玉米叶片水分利用效率与叶绿素a荧光参数的关系

利用Handy PEA植物效率仪测定叶绿素a荧光参数,研究玉米自交系叶片水分利用效率(WUE)与叶绿素a荧光参数的关系。结果表明,玉米自交系叶片WUE与叶绿素a荧光参数呈极显著的正相关。其中,F_o与高水分利用效率(HWUE)玉米自交系WUE的相关系数大于低水分利用效率(LWUE)玉米自交系WUE的相关系数;最大荧光(Fm)、可变荧光(F_v)、PSⅡ原初光能转换效率(F_v/F_m)和PSⅡ潜在活性(F_v/F_o)与水分利用效率不同的玉米自交系叶片WUE的相关系数恰好相反,这是造成不同玉米自交系WUE存在差异的生理原因之一,同时也说明叶绿素a荧光参数可以作为选育HWUE玉米自交系的重要指标。     

玉米株型、果穗性状的遗传和相关性分析

本试验以14个玉米自交系及由其组成的9个杂交组合以及相应的F2代为材料，系统地研究了自交系与杂交种之间及杂交种性状与性状之间的关系，探讨了玉米杂交种自交衰退的数量指标．研究结果表明，(1)玉米穗长，行粒数和百粒重在母本与F₁之间呈极显著正相关；穗位高、穗直径和单穗粒重在父本与F₁之间呈显著正相关，株高在父母本与F₁之间均为显著正相关．(2) F₁单穗粒重与株高、穗长、行粒数、穗粒数和百粒重之间存在显著的正相关．(3) F₁性状优势越强，F₂衰退越重(r＝0.8830)．单穗粒重优势分别与行粒数和穗粒数优势呈极显著正相关(r＝0.8618和r＝0.8441)．(4) 单穗粒重的衰退主要是由穗粒数衰退所致(r＝0.7473)．穗行数，植株叶片数和叶向值的衰退值较小或为负值。     

CO2浓度升高对玉米叶片光合生理特性的影响

以沈糯3号为研究材料,利用开顶式气室(OTCs)法研究了二氧化碳(CO₂)浓度升高处理下,玉米叶片叶绿素含量、光合生理特性及其子粒产量的变化,揭示CO₂浓度升高对玉米光合生理特性及子粒产量的影响机理。结果表明,在整个生育期内,与对照相比,高浓度CO₂处理下,玉米叶片叶绿素a、叶绿素b及叶绿素(a+b)的含量增加,而叶绿素a/b的值则先升高后降低;在整个处理期间,净光合速率均高于对照(p>0.05),升高幅度为12.6%～71.1%,气孔导度低于对照(p>0.05),其降低幅度为2.9%～18.8%。处理至抽雄期和灌浆期,胞间CO₂浓度分别增加152%和161%,均极显著高于对照(p<0.01);蒸腾速率的变化较小。高浓度CO₂处理下,玉米穗粒数和穗粒重均明显高于对照(p<0.05)。CO₂浓度升高在一定程度上促进了玉米的光合作用,从而使玉米子粒产量增加。     

转Cry1A.401基因抗虫玉米CM8302和CM8303对亚洲玉米螟的抗性研究

采用农杆菌介导法获得转Cry1A.401基因抗虫玉米CM8302和CM8303,通过多代回交与自交获得BC₄F₁、BC₄F₂和BC₄F₃世代的转基因玉米材料。利用qRT-PCR和ELISA方法明确转基因抗虫玉米叶片、花丝和子粒均有Cry1A.401基因表达,不同世代间目的基因表达量无显著差异。田间接虫鉴定结果表明,CM8302和CM8303三个世代心叶期和吐丝期的抗性等级均为1级,抗性水平为高抗。室内生测结果表明,亚洲玉米螟幼虫取食CM8302心叶、花丝和子粒第6天存活率分别为0、4.0%和4.0%;取食CM8303心叶、花丝和子粒第6天存活率分别为0、4.0%和2.0%。分析显示转基因抗虫玉米CM8302和CM8303的心叶、花丝和子粒均具有显著杀虫效果且遗传稳定。     

不同普×爆后代群体膨爆特性的分离特征研究

对5个普通玉米自交系与4个爆裂玉米自交系组配的20个普×爆组合F₂,BC₁,BC₂3个世代的膨爆特性分析结果表明:F₂代膨爆特性较差,难以采用常规系谱法从中选育出优良的膨爆玉米自交系;通过回交可以快速恢复其优良的膨爆特性,但不同组合及同一组合不同世代间的膨爆特性存在较大差异.因此,要提高后代的选育效果,首先要选配适宜的普×爆组合,其次是要确定具体的回交世代。     

低温胁迫及恢复对玉米光合特性的影响

以玉米自交系掖478、合344、吉853为材料,在不同低温胁迫及恢复正常温度情况下比较幼苗光合作用及叶绿素荧光参数等指标的变化。结果表明,随着胁迫温度的下降和低温胁迫时间的延长,3个玉米自交系幼苗叶片初始荧光F_o呈上升趋势,F_v/F_o、F_v/F_m整体上均呈下降趋势。叶绿素荧光参数随着低温胁迫程度的加强变化较大,且相同温度下的变化幅度掖478<合344<吉853。3个玉米自交系在各温度胁迫后恢复到常温时的叶片初始荧光F_o下降,F_v/F_m、F_v/F_o整体上呈上升趋势。掖478恢复常温1～2 d后恢复到正常水平,抗冷性最强;吉853的PSⅡ系统受损较重,恢复常温3 d未达正常水平,抗冷性较弱。     

玉米主要株型数量性状的基因效应分析

本研究以植株外部形态差异较大的4个玉米自交系为材料，分别组成两个F₁、F₂、B₁、B₂和相应的P₁、P₂6个世代，研究了7个株型性状的遗传表达特点。结果表明，加性效应是7个株型性状世代间遗传变异的主导因子，其遗传贡献率在50%以上，亦即加性效应决定了7个株型性状一半以上的遗传变异，显性效应和上位性效应对这些性状遗传变异的作用也很重要，但因性状及试材不同，非加性效应的重要程度有一定差异。在玉米株型育种中，对这些性状的选择应以亲本选配为主。     

Ae显性突变体对玉米农艺性状及直链淀粉含量的影响分析

玉米直链淀粉是重要的食品和工业原料,高直链淀粉性状的产生受多种酶和基因-环境等因素的共同影响。玉米ae基因（amylose extender）突变导致子粒中直链淀粉含量增高、子粒表面皱缩、淀粉颗粒呈不规则形状、尺寸不均匀且表面基质蛋白增多,用于玉米育种后获得的品种直链淀粉含量升高,产量显著降低。通过将显性Ae突变体与16份优质玉米自交系杂交,对F₁代植株进行开花期、株型、产量性状调查,分析F₁代子粒总淀粉、直链淀粉的含量。结果表明,Ae突变体与不同的自交系杂交,F₁代直链淀粉含量及产量的变化存在明显差异,与基因型有密切关系,以Ae突变体和W16F41、CA240为亲本杂交,可显著提高直链淀粉含量同时产量变化最小。根据F₁代表现筛选直链淀粉含量提高、产量变化较小的双亲配制杂交种,可加速高直链淀粉玉米新品种培育进程。     

水肥一体化条件下施氮量对小麦旗叶叶绿素荧光特性及产量的影响

为探讨水肥一体化条件下施氮量对小麦旗叶叶绿素荧光特性及籽粒产量的影响,以小麦品种济麦22为试验材料,设每公顷施纯氮0（N0）、150（N1）、180（N2）、210（N3）和240 kg（N4）五个处理,通过大田试验分析了不同处理间小麦旗叶PSⅡ 最大光化学量子效率（F_v/F_m）、PSⅡ实际光化学效率（Φ_PSⅡ）、叶绿素相对含量、籽粒灌浆速率及产量的差异。结果表明,花后14~35 d,小麦旗叶F_v/F_m在N3和N4处理间无显著差异,但二处理显著高于其他处理。花后0~35 d,N3处理的旗叶Φ_PSⅡ最高,施氮量再增加至N4时,Φ_PSⅡ无显著变化。花后14~28 d,N3和N4处理的旗叶叶绿素相对含量显著高于其他处理;花后35 d,N3处理显著高于N4处理。粒重和灌浆速率在灌浆前期均随施氮量增加而降低;灌浆后期N3与N4处理间粒重和灌浆速率无显著差异,但二处理显著高于其他处理。籽粒产量在N3处理下最高;在施氮量增加至N4时,籽粒产量不再增加,且氮肥生产效率和氮肥农学效率分别下降了14.6%和24.0%。在本试验条件下,210 kg·hm^-2是兼顾高产和高效的最佳施氮量。     

水分胁迫对不同抗旱性燕麦品种光合及产量形成的影响

为了解水分胁迫对不同抗旱性燕麦品种光合和产量的影响，以抗旱性不同的蒙燕1号和坝莜3号为材料，在拔节期和抽穗期采用防雨棚盆栽方式，测定分析了不同水分处理［重度胁迫（30%田间持水量（FWC））、中度胁迫（45%FWC），适度控水（60%FWC）和正常供水（CK，75%FWC）］下燕麦叶片叶绿素含量、气体交换速率、叶绿素荧光动力学参数、产量及其构成因素的差异。结果表明，两个燕麦品种叶片叶绿素a含量、叶绿素b含量及叶绿素总含量、净光合速率、蒸腾速率、最大荧光、最大光化学效率（F_v/F_m）、实际光化学效率、光化学猝灭系数均随着水分胁迫程度的加剧而下降，初始荧光与非光化学淬灭系数则呈上升趋势，且水分敏感品种坝莜3号的光合受抑制程度显著大于抗旱品种蒙燕1号。燕麦的光合特性和产量受水分胁迫影响的程度整体上表现为拔节期大于抽穗期。中度和重度水分胁迫下坝莜3号的每穗小穗数、千粒重均下降，而每穗秕粒数显著增加，减产13.9%～25.7%。蒙燕1号的产量在适度控水条件下未显著下降，且水分利用效率较高，而在中度和重度水分胁迫下每穗小穗数和穗粒数均显著降低，导致减产9.1%～23.5%，但其 F_v/F_m和叶绿素a/b值较高；在相同水分条件下蒙燕1号的产量显著高于坝莜3号。这说明在水分胁迫下抗旱性强的燕麦品种的光系统Ⅱ的损伤和光抑制较轻，光合同化能力较强，产量损失少。     

Post-anthesis changes in photosynthetic traits of maize hybrids released in different years

Changes in post-anthesis physiological attributes related to genetic improvement for grain-yield were studied for six Chinese maize (Zea mays L.) hybrids widely grown in North China during the past 50 years. The characteristics assessed included light-saturated photosynthetic rate (P_sat), chlorophyll content, soluble protein content, maximal efficiency of PS2 photochemistry (F_v/F_m), PS2 efficiency (Φ_PS2), ribulose-1,5-bisphosphate carboxylase (RuBPCase) activity and phosphoenolpyruvate carboxylase (PEPCase) activity. We found that P_sat of the newer hybrids was not always higher than the older ones. However, P_sat of the 1950s hybrids was the highest among all at flowering stage, which was associated with their high PEPCase activity and soluble protein content. Post-anthesis changes in P_sat of the older hybrids can be divided into two phases. During the first phase, which was the decisive phase of grain filling, P_sat of the older hybrids declined gradually whereas the new hybrids remained relatively constant. P_sat of 1950s hybrids was not the highest among all maize hybrids any longer although their PEPCase activities were also the highest. The reduction in P_sat of the older hybrids during this phase was associated with a reduction in the chlorophyll content and the soluble protein content but was not influenced by the specific activity of RuBPCase and PEPCase. Adapting to the lowered CO₂ assimilation capacity, a down-regulation of Φ_PS2 occurred in the older hybrids to protect the photosynthetic apparatus from photo-damage by strong light, while F_v/F_m only decreased slightly during this phase, suggesting a functional PS2 apparatus in senescent flag leaves. During the second phase, the older hybrids underwent an irreversible leaf senescence that certain photosynthetic traits declined substantially with P_sat, whereas the photosynthetic components of the newer hybrids remained functional. Newer maize hybrids produced higher grain yield compared to the old ones mainly because they could remain photosynthetically active when the older hybrids aged during the grain-filling period. The decline in photosynthetic rate of older hybrids during senescence is generally attributed to the degradation of both structural and functional components of chloroplasts.     

不同类型小黑麦产量形成的光合特性差异

为了明确不同类型小黑麦产量形成的光合特性,以加工型品种东农8809、饲用型品种东农5305和粮饲兼用型品种东农96026为材料,采用随机区组试验,探讨了不同类型小黑麦主要生育阶段叶绿素荧光参数、光合参数、叶绿素相对含量以及产量的差异。结果表明,加工型品种东农8809生育后期PSⅡ最大光化学效率下降幅度大,非光化学系数高,光能消耗大,籽粒产量形成受到限制;饲用型品种东农5303扬花前光合能力较强,生物产量潜力高,花后非光化学淬灭系数增加量大,花后叶绿素相对含量迅速下降,叶片衰老快;粮饲兼用型品种东农96026净光合速率高,开花后叶绿素相对含量降幅小,叶片衰老慢,光化学淬灭系数高,PSⅡ电子传递活性大,成熟期最大荧光产量和最大光化学效率大及籽粒产量潜力高。说明不同类型小黑麦光合特性不同,花后较强的光合能力是籽粒产量高的基础;对于粮饲兼用型小黑麦来说,较小的热耗散释放比例及较高的花后光合能力是其以大穗实现较高籽粒产量的途径。     

不同生长带玉米自交系和杂交组合品质的差异分析

利用近红外光谱仪对2013年海南三亚种植收获的99份温带自交系(13份高油材料和86份普通材料)、64份热带/亚热带自交系和由这163份自交系随机组配的186份杂交组合的杂交当代F0材料进行无破损子粒品质成分鉴定,分析不同生长带玉米自交系及其不同组合的杂交种后代品质成分的差异性。结果表明,当不考虑高油材料影响时,温带材料与热带/亚热带玉米自交系之间粗蛋白、粗脂肪和粗淀粉含量差异均不显著;去除高油材料后,温带材料与热带/亚热带玉米自交系之间粗蛋白差异不显著,粗脂肪和粗淀粉含量差异极显著。对于不同生长带玉米杂交当代F0而言,考虑与不考虑高油材料影响时,粗脂肪差异都极显著,粗淀粉和粗蛋白都无明显差异;相对于粗蛋白和粗淀粉,粗脂肪表现出更高的超高亲和超中亲优势。     

Leptines and other glycoalkaloids in tetraploidSolanum tuberosum xSolanum chacoense F2 Hybrid and Backcross Families

The leptine glycoalkaloids fromSolanum chacoense Bitter are potential resistance factors to Colorado potato beetle,Leptinotarsa decemlineata Say. A selected sample of 17 F₁ hybrids (4x) from crosses of a 4xS. chacoense clone that synthesizes leptines (8380-1) with 4xS. tuberosum L. lines were selfed to generate F₂ hybrids (4x) and were also backcrossed toS. tuberosum. Glycoalkaloid (GA) content in foliage and tubers was measured for 786 sibling genotypes from the two generations in the field at Beltsville, Maryland. Leptines were found in the foliage of all F₂ hybrids and in 98% of the backcross genotypes. Leptines were not detected in tubers from either generation. Foliage concentrations of leptines for the F₂ hybrids averaged 156 mg/100g fresh weight (FW). The proportion of the total GA content consisting of leptines averaged 42%. By backcrossing the F₁ hybrids toS. tuberosum the average concentration of leptines was reduced to 44 mg/100g FW. The proportion of leptines averaged 16%. The tuber contents of solanine plus chaconine glycoalkaloids averaged 52 mg/100g FW for the F₂ hybrids and 27 mg/100g for the backcross genotypes.     

Perennial O. sativa × O. rufipogon interspecific hybrids: I. Photosynthetic characteristics and their inheritance

A survey of 24 wild Oryza accessions identified Oryza australiensis and Oryza rufipogon as potential sources of enhanced photosynthetic rate for introgression into cultivated rice. Photosynthetic capacity per unit leaf area (CER) was associated with leaf N content but not with leaf chlorophyll concentration, flag leaf area, or specific leaf area. Eight fertile, perennial F₁ hybrids between O. sativa and O. rufipogon were grown in non-flooded soil, and CER was measured at flowering under saturating light. Two F₁ hybrids had greater CER than the average of 26.1 μmol m² s⁻¹. The F₂ progeny from these hybrids were screened for CER in the field, and segregants with even greater rates of photosynthesis were selected. The basis of high photosynthetic rate in the F₂ populations was not leaf thickness or leaf chlorophyll content. One F₂ line had exceptionally high CER and stomatal conductance. Broad-sense heritability on an individual plant basis for CER in two F₂ populations was 0.44 and 0.37. A highly significant offspring-parent regression of 0.89 for CER was observed in a replicated field evaluation (four blocks, five plants per plot) of 20 vegetatively propagated F₂ selections and their F₃ seedling progeny. Broad-sense heritability for CER on a plot-mean basis was estimated as 0.74 for both selected F_2:3 families and for the selected F₂ clones. Genetic resources in the genus Oryza may represent a source of alleles to increase leaf photosynthetic rate in the cultivated species, which we have demonstrated to be a heritable, though environmentally variable, trait in an O. sativa/O. rufipogon population.     

Combining ability analysis to identify suitable parents for heterosis in seed cotton yield,its components and lint % in upland cotton

Combining ability and heterosis were studied in a 6 × 6 diallel cross to see the nature of gene action in Upland cotton (Gossypium hirsutum L.) during 2002 to 2004. Analysis of variance revealed highly significant differences among all the F₁ and F₂ hybrid means and their respective six parental values for all the traits examined. In both generations, the mean squares due to general combining ability (GCA) and specific combining ability (SCA) were also highly significant. SCA genetic variances were greater than GCA and more important for the traits, i.e. boll weight, boll number and seed cotton yield per plant, showing the predominance of non-additive gene action. Lint % in both generations and boll weight in F₂s only were controlled by additive type of gene action due to maximum GCA variances. Cultivar CIM-1100 was found to be the best general combiner and its utilization produced valuable hybrids with desirable SCA in both generations. F₁ and F₂ hybrids, viz., CIM-1100 × CRIS-9, CIM-1100 × FH-682, CIM-1100 × BH-36 and CIM-109 × CIM-1100 as high × low and low × high parents performed well in SCA determination, outstanding mean performance and heterosis. Better SCA effects associated with useful heterosis were more pronounced for yield traits. In F₁ hybrids, maximum heterosis was observed for seed cotton yield followed by boll number, boll weight and lint %. The heterosis over better parent was +3.13 to +65.63% for bolls per plant, +0.75 to +24.40% for boll weight, +0.82 to +115.22% for seed cotton yield and +0.27 to +3.88% for lint %. Involvement of CIM-1100 in most of the F₁ and F₂ hybrids resulted in the synthesis of superior genotypes for most of the traits studied. Inbreeding depression was elevated in good performing hybrids and was the highest for seed cotton yield. Highest yielding F₁ hybrids yielded lesser in the subsequent generation due to over-dominance and inbreeding depression, whereas moderate yielding F₁ hybrids were found more stable even passing through process of segregation due to additive gene action. The combined performance of F₁ and F₂ hybrids could be a good indicator to identify the most promising populations to be utilized either as F₂ hybrids or as a resource population for further selection.     

Performance of hybrids between transgenic oilseed rape (Brassica napus) and wild Brassica juncea: An evaluation of potential for transgene escape

Understanding the potential for the evolution of herbicide tolerance in weeds following gene flow from transgenic crops is important for their management. The inter-specific hybrids formed between four Brassica juncea populations with different glyphosate-susceptibility and transgenic oilseed rape was studied, emphasizing on the possible population difference. Compared with both parents, the fitness-related components and photosynthetic capacity of hybrids decreased dramatically, but significant differences were observed among different hybrids. All F₁ hybrids exhibited highly enhanced but similar herbicide tolerance level regardless of the wild B. juncea parent, indicating that genetically engineered herbicide tolerance may over-dominate phenotype ones by wild-crop hybridization. The analysis of parental loci transmission revealed a higher transfer ratio of male-specific loci detected in F₁ hybrids, suggesting that oilseed rape genetic markers can be transferred at relatively high frequencies to the next generation. Therefore, higher transfer ratio of oilseed rape-specific loci, coupled with variation of populations in fitness-related parameters in F₁ hybrids, could complicate environmental risk assessment of transgenic oilseed rape, especially in current agroecosystems with increasing application of glyphosate.     

玉米无叶舌种质10H045对F1代植株叶片生长态势和产量的影响

以昌7-2和应用EMS对昌7-2诱变选育的无叶舌新种质—10H045为父本，以郑58、WX201620和WX201623表型差异显著的3个自交系为母本进行杂交，研究无叶舌种质10H045对F₁代植株叶片生长态势和产量的影响。结果表明，以10H045为父本杂交的F₁代，其茎叶夹角和叶向值均比以昌7-2为父本杂交的F₁代的植株要小，且差异显著；穗3叶以上的叶片上冲特性尤为突出，植株塔型结构明显，有利于提高杂交种产量。无叶舌种质10H045为父本的组合，其产量均比以昌7-2为父本的组合产量高，组合WX201623×10H045的产量最高，与其他组合产量差异达极显著水平。无叶舌种质10H045不但对后代株型结构有很大的改善作用，而且产量的一般配合力较高，是一个优异亲本。     

Agronomic Performance of F1 Hybrids of Rice (Oryza sativa L.) in Japonica-Indica Crosses

Summary

Generally F₁ hybrids from crosses between japonica and indica rice show variable degrees of sterility. Previous studies revealed that among the indica rice, the Aus type has sexual affinity with japonica cultivars giving higher fertility in F₁ hybrids. Therefore, we made an effort to obtain higher grain yield by producing F₁ hybrids between japonica and Aus-type indica. A field experiment was conducted to investigate the heterosis in these F₁ hybrids for dry matter accumulation, spikelet fertility, yield and yield attributes, to find cross combinations with higher grain yield, and examined the relationships of grain yield with some agronomic characters. F₁ hybrids flowered earlier than their parent cultivars. Heterosis for dry matter accumulation was positive at the panicle initiation stage, at heading and at maturity. The average heterosis for number of panicles, grain and straw yield per plant, number of spikelets per panicle and 1000-grain weight was positive. A few F₁ hybrids showed positive heterosis for number of filled grains per panicle, spikelet fertility and harvest index; but the average heterosis for these traits was negative. Among the yield components, a higher number of panicles per plant and higher number of spikelet per panicle contributed to higher grain yield in F₁ hybrids. A significant and positive relationship existed between spikelet fertility and grain yield per plant. The higher grain yield was attributed to higher dry matter production rather than higher harvest index in F₁ hybrids, although low spikelet fertility limited yield potential in some F₁ hybrids.     

Susceptibility to Insecticides and Ecological Fitness in Resistant Rice Varieties of Field Nilaparvata lugens Stl Population Free from Insecticides in Laboratory

A population of rice brown planthopper(BPH) Nilaparvata lugens collected from a paddy field in Hangzhou was successively reared on susceptible rice Taichung Native 1(TN1) in a laboratory free from insecticides for more than 14 generations. The changes in susceptibility to insecticides and ecological fitness on different resistant rice varieties were monitored in each generation. The resistance ratio to imidacloprid sharply declined with the succession of rearing generations without insecticides from 359.94-fold at F1 to 6.50-fold at F14 compared with the susceptible strain, and the resistance ratio to chlorpyrifos was from 9.90-fold at F1 to 5.94-fold at F14. Nymphal duration and weights of newly hatched female adults were significantly affected by rice variety, generation and their interactions, but nymphal survival was significantly affected by the generation only. The ratio of brachypterous adults in males was affected by the generation and generation × variety interaction, whereas no difference was found in females. Nymphal duration extended with increasing generations, and the female nymphal duration was shorter in the susceptible variety TN1 than those in the resistant varieties IR26 and IR36. In addition, the female adult weight in TN1 was higher than those in IR26 and IR36. These results indicated that the resistance of field BPH population to insecticides was reversed after several generations of no-exposure to insecticides, and the ecological fitness in TN1 was higher than those in IR26 and IR36. These findings suggested the rational and reduced use of insecticides in combination with the manipulation of resistant rice varieties would be effective for BPH management.