施肥水平对巨桉幼树叶片气体交换日变化的影响

以巨桉幼树为对象,研究了不同施肥水平(每株施用含N、P₂O₅和K₂O各15%的复合肥0、90、180和270 g)下巨桉叶片的气孔导度(G_s)、胞间CO₂浓度(C_i)、净光合速率(P_n)、蒸腾速率(T_r)、水分利用效率(WUE)和叶面饱和水汽压亏缺(V_pdl)日变化,及其叶绿素含量变化,探讨巨桉光合特性与施肥和环境因素之间的关系.结果表明:各处理巨桉叶片P_n的日变化呈“单峰”形曲线,峰值出现在14:00,未出现光合“午休”现象;G_s、T_r和V_pdl的日变化与P_n相同,而C_i的最低值出现在14:00;WUE的日变化呈“双峰”形曲线,峰值分别出现在10:00和14:00.与对照处理相比,施肥处理叶片G_s、P_n、T_r、WUE及叶绿素a、叶绿素b和总叶绿素含量平均值分别增加4.6%～15.9%、7.8%～21.8%、4.8%～11.6%、3.2%～8.8%、15.5%～62.0%、14.5%～44.5%和15.3%～57.1%,且随施肥量的增加而增加;而叶片C_i和V_pdl平均值分别降低1.7%～4.6%和6.4%～15.2%,且随施肥量的增加而降低.气温、相对湿度(RH)和光合有效辐射(PAR)与G_s、P_n和T_r,G_s与P_n和Tr均显著相关.施肥可以促进巨桉生长、提高水分利用效率和增加生物固碳能力;气温、RH、PAR和G_s是影响巨桉光合作用和蒸腾作用日变化的主要因素.     

套袋对番茄果实表面光系统Ⅱ光能吸收利用的影响

用白纸淋膜袋对温室番茄‘保罗塔’果实进行套袋处理,采用光纤光谱仪和叶绿素成像荧光仪测定了番茄果实的吸收光谱和叶绿素荧光参数,分析了套袋对番茄果实光系统Ⅱ光能利用效率的影响.结果表明： 在套袋后的前20 d内,与对照(CK)相比,套袋果实表面的叶绿素a (Chl a)含量和光系统Ⅱ最大光化学效率(F_v/F_m)无明显变化,但是套袋降低了果实表面的相对吸光系数A_670/780和光系统Ⅱ实际光化学效率（Y_Ⅱ）,此时番茄果实主要以PSⅡ调节性能量耗散机制为主.随后,番茄果实表面的Chl a和Chl b含量开始明显下降,但是套袋果实的F_v/F_m、Y_Ⅱ和A_670/780与CK无显著差异.在套袋后的第40天,套袋果实表面的Chl a和Chl b含量分别比CK降低了35.2%和52.8%,F_v/F_m和Y_Ⅱ仍然维持较高水平,分别比CK增加了24.5%和35.4%,表明此时番茄果实PSⅡ具有较高的光能利用效率,通过进一步降低非调节性能量耗散量子产额Y_NO为果实的早熟奠定了能量基础.     

发菜类囊体膜色素蛋白复合物分离及其谱性质的研究

Nostoc flagelliforme Born. et Flah is highly adapted to drought stress, cold and light stresses, and suitable for growing in the unfavorable areas. This paper presents the results of the analysis of the membrane (mainly thylakoid membrane) lipids from N. flagelliforme in order to investigate the relationship between membrane lipid composition and stress resistance to this cyanobacteria. The membrane lipids are composed of monogalactosyl diacylglycerol (MGDG), digalactosyl diacylglycerol (DGDG), sulfoquinovosyl diacylglycerol (SQDG) and phosphatidylglycerol (PG). The major fatty acids in these lipids are palmitic (16∶0), palmitoleic (16∶1), stearic (18∶0), oleic (18∶1), linoleic (18∶2) and linolenic (18∶3) acids. In N. flagelliforme, polyunsaturated fatty acids account for 73% of the total fatty acids, much higher than that of the other cyanobacteria reported so far. Among which 16∶1 and 18∶3 are as high as 28.9% and 34.3% respectively. The high resistance of N. flagelliforme to abnormal conditions may be associated with the extent of unsaturation of fatty acids. In addition, the wild N. flagelliforme treated with water for 30 min and cultured for 24 h and the lipid and fatty acid composition were found to be not affected by water-absorption.