Cultivation modes and deficit irrigation strategies to improve 13 C carbon isotope, photosynthesis, and winter wheat productivity in semi-arid regions

Abstract

Determining the effect of ridge-furrow cultivation mode on ¹³C carbon isotope discrimination, photosynthetic capacity, and leaf gas exchange characteristics of winter wheat leaves will help to increase wheat production. To verify these effects of cultivation modes with deficit irrigation will provide scientific basis for determining water-saving strategy. Therefore, a mobile rainproof shelter was used to explore the potential benefit of two cultivation modes: (1) the ridge-furrow (RF) precipitation system and (2) traditional flat planting (TF) with two deficit irrigation levels (150, 75 mm) and three precipitation levels (275 mm, 200 mm, 125 mm) were tested in this study. Plastic film mulching on ridges had significant effects on rainwater collection and improved soil water retention. Analysis of the light-response curve showed that RF2₁₅₀ treatment significantly increased flag leaf net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ concentration (C_i), transpiration rate (T_r), leaf WUE, and total contents of chlorophyll ab of wheat at flowering stage than that of TF planting. The RF system significantly increases maximum net photosynthetic rate (P_nmax) (16.2%), light saturation points (LSP) (6.7%), and P_n under CO₂-response curves compared to the TF cultivation across the two irrigation and three simulated rainfall levels. The RF system significantly increased Δ¹³C (0.7%) and caused a notable increase in the intercellular to ambient CO₂ concentration ratio (7.6%), dry matter translocation (54.9%), and grain yield plant⁻¹ (19%) compared to the TF planting. Furthermore, Δ¹³C was significantly positively correlated with P_n, G_s, C_i/C_a, C_i, T_r, P_nmax, LSP, and grain yield. This study suggested that the RF2₁₅₀ treatment was the best water-saving technique because it increased soil water content, Δ¹³C, biomass, grain yield, and leaf WUE.

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