5 kPa are more suitable for greenhouse cucumber growth when the relative soil water content ranges from 67% to 81%. Reduce water supply at seedling stage, control water supply at flowering stage and increase water supply at fruiting stage of cucumber can increase yield and WUE.

Key words: cucumber, negative pressure water control, yield, water use efficiency, photosynthetic rate