两个品种烟草叶片发育过程中几种光合参数变化的比较

比较烟草2个品种‘NC89’和‘JYH’叶片发育过程中几个光合参数变化的结果表明，烟草叶片发育过程中光合速率变化表现为上升期、高值持续期（APD）和速降期，叶绿素含量变化经历上升期、相对稳定期（RSP）和速降期。光合功能衰退过程中，核酮糖．1，5-二磷酸羧化酶（RuBPCase）活性比电子传递活性下降快。可逆衰退阶段的2个品种类囊体膜多肽组分和‘NC89’的核酮糖-1，5-二磷酸羧化酶加氧酶（Rubisco）大亚基基本上无变化；不可逆衰退阶段的2个品种类囊体膜多肽组分、Rubisco大小亚基均快速降解，尤其是光系统Ⅱ（PSⅡ）复合体和Rubisco小亚基。‘JYH’的叶龄为10-40d的叶中各光合参数与‘NC89’的差别不大，但‘JYH’的光合功能期短，光合功能衰退过程中光合电子传递与碳同化失衡较严重，光合功能衰退比‘NC89’早而迅速。

Comparison on Changes of Several Photosynthetic Parameters in Leaf Developing Process between Two Tobacco Cultivars

Changes of photosynthetic parameters in leaves developing process in two tobacco cultivars(Nicotiana tabacum L.cv.'NC89' & 'JYH')were comparatively analyzed.The results suggested that the photosynthetic rate displayed elevated phase,active photosynthesis duration(APD)and sharp fall phase while the chlorophyll content displayed elevated phase,relative steady phase(RSF)and Sharp fall phase during leaf developing process.The decline of ribulose 1,5-bisphosphate carboxylase(RuBPCase)activities was obviously faster than that of photosynthetic electron transport activity during the period of decline in leaf photosynthetic function.SDS-PAGE showed that thylakoid membrane polypeptide components of two tobacco cultivars and large sub-units(LSU)of ribulose 1,5-bisphosphate carboxylase/oxygenase(Rubisco)of 'NC89' remained relative steady during reversible decline(RD).During irreversible decline(IRD)thylakoid membrane polypeptide components,LSU and small subunits(SSU)of Rubisco of two tobacco cultivars,especially photosystem II(PSII)complex and Rubisco SSU were degraded rapidly.There were no significant differences of photosynthetic parameters in 10-40 day leaves between the 'JYH' and the 'NC89'.But the APD was shorter,the unbalance between electron transport and carbon assimilation during the decline of photosynthetic function was more serious,and the decline of photosynthetic function was sooner and faster in 'JYH' leaves.