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不同水-氮交互下大豆光合限制作用变化及其与叶片水分利用效率的关系

Changes in photosynthetic limitation of soybean under different water nitrogen interactions and their relationships with leaf water use efficiency

  • 摘要: 植株光合限制作用(叶肉限制,lm;气孔限制,lsc;生化限制,lb)的土壤水、氮单因子效应已有大量研究,但其对水-氮交互的响应及其与叶片水分利用效率(WUE)的关系鲜有报道。本文选取我国北方旱地大豆为试验材料,以光合限制作用为研究对象,设计土壤水-氮交互试验,探究其光合限制作用的水-氮交互响应及与叶片瞬时(WUEins)和内在水分利用效率(WUEint)的相关关系。结果显示:(1)大豆叶内CO2扩散性限制作用(叶肉限制,lm;气孔限制,lsc)随水分胁迫逐渐增大,而生化限制作用(lb)则逐渐减小;(2)土壤水-氮交互后,植株lmlsc均减小,而lb显著增大,其中MW植株lmlb随氮添加呈先减小后增大(lm)以及先增大后减小(lb)的起伏变化,而lsc则整体减小,SW植株lmlb分别随氮添加增大和减小,lsc未表现出处理间差异性;(3)lmlb分别与WUEins及WUEint呈显著的负、正相关关系(P < 0.05),而lsc与二者的相关性不显著;(4)较lsclblm变化对大豆光合碳同化及叶片水分利用效率的贡献率最大,其为大豆光合与水分利用能力变化的主导限制因子。

     

    Abstract: The single factor effects of soil water and nitrogen on plant photosynthesis limitation (mesophyll limitation, lm; stomatal limitation, lsc; biochemical limitation, lb) have been extensively studied, but their response to water nitrogen interaction and the relationship with leaf water use efficiency (WUE) have been rarely reported. Dryland soybeans in northern China is selected as experimental materials and photosynthesis limitation is taken as the objects in this study. A soil water-nitrogen interaction experiment is designed to explore the interaction of photosynthetic limitation and its correlation with leaf instantaneous (WUEins) and intrinsic water use efficiency (WUEint). The results showed that (1) The CO2 diffusion limitation (i.e., lm and lsc) gradually increased with water stress, while lb gradually decreased. (2) The interaction of water and nitrogen resulted in a decrease in lm and lsc, while lb significantly increased. Among them, a fluctuating pattern of first decreasing and then increasing and first increasing and then decreasing with nitrogen addition were found in lm and lb of MW plants, respectively, while lsc decreased overall. The lm of SW plants increased while its lb decreased with nitrogen addition, while lsc did not show any statistical difference between treatments. (3) lm and lb showed significant negative and positive correlations with WUEins and WUEint, respectively (P < 0.05), while lsc showed no significant correlation with the two. (4) Compared to lsc and lb, lm makes a greatest contribution to soybean photosynthetic carbon assimilation and leaf water use efficiency, and is the dominant limiting factor for the photosynthetic and water use capacity.

     

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