An improved water use efficiency for hot pepper grown under controlled alternate drip irrigation on partial roots

Hot pepper plants were grown in pots with their roots divided and established in two separate containers. Water was applied through a drip irrigation system in three ways: alternate drip irrigation on partial roots (ADIP), fixed drip irrigation on partial roots (FDIP), even drip irrigation on whole roots (EDIW). For each irrigation method, water was applied when the soil moisture content was below either 65 or 55% of the field capacity. Results showed that when irrigation started at 65% of the field capacity ADIP significantly increased the root/shoot ratio compared to all the other treatments. When irrigating at this moderate (i.e. 65% of the field capacity) soil moisture level, ADIP did not significantly inhibit leaf photosynthesis, but did markedly restrict stomatal opening. Compared to EDIW. there was a relatively small reduction in biomass for ADIP, but the reduction for FDIP was significant. Surprisingly, ADIP maintained high yield with up to 40% reduction in irrigation compared to EDIW and FDIP. Moreover, the maximum yields and best water use efficiency occurred in ADIP and rewatering at 65% level at the same time. FDIP did not show better results than the controls because the yield was considerably reduced. In conclusion, ADIP is an effective and water-saving irrigation method in hot pepper production and may have the potential to be used in the field. (C) 2001 Elsevier Science B.V. All rights reserved.