中国农业科学 ›› 2023, Vol. 56 ›› Issue (22): 4417-4427.doi: 10.3864/j.issn.0578-1752.2023.22.005

• 耕作栽培·生理生化·农业信息技术 • 上一篇    下一篇

光强对苗期大豆叶片水力导度及叶脉性状的影响

高静(), 陈吉玉, 谭先明, 吴雨珊, 杨文钰, 杨峰()   

  1. 四川农业大学农学院/农业农村部西南作物生理生态与耕作重点实验室/四川省作物带状复合种植工程技术研究中心,成都 611130
  • 收稿日期:2023-03-27 接受日期:2023-05-04 出版日期:2023-11-16 发布日期:2023-11-17
  • 通信作者: 杨峰,E-mail:f.yang@sicau.edu.cn
  • 联系方式: 高静,E-mail:1787913440@qq.com。
  • 基金资助:
    国家重点研发计划(2022YFD2300902); 国家自然科学基金(32071963)

Effect of Light Intensity on Leaf Hydraulic Conductivity and Vein Traits of Soybean at Seedling Stage

GAO Jing(), CHEN JiYu, TAN XianMing, WU YuShan, YANG WenYu, YANG Feng()   

  1. College of Agronomy, Sichuan Agricultural University/Key Laboratory of Crop Ecophysiology and Farming System in Southwest China, Ministry of Agriculture and Rural Affairs/Sichuan Engineering Research Center for Crop Strip Intercropping System, Chengdu 611130
  • Received:2023-03-27 Accepted:2023-05-04 Published:2023-11-16 Online:2023-11-17

摘要:

【目的】 探究光强对苗期大豆叶片水力导度、光合特性和叶水势的影响,分析叶脉性状对不同生长光强的适应机制,为提高大豆光能利用提供理论支撑。【方法】选用强耐荫型的大豆品种南豆12和弱耐荫型的大豆品种桂夏7为试验材料,在人工气候室进行盆栽试验,设置高光强((424.47±12.32)µmol·m-2·s-1,HL)、中光强((162.52±20.31)µmol·m-2·s-1,ML)和低光强((93.93±9.87)µmol·m-2·s-1,LL)处理。在处理20 d后研究不同生长光强对苗期大豆叶片水力导度、光合参数、叶片水势及叶脉性状的影响。【结果】相对于高光强处理,低光强处理下南豆12和桂夏7的叶片水力导度显著降低,南豆12的叶片水力导度在3个处理下均显著高于桂夏7。与高光强处理相比,在中、低光强处理下南豆12的叶片水力导度分别降低7.56%和21.24%,气孔导度分别降低43.96%和58.89%,净光合速率分别降低29.44%和46.49%。同样,桂夏7的叶片水力导度分别降低42.16%和23.71%,气孔导度分别降低54.55%和45.79%,净光合速率分别降低37.03%和42.06%。南豆12和桂夏7的叶片水势在处理间均无显著差异。大豆的叶片水力导度与气孔导度在3个光强处理下均达到极显著正相关(P<0.01),随着光强的降低,叶片水力导度与净光合速率呈显著正相关(P<0.05),与气孔导度呈极显著正相关(P<0.01)。对于叶脉结构,与高光强相比,中、低光强处理下两个大豆品种的小叶脉密度以及主叶脉和小叶脉的木质部导管面积均显著降低,且南豆12的小叶脉密度和主叶脉木质部导管面积在中、低光强处理下均显著高于桂夏7。南豆12的主叶脉密度在处理间无显著变化,桂夏7的主叶脉密度在中、低光强处理下较高光强显著降低11.4%和15.0%。光强降低显著增长了叶脉到气孔的距离。南豆12在中、低光强处理下叶脉到气孔的距离较高光强增长21.33%和60.01%,桂夏7叶脉到气孔的距离增长31.50%和53.59%。相关性分析表明,大豆叶片水力导度与小叶脉密度、主叶脉和小叶脉的木质部导管面积呈显著正相关(P<0.05),与叶脉到气孔的距离呈极显著负相关(P<0.01)。【结论】光强会通过调控大豆叶脉结构影响叶片水力导度,弱光降低大豆叶片水力导度,但叶片水力导度和气孔导度保持协调,维持叶片水分供需平衡。弱光下具有较高的叶脉密度能够缩短水分运输的距离,保证较好的叶片水分供应能力,从而有利于CO2的扩散和光合作用,这是耐荫型大豆适应弱光环境的又一策略。

关键词: 大豆, 叶片水力导度, 气孔导度, 光强, 叶脉

Abstract:

【Objective】The objective of this study is to explore the effects of light intensity on leaf hydraulic conductivity, photosynthetic traits, and water potential in soybean seedlings, analyze the adaptive mechanisms of leaf vein traits in response to varying light intensities, and to provide theoretical support for enhancing future light energy utilization in soybean.【Method】Two soybean varieties, Nandou 12 (shade-tolerant) and Guixia 7 (shade-sensitive), were cultivated and placed in growth chambers. The plants were exposed to varying light conditions, including high light intensity (HL) at (424.47±12.32) µmol·m-²·s-¹, medium light intensity (ML) at (162.52±20.31) µmol·m-²·s-¹, and low light intensity (LL) at (93.93±9.87) µmol·m-²·s-¹. After a 20-day treatment period, the impacts of different light intensities on hydraulic conductivity, photosynthetic parameters, leaf water potential, and leaf vein traits in the seedling leaves of soybean were examined.【Result】Compared with HL treatment, the leaf hydraulic conductivity of Nandou 12 and Guixia 7 under LL treatment was significantly decreased, and the leaf hydraulic conductivity of Nandou 12 under the three treatments was significantly higher than that of Guixia 7 under the three treatments. Compared with HL treatment, the leaf hydraulic conductivity of Nandu 12 under ML and LL treatments decreased by 7.56% and 21.24%, stomatal conductance decreased by 43.96% and 58.89%, and net photosynthetic rate decreased by 29.44% and 46.49%, respectively. Similarly, the leaf hydraulic conductivity of Guixia 7 under the ML and LL treatments decreased by 42.16% and 23.71%, stomatal conductance decreased by 54.55% and 45.79%, and net photosynthetic rate decreased by 37.03% and 42.06%, respectively. Additionally, no statistically significant differences were observed in the leaf water potential of both soybean varieties across the various treatments. Notably, leaf hydraulic conductivity and stomatal conductance of soybean exhibited a highly significant positive correlation (P<0.01) under the three light intensity treatments. As the light intensity decreased, a positive correlation was observed between leaf hydraulic conductivity and net photosynthetic rate (P<0.05) as well as stomatal conductance (P<0.01). Conversely, there was a noticeable decrease in the minor leaf vein density and the area of xylem conduits in major and minor veins under the ML and LL treatments for both soybean varieties. In the case of the minor leaf vein density and the area of xylem conduits in major veins, Nandou 12 exhibited significantly higher values than Guixia 7 under the ML and LL treatments. The major leaf vein density of Nandou 12 remained relatively stable across treatments, while that of Guixia 7 experienced a significant reduction of 11.4% and 15.0% under the ML and LL treatments compared to the HL treatment. Furthermore, a decrease in light intensity had a notable effect on increasing the distance between leaf veins and stomata. Specifically, under the ML and LL treatments, the distance from veins to stomata increased by 21.33% and 60.01% for Nandou 12 and by 31.50% and 53.59% for Guixia 7 in comparison to the HL treatment. The correlation analyses revealed significant positive correlations (P<0.05) between the hydraulic conductivity of soybean leaves and the density of minor leaf veins, the area of xylem conduits in major and minor veins. Conversely, a significant negative correlation (P<0.01) was observed between hydraulic conductivity and the distance from veins to stomata.【Conclusion】Light intensity exerts an influence on the leaf hydraulic conductivity by modulating the leaf vein structure of soybean. Under low light conditions, there is a reduction in leaf hydraulic conductivity in soybean; however, the coordination between leaf hydraulic conductivity and stomatal conductance is maintained to establish equilibrium between leaf water supply and demand as light intensity diminishes. The presence of a higher vein density under low light serves to abbreviate the distance required for water transport, thereby enhancing leaf water supply capacity. Consequently, this facilitates CO2 diffusion and photosynthesis, representing an additional strategy employed by shade-tolerant soybean to acclimate to low-light environments.

Key words: soybean, leaf hydraulic conductivity, stomatal conductance, light intensity, leaf vein