Response of greenhouse sweet pepper under alternate partial root-zone irrigation to different irrigation low limits

According to the plot experiments in 2006 and 2007, the growth, yield and water use efficiency (WUE) of sweet pepper with different irrigation low limits under alternate partial root-zone irrigation in greenhouse were investigated. The results show that photosynthesis rate of sweet pepper leaves and WUE are highest, no effective transpiration is reduced significantly when irrigation low limit was 60% of field capacity (T3); the highest yield is gained when irrigation low limit was 70% of field capacity (T4). Regression analysis was used to analyze relationships between sweet pepper yield、WUE and irrigation low limit. The maximum fresh yield in plot was gained when irrigation low limit (30 cm soil) was about 70% of field capacity. Moreover, WUE achieved maximum when irrigation low limit was about 65% of field capacity. Results from this study show that the appropriate irrigation low limit for sweet pepper under alternate partial root-zone irrigation in greenhouse is 65% of field water capacity.