Improved water management using subsurface membrane irrigation during cultivation of Phaseolus vulgaris

Abstract

Subsurface membrane irrigation systems, controlled by changes in the water potential in the soil-plant-atmosphere continuum, were used to cultivate Phaseolus vulgaris over a full growth cycle (64 days). Membrane irrigation systems used a thin polyamide film supported on either a woven hydrophilic support (FO-TFC treatment) or a non-woven hydrophobic support (RO treatment). Water use efficiency was assessed using leaf biomass per unit irrigation water and compared to conventionally irrigated plants (control). Additionally, gas exchange and fluorescence parameters, as well as stable isotopes, were used to assess the plants’ physiological status. Soil water content over the growth cycle was maintained at 0.7 cm3 cm−3 under control conditions and declined from 0.6 to 0.12 cm3 cm−3 during plant growth, below residual moisture content, under both FO-TFC and RO membrane irrigation. Notwithstanding this, the total leaf dry matter was statistically equivalent for control plants (38.4 g) and FO-TFC treated plants (29.6 g) and approximately 68% lower for RO treated plants. The internal over external carbon concentration (Ci/Ca) in the leaves and efficiency of open Photosystem II reaction centres in the light (Fv'/Fm') were statistically equivalent in membrane treatments and control plants. Similarly, carbon (δ13C) and nitrogen (δ15N) isotope composition, as well as %N, of green bean pods and leaves were statistically equivalent for plants grown on FO-TFC and control, indicating no effect on beans protein content. Total bean production per parcel and plant water use efficiency (WUE) for conventional irrigation (0.24 kg at 10.2 kg m−3 WUE) was statistically equivalent to plants grown on FO-TFC treatment (0.19 kg at 12.8 kg m−3 WUE). Although the WUE for RO treatment (11.4 kg m−3) was statistically equivalent to control, the total bean production per parcel was significantly lower (0.07 kg). Results indicate that subsurface membrane irrigation may be a solution for improved water management without compromising yield production and quality.