摘要
[目的]叶片角度直接影响光能的利用,探究荫蔽对大豆叶片角度和光合特性的影响,为揭示荫蔽下叶片如何提高光截获能力、光合效率提供理论支撑.[方法]以耐荫性南夏豆25(ND25)和不耐荫性自贡冬豆(GD)这2个大豆品种为研究对象,设置正常光[600 μmol/(m2·s),CK]处理和弱光[300 μmol/(m2·s),L]2个处理,探究植株形态、叶倾角动态变化、叶枕结构以及光合荧光特征等对荫蔽的响应.[结果]与CK相比,L处理下ND25和GD的株高、叶柄长显著增加,日平均叶倾角分别降低337.26%和478.83%.ND25在CK处理与L处理下叶倾角极差分别为49.46°和56.96°;GD分别为33.16°和73.37°.耐荫性ND25在L处理下皮层占叶枕比例和屈肌细胞层数与CK相比分别增加1.12%和15.38%,不耐荫性GD不具有该显著性变化.与CK相比,L处理下ND25和GD的蒸腾速率、叶绿素a含量、叶绿素b含量增加,净光合速率、胞间CO2浓度降低,类胡萝卜素含量分别增加481.25%和降低58.97%.L处理下ND25和GD的光化学猝灭系数与CK相比降低,最大光化学量子产量增加.ND25的PSⅡ有效光化学量子产量、非光化学猝灭系数降低,而GD增加.[结论]荫蔽环境下,大豆叶倾角变化范围增大,日平均叶倾角降低.耐荫性大豆皮层占叶枕比例及屈肌细胞层数的增加有利于叶枕调控叶片角度与入射光趋于垂直以增加光能截获.
Abstract
[Objective]The leaf angle directly affects the utilization of light energy.This study aimed to explore the effects of shading on the leaf angle and photosynthetic characteristics of different shade-tolerant soybean varieties to reveal how leaves can enhance their light interception ability and photosyn-thetic efficiency.[Method]We selected the shade-tolerant variety Nandou25(ND25)and the shade-intolerant variety Gongdou(GD)for the study.We established a normal light treatment(600 μmol/(m²·s),CK)and a low light treatment(300 μmol/(m²·s),L).The responses of plant morphology,dynamic changes in leaf inclination,anatomical structure of the pulvinus,and photosynthetic fluorescence charac-teristics to shade were investigated.[Result]Under the L treatment,the plant height and petiole length of both ND25 and GD significantly increased compared to CK,while the daily mean leaf inclination decreased by 337.26%and 478.83%,respectively.The leaf inclination ranges for ND25 under CK and L treatments were 49.46° and 56.96°,respectively;for GD,they were 33.16° and 73.37°,respectively.The shade-tolerant soybean ND25,compared to CK,showed an increase of 1.12%in the ratio of cortex to pulvinus and 15.38%in the number of flexor muscle cell layers under L treatment,whereas the shade-intolerant GD did not exhibit this significant change.Compared to CK,the transpiration rate,chlorophyll-a content,and chlorophyll-b content of both ND25 and GD increased under L treatment,while the net photosynthetic rate and intercellular CO2 concentration decreased.Moreover,the carotenoid content increased by 481.25%and decreased by 58.97%,respectively.Under L treatment,the photochemical quenching coefficients of both ND25 and GD decreased,and the maximal PSⅡ photochemical efficiency in the dark increased.The photo-chemical efficiency yield of PSⅡ in the light and the non-photochemical quenching coefficient of ND25 de-creased,while those of GD increased.[Conclusion]Under shaded conditions,the range of leaf inclina-tion increases and the daily mean leaf inclination decreases.Shade-tolerant soybeans increase the ratio of cortex to pulvinus and the number of flexor cell layers to orient leaf inclination perpendicular to incident light,thereby enhancing light energy interception.
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