Fine mapping of two recessive genes TaFLA1 and TaSPL8 controlling flag leaf angle in bread wheat

Flag leaf angle is one of the key target traits in high yield wheat breeding.A smaller flag leaf angle reduces shading and enables plants to grow at a higher density,which increases yield.Here we identified a mutant,je0407,with an 84.34%-89.35%smaller flag leaf angle compared with the wild type.The mutant also had an abnormal lamina joint and no ligule or auricle.Genetic analysis indicated that the ligule was controlled by two recessive genes,which were mapped to chromosomes 2AS and 2DL.The mutant allele on chromosome 2AS was named Tafla1b,and it was fine mapped to a 1 Mb physical interval.The mutant allele on chr.2DL was identified as Taspl8b,a novel allele of TaSPL8 with a missense mutation in the second exon,which was used to develop a cleaved amplified polymorphic sequence marker.F3 and F4 lines derived from crosses between Jing411 and je0407 were genotyped to investigate interactions between the Tafla1b and Taspl8b alleles.Plants with the Tafla1b/Taspl8a genotype had 58.41%-82.76%smaller flag leaf angles,6.4%-24.9%shorter spikes,and a greater spikelet density(0.382 more spikelets per cm)compared with the wild type.Plants with the Tafla1a/Taspl8b genotype had 52.62%-82.24%smaller flag leaf angles and no differences in plant height or spikelet density compared with the wild type.Tafla1b/Taspl8b plants produced erect leaves with an abnormal lamina joint.The two alleles had dosage effects on ligule formation and flag leaf angle,but no significant effect on thousand-grain weight.The mutant alleles provide novel resources for improvement of wheat plant architecture.

Effects of Different Levels of Phosphorus Nutrient on the Photosynthesis Characteristic of Rice Flag Leaf

[Objective] To provide scientific basis for high phosphorus efficiency cultivation and regulation of rice. [Method] Changbai9 （CB9） and Jijing81 （JJ81） were used as experimental materials for pot experiment, and five levels of phosphorus nutrient （ Po - P4 ） were set for each variety, the net photosynthesis rate, Chlorophyll Meter Readings （SPAD Readings）, stomatal conductance, transpiration rate, intercellular CO2 concentration, and stomatal limitation were observed and compared between five different phosphorus levels at filling stage. [ Result] The net photosynthesis rate of CB9 reached the highest at P3, and was significantly different from other treatments （P 〈0.05）;the net photosynthesis rate of groups with phosphorus of J J81 were higher than that of the control group,and reached the highest at P,. The SPAD Readings of CB9 and JJ81 all achieved the highest at P3, and stomatal conductance and transpiration rate were all at first increased then decreased with the phosphor- us increased in CB9 and JJ81. With the phosphorus increased, intercellular CO2 concentration of CB9 decreased at first and then increased, while in JJ81 the trend was inversed,but the tendency of intercellular CO2 concentration were opposite to that of stomatal limitation in both culti- vars. [ Conclusion] Appropriate adding phosphorus could improve photosynthetic characteristic of rice flag-leaf,but displayed significant genotypic difference.

Relationship Between PSⅡ Excitation Pressure and Content of Rubisco Large Subunit or Small Subunit in Flag Leaf of Super High-Yielding Hybrid Rice

The changes in photochemical features of Photosystem Ⅱ (PS Ⅱ) and contents of Rubisco large subunit (RLS) and small subunit (RSS) in flag leaf from 75DAS to 113DAS (from filling to harvesting stages) were investigated in two hybrid rices (Oryza sativa L) cv. Liangyoupeijiu and cv. Shanyou 63 grown in the field. Liangyoupeijiu is a super high-yielding rice and Shanyou 63 has widely been planted in China in these years. The results indicate that soluble protein and chlorophyll in both cultivars degraded slowly at first and dramatically thereafter. The degradation speed of soluble protein in Shanyou 63 was faster than that in Liangyoupeijiu. Both Fv/Fm and qP decreased in parallel with leaf senescence, whereas qN fell at first and then rose. No significant change in excitation pressure (1-qP) was found before 89DAS but a sharply increase in both cultivars after it occurred. Excitation pressure rose more rapidly in Shanyou 63 than that in Liangyoupeijiu. The changes of RLS and RSS content exhibited the same trend as that of soluble protein content. A better linear correlation between RLS, RSS degradation and elevation of (1-qP) were shown in both cultivars. We suggest that the increase in PSⅡ excitation pressure possibly induced the quick senescence process in rice flag leaf. The high-yielding of Liangyoupeijiu may be due to its maintenance of stronger photosynthetic capacity, longer and more stable photosynthetic functional du-ration than that of Shanyou 63.

A Non-destructive Monitoring Technique for Wheat Leaf in Field and Quantification of Geometric Phenotype for Flag Leaf

[Objective] The aim was to conduct non-destructive monitoring on wheat leaf in field and discuss the method to measure geometric phenotype of flag leaf through digital image processing in order to establish relationship between geometric pheno- type of flag leaf and N fertilizer regulation. [Method] Ningmai 13 was applied with N fertilizers in different amounts to discuss relationship among area, length, average width of flag leaf and applied N fertilizers using digital camera and digital image pro- cessing technique. [Result] Fertilizer is a main environmental factor influencing geo- metric phenotype of flag leaf, for example, area of flag leaf would enlarge four times and the length would increase from 15.87 to 25.33 cm by different N fertilizer amount. Thus, geometric phenotype of flag leaf would reflect N fertilizer amount at early stage. The highly accurate relationship between phenotype and N fertilizer is a reliable tech- nique to study on rules of wheat phenotype, N fertilizer and environmental factors. [Conclusion] The research indicated that digital image processing technique with scale label and dynamic background plates is an effective method to obtain geometric phenotype of sessile crops and crops with little leaf, providing a feasible scheme for non- destructive monitoring on growth dynamic of leaf＇s organs.

QTL analysis of flag leaf in barley (Hordeum vulgare L.) for morphological traits and chlorophyll content

To understand genetic patterns of the morphological and physiological traits in flag leaf of barley, a double haploid （DH） population derived from the parents Yerong and Franklin was used to determine quantitative trait loci （QTL） controlling length, width, length/width, and chlorophyll content of flag leaves. A total of 9 QTLs showing significantly additive effect were detected in 8 intervals on 5 chromosomes. The variation of individual QTL ranged from 1.9% to 20.2%. For chlorophyll content expressed as SPAD value, 4 QTLs were identified on chromosomes 2H, 3H and 6H; for leaf length and width, 2 QTLs located on chromosomes 5H and 7H, and 2 QTLs located on chromosome 5H were detected; and for length/width, I QTL was detected on chromosome 7H. The identification of these QTLs associated with the properties of flag leaf is useful for barley improvement in breeding programs.

Altered Expression of Transcription Factor Genes in Rice Flag Leaf under Low Nitrogen Stress

The response of transcription factor genes to low nitrogen stress was studied to provide molecular basis for improving the absorption and utilization efficiency of nitrogen fertilizer in rice. The agilent rice genome arrays were used to study the varied expression of transcription factor genes in two rice varieties （SN 196 and Toyonishhiki） with different chlorophyll contents under low nitrogen stress. The results showed that a total of 53 transcription factor genes （35 down-regulated and 18 up-regulated genes at the transcription level） in flag leaves of super-green rice SN196 and 27 transcription factor genes （21 down-regulated and 6 up-regulated genes at the transcription level） in flag leaves of Toyonishiki were affected by low nitrogen stress. Among those nitrogen-responsive genes, 48 transcription factor genes in SN196 and 22 in Toyonishiki were variety-specific. There were overlapped transcription factor genes responded to low nitrogen stress between SN196 and Toyonishiki, with 1 up-regulated and 4 down-regulated at the transcription level. Distributions of low nitrogen responsive genes on chromosomes were different in two rice varieties.

Physiological response of flag leaf and yield formation of winter wheat under different spring restrictive irrigation regimes in the Haihe Plain,China

In order to identify the optimum period of spring water-restrictive irrigation for winter wheat(Triticum aestivum L.)in the Haihe Plain,China and elucidate its effects on flag leaf senescence and yield formation,field experiments were conducted at the Xinji Experimental Station of Hebei Agricultural University from 2016 to 2019 by using different irrigation regimes in spring,including the conventional regime involving two irrigation periods(control(CK),the 3-leaf unfolding stage and the anthesis stage)and a series of single,restrictive irrigation regimes(SRI)comprising irrigation at the 3-leaf unfolding stage(3 LI),4 LI,5 LI,and 6 LI.There are five major findings:(1)The senescence(determined by the green leaf area,GLA)in the 4 LI treatment occurred moderately earlier than that in CK,showed no significant difference with that in 5 LI and 6 LI,and occurred significantly later than that in 3 LI.(2)Compared with other SRI treatments,the GLA value and photosynthetic rate in 4 LI were 14.82 and 20.1%higher,respectively.Microstructural analysis of flag leaf also revealed that the mesophyll cells and chloroplasts were irregularly arranged under drought stress in 3 LI and 6 LI;however,drought stress had minimal negative effects on the microstructure in 4 LI and 5 LI.(3)Postponed irrigation in spring could significantly increase superoxide dismutase(SOD)and catalase(CAT)activities in the early stage of grain filling;however,these activities would subsequently decrease.Among the four SRI treatments,the overall enzyme activities were the highest in 4 LI,and the combined malondialdehyde(MDA)content in flag leaves in 4 LI and 5 LI was 14.5%lower on average than that in 3 LI and 6 LI.(4)The soluble sugar(SS)and proline(Pro)contents in 4 LI were the highest among the four SRI treatments;however,they were lower than those in CK.The abscisic acid(ABA)hormone content in 4 LI and 5 LI was lower than that in 3 LI and 6 LI,respectively,suggesting a smaller drought stress effect in 4 LI and 5 LI.(5)In two growing seasons,there was a larger number of spikes per unit area in 4 LI(i.e.,13.4%higher than that in 5 LI and 6 LI)and the 1000-grain weight in 4 LI was the highest among the four SRI treatments(i.e.,6.0%higher than that in the other three SRI treatments).Therefore,a single restrictive irrigation regime at the 4-leaf unfolding stage is recommended to be effective in slowing down the senescence process of flag leaves and achieving high yield.

Interactions between cytokinin and nitrogen contribute to grain mass in wheat cultivars by regulating the flag leaf senescence process

Premature senescence after anthesis reduces crop yields.Delaying leaf senescence could maintain photosynthetic activity for a longer period and lead to a higher photosynthetic rate.Recent studies have provided some insights into the interaction between cytokinin and nitrogen(N)in the regulation of plant development.In the present study,foliar application of exogenous 6-benzylaminopurine(6-BA)and lovastatin,an inhibitor of cytokinin synthesis,was combined with three N rates[0 kg ha^(-1)(low nitrogen,LN),240 kg ha^(-1)(normal nitrogen,NN),and 360 kg ha^(-1)(high nitrogen,HN)]in two wheat cultivars,Wennong 6(with a staygreen phenotype)and Jimai 20(with a non-staygreen phenotype).Flag leaf senescence was assessed using a Gompertz growth curve.Grain mass,dry matter accumulation and distribution,total N of flag leaf,and concentrations of zeatin riboside(ZR)and abscisic acid(ABA)were also used to evaluate the functional characteristics of flag leaves.Grain mass was negatively correlated with initial senescence rate(r_0)and duration of rapid chlorophyll loss(Chl_(loss)),whereas it was positively correlated with maximum senescence rate(r_(max)),average senescence rate(r_(aver)),persistence phase(Chl_(per)),total duration of flag leaf(Chl_(total))and inflection point cumulative temperature(M).Compared to Jimai 20,Wennong 6 had larger r_(aver),Chl_(per),and Chl_(total).The concentration of ZR was highest under the 6-BA×NN treatment,followed by the 6-BA×HN and 6-BA×LN treatments.However,the concentration of ABA showed the opposite trend.It was concluded that the staygreen phenotype Wennong 6 was associated with greater grain mass and altered cytokinin metabolism and could be classified as a functional staygreen type.Foliar application of 6-BA interacting with N at the NN level(240 kg ha^(-1))may be a beneficial strategy for improving grain yield of wheat by regulating endogenous hormones and the flag leaf senescence process.Increasing endogenous cytokinin promoted the transport of dry matter to grain.

Genetic Analysis and QTL Mapping of Large Flag Leaf Angle Trait in Japonica Rice

Genetic segregation analysis for flag leaf angle was conducted using six generations of P1, P2, F1, B1, B2 and F2 derived from a cross of 863B （a maintainer line of japonica rice） and A7444 （a germplasm with large flag leaf angle）. Genotypes and phenotypes of flag leaf angle were investigated in 863B （P1）, A7444 （P2） and 141 plants in BC^F~ （863BIA744411863B） population. An SSR genetic linkage map was constructed and QTLs for flag leaf angle were detected. The genetic map containing 79 information loci was constructed, which covers a total distance of 441.6 cM, averaging 5.6 cM between two neighboring loci. Results showed that the trait was controlled by two major genes plus polygene and the major genes were more important. Fifteen markers showed highly significant correlations with flag leaf angle based on single marker regression analysis. Two QTLs （qFLA2 and qFLA8） for flag leaf angle were detected by both composite interval method in software WinQTLCart 2.5 and composite interval method based on mixed linear model in QTL Network 2.0. The qFLA2 explained 10.50% and 13.28% of phenotypic variation, respectively, and was located at the interval of RM300 and RM145 on the short arm of chromosome 2. The qFLA8 explained 9.59% and 7.64% of phenotypic variation, respectively, and was located at the interval flanking RM6215 and RM8265 on the long arm of chromosome 8. The positive alleles at the two QTLs were both contributed from A7444.

Analysis of QTLs for Flag Leaf Shape and Its Response to Elevated CO_2 in Rice(Oryza sativa)

To understand the responses of flag leaf shape in rice to elevated CO2 environment and their genetic characteristics, quantitative trait loci （QTLs） for flag leaf shape in rice were mapped onto the molecular marker linkage map of chromosome segment substitution lines （CSSLs） derived from a cross between a japonica variety Asominori and an indica variety IR24 under free air carbon dioxide enrichment （FACE, 200 μmol/mol above current levels） and current CO2 concentration （Ambient, about 370 μmol/mol）. Three flag-leaf traits, flag-leaf length （LL）, width （LW） and the ratio of LL to LW （RLW）, were estimated for each CSSL and their parental varieties. The differences in LL, LW and RLW between parents and in LL and LW within IR24 between FACE and Ambient were significant at 1% level. The continuous distributions and transgressive segregations of LL, LW and RLW were also observed in CSSL population, showing that the three traits were quantitatively inherited under both FACE and Ambient. A total of 16 QTLs for the three traits were detected on chromosomes 1, 2, 3, 4, 6, 8 and 11 with LOD （Log10-1ikelihood ratio） scores ranging from 3.0 to 6.7. Among them, four QTLs （qLL-6＊, qLL-8＊ qLW-4＊ and qRLW-6＊） were commonly detected under both FACE and Ambient. Therefore, based on the different responses to elevated CO2 in comparison with current CO2 level, it can be suggested that the expressions of several QTLs associated with flag-leaf shape in rice could be induced by the high CO2 level.

Identification of a major QTL for flag leaf glaucousness using a high-density SNP marker genetic map in hexaploid wheat

Cuticular wax plays an important role in protecting land plant against biotic and abiotic stresses. Cuticular wax production on plant surface is often visualized by a characteristic glaucous appearance. This study identified quantitative trait loci （QTLs） for wheat （Triticum aestivum L.） flag leaf glaucousness （FLG） using a high-density genetic linkage map developed from a recombinant inbred line （RIL） population derived from the cross HeynexLakin by single-seed descent. The map consisted of 2 068 single nucleotide polymorphism （SNP） markers and 157 simple sequence repeat （SSR） markers on all 21 wheat chromosomes and covered a genetic distance of 2 381.19 cM, with an average marker interval of 1.07 cM. Two additive QTLs for FLG were identified on chromosomes 3AL and 2DS with the increasing FLG allele contributed from Lakin. The major QTL on 3AL, QFIg.hwwgr-3AL, explained 17.5-37.8% of the phenotypic variation in different environments. QFIg.hwwgr-3AL was located in a 4.4-cM interval on chromosome 3AL that was flanked by two markers IWA1831 and IWA8374. Another QTL for FLG on 2DS, designated as QFIg.hwwgr-2DS which was identified only in Yangling in 2014 （YL14）, was flanked by IWA1939 and Xgwm261 and accounted for 11.3% of the phenotypic variation for FLG. QFIg.hww- gr-3AL and QFIg.hwwgr-2DS showed Additive×Environment （AE） interactions, explaining 3.5 and 4.4% of the phenotypic variance, respectively. Our results indicated that different genes/QTLs may contribute different scores of FLG in a cultivar and that the environment may play a role in FLG.

干旱和品种对小麦灌浆期旗叶下午光合速率、关键酶活性和产量的影响

为了探讨干旱和品种对小麦灌浆期旗叶下午净光合速率(Pn)、光合关键酶活性和产量的影响,2019—2021年度在池栽全生育期遮雨条件下设置包括重度(W1)、中度(W2)、轻度(W3)干旱和适墒(W4)的4个水分处理,在灌浆前期、中期的14:00—16:00测定了强抗旱性品种晋麦47(JM47)和弱抗旱性品种偃展4110(YZ4110)的旗叶Pn、1,5-二磷酸核酮糖羧化酶/加氧酶(Rubisco)、Rubisco活化酶(RCA)、ATP合成酶(ATPase)、磷酸烯醇式丙酮酸羧化酶(PEPC)和丙酮酸磷酸双激酶(PPDK)活性以及成熟期的产量。结果表明,干旱使小麦灌浆期旗叶下午Pn、多数光合酶活性以及产量降低,总体表现为干旱胁迫程度越大,上述指标的降幅也越大,但其影响效应存在品种和年际差异。W1、W2和W3与W4相比,旗叶下午Pn, JM47分别降低33.6%~40.6%,12.0%~30.5%和5.0%~13.5%,YZ4110分别降低44.0%~52.0%,22.5%~38.1%和11.5%~20.5%;旗叶下午Rubisco活性,JM47灌浆前期降低、灌浆中期增加,而YZ4110分别降低13.3%~25.6%,7.1%~14.0%和11.2%~11.6%;旗叶下午RCA活性,灌浆前期多显著降低,灌浆中期JM47在W2和W3下增加,而YZ4110在W1和W2下降低;旗叶下午ATPase活性,JM47在W1下降低、W3下提高,而YZ4110分别降低19.3%~48.7%,7.2%~24.2%和0.1%~8.9%。不同水分处理的旗叶下午PEPC活性因生长季和品种而异,但W1与W4相比,JM47和YZ4110的旗叶下午PPDK活性分别降低12.4%~18.8%和16.7%~18.2%。与YZ4110相比,JM47旗叶下午Pn和光合酶活性在适墒下多无显著差异,但干旱下多表现为升高。相关性分析结果表明,产量、旗叶下午Pn与灌浆期旗叶下午ATPase活性和灌浆前期旗叶下午PEPC活性呈极显著正相关,因而在灌浆期下午保持较高的旗叶ATPase和PEPC活性有利于提高小麦旗叶下午Pn和籽粒产量。

小麦品种百农207开花后的形态、光合性能及干物质积累特性

生产试验于2023—2024年度研究了百农207和周麦36号在开花后的形态、光合及干物质转运特性.结果表明百农207的旗叶面积、厚度、spad及持绿期均大于周麦36号.开花至灌浆后期,2个小麦品种的光合速率均显著降低,百农207旗叶光合速率均显著高于周麦36号.2个品种的光合速率日变化和旗叶光合速率的光相应曲线也表明,百农207在8—10时及16—18时旗叶光合速率高于周麦36号,而周麦36号在10—16时旗叶光合速率高于百农207.百农207从灌浆初期至成熟期,单茎干物质质量均高于周麦36号.单位面积产量百农207高于周麦36号但差异不显著.

大田和旱棚环境下小麦旗叶气孔性状变异及其与光合参数的关系

为了明确小麦旗叶与气孔性状的变异及其对干旱胁迫的响应,在大田和旱棚环境下种植204个小麦品种,测定其旗叶和气孔性状,并对10份气孔性状极端的材料的光合参数进行测定分析。结果表明,小麦品种间旗叶和气孔性状存在显著差异,在旱棚环境下旗叶长度、旗叶面积、气孔长度和气孔面积较大田分别降低了6.6%、7.0%、1.4%和3.0%,气孔密度增加了12.0%。旗叶长度与气孔长度、旗叶宽度与气孔宽度和旗叶面积与气孔面积的相关系数在大田环境下分别为0.18、0.15和0.18,在旱棚环境下分别为0.31、0.18和0.25。极端材料中,与气孔密度大的材料相比,气孔密度小的材料的净光合速率在大田环境下增大了9.67%,蒸腾速率增加27.57%,瞬时水分利用效率减少26.04%。在大田环境下气孔长度与蒸腾速率和气孔导度均呈正相关(相关系数均为0.37),气孔面积与蒸腾速率呈正相关(相关系数为0.39),气孔密度与蒸腾速率和净光合速率均呈负相关(相关系数均为-0.38);在旱棚环境下气孔长度与蒸腾速率和净光合速率均呈正相关(相关系数分别为0.36和0.42)。这说明,环境条件对小麦旗叶性状之间的相关性影响较大,较大的旗叶面积和较低的气孔密度会促进小麦光合作用,有利于提高小麦的产量及抗旱性。

适时一次灌溉对8个冬小麦品种产量和生理特性的影响

为了探讨适时一次灌溉的灌溉效果和增产机制,以黄淮海麦区主推的8个小麦品种为材料,在大田和池栽条件下,设置适时一次灌溉和无灌溉(自然降雨)2种处理,测定抽穗期、灌浆前期、灌浆中期、灌浆后期旗叶生理指标和成熟期籽粒产量,研究适时一次灌溉对冬小麦产量和旗叶生理特性的影响。结果表明,适时一次灌溉改善了4个生育时期的旗叶生理特性。大田、池栽条件下适时一次灌溉处理旗叶超氧化物歧化酶(SOD)活性分别较无灌溉处理增加23.63%~39.07%、27.82%~54.53%,过氧化物酶(POD)活性增加16.39%~53.76%、16.93%~38.62%,过氧化氢酶(CAT)活性增加33.74%~51.59%、26.13%~45.06%,可溶性糖含量增加27.73%~46.34%、24.75%~37.31%,脯氨酸含量增加26.29%~37.84%、21.41%~41.33%,可溶性蛋白含量增加16.56%~42.06%、14.85%~31.69%,净光合速率增加11.51%~47.25%、24.36%~43.33%,丙二醛(MDA)含量下降12.32%~18.64%、14.85%~22.79%,小麦籽粒产量平均增加17.95%和29.27%。适时一次灌溉条件下,不同品种间比较,以周麦32和周麦36较无灌溉增产幅度较大,分别为31.50%和28.23%,可作为丰产抗旱性品种在有限灌溉旱作区进行推广。本研究结果为冬小麦适时一次灌溉研究及品种优化布局提供了参考。

利用高密度遗传图谱定位两种不同环境的水稻剑叶形态性状QTL差异

水稻剑叶形态性状是构成理想株型的重要因素之一,发掘新的控制剑叶形态性状的基因资源是提高水稻产量的重要途经。本研究利用高密度遗传图谱对在杭州和海南陵水种植的印度粳稻品种M494和中国籼稻品种中9B(Z9B)杂交衍生的重组自交系(recombinant inbred lines,RIL)群体剑叶长、剑叶宽、剑叶面积和剑叶长宽比进行数量性状位点(Quantitative trait locus,QTL)定位检测。研究共检测到10个QTL,包括1个剑叶长QTL、4个剑叶宽QTL、4个剑叶面积QTL和1个剑叶长宽比QTL,分布于第4、第7、第8、第9和第10号染色体,贡献率介于6.47%~13.28%之间;鉴定到2个多效性QTL区间,其中在第4号染色体Block536~Block544区间检测到同时控制剑叶宽和剑叶面积的QTL,在第10号染色体Block942~Block961区间检测到同时控制剑叶宽和剑叶长宽比的QTL,其贡献率分别为8.82%、13.28%、12.28%和12.60%。两地间QTL差异较大,仅在Block536~Block544区间同时定位到控制剑叶宽及剑叶面积的QTL及在Block942~Block961区间同时定位到控制剑叶宽及剑叶长宽比的QTL。

氮肥后移对高温胁迫下春小麦旗叶生理特性和产量的影响

[目的]探究氮肥后移对高温胁迫下春小麦(Triticum aestivum L.)旗叶膜脂过氧化作用、抗氧化酶活性、渗透调节物质含量和产量的影响,筛选缓解春小麦花后高温早衰的科学施肥方法。[方法]2022年3月至2023年9月,以宁3015为试验材料,在宁夏农垦平吉堡农六队试验基地进行试验。采用裂区试验设计,主区为温度,设(25±2)℃(常温RT)和(35±2)℃(高温HT),副区为氮肥运筹。施氮总量一定(300 kg·N·km^(-2)),2022年设G1(分蘖期30%)、G2(拔节期30%)、G3(孕穗期30%)、G4(抽穗期20%)和G5(灌浆期20%)共5种施肥方式,2023年由前一年试验结果筛选出G1(分蘖期30%)、G3(孕穗期30%)和G5(灌浆期20%)共3个处理。于开花期开始取样,每5天取样一次,测定旗叶膜脂过氧化作用、抗氧化酶活性和渗透调节物质等指标。[结果]连续两年氮肥运筹试验中旗叶的超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性、脯氨酸(Pro)含量和产量均在G5处理达到最高,丙二醛(MDA)和膜透性均在G5处理下最低,且与G1处理存在显著性差异(P<0.01)。根据皮尔逊(Pearson)相关性分析可知,春小麦籽粒产量和SOD、POD、CAT活性和脯氨酸含量显著正相关(P<0.05),与MDA含量和膜透性显著负相关(P<0.05)。综合评价表明,2022和2023年氮肥运筹的主成分得分排序为G5>G3>G4>G2>G1和G5>G3>G1,两年试验结果趋势一致。[结论]适当的氮肥后移可以降低高温胁迫下春小麦旗叶膜脂过氧化作用,增加抗氧化酶活性和渗透调节物质含量,进而增加产量,本试验中灌浆期施氮总量20%的处理较为适宜。

限水条件下灌水量对强筋小麦旗叶衰老特性和籽粒产量的影响

为探究灌水量对强筋小麦花后旗叶衰老和籽粒产量的调控效应,以2个强筋小麦品种(中麦998和中麦1062)为供试材料,设置0 m^(3)·hm^(-2)(W_(0))、450 m^(3)·hm^(-2)(W_(1))和900 m^(3)·hm^(-2)(W_(2))3个灌水量(拔节期和开花期各灌水50%),分析了不同处理下小麦旗叶叶绿素含量、同化物含量、丙二醛含量、抗氧化酶活性、抗衰老激素含量、蛋白质含量和籽粒产量的差异。结果表明,增加灌水量可延缓强筋小麦花后旗叶衰老。灌浆前中期旗叶叶绿素含量在不同处理间无显著差异,灌浆后期叶绿素含量在W_(2)处理下最高。W_(2)处理下小麦旗叶可溶性糖含量显著高于其他处理;旗叶可溶性蛋白含量在花后0~21 d保持较高水平,在花后21~35 d含量逐渐下降,且W_(1)处理下花后21~35 d旗叶可溶性蛋白含量较W_(0)处理显著提高。灌水量对花后0~21 d强筋小麦旗叶中游离氨基酸含量无显著影响,而在灌浆后期以W_(2)处理最高;与W_(0)处理相比,增加灌水量可显著提高旗叶过氧化氢酶活性、过氧化物酶活性和生长素含量,显著降低丙二醛和脱落酸含量,并且显著延长测定酶活性和激素含量峰值出现时间。随灌水量的增加,籽粒蛋白质含量下降,但产量显著升高。总体来看,在本试验条件下,W_(2)处理(拔节水450 m^(3)·hm^(-2)+开花水450 m^(3)·hm^(-2))能够显著延缓强筋小麦旗叶衰老,在维持较高蛋白质含量同时,获得最高籽粒产量。

Effects of Shading on Photosynthetic Properties of Canopy and Single Leaf of Winter Wheat

[Objective] The aim was to study on the effects of long-term low radiation on canopy apparent photosynthetic rate （CAP） and photosynthetic properties of top three leaves of winter wheat, especially the flag leaf. [Method] Two winter wheat （Triticum aestivum L） cultivars, Yangmai 158 and Yangmai 11, which differed in low radiation resistance, were used to measure the CAP, photosynthetic rate （Pn） of the top three leaves, chlorophyll content of flag leaf and grain yield. In the test, three treatments were designed from jointing to maturity, as follows： control without shad- ing （So）, S1 and S2 treatments with 22% and 33% sunshine shaded. [Result] CAP of Yangmai 158 and Yangmai 11 declined with shading. Under low radiation, Pn of flag leaf declined significantly, while no obvious effects were found on Pn of the 2nd leaf, and Pn of the 3rn leaf increased significantly, which partially compensated the decrease of Pn of the flag leaf. In addition, the compensation effect differed in shading and cultivars： compensation effect in S1 group was higher than that of S2 and effect of Yangmai 158 was higher than that of Yangmai 11. During the period of high Pn. shading decreased the content of total chlorophyll, chlorophyll a, b, and a/b. [Conclusion] Under low radiation, the decrease of chlorophyll a and a/b led to substantial declining of Pn. and CAP declined accordingly, finally resulting in drop of grain yield. The research provides important theoretical basis for wheat production in the middle and lower reaches of Yangtze River.

Changes in the Activities of C4 Pathway Enzymes and Stable Carbon Isotope Discrimination in Flag Leaves of Super High-yield Hybrid Rice

Activities of several key enzymes of C-4 photosynthesis pathway and stable carbon isotope discrimination were investigated in flag leaves of a super high-yield hybrid rice (Oryza sativa L.) cv. Peiai 64S/E32 and a traditional hybrid rice cv. Shanyou 63 at different developing stages. Results show that the activity of PEP carboxylase (PEPCase) increased with age of flag leave; the activity of NADP-malate dehydrogenase (NADP-MDH) increased and reached to a peak value at grain filling stage (68-75 d after transplanting), then fell down; the activity of NADP-MDH in cv. Peiai 64S/E32 was much higher than that in cv. Shanyou 63. Before ripening stage (95 d after transplanting), NADP-malic enzyme activity rose gradually. The level of stable carbon isotope discrimination (Delta(13)C) in flag leaves and grains at different developing stages were similar and exhibited a comparative high value at ripening stage. The average Delta(13)C in leaf of cv. Peiai 64S/E32 during different developing stages was 0.43parts per thousand more than that in cv. Shanyou 63.