田间增加UV-B辐射对丝瓜光合作用日变化及水分利用效率的影响

在自然条件下，增加不同强度的UV—B辐射，对攀援植物丝瓜叶片光合速率日变化和水分利用效率进行了研究，发现经增加R1强度UV—B辐射处理的丝瓜的净光合速率和蒸腾速率比对照上升了28％和33％，水分利用效率则下降了3．4％，而经增加R2强度UV—B辐射处理的丝瓜的净光合速率和蒸腾速率比对照上升了47％和13％，水分利用效率也上升了28％，且其光合作用不受午间强光的抑制，光合午休现象消失了．这表明，在该实验的UV—B强度下，丝瓜的光合作用不但未受抑制，反而还增强了，说明适当增加UV—B辐射对丝瓜的生长有利．     

Study on the photosynthetic performances of Enteromorpha prolifera collected from the surface and bottom of the sea of Qingdao sea area

In this work, the photosynthetic performances of Enteromorpha prolifera thalli collected from the surface and bottom of the sea of Qingdao sea area were studied with chlorophyll fluorescence and oxygraph technology. The samples with the highest photosynthetic activity among their kinds, the floating thalli from the sea surface of the south of the Qingdao Olympic Sailing Center and the sedimentary thalli from the mud surface of the bottom Tuandao bay, were chosen as representatives of surface thalli and bottom thalli, respectively. The results showed that the maximal PSII quantum yield of the floating thalli was significantly lower than the normal level although their photosynthetic activities were relatively high; the photosynthetic potential of the thalli form the mud surface was extremely low. Thus, it is indicated that the floating thalli are seriously stressed by their environment and the thalli from the mud surface are already dead or are dying. On the other hand, the results of the laboratory cultivation showed that the sedimentary thalli cannot regain normal photosynthetic activity even under normal illumination conditions. Thus, the thalli from the mud surface cannot become reproductive source of the alga even if they can reach sea surface again. Therefore, a preliminary conclusion can be reached that, up to mid-July 2008, the environmental conditions of the Qingdao sea area are not suitable for the growth of the alga E. prolifera and for this reason the biomass of E. prolifera, in the area, could be declining. Supported by National Natural Science Foundation of China (Grant No. 30830015), Key Projects in the National Science & Technology Pillar Program in the Eleventh Five-year Plan Period (Grant No. 2006BAD09A04) and National High Technology Research and Development Program of China (Grant Nos. 2006AA10A402, 2007AA09Z406, 2006AA05Z112, 2006AA10A413)     

水分胁迫下玉米幼苗光合变化和生理特性分析

对不同水分胁迫下玉米幼苗光合变化和生理特性的系统研究表明,在轻度干旱初期,玉米叶片光合速率(Pn)、蒸腾速率(Tr)有所下降,同正常供水(CK)条件相比差异不显著;在中度和重度干旱条件下,Pn,Tr开始就比CK明显降低并不断增大,其间气孔导度(Gs)则同光合速率、蒸腾速率几乎呈平行关系,同时幼苗生长也受到了明显抑制;3种胁迫下,叶片含水量也逐渐减少,丙二醛(MDA)含量、细胞膜透性和渗透调节物质含量随着胁迫程度加深和胁迫时间延长明显增加,保护酶系统(SOD,POD,CAT)活性随着胁迫时间的延长,总体呈现出先升高后降低的趋势.     

伏牛山自然保护区北坡主要乔木优势种光合作用特性研究

本文采用群落生态学的调查方法,设置典型样地,通过计算重要值,对伏牛山自然保护区北坡的乔木优势种进行了统计分析.接着对上述优势种及其幼树、幼苗的光合速率日变化及其光合-光响应特性进行了研究.     

水分胁迫对蚕豆（Vicia faba L.）光合作用及产量的影响

以重庆市的蚕豆当家品种香珠豆为材料,通过人工水分胁迫处理,发现随土壤干旱程度的增加,蚕豆叶片的净光合速度下降,光饱和点降低,光补偿点提高,CO2补偿点提高,光呼吸增大;生长减弱,同化产物的积累减少,最终表现为植株的株高、根长、鲜干重、叶面积、根瘤的数量与重量、开花数、结荚数都明显下降,根冠比则上升。这是导致生物量积累减少的主要原因。     

苏铁耐旱、抗寒及光合生理特性研究

采用干旱胁迫及人工模拟冷冻试验 ,进行苏铁耐旱、抗寒及光合生理特性研究 ,结果表明 :不同年龄苏铁的耐旱性、抗寒性及光合生理指标存在明显差异 ,随苏铁叶龄增加 ,苏铁叶片水势、冻害敏感指数和 NR活力下降 ,蒸腾速率、自然饱和亏和叶绿素含量增加 ,苏铁耐旱及抗寒性增强 ;苏铁水分及光合生理指标对干旱胁迫反应敏感 ,随干旱胁迫加剧 ,苏铁叶片水势、蒸腾速率、叶绿素、NR活力及净光合速率下降 ,而自然饱和亏增大 ,以适应胁迫环境 ,使苏铁表现出较强的抗旱性和生命力。     

大粒小麦高产原因的探讨

以中粒小麦４１８５为对照品种,研究了不同大粒小麦品系在灌浆至成熟期间的光合性能、灌浆强度及最 产量。结果表明,大粒小麦的叶面积大,光合强度高,灌浆强度高,千粒重明显高于中粒品系,是有推广价值的高产品种。     

不同盐分在不同浓度条件下对玉米幼苗基础生理效应的研究

用一系列含同摩尔Ｎａ＾＋浓度的ＮａＣｌ、Ｎａ２ＣＯ３、Ｎａ２ＳＯ４溶液以及用磷酸中和至ＰＨ值与含同摩尔Ｎａ＾＋浓度的ＮａＣｌ溶液的ＰＨ值相等的Ｎａ２ＣＯ３溶液处理生长期为３０天的玉米幼苗。处理一周后,测定离子含量、渗透势、光合性能和叶绿素含量等各项生理指标。结果表明：在同摩尔Ｎａ＾＋浓度条件下,玉米幼苗在ＮａＣｌ、ＮａＣＯ３和Ｎａ２ＳＯ４胁迫下产生胁变的顺序为：Ｎａ２ＣＯ３〉ＮａＣｌ〉Ｎａ２ＳＯ４     

光合作用模型化合物的研究现状及发展趋势

光合作用模型化合物包括二元化合物、多元化合物和非共价键相连的超分子体系,超分子体系的光化学和光物理是近几年该领域的研究热点,目前,人们合成的光合作用模型化合物已经具备了自然界光合作用反应中心的某些性质,预计,今后该领域的研究工作将集中在固相和超分子体系模型化合物的研究上。     

Simulation for the primary electronic donor of photosystem Ⅱ in vitro

Histidine coordinated to Chl a is a distinct characteristic of Chl a in vivo. By using histidine analogue of 1-methylimidazole (C4H6N2) and measuring the UV/vis absorption, CD and MCD spectra of the interaction between C4H6N2 and Chl a in CCl4, we have obtained that: (ⅰ) In pure CCl4 solvent, Chl a molecule is in five-coordinate state, and two Chl a molecules form an asymmetric compact-dimer with strong coupling interaction. We propose that the two Chl a molecules are connected by two unequally coordinated Mg-O bonds (the two oxygen atoms come from the C== O of C131 keto and C17 ester, respectively); (ⅱ) when the molar ratio of C4H6N2/Chl a is 0.5 or 1 (corresponding to 2Chl a·1C4H6N2 and 2Chl a·2C4H6N2, respectively), significant changes have been observed in the absorption, CD and MCD spectra, which indicate that the Chl a remains in dimer form, but the coupling interaction between them reduces greatly. We postulate that C4H6N2 replaces the ligation of C== O of C17 ester and C131 keto to Mg atoms sequentially. The two Chl a molecules linked by two weakly interacted Mg...O bonds form a relaxed-dimer. The structure of the model is essentially similar to that of the primary electronic donor, P680, of photosystem Ⅱ in high plants and algae.