The wheat sucrose synthase gene TaSus1 is a determinant of grain number per spike

Some haplotypes of the sucrose synthase gene TaSus1 are associated with thousand-grain weight(TGW)in wheat(Triticum aestivum L.).However,no mutations have been identified within the gene to test this association.The effects of TaSus1 on grain number per spike(GNS)also are largely unknown.Our previous genome-wide association study identified TaSus-A1 as a candidate gene controlling fertile spikelet number per spike(FSN).In the present study,we generated two independent mutants for the three TaSus1 homoeologs by CRISPR/Cas9-mediated genome editing.The triple mutants displayed lower FSN,GNS,grain number per spikelet(GNST),and TGW than wild-type plants.In 306 hexaploid wheat accessions,two single-nucleotide polymorphisms in TaSus-A1 contributed differently to GNS.Introgression of the two alleles into a wheat genetic background confirmed their effects.The alleles differed in geographical distribution among the accessions.

A novel Effective Panicle Number per Plant 4 haplotype enhances grain yield by coordinating panicle number and grain number in rice

Increasing effective panicle number per plant(EPN)is one approach to increase yield potential in rice.However,molecular mechanisms underlying EPN remain unclear.In this study,we integrated mapbased cloning and genome-wide association analysis to identify the EPN4 gene,which is allelic to NARROW LEAF1(NAL1).Overexpression lines containing the Teqing allele(TQ)of EPN4 had significantly increased EPN.NIL-EPN4^(TQ) in japonica(geng)cultivar Lemont(LT)exhibited significantly improved EPN but decreased grain number and flag leaf size relative to LT.Haplotype analysis indicated that accessions with EPN4-1 had medium EPN,medium grain number,and medium grain weight,but had the highest grain yield among seven haplotypes,indicating that EPN4-1 is an elite haplotype of EPN4 for positive coordination of the three components of grain yield.Furthermore,accessions carrying the combination of EPN4-1 and haplotype GNP1-6 of GNP1 for grain number per panicle showed higher grain yield than those with other allele combinations.Therefore,pyramiding of EPN4-1 and GNP1-6 could be a preferred approach to obtain high yield potential in breeding.

Decrement of Sugar Consumption in Rice Young Panicle Under High Temperature Aggravates Spikelet Number Reduction

Two rice genotypes Huanghuazhan(HHZ, heat-resistant) and IR36(heat-susceptible) were subjected to high-temperature(HT, 40℃) and normal-temperature(NT, 32℃) treatments at the spikelet differentiation stage. HT treatment inhibited spikelet differentiation, aggravated spikelet degeneration, reduced spikelet size, and disordered carbohydrate allocation. Meanwhile, HT treatment increased nonstructural carbohydrate content in leaves, but decreased that in stems and young panicles, and the same tendencies of sucrose and starch contents were observed in leaves and stem. However, HT treatment significantly increased the sucrose content and sharply decreased the glucose and fructose contents in young panicles. Lower activity levels of soluble acid invertase(EC3.2.1.26) and sucrose synthase(EC2.4.1.13) were observed under HT treatment. Moreover, HT treatment reduced the activities of key enzymes associated with glycolysis and the tricarboxylic acid cycle, which indicated sucrose consumption was inhibited in young panicles under HT treatment. Exogenous glucose and fructose applied under HT treatment increased the spikelet number more than exogenous sucrose. In conclusion, the results demonstrated that the reduction of spikelet number under high temperature was more affected by the decrease in sugar consumption than the blocking of sucrose transport. The impairment of sucrose hydrolysis was the main reason for the inhibition of sugar utilization.

Fine Mapping and Cloning of the Grain Number Per-Panicle Gene (Gnp4) on Chromosome 4 in Rice (Oryza sativa L.)

Grain number per-panicle is one of the most important components for rice yield. Spikelets on the primary and secondary branches determine the grain number per-panicle in rice. In this study, we identified a natural mutant, gnp4, lack of lateral spikelet on the secondary branches in the field condition. In addition, the Gnp4 and Lax1-1 double mutant showed dramatically reduced secondary branches and spikelets in panicle at reproductive stage, and tillers at vegetative stage. By map-based cloning approach, and using four F2 segregating populations, the Gnp4 gene was finally mapped to a 10.7-kb region on the long arm of chromosome 4 in rice. In this region, only one gene was predicted, and genomic DNA sequencing of the 10.7-kb region showed no nucleotide differences between the mutant and wild type. Interestingly, we found that the methylation level of several cytosines in the promoter CpG islands region of the predicted gene in gnp4 were different from the wild type. Thus, we propose that the DNA methylation changes at these sites may induce to decrease expression level of Gnp4, consequently, resulting in phenotypic variation.

TCD5 Enhances the Photosynthesis Capacity,Increases the Panicle Number and the Yield in Rice

Improvement of photosynthetic efficiency is a major approach to increase crop yield potential.Previously,we cloned a gene encoding the chloroplast-located putative monooxygenase TCD5,which is essential in plastid development under low temperature in rice(Oryza sativa L.).In this study,the effects of TCD5 on the photosynthesis and the yields were investigated in rice.Two sets of genetic materials with three levels of TCD5 expression,including tcd5 mutant or TCD5 RNAi transgenic lines and TCD5 over-expression transgenic lines in Jiahua1 and Nipponbare backgrounds,were used in the field trails of multi-locations and multi-years.TCD5 positively affected the panicle number and the yield at dosage.Compared with the wild-types,the panicle numbers were 12.4%-14.6%less in tcd5 mutant and 8.3%-38.6%less in TCD5 RNAi lines,but 26.2%-61.8%more in TCD5 over-expression lines.The grain yields per plant were 9.1%-18.4%less in tcd5 mutant and 14.3%-56.7%less in TCD5 RNAi lines,but 6.9%-56.5%more in TCD5 over-expression lines.The measurements of net photosynthetic rate indicated that mutation or knock down of TCD5 decreased the net photosynthetic rate by 10.4%and 15.6%,respectively,while increasing it by 8.9%and 8.7%in the TCD5 over-expression lines in Jiahua1 and Nipponbare backgrounds,respectively.Accordingly,the measurements of chlorophyll fluorescence parameters showed that the electron transport rate and quantum yield decreased in tcd5 mutant or TCD5 RNAi lines but increased in TCD5 overexpression lines,both in Jiahua1 and Nipponbare backgrounds.IP-MS screening revealed that TCD5 interacts with 29 chloroplast proteins involved in chlorophyll synthesis,photo-reactions of the photosynthesis,carbon assimilation and metabolism,energy metabolism,redox balance,protein synthesis and transportation.Two TCD5 interacted proteins,D1 and FBA were effective targets for improving photosynthesis.These results suggest a potentially new strategy for increasing rice yield by enhancing photosynthesis.

Mining Elite Alleles of Growth Duration and Productive Panicle Number per Plant by Association Mapping with Conditional Phenotypic Value in Japonica Rice

To provide genetic information and materials for breeding hybrid japonica rice with wide adaptability and strong competitive advantage of yield, elite alleles and their carrier varieties of growth duration （GD） and productive panicle number per plant （PN） were detected. A natural population composed of 94 japonica varieties was phenotyped for the GD, PN and plant height （PH） in two environments. The conditional phenotypic data were transferred by the linear model method in software QGAStation 1.0, and association mapping based on the unconditional and conditional phenotype values of GD and PN was analyzed by using general linear model in software TASSEL. A total of 34 simple sequence repeat （SSR） marker loci associated with GD and PN were detected in the two environments. Among them, 15 were associated with GD, and 19 were associated with PN. Four elite alleles of RM8095-120bp, RM7102-176bp, RM72-170bp and RM72-178bp were associated with GD, and their carrier varieties were Hongmangshajing, Nipponbare, Hongmangshajing and Nannongjing 62401, respectively. These elite alleles from the carrier varieties can shorten GD by 2.03-9.93 d when they were introduced into improved materials. RM72-182bp associated with PN was an elite allele, and its carrier variety was Xiaoqingzhong. It can increase PN by three when introduced into improved materials. Moreover, these elite alleles can be used to improve target traits without influencing another two traits.

Comparison of QTL for Grain Number per Panicle in Three Populations Sharing 3 Parents and Fine Mapping of Gn1c

Complex traits, such as yield components, are inherited in a quantitative manner and typically controlled by quantitative trait loci (QTL). Grain number per panicle (GN) is an important component of yield in rice and

Determination of rice panicle numbers during heading by multi-angle imaging

Plant phenomics has the potential to accelerate progress in understanding gene functions and environmental responses. Progress has been made in automating high-throughput plant phenotyping. However, few studies have investigated automated rice panicle counting. This paper describes a novel method for automatically and nonintrusively determining rice panicle numbers during the full heading stage by analyzing color images of rice plants taken from multiple angles. Pot-grown rice plants were transferred via an industrial conveyer to an imaging chamber. Color images from different angles were automatically acquired as a turntable rotated the plant. The images were then analyzed and the panicle number of each plant was determined. The image analysis pipeline consisted of extracting the i2 plane from the original color image, segmenting the image, discriminating the panicles from the rest of the plant using an artificial neural network, and calculating the panicle number in the current image. The panicle number of the plant was taken as the maximum of the panicle numbers extracted from all 12 multi-angle images. A total of 105 rice plants during the full heading stage were examined to test the performance of the method. The mean absolute error of the manual and automatic count was 0.5, with 95.3% of the plants yielding absolute errors within ± 1. The method will be useful for evaluating rice panicles and will serve as an important supplementary method for high-throughput rice phenotyping.

QTL mapping for grain number per spikelet in wheat using a high-density genetic map

Grain number per spikelet (GNS) is a key determinant of grain yield in wheat.A recombinant inbred line population comprising 300 lines was developed from a cross between a high GNS variety H461 and Chinese Spring from which the reference genome assembly of bread wheat was obtained.Both parents and the recombinant inbred lines were genotyped using the wheat 55K single nucleotide polymorphism(SNP) array.A high-density genetic map containing 21,197 SNPs was obtained.These markers covered each of the 21 chromosomes with a total linkage distance of 3792.71 c M.Locations of these markers in this linkage map were highly consistent with their physical locations in the genome assembly of Chinese Spring.The two parents and the whole RIL population were assessed for GNS in two consecutive years at two different locations.Based on multi-environment phenotype data and best liner unbiased prediction values,three quantitative trait loci (QTL) for GNS were identified.One of them located on chromosomes 2B and the other two on 2D.Phenotypic variation explained by these loci varied from 3.07%to26.57%.One of these QTL,QGns.sicau-2D-2,was identified in each of all trials conducted.Based on the best linear unbiased prediction values,this locus explained 19.59%–26.57%of phenotypic variation.A KASP(Kompetitive Allele-Specific PCR) marker closely linked with this locus was generated and used to validate the effects of this locus in three different genetic backgrounds.The identified QTL and the KASP marker developed for it will be highly valuable in fine-mapping the locus and in exploiting it for markerassisted selection in wheat breeding programs.

Characterization of a new hexaploid triticale 6D(6A) substitution line with increased grain weight and decreased spikelet number

Hexaploid triticale(×Triticosecale,AABBRR)is an important forage crop and a promising energy plant.Transferring D-genome chromosomes or segments from common wheat(Triticum aestivum)into hexaploid triticale is attractive in improving its economically important traits.Here,a hexaploid triticale 6D(6A)substitution line Lin 456 derived from the cross between the octoploid triticale line H400 and the hexaploid wheat Lin 56 was identified and analyzed by genomic in situ hybridization(GISH),fluorescence in situ hybridization(FISH),and molecular markers.The GISH analysis showed that Lin 456 is a hexaploid triticalewith 14 rye(Secale cereale)chromosomes and 28 wheat chromosomes,whereas non-denaturing fluorescence in situ hybridization(ND-FISH)and molecular marker analysis revealed that it is a 6D(6A)substitution line.In contrast to previous studies,the signal of Oligo-pSc119.2 was observed at the distal end of 6DL in Lin 456.The wheat chromosome 6D was associatedwith increased grain weight and decreased spikelet number using the genotypic data combined with the phenotypes of the F2 population in the three environments.The thousand-grain weight and grain width in the substitution individuals were significantly higher than those in the non-substitution individuals in the F2 population across the three environments.We propose that the hexaploid triticale 6D(6A)substitution line Lin 456 can be a valuable and promising donor stock for genetic improvement during triticale breeding.

Mapping of QTLs Controlling Panicle Length and Effective Panicle Number of Rice

Panicle length and effective panicle number of rice are closely related to yield. In this experiment, indica V20B as female parent was crossed with javanica CPSLO17 as male parent, recombinant inbred line （RIL） populations were obtained by single seed descent method, and with the RIL populations as mapping populations, QTL mapping and analysis were performed to the two panicle traits, panicle length and effective panicle. A high-density genetic map was constructed with SLAF labels, interval mapping was performed by software Map QTL5 under the threshold of 3.9, and 7 QTLs were detected on 3 chromosomes in total. Among the 7 QTLs, 5 QTLs controlling panicle length （qPLI-1, qPL1-2, qPL6-1, qPI_6-2 and qPL6-3） were located on chromosomes 1 and 6, respectively, and showed the contribution rates of 6.41%, 22.22%, 6.15%, 12.24% and 13.01%, respectively, their effect-increasing loci were mainly from CPSLO17, and qPL1-1 is a new QTL; and 2 QTLs controlling effective panicle number （qPN1 and qPN4） were located on chromosomes 1 and 4, respectively, and exhibited the contribution rates of 13.15% and 8.18%, respectively, and the effect-increasing loci were from parent V2OB. The marking of these loci lays a foundation for further cloning of genes controlling panicle length and effective panicle number and molecular marker-assisted selection.

Genetic control of panicle architecture in rice

Rice panicle architecture affects grain number per panicle and thereby grain yield.Many genes involved in control of panicle architecture have been identified in the past decades.According to their effect on phenotype,these genes are divided into three categories:panicle branch and lateral spikelets,multifloret spikelets,and panicle type.We review these genes,describe their genetic regulatory network,and propose a strategy for using them in rice breeding.These findings on rice panicle architecture may facilitate related studies in other crops.

A natural allele of TAW1 contributes to high grain number and grain yield in rice

Grain number per panicle (GNP) is a complex trait controlled by quantitative trait loci (QTL),directly determining grain yield in rice.Identifying GNP-associated QTL is desirable for increasing rice yield.A rice chromosome segment substitution line (CSSL),F771,which showed increased panicle length and GNP,was identified in a set of CSSLs derived from a cross between two indica cultivars,R498 (recipient) and WY11327 (donor).Genetic analysis showed that the panicle traits in F771 were semidominant and controlled by multiple QTL.Six QTL were consistently identified by QTL-seq analysis.Among them,the major QTL q PLN10 for panicle length and GNP was localized to a 121-kb interval between markers N802 and N909 on chromosome 10.Based on quantitative real-time PCR and sequence analysis,TAWAWA1(TAW1),a known regulator of rice inflorescence architecture,was identified as the candidate gene for q PLN10.A near-isogenic line,NIL-TAW1,was developed to evaluate its effects.In comparison with the recurrent parent R498,NIL-TAW1 showed increased panicle length (14.0%),number of secondary branches (20.9%) and GNP (22.0%),and the final grain yield per plant of NIL-TAW1 was increased by18.6%.Transgenic experiments showed that an appropriate expression level of TAW1 was necessary for panicle development.Haplotype analysis suggested that the favorable F771-type (Hap 13) of TAW1was introduced from aus accessions and had great potential value in high-yield breeding both in indica and japonica varieties.Our results provide a promising genetic resource for rice grain yield improvement.

Discovery of and Preliminary studies on a Rapid-Leafing Rice Genotype at the Vegetative Growth Stage

The leafing rates of fourteen rice varieties were measured in a sowing-time experiment, and a rapid leafing genotype at the vegetative growth stage was discovered in an indica variety Yanhui 559. The leaf number on the main culm of Yanhui 559 was always 4-5 leaves more than that of Lemont, and the leafing rate of Yanhui 559 was significantly higher than that of Lemont based on similar growth durations from sowing to heading. Furthermore, the difference of the leafing rate was significant at the vegetative growth stage, but not distinctive at the panicle initiation stage. Genetic analysis of the leafing rates in the two backcross populations of Yanhui 559 and Lemont showed that major and quantitative genes controlled the expression of rapid leafing character. Based on results of investigation for some plants with similar growth durations in the backcrossing populations, the rapid leafing genotypes exhibited earlier tillering and more tiller numbers per plant, and its yield components including the number of panicles per plant and number of grains per panicle were superior to those of the slow leafing genotypes. Further research and application feasibility of the rapid leafing genotype in breeding were discussed.

耕作方式和药剂处理对小麦产量和赤霉病发生的影响

研究旨在明确不同耕作措施和药剂处理对小麦产量以及赤霉病防控效果的影响。2019-2022年,设置2种耕作方式(深旋+秸秆旋埋和免耕+秸秆覆盖)、3种药剂(对照、化学药剂和生防制剂)以及5个小麦品种,研究不同耕作和秸秆利用方式下,小麦赤霉病发生情况、药剂防治效果以及基因型差异。结果表明,2022年赤霉病发生较2020年重,主要与花后的降雨量有关;免耕+秸秆覆盖处理的产量较深旋+秸秆旋埋处理高11.76%~58.82%,主因是穗数较高,免耕+秸秆覆盖的土壤禾谷镰刀菌含量和病籽率明显低于旋耕处理,但病穗率和子囊壳数量显著高于深旋+秸秆旋埋处理;在赤霉病发生较轻年份,生防制剂防控效果最佳,其次是化学药剂处理,但在赤霉病发生偏重年份,化学药剂的防治效果略优于生防制剂;‘绵麦902’产量高但易感染赤霉病,‘川麦618’产量较高且赤霉病抗性好。总体来看,免耕秸秆覆盖产量高,选用抗性品种和合理运用药剂能够有效抑制小麦赤霉病的发生。

小麦秸秆还田后不同水稻品种对简化穗肥施用的响应及其成因

【目的】探讨小麦秸秆还田条件下不同水稻品种产量、颖花分化和退化、土壤微生物活性及碱解氮对简化穗肥施用响应的差异及其原因。【方法】以迟熟中粳南粳9108和中籼扬稻6号两个品种为试材,研究秸秆还田方式(全量还田和不还田)和简化穗肥处理(0﹕0,不施穗肥;2﹕0,全施促花肥;1﹕1,促花肥和保花肥各施一半;0﹕2,全施保花肥)互作条件下产量、颖花分化和退化等的差异及其相互关系。从秸秆腐解和养分释放、土壤微生物量和酶活性变化、土壤碱解氮含量等角度分析水稻颖花分化和退化的机制。【结果】(1)秸秆还田后,南粳9108和扬稻6号的产量分别平均增加4.2%和3.2%。穗肥处理中,两品种分别以2﹕0和1﹕1处理的产量最高;而秸秆不还田处理下,两品种产量均以1﹕1处理最高。在施氮量180—360 kg N·hm-2范围内穗肥处理的产量趋势一致;(2)秸秆还田后0—30 d为快速腐解期,秸秆中的碳和氮迅速释放,30d时土壤中的细菌、真菌和放线菌的数量平均增加179.2%,脲酶、酸性磷酸酶和蔗糖酶的活性平均增加88.8%;40—60d秸秆腐解和碳氮释放速率变缓,微生物数量和酶活性迅速降低;60—90 d秸秆腐解和碳氮释放基本停滞,微生物数量和酶活性缓慢下降。秸秆还田后10—40 d,土壤碱解氮含量平均降低4.8%,50—90 d平均增加5.2%;(3)秸秆还田后,土壤碱解氮的增加使供试水稻的颖花分化数平均增加1.4%,颖花退化数平均降低12.3%,颖花现存数平均增加4.4%,每穗粒数(每穗颖花现存数)的增加是水稻增产的主要原因。南粳9108和扬稻6号2﹕0处理下颖花退化率秸秆还田较不还田处理分别降低23.5%和7.6%。南粳9108在2﹕0处理下的颖花分化数和退化数较1﹕1处理分别增加8.9和5.7朵/穗,扬稻6号分别增加6.8和11.6朵/穗。由于颖花分化数的增幅大于颖花退化数的增幅,故南粳9108的颖花现存数以2﹕0处理最多,而扬稻6号则以1﹕1处理最多。【结论】秸秆还田提高了水稻产量,全施促花肥南粳9108产量最高,扬稻6号则是促保均施处理的最高。产量提高的原因主要通过显著降低颖花退化率和退化数,增加每穗粒数实现的。南粳9108颖花退化率下降的幅度大于扬稻6号,是两个品种颖花现存数对不同穗肥处理响应差异的主要原因。

小麦TabHLH112-2B基因克隆及每穗小穗数相关功能标记开发

bHLH(basic Helix-Loop-Helix)转录因子在植物生长发育过程中发挥着重要作用。本研究克隆了小麦TabHLH112-2B,该基因由7个外显子和6个内含子构成,编码444个氨基酸,在315~364位氨基酸处具有一个典型的HLH保守结构域。组织表达模式分析表明TabHLH112-2B在小麦幼苗期、拔节期、抽穗期和开花期的各个组织中均有表达,其中在叶和根中表达量较高。顺式作用元件分析发现TabHLH112-2B启动子区含有植物激素应答、胁迫响应、与分生组织发育相关的多种顺式作用元件, qRT-PCR结果显示其表达响应ABA、IAA、MeJA等植物激素和干旱、高盐、低温、高温等胁迫处理。基因组序列多态性分析检测到启动子区域的2个SNP,分为2种单倍型。根据SNP-682开发分子标记并进行关联分析,发现该标记与干旱、高温等多种环境下的每穗小穗数显著相关,Hap-2B-2为每穗小穗数多的优异单倍型。研究结果为培育高产广适小麦新品种的分子标记辅助育种提供了优异基因资源和技术支撑。

寒地粳稻在长江下游地区作双季早粳稻产量和品质表现分析

【目的】分析引自寒地不同积温带粳稻品种作双季早稻时产量及构成以及品质差异,为筛选适宜长江下游种植的双季早粳稻品种提供理论依据。【方法】分别于2018、2021、2022年在浙江台州(121°13′E,28°78′N)和杭州(119°94′E,30°08′N)进行大田试验,分别以6、13和41个寒地粳稻品种为材料,主要来自黑龙江省第一至四积温带,以当地主栽的早籼稻品种中早39作为对照。分析寒地粳稻在南方稻区作双季早稻时产量和品质表现,并在2022年进行早粳稻品种的大田生产验证。【结果】通过提前早粳稻播期,3年的水稻收获期比当地双季早籼稻提前约0—15 d。2018年种植早粳稻品种的产量均值为6637.77 kg·hm^(-2),其中空育131产量最高,为7724.70 kg·hm^(-2),且在2022年的大田生产验证中产量达7194.77 kg·hm^(-2);所有品种在南方作为双季早粳稻种植的垩白度、透明度、胶稠度、直链淀粉含量符合二等优质食用稻品种品质标准,但整精米率较低。2022年早粳稻的平均产量为6630.45 kg·hm^(-2),排名前三的依次为:龙垦257(8324.99 kg·hm^(-2))>龙垦263(8170.94 kg·hm^(-2))>莲稻1号(8108.34 kg·hm^(-2))。与中早39相比,早粳稻有效穗数多,但每穗粒数、千粒重和结实率低,导致其产量为中早39的54.75%—93.28%。第三积温带品种因高结实率从而产量表现优于其他积温带。寒地粳稻品种间产量及构成的相关性分析结果表明,产量与有效穗数呈显著正相关,与单位面积颖花数呈极显著正相关。【结论】引自黑龙江省不同积温带的粳稻品种在长江下游作双季早稻时的生育期、产量和品质表现均验证了南方稻区种植双季早粳稻的可行性,空育131、龙垦257、龙垦263和莲稻1号可作为早粳稻进行下一步大面积示范种植。

水稻分蘖期干旱锻炼对幼穗分化期高温下穗发育和产量形成 的影响

【目的】明确分蘖期干旱锻炼对幼穗分化期高温下水稻穗发育和产量形成的影响,并探究其生理机理。【方法】以两优培九(热敏感型)和汕优63(耐热型)为材料,在盆栽条件下设置全生育期淹灌和分蘖期干旱锻炼、幼穗分化期适温和高温共四种水分和温度处理组合,研究干旱锻炼对高温胁迫下水稻颖花分化与退化、花粉活力、颖花育性、颖花大小、产量及穗生理特性的影响。【结果】与淹灌相比,在适温下干旱锻炼对两个品种产量无显著影响,但高温下干旱锻炼后两优培九和汕优63的产量分别显著提高了54.0%和20.1%,这主要是因为结实率和千粒重显著提高。与淹灌相比,幼穗分化期高温下,分蘖期干旱锻炼显著增强两优培九颖花过氧化物酶和超氧化物歧化酶活性,降低了丙二醛含量,其花粉活力和颖花育性分别显著提高了26.0%和39.0%。与适温相比,全生育期淹灌下,高温显著降低了两个品种的颖花大小和总颖花分化数。与淹灌相比,分蘖期干旱锻炼显著提高了幼穗分化期高温下两品种穗非结构性碳水化合物含量和颖花细胞分裂素(反式玉米素+反式玉米素核苷)含量,两个品种颖花长、颖花宽和总颖花分化数平均显著增加了3.2%、4.4%和15.0%。【结论】分蘖期干旱锻炼可通过增加抗氧化酶活性、非结构性碳水化合物和细胞分裂素含量来促进颖花发育和提高颖花育性,进而缓解幼穗分化期高温对水稻产量的不利影响,研究结果可为高温热害频发地区的水稻生产实践提供理论指导。