施氮量对甘蔗叶绿体超微结构和光合速率的影响

【目的】研究施氮量对甘蔗叶片叶绿体超微结构和光合速率的影响,明确氮素影响甘蔗光合作用的细胞学机理,为甘蔗合理施肥提供科学依据。【方法】以甘蔗品种GT11、ROC22和GXB9为试验材料,在温室内进行桶栽试验,设低氮、中氮和高氮3个施氮水平,即分别施用0、150和300 kg/ha尿素,于伸长期取叶片样品分析叶绿素相对含量(SPAD)、叶面积、比叶重和叶绿体超微结构,并测定光合速率。【结果】3个甘蔗品种叶片的SPAD和叶面积均随施氮水平的增加而增加。GT11和ROC22的比叶重随施氮量的增加显著降低(P0.05,下同),GXB9的比叶重在中氮水平最低。GT11在高氮水平下叶绿体超微结构正常;ROC22在中氮水平下叶绿体数量最多,但基粒片层数量显著少于高氮水平;GXB9在中氮水平下叶绿体数量最多,基粒片层与高氮水平时无明显差异。GT11和ROC22的净光合速率随施氮水平的增加而增加,GXB9净光合速率在中氮水平最高。【结论】甘蔗光合速率与叶绿体数量、叶绿体超微结构及基粒片层数量密切相关,且均受甘蔗品种和施氮量的共同影响。

Effects of nitrogen application rate on chloroplast ultrastructure and photosynthetic rate in sugarcane

Objective]Effects of different nitrogen application rates on chloroplast ultrastructure and photosynthetic rate in leaves of sugarcane were investigated, cytological mechanism of nitrogen influencing sugarcane photosynthesis was also studied to provide reference for rational fertilization of sugarcane. Method]Three sugarcane cultivars, GT11, ROC22 and GXB9, were planted in tub in greenhouse. Three nitrogen levels(low nitrogen, medium nitrogen and high nitrogen) were set up, equally 0, 150 and 300 kg/ha urea were applied to the sugarcanes. Sugarcane leaves were sampled, and chlorophyll relative content(SPAD), leaf area, specific leaf weight, chloroplast ultrastructure were analyzed at the elonga-tion stage, and photosynthetic rate was determined. Result]SPAD and leaf area of the three sugarcane cultivars in-creased with the increase of nitrogen level. The specific leaf weight in GT11 and ROC22 decreased significantly with the increase of nitrogen level(P<0.05, the same below), and specific leaf weight of GXB9 was the lowest at medium nitro-gen level. The chloroplast ultrastructure in GT11 was normal at high nitrogen level. ROC22 had the largest chloroplast number at medium nitrogen level, but grana lamella number was significantly less than that at high nitrogen level. Chloro-plast number in GXB9 was the highest at medium nitrogen level, but grana lamella number showed no significant difference compared with that at high nitrogen level. Photosynthetic rate in GT11 and ROC22 increased with the increase of nitrogen application rate. Photosynthetic rate in GXB9 reached the maximum at medium nitrogen level. Conclusion]Photosyn-thetic rate of sugarcane is closely related to chloroplast number, chloroplast ultrastructure and grana lamella number, and these traits are affected by sugarcane varieties and nitrogen application rates.