小麦旗叶叶绿素含量及荧光动力学参数与产量的灰色关联度分析

为探讨干旱胁迫条件下小麦旗叶光合性状的变化及其对产量的影响,以小麦RIL群体(旱选10号×鲁麦14) F₈代的305个株系及其亲本为材料,分析雨养和灌溉两种水分条件下,开花期和灌浆期旗叶叶绿素含量和叶绿素荧光动力学参数的变化情况、相关关系、遗传力、基因数目以及不同性状与产量的关系。结果表明,在两种水分条件下,RIL群体性状多数表现超亲现象,变异系数为1.12%~67.05%。雨养条件下抗旱亲本旱选10号的旗叶叶绿素含量及叶绿素荧光动力学参数比水地品种鲁麦14表现稳定。两种水分条件下,两个生育时期的旗叶叶绿素含量极显著正相关,而荧光动力学参数相关性表现复杂,F_m与F_v、F_o/F_m与F_v/F_m之间相关性最高,相关系数大于0.994。在所有性状中,叶绿素含量的遗传力最高;多数性状在雨养条件下的基因数目多于灌溉条件的,控制灌浆期F_v/F_o的基因数目最多,达34对。灰色关联度分析显示,灌浆期F_m、F_v及F_o与F_m曲线之间的面积对产量影响较大,可以作为选择抗旱高光效小麦的重要评价指标。     

氮肥对大麦灌浆期叶片光合性能的影响及其相关性分析

为探究氮肥对春大麦叶片光合性能的影响,以蒙啤3号和蒙啤5号两个品种为材料,研究不同施氮水平下内蒙古东部灌区春大麦灌浆期间叶片叶绿素（Chl）含量,叶绿素荧光参数（最大荧光F_m、最大光化学效率F_v/F_m、光化学猝灭系数q_P）,光合参数（净光合速率P_n、气孔导度G_s、蒸腾速率T_r）的动态变化及其相关性。结果表明:随着灌浆时间延长,不同氮肥处理两品种大麦叶片Chl含量、F_m、F_v/F_m、q_P均呈先升高后降低的趋势,P_n、G_s、T_r均呈下降趋势;随着施氮水平升高,叶片Chl含量、F_m、F_v/F_m、q_P、P_n、G_s、T_r均逐渐升高。相关分析结果显示,叶片Chl含量、F_m、F_v/F_m、q_P、P_n、G_s、T_r间均呈极显著正相关关系。显示增施氮肥可促进大麦灌浆期间叶片光合性能。本研究为优质高产大麦生产实践提供理论依据。     

强光高温同时作用下不同小麦品种的光合特性

以小麦品种藁城8901、豫麦49、郑麦9405、周18为试材,用强光(1 900 μmol m^-2 s^-1)、高温(35℃)同时处理材料3 h,研究了高光强和高温共同合胁迫对小麦旗叶光合作用和叶绿素荧光特性的影响。结果表明,正常生长条件下,郑麦9405和周18的光饱和速率、饱和光强均高于藁城8901和豫麦49,郑麦9405的表观量子效率也最高。强光高温处理使藁城8901、豫麦49和周18的光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、胞间CO₂浓度(C_i)较对照大幅下降;郑麦9405的P_n、G_s也出现了下降,但降幅最小,P_n仍保持11.6 μmol CO₂ m^-2 s^-1,T_r较对照略有上升;4种基因型小麦的Ci未较对照明显变化;与对照相比,4个材料的最大光量子效率(F_v/F_m)、开放的光系统II反应中心的激发能捕获效率(F_v’/F_m’)、作用光下光系统II的实际量子效率(Ф_PSII)、光化学猝灭系数(q_P)均下降,而非光化学猝灭系数(NPQ)大幅上升;其中郑麦9405的各项荧光参数均较高。研究表明,小麦旗叶对强光高温的适应性存在品种间差异,郑麦9405的耐强光高温特性优于其他3品种;强光高温下较高的蒸腾速率和较大的NPQ可能是郑麦9405维持光合机构功能的重要原因。     

小麦叶绿素荧光参数叶位差异及其与植株氮含量的关系

以中蛋白质含量小麦品种矮抗58和高蛋白质含量品种郑麦366为试验材料,2008-2010年连续2个生长季进行了施氮梯度下(0、90、180和270 kg hm^-2)的田间试验。在关键生育时期同步测定叶片荧光参数、叶和茎生物质量及氮含量,建立了基于叶位差的小麦植株氮含量荧光估算模型。结果表明,在小麦旺盛生长的拔节至孕穗期叶绿素荧光参数F_m、F_v、F_v/F_m和F_v/F_o与对应叶片氮含量的相关系数分别为0.557、0.601、0.619和0.633,均达极显著水平(P<0.01)。顶三叶间荧光参数差异较小,随施氮水平提高,顶部第4叶荧光参数与顶三叶间差异逐渐缩小,说明其对增施氮肥反应敏感。顶部第4叶与顶部第1叶间的荧光参数差异(LPD_4-1)可较好拟合小麦拔节期植株氮含量变化,F_v/F_o和F_v/F_m方程决定系数R²分别为0.644 (P<0.001)和0.651 (P<0.001);顶部第4叶与顶部第2叶间的荧光参数差异(LPD_4-2)方程拟合决定系数有所降低,分别为0.626 (P<0.002)和0.592 (P<0.005);而顶部第4叶与顶三叶之间的差异(LPD_4-n)与小麦孕穗期植株氮含量间呈显著线性关系,其F_o、F_v和F_m方程决定系数分别为0.726 (P<0.001)、0.791 (P<0.001)和0.784 (P<0.001)。独立数据检验结果表明,小麦拔节期对F_v/F_o和F_v/F_m的LPD_4-1预测精度R²分别为0.844( P<0.001)和0.828 (P<0.001),相对误差(RE)分别为13.0%和16.7%,而LPD_4-2估算植株氮含量精度有所降低,R²分别为0.793 (P<0.001)和0.813 (P<0.001),RE分别为16.9%和18.4%。小麦孕穗期对F_v和F_m的LPD_4-n预测方程的R²分别为0.831 (P<0.001)和0.815 (P<0.001),RE分别为13.2%和16.4%。比较而言,小麦拔节期F_v/F_o的LPD_4-1和孕穗期F_v的LPD_4-n可更好地用于评估不同条件下植株氮含量的变化,为施肥调控提供决策依据。     

氨基多糖水溶肥对小麦生理特性、产量及籽粒品质的影响

为了探明氨基多糖水溶肥对小麦生理特性、产量及籽粒品质的影响,以‘淮麦33’为试验材料,研究小麦不同生育期叶面喷施氨基多糖水溶肥1次、2次和3次对小麦产量和品质的影响,并在处理后12天测定小麦旗叶净光合速率(P_n)、蒸腾速率(T_r)、胞间CO₂浓度(C_i)、气孔导度(G_s),叶绿素(Chl)、可溶性糖、可溶性蛋白和丙二醛(MDA)含量,抗氧化酶活性及根系活力。结果表明：氨基多糖水溶肥明显提高小麦旗叶Chl、可溶性糖和可溶性蛋白含量,提高超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性和小麦根系活力,增加旗叶P_n和G_s,降低旗叶C_i、T_r和MDA含量,提高小麦籽粒千粒质量和产量以及籽粒总蛋白质、总淀粉和支链淀粉含量,降低直/支比。喷施3次和2次在产量和品质上的差异未达显著水平(P<0.05),但二者与喷施1次和对照之间的差异达显著水平(P<0.05)。可见,氨基多糖水溶肥可明显提高小麦旗叶抗氧化和籽粒灌浆能力,提高小麦的籽粒产量和品质,以小麦抽穗后喷施2次为宜。     

灌浆期高温对小麦旗叶与非叶器官光合和抗氧化酶活性的影响

为揭示小麦叶与非叶器官抗氧化系统对灌浆期高温胁迫的反应特征,探讨不同品种和不同器官耐热性差异机制,以小麦强耐热品种石家庄8号和弱耐热性品种河农341为材料,于灌浆期用塑料膜搭棚进行增温处理(花后第8天至第22天),研究高温胁迫对旗叶光合速率(Pn)、叶绿素含量、旗叶和非叶器官中丙二醛(MDA)和脯氨酸(Pro)含量及超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)活性的影响。高温处理下,两品种Pn比正常温度下(对照)低18.7%~24.9%,叶绿素含量低5.7%~6.2%;旗叶、旗叶鞘、穗下节、颖片和籽粒的MDA含量和Pro含量均升高,其中MDA升高幅度为旗叶非叶器官,Pro升高幅度为非叶器官旗叶。旗叶、颖片、籽粒的SOD活性和旗叶、旗叶鞘、籽粒的CAT活性以及旗叶、旗叶鞘、颖片的POD活性在高温胁迫初期即诱导增强,而其他器官的抗氧化酶活性则在高温持续一段时间后诱导增强,之后随着高温的持续各器官抗氧化酶活性多表现为低于对照,高温解除后旗叶鞘、穗下节、颖片的SOD活性和旗叶、颖片、籽粒的POD活性有恢复迹象,高温对其他器官的SOD和POD活性以及所有器官的CAT活性造成不可逆影响;总体来看,非叶器官持续抗氧化能力和耐热性强于叶片。石家庄8号叶与非叶器官细胞膜稳定性、抗氧化酶活性均高于河农341,显示其整株耐热性强于河农341,这是石家庄8号在高温胁迫下产量下降幅度低于河农341的重要生理基础。因此认为,非叶器官在小麦适应灌浆期高温逆境中发挥重要作用。     

低温处理对抗寒差异侧钝叶草光合性能的影响

本研究以2份抗寒性具有显著差异的侧钝叶草(Stenotaphrum secundatum)品系S13 (抗寒材料)与S55(敏感材料)进行模拟低温处理,在0 (CK)、3、7、14 d测定其光合性能,对其光合差异进行分析。结果表明,随着低温胁迫时间的延长,两份材料的净光合速率(P_n)、气孔导度(G_s)和蒸腾速率(T_r)均显著(P<0.05)下降,而S13胞间CO₂浓度(C_i)呈先显著(P<0.05)降后显著(P<0.05)升的趋势,S55前期平稳后期显著(P<0.05)上升,说明低温胁迫前期是由于气孔限制因素引起的侧钝叶草P_n下降,后期是非气孔因素;叶绿素含量(Chl)、类胡萝卜素含量(Car)和叶绿素荧光参数(F_v/F_m)均呈逐步下降趋势,说明侧钝叶草受到光抑制。两份材料规律基本一致,但对低温胁迫的反应存在显著差异(P<0.05)。低温处理3 d后,S13的Chl、Car和F     

外源5-氨基乙酰丙酸对低温胁迫下玉米幼苗生长及光合特性的影响

为探究外源5-氨基乙酰丙酸（ALA）对低温胁迫下玉米幼苗生长及光合特性的调控效应,以绥玉13（低温敏感型）和郑单958（耐低温型）为试验材料,于三叶一心期叶面喷施20mg/L ALA,在昼/夜温度为14℃/5℃的低温条件下培养48h,恢复常温48h后取样,分析外源ALA对玉米幼苗生长、叶绿素含量、光合作用参数及叶绿素荧光特性的影响。结果表明：低温胁迫显著抑制两个玉米品种幼苗的株高、叶面积、鲜重和干重。低温处理导致幼苗SPAD值下降,叶片净光合速率（P_n）、蒸腾速率（T_r）、气孔导度（G_s）、胞间CO₂浓度（C_i）、最大荧光（F_m）、最大光化学效率（F_v/F_m）、潜在光化学效率（F_v/F_o）及光化学猝灭系数（q_P）水平降低,初始荧光（F_o）和非光化学猝灭系数（NPQ）升高。外源ALA能够促进低温胁迫下玉米幼苗形态建成与物质积累,叶片SPAD值增加。外源ALA能够缓解由低温胁迫导致的叶片P_n、T_r、G_s和C_i下降,提高F_m、F_v/F_m、F_v/F_o及q_P水平,降低F_o和NPQ水平。由此可见,外源ALA能够促进叶片光合作用,提高PSⅡ反应活性,促进物质积累,增强玉米苗期的抗低温能力,且对低温敏感型玉米品种的缓解低温伤害效果更好。     

大田遮阴对夏玉米光合特性和叶黄素循环的影响

以郑单958和振杰2号为试验材料,大田条件下设置花粒期遮阴(S1)、穗期遮阴(S2)、全生育期遮阴(S3) 3个处理,遮光度为60%,以自然光照为对照,研究遮阴对夏玉米光合特性和叶黄素循环的影响。结果表明,遮阴后夏玉米产量显著降低,且遮阴时期对产量的影响表现为S3>S1>S2,郑单958和振杰2号的S3分别减产96.87%和90.78%。遮阴后叶片的光合速率(P_n)、蒸腾速率(T_r)、气孔导度(G_s)、叶绿体色素含量显著降低,胞间CO₂浓度(C_i)较同期对照先降低后升高,即叶片光合作用的降低受到气孔与非气孔因素双重影响,2个供试品种变化一致。遮阴期间光合电子传递量子效率(Ф_PSII)降低,原初光能转换效率(F_v/F_m)和非光化学猝灭(NPQ)显著升高,叶黄素循环库(A+Z+V)和脱环化状态(A+Z)/(A+Z+V)升高,即在长期遮阴条件下叶片捕获的光能分配发生了变化,光合电子传递的能量占吸收光能的比例降低,叶黄素循环的启动辅助过剩光能的热耗散。遮阴结束初期(A+Z)/(A+Z+V)和NPQ迅速升高,说明光恢复初期叶片对弱光适应后的自然光照比较敏感,叶黄素循环增强抑制强光对光合机构的破坏。     

去叶处理对小麦叶绿素含量及产量的影响

为了探讨去叶对不同小麦品种产量的影响,为小麦的稳产高产提供理论依据。采用大田试验,研究了开花期3种不同的叶片处理对江淮地区种植的八个小麦品种的叶绿素含量以及产量构成的影响。结果表明,从去叶对叶绿素含量的变化来看,旗叶的叶绿素含量首先表现为只保留旗叶处理>剪去1/2旗叶处理>对照,但随着花后时间的推移,只保留旗叶处理的叶绿素含量的增加幅度逐渐变小,在花后20~25天左右逐渐低于对照;倒二叶的叶绿素含量表现为剪去全旗叶处理>剪去1/2旗叶处理>对照,随着花后时间的推移,比对照增加幅度逐渐变大。从去叶对产量构成方面来看,与对照相比,剪去全旗叶处理下的穗粒数、千粒重和单穗重降低,且在3种去叶处理中降低幅度最大;剪去1/2旗叶处理和只保留旗叶处理下的千粒重均下降,但供试小麦品种的穗粒数因品种不同有增有减,从而导致了部分品种的单穗重略有升高或降低幅度较小。花期不同的去叶处理对‘连麦2号’、‘衡7228’两个小麦品种的影响相对较小,在生产上的稳产性更好。     

去除遮阴后自然强光对小偃54和8602及其杂交后代光合特性的影响

黄淮地区冬小麦生育后期常出现阴雨寡照及连阴骤晴等不良气候,本试验目的是阐明弱光逆境解除后自然强光对冬小麦光合特性的影响。在抽穗至开花期对小偃54和8602及其杂交后代小偃81和212遮阴处理(约自然光40%),10 d后去除遮阴,测定恢复过程中亲本与杂交后代旗叶叶绿素含量、光合气体交换、叶绿素荧光等参数。去除遮阴初期,亲本与杂交后代都发生了光抑制,净光合速率(Pn)、叶绿素a/b比值、胞间CO2浓度(Ci)、气孔导度(Gs)、光系统II(PSII)最大量子效率(Fv/Fm)、PSII实际光化学效率(ΦPSII)、非光化学猝灭(NPQ)和电子传递到QA下游的概率(Ψo)都低于对照,并且随着去除遮阴时间的延长逐渐恢复。杂交后代小偃81在去除遮阴后比其2个亲本和另一杂交后代品系212具有相对更高的Pn、ΦPSII和Ψo,表明小偃81对环境光强变化的适应性优于其亲本,且相对较高的PSII光化学效率活性和稳定性是其在去除遮阴后拥有更高Pn的原因之一。小偃81更能适应黄淮地区小麦生育后期光照不足和连阴骤晴的不良气候。     

QTLs for chlorophyll and chlorophyll fluorescence parameters in barley under post-flowering drought

Drought is one of the major factors limiting barley yields in many developing countries worldwide. The identification of molecular markers linked to genes controlling drought tolerance in barley is one way to improve breeding efficiency. In this study, we analyzed the quantitative trait loci (QTL) controlling chlorophyll content and chlorophyll fluorescence in 194 recombinant inbred lines (RILs) developed from the cross between the cultivar ‘Arta’ and Hordeum spontaneum 41-1. Five traits, chlorophyll content, and four chlorophyll fluorescence parameters, namely initial fluorescence (F_o), maximum fluorescence (F_m), variable fluorescence (F_v), and maximum quantum efficiency of PSII (F_v/F_m) which are related to the activity of the photosynthetic apparatus, were measured under well-watered and drought stress conditions at post-flowering stage. QTL analysis identified a total of nine and five genomic regions, under well-watered and drought stress conditions, respectively, that were significantly associated with the expression of the five target traits at post-flowering stage. No common QTL was detected except one for chlorophyll content, which was identified in both growth conditions, demonstrating that the genetic control of the expression of the traits related to photosynthesis differed under different water conditions. A QTL for F_v/F_m, which is related to the drought tolerance of photosynthesis was identified on chromosome 2H at 116 cM in the linkage map under drought stress. This QTL alone explained more than 15% of phenotypic variance of maximum quantum yield of PSII, and was also associated with the expression of four other traits. In addition, another QTL for F_v/F_m was also located on the same chromosome (2H) but at 135.7 cM explaining around 9% of the phenotypic variance under drought conditions. The result presented here suggest that two major loci, located on chromosome 2H, are involved in the development of functional chloroplast at post-flowering stage for drought tolerance of photosynthesis in barley under drought stress. If validated in other populations, chlorophyll fluorescence parameters could be used as selection criteria for drought tolerance.     

水稻光氧化突变体812HS的光合和抗氧化特性

本研究旨在通过梅雨前后自然光强明显变化的情况下对水稻叶片光氧化突变体812HS与野生型812S的PSII光化学活性、抗氧化酶活性等生理特性的比较研究,探讨812HS易受光氧化损伤现象的光合生理原因。结果表明,大田自然光照出现强光照前,812HS与812S的叶绿素含量、PSII活性、光合磷酸化活性、净光合速率、抗氧化酶活性和活性氧含量均无显著差异。自然强光照开始(梅雨结束)一段时间后,两种水稻的上述各项指标都发生了明显的变化。突变体812HS的叶绿素含量、PSII活性、非循环式光合磷酸化活性和净光合速率均较812S明显降低。高光强下812HS叶片中抗氧化酶CAT和POD活性的上升幅度则小于812S,从而使其体内富集了更多的O₂^?、H₂O₂和MDA。光氧化突变体812HS对高光照强度较敏感的PSII活性和较低的CAT、POD活性可能是其发生叶片光氧化现象的生理成因。     

Characterizing Submergence Survival Strategy in Rice Via Chlorophyll Fluorescence

Rice plants cope with flash floods using either an ‘escape strategy’ involving rapid shoot elongation or a ‘quiescence strategy’ involving survival underwater with minimal activity. To clarify the differences in the response of leaf photosynthesis properties to conditions during and after submergence, two rice cultivars were compared: a non‐shoot‐elongating cultivar IR 67520‐B‐14‐1‐3‐2‐2 (IR67520) and a shoot‐elongating cultivar IR72442‐6B‐3‐2‐1‐1 (IR72442). Twenty‐three‐day‐old seedlings were submerged in 80‐cm‐deep water for 14 days. During submergence, the chlorophyll contents of the upper fully expanded leaf (5th leaf) and newly developed leaf later (6th leaf) and the maximal quantum yield of photosystem II (F_v/F_m) of the fifth leaf decreased earlier in IR72442 than in IR67520. In the submerged sixth leaf, F_v/F_m was higher in IR72442 than in IR67520 at early measurement. Although F_v/F_m of the sixth leaf in submerged IR67520 increased substantially from 2 days post‐submergence, IR72442 decreased because of leaf chlorosis. Therefore, a non‐shoot‐elongating cultivar coped with submergence by inhibiting photodamage and maintaining high chlorophyll content in the leaves. The shoot‐elongating cultivar was able to maintain the photosynthetic capacity of the newly developed leaf during submergence by prompt reduction of chlorophyll and chlorophyll fluorescence in the leaf that developed before submergence.     

Effects of Shading on Chlorophyll Content,Chlorophyll Fluorescence and Photosynthesis of Subterranean Clover

A field‐experiment (2004/2005 and 2005/2006 seasons) was conducted in the coastal plain of south‐eastern Sicily (37°03′N, 15°18′E, 15 m a.s.l.), on a Calcixerollic Xerochrepts soil, aimed at quantifying the effect of shading on chlorophyll (Chl) content, Chl fluorescence, photosynthesis and growth of subterranean clover. Four levels of photosynthetically active radiation reduction (from 0 % to 90 %) were tested on Trifolium brachycalycinum cv. ‘Clare’ and Trifolium subterraneum ecotype ‘Ragalna’. In both species shading progressively increased F_v/F_m, internal CO₂ concentration, diffusive leaf resistance and specific leaf area (up to 8 %, 34 %, 18 % and 68 %, respectively), and decreased Chl content, T_max, photosynthetic rate and plant dry weight (up to 9 %, 24 %, 79 % and 39 %, respectively). As plants aged, characteristic bell‐shaped trends were evident for photosynthetic parameters, with F_v/F_m increasing up until the onset of flowering, and thereafter declining. This implies that F_v/F_m may be a useful indicator of earliness in subterranean clover genotypes. The aboveground dry biomass response to shading was both genotype‐ and season‐dependent, but was predictable from the measurement of relative leaf Chl content. Moreover, our results suggest that an improvement in the interaction between host‐rhizobium may represent a major potential breeding target for enhancing subterranean clover tolerance to shading.     

The relationship between water status and chlorophyll a fluorescence in grapes (Vitis spp.)

The purpose of this study was to explore the utility of chlorophyll fluorescence to non-destructively monitor water status in plant tissue, specifically water loss in grapes (Vitis spp.) destined for wine production. An automated remote-sensing (ARS), pulse amplitude modulation (PAM) fluorometer prototype, capable of scanning a large surface area, was used to monitor chlorophyll fluorescence from ‘L’Acadie’ (LAc) and ‘Thompson Seedless’-type (TS) grape clusters during postharvest dehydration. Increasing mass loss (%) in grapes correlated with increasing soluble solids (SS) content and decreasing osmotic potential (Ψ_s) (p < 0.001). All of the primary fluorescence parameters monitored (F₀, F_m, F_v and F_v/F_m) had a strong curvilinear relationship (p < 0.001) with grape mass loss. In both cultivars, F₀ increased during the later stages of dehydration, likely as a result of increased disorder within the thylakoid membranes and/or a reduction in energy transfer between LHCII and PSII. F_m, F_v and F_v/F_m declined, likely due to several factors that are known to inhibit photosynthesis and the primary charge recombination during osmotic stress. Chlorophyll degradation during dehydration was a major factor influencing cultivar differences in the fluorescence relationships. An inflection point in the F₀ value at ≈20–25% mass loss appeared to correspond with an inflection point in the decreasing glucose:fructose ratio. The relationship between chlorophyll fluorescence and water loss, SS, Ψ_s and potentially other indicators of metabolic change, could lead to practical applications of this technology in the slow dehydration of grapes and other fruits used to make high value wines.     

Use of chlorophyll fluorescence to evaluate the cold acclimation and freezing tolerance of winter and spring oats

The efficiency of the excitation capture by open Photosystem II (PSII) reaction centres was measured by the F_v/F_m ratios in a collection of winter and spring oats in order to assess the effects of hardening and freezing on the functionality of PSII and also the suitability of a chlorophyll fluorescence‐based method to screen oat cultivars for frost tolerance. A significant reversible decrease in F_v/F_m was found in all genotypes during acclimation to low, non‐freezing temperatures. F_v/F_m analysis appears to be an attractive test for the evaluation of frost tolerance in oats, being rapid, non‐invasive and capable of monitoring a trait related to a crucial stage in the acquisition of frost tolerance. It is more sensitive and precise than other standard methods and highly correlated with field‐evaluated frost damage. The measurements made during recovery 1 or 2 days after stress when the visual symptoms are not yet expressed, were especially advantageous because of the large variability in genotype response. The r‐values (close to 0.8) were reduced due to the non‐standard behaviour of the winter cultivar ‘Aintree’. The cold acclimation response of this genotype has been analysed in detail and the limits of artificial freezing tests are discussed.     

Characterization,inheritance, and molecular study of opaque leaf mutant in mungbean (<Emphasis Type="Italic">Vigna radiata</Emphasis> (L.) Wilczek)

Chlorophyll-deficiency mutants are useful as genetic markers and as materials for studying the photosynthesis process. We characterized the inheritance of the gene controlling an opaque leaf (OL) trait in mungbean (Vigna radiata (L.) Wilczek). An F₂ population was developed from the cross between the OL mutant and ‘Berken’, an Australian mungbean cultivar, to study inheritance and molecular tagging. The population was advanced by selfing to produce F₅ lines from which two normal lines and two OL lines were randomly chosen to study chlorophyll content, seed growth and development, and seed cell morphology. The chlorophyll content in opaque leaf was lower than normal and thus was expected to have lower photosynthetic activity. This resulted in yellowish and shrinking pods and seeds within 15 days after flowering, while those from normal plants extended their growth up to 18 days. The cotyledon transfer cells of the OL plants deformed at 12 days and deteriorated at 14 days after flowering. The OL trait was controlled by a single recessive ol gene which was independent from the genes controlling petiole color and growth habit. We used 193 AFLP primer combinations to tag this gene and found that the marker AGG/ATA was linked with the ol gene at a distance of 3.4 cM.     

小麦小穗不同粒位粒重形成的生理特性差异

为探明小麦小穗上不同粒位籽粒粒重形成的生理机制,明确限制小穗上位弱势粒充实的主要原因,本试验选用大穗型小麦品种泰农18(TN18)和多穗型小麦品种山农20(SN20)为材料,调查检测了灌浆过程中小穗上不同粒位籽粒内源激素、可溶性糖、全氮含量的动态变化以及籽粒与籽粒柄连接处横面的组织结构与不同粒位籽粒粒重的关系。花后籽粒灌浆过程中灌浆速率与籽粒内GA和IAA含量呈极显著或显著相关,小穗基部籽粒中较高的GA和IAA含量可使蔗糖向淀粉转化开始早,籽粒分化快,灌浆速率高,是小穗基部籽粒粒重高的生理机制;扫描电镜图显示小麦籽粒灌浆初期小穗基部籽粒柄维管束横面面积明显大于上位籽粒,微观空隙小且排列较整齐,有利于同化物和生理活性物质的运输,是小穗基部籽粒粒重增长快、灌浆速率高的解剖学基础。