Relationship Between Diurnal Changes of Net Photosynthetic Rate and Influencing Factors in Rice under Saline Sodic Stress

The net photosynthetic rate of flag leaves and influencing factors under saline sodic soil conditions were investigated at the full heading stage of rice. The net photosynthetic rate of rice leaves showed a double-peak curve in a day in both non-saline sodic and saline sodic soil treatments. The first peak of the net photosynthetic rate appeared at 9：00-10：00 and 9：00 in the saline sodic and non-saline sodic soil treatments, respectively, whereas the second peak both at 14：00. The midday depression of the net photosynthetic rate always appeared regardless of non-saline sodic or saline sodic soil conditions. In addition, the net photosynthetic rate significantly decreased in all day under saline sodic conditions compared with that under non-saline sodic conditions. Some differences were observed in correlation characters between the net photosynthetic rate and all influencing factors during 9：00-13：00. Under non-saline sodic conditions, the diurnal changes of the net photosynthetic rate in a day were mainly caused by stomatal conductance, and the limitation value and the stomatal factors served as determinants; whereas under saline sodic stress, the diurnal changes of the net photosynthetic rate in a day were mainly caused by non stomatal factors including light intensity and air temperature.

Diurnal changes in net photosynthetic rate of Pueraria lobataand its impact factors

In order to identify the relationship between diurnal changes in the net photosynthetic rate（Pn） of Pueraria lobata and environmental factors,diurnal changes in the Pn of leaves of two P.lobata cultivars were measured using a CIRAS-1 portable photosynthesis measurement system（PP-Systems,UK）.The results show that diurnal changes in Pn of both cultivars could be interpreted as double-peak curves,indicating the occurrence of an obvious midday depression.Further analyses indicate that the correlation between Pn and stomatal conductance was positive and extremely significant（p 〈 0.01）.The correlations of Pn with intercellular CO2 concentration and transpiration rate were positive and significant（p 〈 0.05）,while the correlations of Pn with air and leaf temperatures were negative and significant（p 〈 0.05）.The results indicate that among the factors affecting photosynthetic properties,some can be grouped as stomatal limitations while others are non-stomatal limitations.

Study on the Daily Change of Photosynthetic Rate for Prunus domestica × armeniacain Different Seasons

[Objective] The aim of this study was to explore the daily change of photosyntheticratefor Prunus domestica ×armeniacain different growing seasons. The study can provide theoretical basis for arid area high yield and quality cultivation.[Method] The photosynthetic physiological properties of leaves of different types of Prunus domestica × armeniaca were measured by the Li-6400 portable photosynthesis system indifferent seasons. By this method could analysis of photosyntheticcharacteristicsfor different types of Prunus domestica×armeniaca in different seasons.[Result] Daily change of photosyntheticrate（Pn） for Prunus domestica×armeniaca in differentseasons showed a ＂double-peak＂ curve. The peak values were at 10：00 and16：00. The Pn of ‘Fengweihuanghou＇, ‘Konglongdan＇, ‘Weihou＇, ‘Weiwang＇ and‘Weidi＇ reached the maximum in July, theywere 13.75, 14.76, 12.96, 13.3, and 11.9μmol/（m^2·s）, respectively. The Pn of Prunus domestica×armeniaca reached minimumin August, they were 9.78, 10.71, 12.02, 10.43 μmol/（m^2·s）. The Pn overall average of ‘Konglongdan＇ was highest,it reached 12.65 μmol/（m^2·s）.The Pn overall average of ‘Weiwang＇ was lowest, it reached 11.31μmol/（m^2·s）. There were extremely significant positive correlation between the Pn and Gs（P0.01）. [Conclusion] Daily change of photosyntheticrate for Prunus domestica ×armeniaca in differentseasons showed a ＂double-peak＂ curve, showing significant phenomenon of ＂midday depression＂.The photosynthesis intensity of Prunus domestica ×armeniaca was strongest in July, and the photosynthesis intensity was weakest in August. ‘Konglongdan＇showed the strongest photosynthesis capacity, ‘Weihou＇ and ‘Weiwang＇, followed.There were highest correlation between the Pn and stoma conductance（Gs）.

Photosynthetic response of floating Ulva prolifera to diurnal changes of in-situ environments on the sea surface

During yellow sea green tide outbreak, the thalli of Ulva prolifera drifted more than 350 km on the sea surface from off shore of Jiangsu Province to Qingdao city, where they were exposed to complex changes of local environments. The purpose of this study is to investigate the response of the thalli to diurnal changes of environments on the sea surface, and a sea surface environment simulator (SSES) was designed to simulate the natural environment of floating U . prolifera mat. A control experiment is designed in the laboratory, which was processed under suitable conditions (20°C for temperature, 72 μmol photons/(m 2 ·s) for light intensity and 30 for salinity), and an in-situ research was conducted to study the photosynthetic responses of floating U . prolifera to diurnal changes of environments. The results show that the photosynthetic efficiency of the thalli decreased gradually with time, and decreased rapidly after 14:00 local time (LT). After exposed to the environment on the sea surface for 6 h, the photosynthetic activity of the thalli decreased significantly. Furthermore, physiological-level and molecular-level experiments revealed that non-photochemical quenching (NPQ), cyclic electron flow (CEF) and energy redistribution between PSI and PSII all played an important role in the strong photosynthetic plasticity of U . prolifera . NPQ is the most important photoprotective responses to environmental changes before 12:00 LT. The results also confirmed that the CEF and energy redistribution between PSI and PSII are the main synergistic eff ects for the thalli to adapt to the environmental changes when the process NPQ cannot work. And the result can further reveal the reason why U . prolifera can adapt to the living condition of long distance drift on the sea surface. The findings of this research could provide a theoretical basis for explaining outbreaks of the green tide and instructing the management of the problem.

Relationship Between Net Photosynthetic Rate of Cassava SC205 and Its Physio-ecological Factors

[Objective]The aim was to measure photosynthetic characters of SC 205, a cassava cultivar, and explore the relationships of the net photosynthetic rate （Pn） with physiological and ecological factors. [Method] The diurnal variations of photosyn-thesis in leaves of SC205 were studied by LICOR-6400 portable photosynthesis system, and the relationships of the net photosynthetic rate （Pn） with physiological and ecological factors were studied by simple correlation analysis and path analysis. [Result] The curve of diurnal variation of Pn showed single peak at 10：00 am at 24.07 μ mol CO2 m2/s, without showing midday depression; the diurnal changes of stomatal conductance （Gs）, transpiration rate （Tr）, leaf temperature （Tl）, air tempera-ture （Ta） and photosynthetic active radiation （PAR） al showed single peak curves, and there were positive relationships of Pn with Gs, Tr, Tl, Ta and PAR. The diur-nal variations of intercellular CO2 concentration （Ci）, atmospheric CO2 concentration （Ca）, relative humidity （RH） showed in a U-shape curve. There were highly signifi-cant positive correlation of Pn with Gs and PAR; the diurnal variation of Pn had highly significant negative correlations with Ci and Ca. The direct impact of physio-logical factors on Pn was as fol ows： Ci＆gt;Gs＆gt;Tl＆gt;Tr, and the direct impact of ecologi-cal factors was RH＆gt;PAR＆gt;Ca＆gt;Ta. [Conclusion] The research showed that Ci, Gs and Tr play very important roles in the changes of Pn among the physiological fac-tors, and PAR and Ca affect the changes of Pn among the ecological factors.

Leaf Photosynthetic Rate and Related Influencing Factors in Super High-yield Combination C Liangyou H255

[ Objective] Study on the photosynthesis and influencing factors in super high-yield combination C Liangyou H255. [ Method] The photosynthetic characteristies were measured at a hot and muggy day under natural conditions. [ Result] A respective single peak at 11：30 was observed in diurnal variation curves of net photosynthetic rate （Pn） and transpiration rate（Tr）. Correlation analysis shows that Pn presents an extremely significant correlation with photon flux densities （PFD） of photosynthetically active radiation, in comparison assumes a significant correlation either with stomatal conductance （Gs） or with ambient CO2 concentration （Ca）. [ Conclusion] Gs followed by PFD presented most influence on Pn of super high-yield combination C Liangyou H255.

3个沙棘品种叶片形态与光合特性比较

为揭示“北欧1号”“宇璐”“深秋红”3个沙棘品种光合特性的差异,探究不同沙棘品种成熟叶片形态特征对其净光合速率的影响,分别测定了叶片形态特征及其光合生理指标,并进行相关性分析。结果表明:(1)“宇璐”叶面积最大,“深秋红”叶面积最小,但3个品种叶片形态及各项指标差异均不显著;(2)“北欧1号”的净光合速率(Pn)、蒸腾速率(Tr)、胞间CO_(2)浓度(Ci)、气孔导度(Gs)均显著大于其他2个品种,水分利用效率和气孔限制值均显著小于其他2个品种;(3)逐步回归分析表明蒸腾速率、胞间CO_(2)浓度为3个品种净光合速率的主要影响因子,“北欧1号”“深秋红”的净光合速率降低是受气孔导度的影响,而“宇璐”净光合速率降低则是非气孔限制导致。综上说明“北欧1号”通过消耗更多水分维持较高的光合生产能力,“深秋红”通过更高的水分利用率,维持光合生产能力,但“宇璐”与“深秋红”光合速率等指标无显著差异、光合能力相近,说明“宇璐”通过较大的叶面积来保障其光合生产能力。

宁夏贺兰山东麓新引酿酒葡萄品种光合特性比较

【目的】对宁夏贺兰山东麓产区种植的酿酒葡萄品种马瑟兰、马尔贝克、小芒森和维欧妮与产区广泛种植的酿酒葡萄品种赤霞珠(CK_(1))和霞多丽(CK_(2))光合生理特征进行研究,筛选适宜该地区种植的新品种。【方法】测定不同品种成熟叶片的光响应曲线、CO_(2)响应曲线以及自然条件下的光合日变化特征。【结果】不同品种光合性状存在显著差异,在光响应曲线特征参数中,马瑟兰的最大净光合速率(P_(m))、光饱和点(LSP)显著高于其他品种,CK_(2)的光补偿点(CCP)和暗呼吸速率(R_(d))最大且表观量子效率(AQY)低于其他品种。由CO_(2)响应曲线特征参数可知,维欧妮的羧化效率(CE)、最大光合能力(A_(max))和光呼吸速率(R_(q))均显著高于其他品种,各品种的CO_(2)饱和点(CSP)变化范围在1 109.98~1 318.83μmol/(m^(2)·s)之间,CK_(2)的CO_(2)补偿点(CCP)最高,为77.74μmol/(m^(2)·s),其次为马尔贝克,维欧妮的最低,为60.18μmol/(m^(2)·s)。不同品种的光合日变化中,马瑟兰和马尔贝克的日P_n呈现双峰曲线,并具有明显的“光合午休”现象,其他4个品种的日P_n呈现单峰曲线,其中,维欧妮的净光合速率日均值最大,马尔贝克的最小。【结论】4个新引品种在贺兰山东麓产区的光合适应性均较好,光合能力大小依次是维欧妮>小芒森>CK_(2)>马尔贝克>马瑟兰>CK1。

遮荫对景宁玉兰幼苗生理生化季节变化的影响

以2年生景宁玉兰Yulania sinostellata幼苗为研究对象,通过遮阳网设置自然光强的100%(I_(100))、40%(I_(40))和10%(I_(10))3种遮荫处理,探讨不同遮荫处理下景宁玉兰生理生化特性的季节变化规律。结果表明:(1)景宁玉兰幼苗的净光合速率(P_(n))春季为I_(100)处理显著高于I_(40)、I_(10)处理(P<0.05),夏、秋季为I_(40)处理显著高于I_(100)、I_(10)处理(P<0.05)。I_(100)、I_(40)处理的P_(n)在夏季显著高于春、秋季(P<0.05),而I_(10)处理的P_(n)在夏季则显著低于春、秋季(P<0.05)。(2)3个季节的叶绿素(Chl)含量均随着遮荫强度的增加而增加,而类胡萝卜素/叶绿素(Car/Chl)值随着遮荫强度的增加而下降。3种遮荫处理的叶绿素、类胡萝卜素含量均以春季最高,叶绿素a/b(Chla/b)、Car/Chl值均以夏季最大。(3)春、秋季超氧化物歧化酶(SOD)活性随着遮荫强度的增加而下降。夏、秋季过氧化物酶(POD)随着遮荫强度的增加而升高,过氧化氢酶(CAT)活性以I_(100)处理较低。3种遮荫处理SOD活性以秋季最高,POD、CAT活性均以春季最高。(4)3个季节的抗坏血酸(As A)含量以I_(10)处理最低。谷胱甘肽(GSH)含量夏季以I_(100)处理最高,秋季以I_(40)处理最高。(5)I_(100)处理夏季的电导率显著高于I_(10)处理(P<0.05),秋季则显著高于I_(40)、I_(10)处理(P<0.05)。3种处理电导率均以秋季最高,春季最低。总之,I_(100)处理的景宁玉兰幼苗在夏、秋季叶绿素含量较低,并且POD、CAT活性较弱,无法有效清除活性氧,致使细胞膜透性增加,叶片受到光胁迫。而I_(10)处理由于光强过低使得光合能力弱。因此在栽培过程中,适当遮荫有利于景宁玉兰的生长,但光照强度不应低于40%。

盐胁迫条件下竹柳光合作用日变化特征研究

以竹柳盆栽苗木为试验材料,分析其在不同盐分浓度下的净光合速率、气孔导度、蒸腾速率、胞间CO_(2)浓度等光合生理指标的日变化特征。结果表明:竹柳在对照与轻度胁迫条件下,净光合速率的日变化特征表现为双峰型;在中度和重度胁迫条件下,为单峰型曲线,变化趋势表现为先上升后下降。气孔导度在对照与轻度胁迫条件下的日变化特征表现为双峰型;在中度和重度胁迫条件下为单峰型曲线,呈逐渐下降的趋势。蒸腾速率的日变化特征与气孔导度类似。各胁迫处理胞间CO_(2)浓度均较对照高,且随胁迫程度的加剧,胞间CO_(2)浓度也随之上升。

不同类型山苍子植株光合特性研究

为给山苍子(Litsea cubeba)植株的栽培管理提供科学依据,以不同类型山苍子植株为研究对象,测定其光合作用参数,探索不同类型山苍子植株的光合特征差异,并对其净光合速率与主要环境因子的相关性进行分析。结果表明,不同类型山苍子植株净光合速率均随光合有效辐射增加呈上升趋势,光合有效辐射为1 800μmol·m~(-2)·s~(-1)时,均达到光饱和点;4年生雄株的净光合速率高于1和2年生植株和4年生雌株。不同类型山苍子植株的光饱和点、光补偿点和表观量子效率均差异显著,4年生雄株的这3个参数均最大,分别为0.264 6μmol·m~(-2)·s~(-1)、1 382.31μmol·m~(-2)·s~(-1)和0.009 1 mol/mol。不同类型山苍子植株净光合速率和蒸腾速率日变化曲线(1年生植株除外)均为双峰形,存在光合“午休”现象。不同类型山苍子植株净光合速率与光合有效辐射均呈显著正相关。种植山苍子时应选光照较强的地方,后期进行适当修剪,并及时给雌性植株补充肥料。

Photosynthesis of Submerged and Surface Leaves of the Dwarf Water Lily(Nymphoides aquatica)Using PAM Fluorometry

Dwarf Water Lilies Nymphoides aquatica(J.F.Gmel)Kuntze have floating and submerged leaves.Some submerged aquatic vascular plants have a form of CAM(Crassulacean Acid Metabolism)called Submerged Aquatic Macrophyte(SAM)metabolism.Blue-diode based PAM technology was used to measure the Photosynthetic Oxygen Evolution Rate(POER:1O_(2)≡4e^(-)).Optimum Irradiance(E_(opt)),maximum POER(POER_(max))and quantum efficiency(α_(0))all vary on a diurnal cycle.The shape of the POER vs.E curves is different in seedling,submerged and surface leaves.Both E_(opt) and POER_(max) are very low in seedling leaves(E_(opt)≈104μmol photon m^(-2) s^(-1),PPFD;POER_(max)≈4.95µmol O_(2) g^(-1) Chl a s^(-1)),intermediate in mature submerged leaves(E_(opt)≈419µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈38.1µmol O_(2) g^(-1) Chl a s^(-1))and very high in surface leaves(E_(opt)≈923µmol photon m^(-2) s^(-1) PPFD,POER_(max)≈76.1µmol O_(2) g^(-1) Chl a s^(-1)).Leaf titratable acid(C4 acid pool)is too small(≈20 to 50 mol H+m^(-3))to support substantial SAM metabolism.Gross daily photosynthesis of surface leaves is≈3.71 g C m^(-2) d^(-1) in full sun and as much as 1.4 gC m^(-2) d^(-1) in shaded submerged leaves.There is midday inhibition of photosynthesis.

不同密度条件下玉米植株光合日变化特征分析

为探究不同密度条件下玉米植株各生育时期净光合速率Pn和叶绿素含量SPAD值的日变化特征,于2016—2017年在河南浚县高产试验田进行了试验.以郑单958和浚单29作为试验材料,设置高(8.25万株/hm^(2))和低(6.75万株/hm^(2))两个密度,三次重复,使用LI-6400型便携式光合仪在玉米5个生长时期(苗期,拔节期,灌浆期,抽雄吐丝期和成熟期)一天内每隔2 h,测定8点到16点之间植株的净光合速率,并用SPAD仪在后四个时期测定SPAD值.结果表明,玉米在苗期的Pn日变化呈单峰线,最高值出现在上午,在拔节期Pn日变化也为单峰线,峰值出现在下午,而SPAD值则呈现下降-上升趋势.抽穗期Pn日变化出现双峰与单峰交叉,不同密度间出现差异,玉米午休现象出现;SPAD值表现下降-上升-下降的现象;不同密度间各品种表现出差异,该生育期SPAD值较其它生育期高.在灌浆期和成熟期,玉米Pn日变化为双峰线,变化幅度因品种和密度而不同,但趋势一致,高峰出现在上午,午休现象较为明显;灌浆期SPAD值呈现下降-上升-下降-上升趋势.成熟期SAPD整体减小,并且SPAD日变化幅度也减小.Pn与SPAD在拔节期和抽穗期的日变化存在显著相关性,可以通过测定SPAD值来推断玉米植株的光合性能,从而为高密度集约化生产中玉米高产栽培提供理论依据.

3个哈克勒雷冬青品种光合日变化比较

以‘贝尔奇卡金Belgica Aurea’、‘金皇帝Gold King’、‘牢苏尼阿纳Lawsoniana’3个哈克勒雷冬青Ilex×altaclerensis品种13 a生嫁接植株成熟叶片为试材,采用LI-6400光合仪测定其净光合速率(Pn)、蒸腾速率(Tr)、胞间CO_(2)浓度(Ci)、气孔导度(Gs)等光合参数日变化,测定叶片相关生理指标,并进行相关性分析。结果表明:3个哈克勒雷冬青品种的Pn受生理及环境因子不同程度的影响,影响Pn的主要生理因子是Gs,环境因子为大气温度。3个品种的Pn日变化均呈双峰曲线,“午休”现象,原因主要是非气孔因素;Pn、Tr、叶绿素含量和比叶重均表现为‘牢苏尼阿纳’>‘贝尔奇卡金’>‘金皇帝’。综上所述,‘牢苏尼阿纳’光合生产能力最高,能够快速生长;‘贝尔奇卡金’次之,且受环境影响最小;‘金皇帝’综合光合性能最弱。

山核桃丰产生理基础研究

[目的]为山核桃丰产、科学制定栽培措施提供应用基础依据。[方法]基于对山核桃生物学特性和物候期的观察和对比;使用美国Licor-6400光合作用测定系统直接输出自然光照下叶温、进气CO_(2)浓度、叶室CO_(2)浓度、细胞间隙CO_(2)浓度、光合速率、蒸腾速率、气孔导度等指标的数据,从而确立山核桃净光合速率日变化规律。[结果]山核桃果实动态生长表现为单果质量总体不断增长,呈“S”型生长曲线,初果后20 d内增长极慢,此后的40 d缓慢增长,7月上旬果实开始快速生长,并维持30 d以上。影响山核桃光合速率日变化的因素不仅有光照、CO_(2)浓度,还有叶片的气孔导度、蒸腾速率、叶温等因素。净光合速率在上午高于下午,有“午休”现象;叶片气孔导度与叶片光合速率的日变化趋势呈正相关关系;胞内CO_(2)浓度日变化和大气中CO_(2)浓度日变化与光合速率日变化呈负相关;空气中CO_(2)浓度在一天内,早晚浓度较高;一天内,蒸腾速率和光合速率的日变化趋势类似,均受到叶片气孔开启的调节作用;一天中随气温、光强的增加,叶温增加,当蒸腾作用受阻时,叶温升高;光合作用后的CO_(2)浓度降低,此时应及时补充CO_(2)以保证光合作用,为山核桃的丰产奠定基础。[结论]该研究结果进一步证实了山核桃的喜温特性与光合性能密切相关。提高光合性能,或从品种到栽培措施来改善光合物质的积累是山核桃丰产的基础工作;山核桃的日光合速率有明显光“午休”现象,光合作用呈双峰曲线。

2个山楂品种的光合特性研究

【目的】光合作用是植物进行生长发育、开花结果的生理生化基础,直接影响果树的生长和结实,能在一定程度上反映出果树产量的高低。为此,对‘大金星’‘红五棱’2个山楂品种光合特性进行研究,以期为品种引进、筛选和栽培工作提供理论依据。【方法】以‘大金星’和‘红五棱’为研究对象,采用Li-6400型便携式光合仪测定了2个山楂品种光合特性的日变化趋势,结合叶绿素含量等指标分析了二者的光合特性和差异。【结果】2个山楂品种净光合速率的日变化呈双峰趋势,但午休时间不同,且一定时间差异显著;气孔导度日变化趋势与净光合速率的日变化表现相近,且大部分时间差异显著;胞间CO 2浓度的日变化不同,差异较大;蒸腾速率的日变化不同,差异较大。【结论】‘大金星’各光合指标之间具有显著相关性,而‘红五棱’各光合指标之间相关性则不显著。2个品种光合特性差异较大,这也有可能是长期以来二者栽培管理模式大不相同的原因之一。

海南东寨港两种红树植物旱季和雨季的光合生理特征比较

植物光合生理生态特性是退化植物群落恢复、重建植物种选择的重要依据。为研究不同红树植物光合生理生态特性,该研究于2021年旱季的4—5月、雨季的7—9月利用LI-6400光合仪,测定红树植物秋茄和海莲的光合生理参数和主要生态因子,并采用通径分析方法分析主要生态因子对净光合速率的影响。结果表明:(1)秋茄旱季净光合速率日均值(8.43μmol^(-2)·s^(-1))略低于雨季(8.67μmol^(-2)·s^(-1)),差异不显著;海莲旱季净光合速率日均值(7.03μmol^(-2)·s^(-1))显著低于雨季(9.41μmol^(-2)·s^(-1));旱季秋茄净光合速率日均值显著高于海莲,而雨季秋茄净光合速率日均值显著低于海莲。(2)旱季、雨季秋茄蒸腾速率、气孔导度、胞间CO_(2)浓度等光合生理因子日均值变化幅度小于海莲,水分利用效率也低于海莲。(3)旱季、雨季两种红树植物均存在“光合午休”现象。旱季,秋茄属于非气孔限制,而海莲属于气孔限制;雨季,秋茄和海莲均属于气孔限制。(4)旱季影响秋茄净光合速率的主要决策因子是光合有效辐射,主要限制因子是相对湿度,而生态因子对海莲净光合速率均起限制作用,其中饱和水汽压差是主要限制因子;雨季秋茄和海莲的主要决策因子均是光合有效辐射,主要限制因子均是饱和水汽压差。综上研究表明,秋茄对于生境变化有着更强的适应性,海莲不仅具有较好耐旱性能,而且更适合高温多雨生境,该研究结果为退化红树林的恢复重建植物种选择提供了科学依据。

菰叶片净光合速率日变化及其与环境因子的相互关系

【目的】通过研究菰叶片净光合速率日变化及其与环境因子的相互关系,目的为菰资源的开发和利用提供参考。【方法】利用Li-6400型光合作用测定系统,测定了菰叶片净光合速率和环境因子的日变化,通过相关性分析,考察了环境因子对净光合速率日变化的影响。【结果】菰功能叶片净光合速率为15.0～21.5μmol·m-2·s-1,光补偿点为45μmol·m-2·s-1,光饱和点为1040μmol·m-2·s-1。菰叶片净光合速率、气孔导度和蒸腾速率的日变化均呈单峰曲线,净光合速率的峰值出现在上午11:00时,上午8:00～11:00时的平均净光合速率比下午13:00-16:00时的平均净光合速率高4.7μmol·m-2·s-1。气孔导度和蒸腾速率的峰值分别出现在13:00和14:00时。一日中上午5:00～11:00和下午15:00～19:00时净光合速率与光量子通量密度之间呈显著正相关(r=0.9874**、0.9321**),11:00～15:00时两者之间呈不显著正相关(r=0.4440)。上午5:00～11:00和下午15:00～19:00时净光合速率与空气温度之间呈显著正相关(r=0.9617**、0.9852**),11:00～15:00时两者之间呈显著负相关(r=-0.8110*)。净光合速率与气孔导度之间呈正相关(r=0.7936*),与胞间CO2浓度呈负相关(r=-0.8026*)。气孔导度和蒸腾速率与光量子通量密度之间呈显著的正相关(r=0.9104**、0.7858*)。【结论】菰叶片的光补偿点较低,而光饱和点较高,对光环境的适应性较强,为典型的阳生植物。影响净光合速率日变化的主要环境因子是光量子通量密度和空气温度。

遮荫处理对东北铁线莲生长发育和光合特性的影响

以东北铁线莲C lematis manshurica为材料,研究了不同遮荫处理(全光照CK、遮荫30%、50%、70%和90%)对东北铁线莲生长发育和光合特性的影响,为吉林省东北铁线莲规范化种植提供理论依据。结果表明,不同光照条件下叶片总叶绿素、叶绿素a、叶绿素b含量均显著高于全光照的,且随遮荫程度的提高叶绿素含量呈上升趋势,90%遮荫下东北铁线莲叶片叶绿素含量最高,相反叶绿素a/b的值却最低;东北铁线莲比叶面积随着光照强度的减弱而增加,说明东北铁线莲在较弱的光照下通过总体光合面积的增加来保证一定的光合积累。全光照条件下东北铁线莲净光合速率呈明显的"午休"现象,30%遮荫处理条件下东北铁线莲净光合速率较呈不明显"午休"现象,遮荫对蒸腾作用和气孔导度均有显著的影响,随着光照强度的减弱,蒸腾速率和气孔导度均显著下降;30%遮荫处理净光合速率、各部分生物量均较高,与其他处理差异显著。但随着遮荫梯度的增加,东北铁线莲的净光合速率降低,光合作用合成产物总量减少,导致70%和90%遮荫条件下主茎长度变短,各构件生物量下降,不利于植株拓展,而50%、70%和90%遮荫条件下东北铁线莲的净光合速率变化趋势为单峰曲线,没有表现出午休现象,但由于光照强度较低造成光合效率低,不利于东北铁线莲的生长。因此,在生产实践上,适当调控光照强度,有利于东北铁线莲净光合速率的提高,这是提高东北铁线莲产量的重要措施。

影响水稻叶片光合日变化因素的分析

选择典型的干热天气，测定了盆栽水稻二九丰孕穗期的光合日变化及其影响因子，利用相关性分析和通径分析，考查了光强、叶温、胞间CO2浓度、气孔导度、蒸腾速率和相对湿度对光合速率的影响。早晨8：30以前，光合速率的上升主要是光强造成的；光合速率在8：30达最大值，此后逐渐下降，其间光合速率的降低，尤其是“午睡”期间的下降，气孔因素是主要限制因子；下午14：30～18：00，光合速率与胞间CO2浓度呈一定负相关，但未达显著水平，与光强、气孔导度、叶温和相对湿度有一定关系，相关系数达显著水平。