人参叶片的叶龄对光合作用和呼吸作用的影响

叶片光合作用效率受叶龄的影响。在叶片发育期间光合作用发生明显变化。人参为多年生草本阴生植物,在整个生长季节只形成一次叶片。前人对其光合作用特征的研究已有报道,但关于人参叶片发育过程中光合作用的变化尚未见到报道。研究人参植株不同     

呼吸作用对叶片光合作用和异戊二烯释放的影响

将杨树叶片置于持续的光照下增加了其光合速率和异戊二烯的释放水平。持续的光照也诱导了总呼吸、细胞色素途径和交替呼吸途径容量的增加。用细胞色素途径和交替呼吸途径的抑制剂氰化钾和水杨基氧肟酸降低了光照下叶片的光合速率和异戊二烯的释放水平,也导致了光系统Ⅱ的光合效率和光化学淬灭系数的降低。这些结果表明了呼吸作用可能有助于光合作用的正常运行和光照下植物异戊二烯的释放。     

水分对番茄不同叶龄叶片光合作用的影响

以番茄品种"金棚1号"为材料,采用盆栽方式,按照蒸腾蒸发量(ET)的50%、75%、100%和125%作为补充灌溉量研究了不同水分下番茄结果期叶片气体交换特性和光响应特征参数随叶龄的变化。结果表明:番茄叶片随着叶龄的增加,净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)逐渐降低,水分利用效率(WUE)呈先上升后下降趋势;叶龄为18 d和29 d的叶片最大净光合速率(Pmax)随灌溉量的增加均先增加后降低,分别在75%ET和100%ET处理达到最大值。叶龄为38 d和47 d的叶片Pmax均以125%ET处理最大。表观量子效率(α)随叶龄的增大也先升高后下降,在叶龄为38 d时最大;番茄叶片的光饱和点(LSP)随叶龄的加大而减小。不同水分处理下不同叶龄叶片的光响应特征参数为:叶片在叶龄为18 d时,Pmax为20.64—26.73μmol.m-.2s-1,α为0.0518—0.0556;叶龄为29 d时,Pmax为11.00—24.24μmol.m-.2s-1,α为0.0522—0.0594;叶龄为38 d时,Pmax为11.77—18.18μmol.m-.2s-1,α为0.0619—0.0693;叶龄为47 d时,Pmax为9.09—18.17μmol.m-.2s-1,α为0.0538—0.0606。随叶龄加大,增加补充灌溉量有利于延缓叶片光合能力的降低。气孔限制是水分影响番茄叶片光合作用的主要因素,气孔限制与非气孔限制因素是番茄叶片Pn随叶龄变化的原因。     

叶龄对苋菜光合作用特性的影响

苋菜Amaranthus tricolor是生长期短的C_4双子叶蔬菜,叶片较易进行细胞器的分离,可作为研究C_4光合作用特性的一种好材料。我们前已报道,苋菜属于C_4双子叶的NADME亚类的范围。本文报道苋菜的光合速率,气孔传导性,细胞间CO_2浓度以及PEP羧化酶、乙醇酸氧化酶活性与叶片年龄的关系并确证其C_4途径亚类。     

补光对出口模拟贮运人参榕叶片生长和光合作用的影响

为减轻出口人参榕贮运暗胁迫下叶片的黄化与脱落,以人参榕(接穗为泰国榕)为材料,采用28 W荧光灯补充光照,研究不同补光时长(0~12h·d-1)处理28d后对模拟贮运人参榕生长和光合作用的影响,以探索人参榕贮运期间适宜的补光时长。结果显示:(1)模拟暗贮运28d时,补光0h·d-1处理的人参榕落叶率、黄化指数分别为89.64%、0.52,而补光8~12h·d-1处理的落叶率、黄化指数显著下降,落叶率比对照(0h·d-1)分别显著下降为35.7%、39.19%、26.08%,黄化指数分别显著下降为0.25、0.28、0.19。(2)随着补光时间的延长,人参榕叶片的相对含水量(RWC)显著降低,而比叶重(SLW)显著升高;其叶绿素a、叶绿素b、叶绿素(a+b)含量、类胡萝卜素含量、叶绿素a/b、净光合速率(Pn)、气孔导度(Gs)均呈上升趋势,且在补光8~12h·d-1处理下各指标均明显高于其他处理,但胞间二氧化碳浓度(Ci)呈下降趋势。(3)相关分析显示,模拟贮运人参榕的落叶率与黄化指数呈极显著正相关;落叶率、黄化指数均与其叶绿素含量、Pn呈极显著负相关,与Ci呈极显著正相关;且叶片Pn与叶绿素含量、Gs呈显著正相关,与Ci呈极显著负相关。研究表明,通过补光措施可显著减缓贮运人参榕叶片的黄化与脱落,28 W荧光灯光照8~12h·d-1的补光效果均较好,综合考虑成本认为在实际人参榕贮运过程中最适补光时长为8h·d-1;贮运时较长时间的暗胁迫环境对人参榕叶片光合系统造成损伤并导致Pn下降,其主要是叶绿素含量降低的非气孔限制因素所致。     

光合作用和呼吸作用关系图解

在植物生命活动过程中，光合作用与呼吸作用的关系非常密切。这两种生理生化过程，既相互对立，又相互依存，共同存在于统一有机体中。为了简单明确地把光合作用与呼吸作用的关系以图解形式表达出来，应用于教学之中，过去钟被波【门、葛培根【＼潘瑞炽和董愚得［’］都曾做过尝试，有一定教学参考价值。但是，我认为这些图解过于繁杂或仅局限于能量关系。我们在编写新教材中也设计了一个图解（图1），比较全面地表达了光合作用与呼吸作用在能量代谢和物质代谢之间的关系，简单明确，学生和读者易于领会。这一图解具体说明了以下问题：（1）…     

关于光合作用和呼吸作用的比较实验

光合作用和呼吸作用是植物生命活动的两个重要的生理过程,它们既有区别又有联系。那么如何用实验说明光合作用和呼吸作用的区别呢?在这里介绍一种方法。     

蒙古栎叶片光合作用随叶龄的变化及其与叶片功能性状的关系

叶片光合能力直接决定着植物生产力的高低,它既受外界环境条件的影响,也受叶片内部因素的制约。本文以日为单位对叶龄进行度量,从爆芽日开始,对蒙古栎光合作用参数随叶龄的变化及其与叶片功能性状的关系进行了分析。结果如下:(1)蒙古栎叶片生长季初期(爆芽后3日内)其呼吸速率大于光合速率,净光合速率为负值;生长季中期,光合参数P_(max)(最大净光合速率)、J_(max)(CO2饱和时最大净光合速率)、V_(cmax)(最大Rubisco催化反应速率)的变化主要受环境因子(降雨、土壤含水率)的影响。(2)整个生长季初期,光合参数与叶绿素含量及叶面积呈极显著正相关(P0.01);生长季初期爆芽阶段光合参数与比叶重呈负相关,生长季初期展叶阶段光合参数与比叶重呈正相关,在生长季初期叶片完全展开后,光合参数与比叶重呈负相关;生长季中期,所有的光合参数与叶片功能性状无显著相关性;生长季后期,光合参数与叶片功能性状均呈显著正相关(P0.05)。建议今后研究中,考虑根据叶片的生长过程分阶段探讨其光合能力及其生理生化影响机制,以增加森林生态系统碳收支估算的准确性。     

测定植物光合作用和呼吸作用的比色法

光合作用是对积累有机物质的能量和产量高低具决定意义的过程之一;在许多情况下,必须在植物生长地计算光合作用。在各个不同时期,曾经提出了许多测定光合作用的方法。可以把现有的很多方法分成基本的四类:1)     

Leaf Photosynthesis,Dark Respiration and Fluorescence as Influenced by Leaf Age in an Evergreen Tree,Prosopis Juliflora

P. juliflora trees produce leaves during two growth periods. The first cohort of leaves is produced during spring in cool conditions, while the second cohort is produced during monsoon under warm conditions. I studied photosynthetic characteristics of young, mature, and old leaves of the previous season (monsoon) in the spring season. Maximum net photosynthetic rate of a young leaf was lower than that of the mature and old leaves. The total CO₂ fixed per day by the young leaves was just 36 % of that in the mature leaves while the old leaves fixed 76 % of that of the mature leaf. The total transpiration rate and water use efficiency (WUE) were similar in the mature and old leaves, while they were much lower in the young leaves. Dark respiration rate was maximal in the young leaves as compared to the mature and old leaves. About 92 % of the total CO₂ fixed per day were respired by the young leaves. The diurnal fluorescence characteristics (F/F_m, q _p, and q _N) of the young, mature, and old leaves showed that photochemical efficiency of photosystem 2 during midday decreased more in the young and old leaves than in the mature ones. However, the fluorescence characteristics showed that in all the three leaf types there was complete recovery of the photochemical efficiency at sunset from the midday depression. F_v/F_m in the young and mature leaves also confirmed this. Hence the young and old leaves were photosynthetically less efficient than mature leaves, but they were well adapted to withstand the harsh environmental conditions.     

Dark Respiration during Photosynthesis in Wheat Leaf Slices

The metabolism of [¹⁴C]succinate and acetate was examined in leaf slices of winter wheat (Triticum aestivum L. cv Frederick) in the dark and in the light (1000 micromoles per second per square meter photosynthetically active radiation). In the dark [1,4-¹⁴C]succinate was rapidly taken up and metabolized into other organic acids, amino acids, and CO₂. An accumulation of radioactivity in the tricarboxylic acid cycle intermediates after ¹⁴CO₂ production became constant indicates that organic acid pools outside of the mitochondria were involved in the buildup of radioactivity. The continuous production of ¹⁴CO₂ over 2 hours indicates that, in the dark, the tricarboxylic acid cycle was the major route for succinate metabolism with CO₂ as the chief end product. In the light, under conditions that supported photorespiration, succinate uptake was 80% of the dark rate and large amounts of the label entered the organic and amino acids. While carbon dioxide contained much less radioactivity than in the dark, other products such as sugars, starch, glycerate, glycine, and serine were much more heavily labeled than in darkness. The fact that the same tricarboxylic acid cycle intermediates became labeled in the light in addition to other products which can acquire label by carboxylation reactions indicates that the tricarboxylic acid cycle operated in the light and that CO₂ was being released from the mitochondria and efficiently refixed. The amount of radioactivity accumulating in carboxylation products in the light was about 80% of the ¹⁴CO₂ release in the dark. This indicates that under these conditions, the tricarboxylic acid cycle in wheat leaf slices operates in the light at 80% of the rate occurring in the dark.     

B9和PP333对人参生长和叶片光合特性的影响

人参叶片展叶前喷施3 000 mg*L-1的B9或400 mg*L-1的PP333后,人参植株的叶片面积、叶柄长、茎长和花梗长降低,茎直径增加,叶片叶绿素含量、叶绿素a/b比值、净光合速率、气孔导度和蒸腾速率显著提高,PP333的效果更为明显.     

Growth Rate, Photosynthesis and Respiration in Relation to Leaf Area Index

This work examined three possible explanations of growth rateresponses to leaf area index (LAI) in which growth rate perunit of ground area (crop growth rate, CGR) increased to a plateaurather than decreasing above an optimum LAI at which all lightwas intercepted. Single leaf photosynthetic measurements, andwhole plant 24 h photosynthesis and respiration measurementswere made for isolated plants and plants in stands using Amaranlhushybridus, Chenopodium album, and two cultivars of Glycine maxgrown at 500 and 1000 µimol m^–2 S^–1 photosyntheticphoton flux density at 25 °C. CGR, relative growth rate(RGR), and LAI were determined from 24 h carbon dioxide exchangeand leaf area and biomass measurements. Respiration increasedrelative to photosynthesis with crowding in A. hybridus andthere was an optimum LAI for CGR. In contrast, the ratio ofrespiration to photosynthesis was constant across plant arrangementin the other species and they had a plateau response of CGRto LAI. Neither increased leaf photosynthetic capacity at highLAI nor a large change in biomass compared to the change inLAI could account for the plateau responses. It was calculatedthat maintenance respiration per unit of biomass decreased withdecreasing RGR in C. album and G. max, but not A. hybridus,and accounted for the plateau response of CGR to LAI. Sincesimilar decreases in maintenance respiration per biomass atlow RGR have been reported for several other species, a constantratio of respiration to photosynthesis may occur in more speciesthan constant maintenance respiration per unit of biomass. Amaranlhus hybridus L., Chenopodium album L., Glycine max L Merr, soybean, photosynthesis, respiration, growth, leaf area index     

Effects of exogenous hormones on leaf photosynthesis of Panax ginseng

Ginseng (Panax ginseng) is a typical perennial shade plant. Aim of this study was to investigate the effects of exogenous hormones on photosynthesis of P. ginseng. At different growth stages, the aerial parts of P. ginseng plants were cut at the stem base and they were inserted into the nutrient solutions containing different exogenous hormones. Then the leaf photosynthesis and water absorbing capacity (absorbing water mass) of the excised plants were measured. The results showed that exogenous abscisic acid (ABA) decreased significantly net photosynthetic rate (P _N), stomatal conductance, transpiration rate, and absorbed water mass of excised P. ginseng at all growth stages, while both cytokinin (CTK) and indole-3-acetic acid (IAA) enhanced those parameters. Comparing different growth stages, ABA caused more severe inhibition of leaf photosynthesis at the early growth stage, while CTK and IAA showed significant enhancement of leaf photosynthesis at later growth stage. ABA reduced highly intercellular CO₂ concentration of P. ginseng at the flowering and green fruit stages, but it had only a small effect at red fruit early and red fruit stages. During the early growth stage, the inhibitory effect of ABA on leaf P _N might be caused mainly due to the stomatal limitation. However, the reason for this reduction was complex at the later growth stage and it included stomatal and other factors.     

人参抗疲劳作用研究进展

人参是古今著名的滋补强壮良药,药理研究、临床观察和流行病学调查,结果均证实人参具有多种生物活性。本文着重从人参抗中枢疲劳、抗自由基、调节糖代谢和乳酸代谢,以及对血红蛋白含量的影响等方面进行综述。     

三七环二肽成分和人参内酰胺成分

From the roots of Panax notoginseng fourteen cyclodipeptides 1-14 were isolated including one new compound (1),seven new natural compounds (4-10) and six known compounds (2-3,11-14) together with one known other compound 15.The chemical structure of 1 was elucidated as cyclo-(Leu-Thr) based on spectral methods.From the roots of Panax ginseng five known lactams (16-20) includingpyrng lutamic acid were isolated together with butyric diacid,daucosterol and sucrose.The primary binactivity test showed that pyroglutamic acid and its n-butyl derivative have weak Ca^2 antagonistic activity.     

Effect of Leaf Age and Shading on Photosynthesis in Potatoes (Solanum tuberosum)

The effects of leaf age and of shading on photosynthetic rateand on other leaf parameters of potato (Solanum tuberosum L.)were studied using a portable gas exchange system. A rapid decreasein the rate of photosynthesis during leaf senescence was observed.This was accompanied by an increase in stomatal resistance,and as a result a fairly constant level of sub-stomatal CO₂concentration was maintained at all leaf ages. The reductionin the photosynthetic rate in older leaves was therefore assumedto be essentially mesophyllic in origin, whereas the stomatalresponse was probably secondary. Canopy density significantly affected the rate of photosyntheticreduction with leaf age. Leaves maintained under high radiationintensities manifested a slower decline in their photosyntheticrate, especially in the early stages of their senescence, thanleaves kept under shade conditions. The latter leaves were foundto be more adapted to low radiation intensities, as indicatedby changes in their chlorophyll a:b ratio and specific leafweight Solanum tuberosum L, potato, photosynthetic rate, mesophyll, stomata, leaf age, radiation intensity, chlorophyll a:b ratio