An artificial capillary barrier to improve root-zone conditions for horticultural crops: Response of pepper plants to matric head and irrigation water salinity

Reduced water availability and increased salinity result in similar plant responses including reduced root mass and conductivity with consequential reduced transpiration and biomass production. We hypothesized that the increased soil matric head created by a capillary barrier (CB) positioned at the bottom of the root-zone would improve plant production, especially when irrigated with brackish water. Field and lysimeter studies were conducted with bell pepper (Capsicum annuum) plants, comparing root-zones with and without an underlying CB, irrigated either with desalinated (DW, EC = 0.2 dS m−1) or brackish (SW, EC = 3.8 dS m−1) water, at various rates. When irrigated with SW, plants grown above a CB yielded 24% higher biomass than control plants (without CB) for all irrigation applications. But, when DW was applied, only a 6% advantage for the CB root-zone was observed. Biomass yield with the CB treatment was only slightly affected by water salinity while without CB, yields significantly decreased when irrigated with SW. The extent of evapotranspiration, plant growth and yield responses to the presence of a CB appeared to be climate dependent. When vapor pressure deficit (VPD) was low (i.e. <1.5 kPa), smaller responses were measured, while more pronounced response was found when VPD increased.