Comparison of leaf traits and photosynthetic characteristics of different genotypes of Ailanthus altissima var. erythrocarpa

By exploring the correlation between photosynthetic characteristics and environmental factors of different genotypes of Ailanthus altissima var. erythrocarpa, a theoretical basis is provided for the breeding of excellent new varieties of Ailanthus altissima var. erythrocarpa.

In this study, Ailanthus altissima (control: CK), leaf area, specific leaf weight, photosynthetic pigment and net photosynthetic rate of leaves of different genotypes (‘P1’‘P10’, Ailanthus altissima ‘Liaohong’) were determined systematically, and the correlation between photosynthetic characteristics and environmental factors such as photosynthetically active radiation, temperature, humidity and CO₂ content were analyzed.

1) There were significant differences only in dry matter content of ‘P1’‘P10’, Ailanthus altissima ‘Liaohong’and CK (P < 0.05). The leaf area, specific leaf weight and dry matter content of ‘P1’ and ‘P10’ were significantly lower than those of’ Ailanthus altissima ‘Liaohong’ and CK (P < 0.05), and the leaf water content was significantly higher than that of Ailanthus altissima ‘Liaohong’and CK (P < 0.05); 2) The contents of photosynthetic pigments in ‘P10’ were significantly lower than those in ‘P1’, Ailanthus altissima ‘Liaohong’ and CK (P < 0.05); The pigment content of ‘P1’ was not significantly different from that of Ailanthus altissima ‘Liaohong’ and CK; 3) The daily net photosynthetic rate (P_n) of different genotypes in June was affected by high temperature (> 40 ℃), and the photosynthetic rate was lower than 3.688 μmol·m^-2·s^-1. In different months, P_n, G_s and C_i of ‘P1’ are higher, T_r, L_s, LUE and WUE of ‘P1’ and ‘P10’ are similar; PAR and T_a had greater influence on P_n of different Ailanthus altissima var. erythrocarpa, while RH and C_a had less influence on P_n. Among the physiological factors, P_n was positively correlated with G_s, and negatively correlated with C_i. The daily P_n change of ‘P1’ has a relatively large correlation with T_r, but a small correlation with C_a.

Under high temperature and high radiation environment in summer, the water content of ‘P1’ and ‘P10’ leaves was significantly higher than that of Ailanthus altissima ‘Liaohong’ and CK, and their photosynthesis was limited by non-stomatal factors. PAR and Ta had the greatest influence on P_n of different Ailanthus altissima var. erythrocarpa. When T_a was greater than 40 ℃, P_n and T_a showed an extremely significant negative correlation, P_n remained at a low level, and the leaf damage was not obvious, suggesting that Ailanthus altissima var. erythrocarpa had a certain tolerance to high temperature and radiation. When T_a was less than 40 ℃, the P_n of ‘P1’ and ‘P10’ showed a significant positive correlation with PAR, and the P_n of ‘P1’ and ‘P10’ had no significant difference with that of Ailanthus altissima ‘Liaohong’ and CK, and had the same photosynthetic performance.