不同施氮水平对块根膨大期木薯叶片光合特性的影响

摘要

[Objective] The effect of nitrogen level on photosynthetic characteristics at the stage of root tuber expansion of cassava was investigated to provide a theoretical basis for the best nitrogen management in cassava production.[Method] There were two cultivars of cassava (FX 01 and SC 124) as research material and six nitrogen levels at0 (N0),18 (N1),36 (N2),72 (N3),108 (N4) and 144(N5) kgN·hm-2.At the stage of root tuber expansion,the total dry matter accumulation,leaf area,leaf SPAD,photosynthetic parame ters,stomatal conductance,intercellular CO2 concentration,and transpiraton were analyzed.[Result] The dry matter accumulation of SC124 increased by 39.92 ％-143.03 ％ within the range of nitrogen supply,and peaked at 538.8 g · plant-1 under the 72 kgN · hm-2 nitrogen level.At the same time,the dry matter accumulation of FX01 increased by 11.79 ％-185.60 ％,and peaked at 779.7 g · plant-1 under the 108 kgN · hm-2nitrogen level.It was indicated that FX 01 has the higher photosynthetic production capacity.The total dry matter accumulation,leaf area,leaf SPAD and photosynthetic parameters of FX 01 and SC 124 all increased firstly and then decreased with the increase of nitrogen level,and the leaf area,leaf SPAD and photosynthetic parameters of cassava at root tuber expansion stage were significantly affected by cultivar differences and nitrogen levels.The optimal nitrogen fertilization increased the leaf area.photosynthetic intensity was enhanced,the leaf net photosynthetic rate had a very significant positive correlation with the total dry matter accumulation.[Conclusion] The study indicated that the optimal nitrogen supply increased the net photosynthetic rate and leaf area,which was the main factors to improve the photosynthetic intensity and further raise the tuber yield of cassava.%[目的]研究不同氮素供应水平对木薯块根膨大期光合特性的影响,为木薯生产的最佳氮肥管理提供理论依据.[方法]采用田间试验方法,以木薯品种辐选01(FX 01)和华南124(SC 124)为材料,设置0(N0)、18(N1)、36(N2)、72(N3)、108(N4)、和144(N5)kg·hm-2共6个施氮水平,分析不同施氮水平对两个品种木薯块根膨大期总干物质累积量、叶面积、叶片SPAD值以及叶片净光合速率、气孔导度、胞间CO2浓度、蒸腾速率等光合特性的影响.[结果]在施氮水平范围内,SC 124总干物质累积量增加39.92％ ～143.03％,最高值为538.8 g·plant-1(72 kgN·hm-2处理下);FX 01总干物质累积量增加11.79％～185.60％,最高值为779.7 g·plant-(108 kgN·hm-2处理下),表明FX 01较SC 124具有更高的光合生产能力.两个品种木薯的总干物质累积量、叶面积、叶片SPAD值以及叶片光合作用指标总体均表现出随施氮量的提高呈先增加后降低的趋势,且品种差异与施氮水平对叶面积、叶片SPAD值以及叶片光合作用指标均有极显著影响.适宜的氮素供应水平下两个品种的木薯单株叶面积提高,同时光合强度增大,且不同氮素供应水平下两个品种的木薯叶片净光合速率与总干物质累积量呈极显著正相关.[结论]适宜的施氮水平主要通过调节木薯的净光合速率和叶面积,使木薯具有较高的光合强度,促进干物质的生产与累积.