Tomato yield and water use efficiency – coupling effects between growth stage specific soil water deficits
2015
Chen, Si | Zhou, Zhen-jiang | Andersen, Mathias N. | Hu, Tian-tian
To investigate the sensitivity of tomato yield and water use efficiency (WUE) to soil water content at different growth stages, the central composite rotatable design (CCRD) was employed in a five-factor-five-level pot experiment under regulated deficit irrigation. Two regression models concerning the effects of stage-specific soil water content on tomato yield and WUE were established. The results showed that the lowest available soil water (ASW) content (around 28%) during vegetative growth stage (here denoted θ ₁) resulted in high yield and WUE. Moderate (around 69% ASW) during blooming and fruit setting stage (θ ₂), and the highest ASW (around 92%) during early fruit growth stage (θ ₃), fruit development (θ ₄) and fruit maturity (θ ₅) contributed positively to tomato yield, whereas high WUE was achieved at lower θ ₂ and θ ₃ (around 44% ASW) and higher θ ₄ and θ ₅ (around 76% ASW). The strongest coupling effects of ASW in two growth stages were between θ ₂ and θ ₅, θ ₃. In both cases a moderate θ ₂ was a precondition for maximum yield response to increasing θ ₅ and θ ₃. Sensitivity analysis revealed that yield was most sensitive to soil water content at fruit maturity (θ ₅). Numerical inspection of the regression model showed that the maximum yield, 1166 g per plant, was obtained by the combination of θ ₁ (c. 28% ASW), θ ₂ (c. 82% ASW), θ ₃ (c. 92% ASW), θ ₄ (c. 92% ASW), and θ ₅ (c. 92% ASW). This result may guide irrigation scheduling to achieve higher tomato yield and WUE based on specific soil water contents at different growth stages.
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