Relationship of Carbon Isotope Discrimination with Biomass and Water Use Efficiency for Alfalfa in Northwestern China

Crop Science

Xue Gao^1,2¹  Lin Zhu^1,2² 

[1] Key Lab. for Restoration and Reconstruction of Degraded Ecosystem in North-western China, Ministry of Education, Ningxia Univ., Yinchuan 750021, China^2;State Key Lab. Breeding Base of Land Degradation and Ecological Restoration of Northwestern China, Ningxia Univ., Yinchuan 750021, China^1

关键词: AGB;    aboveground biomass;    C i /C a;    ratio of internal leaf carbon dioxide concentration to ambient carbon dioxide concentration;    Δ;    carbon isotope discrimination;    Δ AGS;    carbon isotope discrimination in aboveground shoots;    Δ WSC;    carbon isotope discrimination in leaf water-soluble carbohydrates;    ET;    evapotranspiration;    G s;    stomatal conductance;    PDB;    Pee Dee Belemnite;    PH;    plant height;    P n;    net photosynthesis;    P n / G s;    single-leaf intrinsic water use efficiency;    the ratio of carbon dioxide assimilation to leaf conductance to water vapor;    R S/L;    stem/leaf weight ratio;    TE;    transpiration efficiency;    WUE;    water use efficiency;   

DOI  :  10.2135/cropsci2017.08.0475

学科分类：农业科学（综合）

来源: Crop Science

【 摘 要 】

Carbon isotope discrimination (Δ) has been proposed as a method for evaluating transpiration efficiency in C₃ plants. It is important to study the association of Δ in different parts with the long-term water use efficiency (WUE). In this paper, plant height, Δ in leaf water soluble carbohydrates (Δ_WSC), photosynthetic gas exchange parameters, Δ in aboveground shoot (Δ_AGS), stem/leaf weight ratio , aboveground biomass (AGB), evapotranspiration, and WUE were determined in a collection of 10 alfalfa (Medicago sativa L.) genotypes under three water treatments (230 [T₁], 460 [T₂], and 700 mm irrigation [T₃]) in a Ningxia central desert steppe in 2012 and 2013. Significant interactions were found for AGB and WUE among year, treatment, and genotype, whereas significant interactions of year × treatment and year × genotype were only found for Δ_AGS but not for Δ_WSC. Generally, more water input increased the values of the traits tested except for WUE and single-leaf intrinsic WUE (P_n/G_s). More irrigated water input resulted in increase in AGB, Δ_AGS, and Δ_WSC and decrease in P_n/G_s. The greatest WUE was recorded under T₂ in 2012. Significant and positive correlations were observed between AGB and Δ_AGS (r = 0.588, 0.574, and 0.386 under T₁, T₂, and T₃, respectively). Under T₂ and T₃, Δ_WSC correlated negatively with WUE (r = −0.383 and 0.602, respectively). Ningmu No. 1 was found to have the greatest WUE (18.34 kg ha⁻¹ mm⁻¹) and yield (17.71 Mg ha⁻¹) across water treatments and years. The findings suggest that in the semiarid areas applying irrigation of 230 to 700 mm yr⁻¹, Δ in aboveground shoots or in leaf water-soluble carbohydrates at the flowering stage seems to be a useful indicators reflecting aboveground biomass and integrated WUE for alfalfa.

【 授权许可】

CC BY