Temperature Difference Between the Air and Organs of Rice Plant and Its Relation to Spikelet Fertility

Based on the experiment of measuring panicles and leaves, air temperature, and humidity above the canopy of rice cultivars after heading in 2005 and 2006, we investigated the temperature difference （TD） between the air and organs of rice plant and its relationship with spikelet fertility. The results showed that TDs between the air and organs of rice varied with air temperature, air humidity, and plant type. For similar air humidity, TDs were lower at the air temperature of 28.5℃ than at higher temperature of 35.5℃, whereas for the same air temperature, the TDs decreased as the air humidity increased. TDs were also affected by plant type of the cultivars. Erect panicle cultivars showed higher TDs than those with droopy panicles under similar climatic conditions, and cultivars with panicles above flag leaf （PAFL） had higher TDs than those with panicles below the flag leaf （PBFL）. Cultivars grown in a location with lower air humidity and higher temperature, such as Taoyuan, China, had higher spikelet fertility than those in higher humidity under the similar air temperature during the grain filling stage. This is partially attributed to the larger TDs under the lower humidity. Rowspacing and the ratio of basal-tillering to panicle-spikelet fertilizer showed a significant influence on TD and subsequently on spikelet fertility, suggesting the possibility of increasing spikelet fertility by agronomic management.

Enclosed stigma contributes to higher spikelet fertility for rice(Oryza sativa L.) subjected to heat stress

With global warming, rice plants may be subjected to heat stress more regularly during the heatsensitive flowering stage, causing spikelet sterility and grain yield loss.Stigma exsertion is considered to increase pollen reception and promote female reproductive success.The aim of this study was to investigate the role of stigma exsertion on spikelet fertility at high temperatures.Five rice cultivars(Liangyoupeijiu, Shanyou 63, Huanghuazhan, Nagina 22, and IR64) with differing degrees of stigma exsertion were cultivated and exposed to high temperature at anthesis.Heat-tolerant cultivars did not always show a high percentage of spikelets with exserted stigmas, and vice versa.Irrespective of the presence of more pollen grains on exserted stigmas, spikelets with exserted stigmas did not show greater spikelet fertility than spikelets with fewer exserted stigmas or hidden stigmas under heat stress.GA3 application augmented the percentage of spikelets with exserted stigmas;however, it did not increase spikelet fertility under heat stress.Spikelet fertility of whole panicles was negatively correlated with the percentage of spikelets with exserted stigmas, but positively with that with hidden stigmas.Viability of the hidden stigmas was less reduced than that of exserted stigmas under heat stress, suggesting that hidden stigmas have an advantage in maintaining viability.Heat stress delayed anther dehiscence and reduced the viabilities of both exserted stigmas and pollens, thereby causing low spikelet fertility.Together, these results suggest that high spikelet fertility does not depend on stigma exsertion and that enclosed stigma generally contributes to higher spikelet fertility and heat tolerance under high-temperature conditions during flowering in rice.

Screening for Spikelet Fertility and Validation of Heat Tolerance in a Large Rice Mutant Population

A total of 10 000 M4 individuals in Jao Hom Nil (JHN) mutant population was treated with high temperature (40 ℃ to 45 ℃) during the day time (6 h) from the booting to the harvesting stages, and ambient temperature (33 ℃ to 35℃) was used as the control. The results of screening and yield trials found that the mutant line M9962 had a high spikelet fertility of 78% under heat stress. In addition, the other mutant lines, including M3181 and M7988, had a spikelet fertility of approximately 70%. However, the JHN wild type, Sin Lek, RD15 and RD33 had very low spikelet fertility of 34%, 14%, 9% and 4%, respectively. The lower spikelet fertility at an elevated temperature resulted in a dramatic decrease of filled grain and contributed to a loss in 100-grain weight. M9962 is a potential genetic stock for use in a heat tolerance breeding programme. In addition, spikelet fertility at high temperature was representative of heat tolerance and can be used as a screening trait for heat tolerance during the reproductive phase on a large scale.

Avoidance of Linkage Drag Between Blast Resistance Gene and the QTL Conditioning Spikelet Fertility Based on Genotype Selection Against Heading Date in Rice

Previous study showed that a linkage drag between a blast resistance gene Pi25（t） and QTLs conditioning spikelet fertility （qSF-6） and number of filled grains per panicle （qNFGP-6） was detected on the short arm of chromosome 6. A larger population was used for further verification, and the results confirmed the linkage drag between the blast resistance gene and QTL conditioning spikelet fertility, other than QTL conditioning number of filled grains per panicle. Breakdown or avoidance of the linkage drag could be achieved by selection against the genotype background of a heading-date gene （qHD-7） that resided in the region between RM2 and RM214 on chromosome 7. For further validation, two lines with almost identical genotypes on all chromosomal regions except the Pi25（t） region on chromosome 6 were chosen to develop a new population The results showed that qSF-6 could be further subdivided into qSF-6-1 and qSF-6-2. When the genotype of the region between RM2 and RM214 was from rice variety Zhong 156, the linkage drag between Pi25（t） and qSF-6-2 was detected and the allele of qSF-6-2 from rice variety Gumei 2 reduced the spikelet fertility. When the genotype of the region between RM2 and RM214 was from Gumei 2, no linkage drag was detected. This indicates that the linkage drag between the blast resistance gene and the QTL conditioning spikelet fertility could be broken down or avoided under a certain background genotype selection against heading-date and provides a marker aided solution for high level of blast resistance and yield breeding in rice and other crops as well.

Effects of Heat Stress at Vegetative and Reproductive Stages on Spikelet Fertility

Seed-setting rate, yield components and grain quality traits of 169 accessions from an exotic rice germplasm were tested under high temperatures from 40 oC to 45 oC for 6 h during the daytime at the vegetative and reproductive stages, respectively. The results showed that heat stress significantly decreased the seed-setting rate of all the accessions, but the heat stress effects varied among accessions. Based on the decreases in seed-setting rate at high temperatures, N22 was the most tolerant, followed by AUS17, M9962, SONALEE and AUS16. Moreover, the reductions in seed-setting rate and yield under heat stress were more serious at the vegetative stage （45 d before heading） than at the booting stage （15 d before heading）. In addition, heat stress also affected grain quality, especially by conferring chalkiness to most of the accessions, but SONALEE did not change much. The heat-tolerant accessions identified here and the phenotype protocols developed could be used in future genetic studies and breeding programmes focused on heat tolerance.

Specific Spikelet Fertility as an Indicator of Cold Tolerance Identification at Booting Stage in Rice

By using the parents, Kunmingxiaobaigu, a landrace variety with cold tolerance from Yunnan, China, and Towada, a cold-sensitive variety bred in Japan, as well as their F8 and F9 RIL progenies as test materials, cold tolerance of rice at the booting stage in 2002 and 2003 under four different altitudes （environments）, and the correlationship between spikelet fertility and specific spikelet fertility （spikelet fertility of nine spikelets from the 3rd to the 5th spikelets of three primary branches at the top of each panicle） of single plant were analyzed, The data revealed a significant correlationship between spikelet fertility and specific spikelet fertility with the range from 0.7364 to 0.9011. However, under the cold stress environments, the correlation coefficients were higher than those without cold stress. On the other hand, the panicle exsertion was correlated to both spikelet fertility and specific spikelet fertility. Moreover, the heredity analysis suggested that specific spikelet fertility could replace spikelet fertility as an identification indicator, while panicle exsertion could be used as a partial indicator of cold tolerance identification at the booting stage in rice.

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。

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。

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.

不同促花肥与保花肥配方对粳稻产量与产量结构的影响

为了探讨在湿润渗透施肥法下,水稻促花肥与保花肥使用N与P2O5的不同配方组合对粳稻产量与产量结构的影响,选用生产上种植面积较大的粳稻品种淮稻5号为试验材料,将磷酸二铵、过磷酸钙与普通尿素在水稻促花肥中进行配施,设置1个不施促花肥与保花肥对照和3种促花肥施肥模式(处理1—3)。结果显示:施促花肥与保花肥的3个处理间水稻产量及产量结构无统计学意义,其产量平均较对照增产24.5%;促花肥中增施P2O5的2个处理(处理1、2)平均较对照增产26.5%,比促花肥只施尿素的处理3增产5.2%;促花肥中增施磷酸二铵的处理1比增施过磷酸钙的处理2增产2.3%。因此,粳稻一定要施促花肥与保花肥。建议在粳稻施促花肥时,增施磷酸二铵(8 kg/667 m^(2))或过磷酸钙(20 kg/667 m^(2))。

Response of spikelet water status to high temperature and its relationship with heat tolerance in rice

In rice, high-temperature stress(HT) during flowering results in decreased grain yield via a reduction in spikelet fertility;however, the effect of plant water status on spikelet fertility under HT remains unknown. To investigate the relationship between spikelet water status and spikelet fertility under HT, two experiments were performed under temperature-controlled conditions using four genotypes with varying tolerance to HT. Rice plants were exposed to HT for seven consecutive days during the flowering stage under three soil water treatments(soil water potential 0, -20, and -40 kPa), as well as under hydroponic conditions in a separate experiment. HT significantly decreased spikelet fertility, pollen fertility, and anther dehiscence under each of the three water treatments. HT significantly increased the spikelet transpiration rate, and this change was accompanied by a significant decrease in the internal temperature of the spikelets. HT decreased pollen grain diameter in heat-sensitive genotypes. HT had varying effects on the water potential of panicles and anthers but increased anther soluble-sugar concentration. Different aquaporin genes showed different expression profiles under HT, and the expression levels of PIPs for plasma membrane intrinsic proteins and TIPs for tonoplast intrinsic proteins increased in anthers but decreased in glumes.Correlation analyses showed that anther dehiscence and pollen(spikelet) fertility were tightly associated with anther water status, and the expression levels of almost all anther aquaporin genes were significantly correlated with anther dehiscence under HT. In summary, an increased spikelet transpiration rate and decreased internal spikelet temperature were associated with alleviation of the effects of HT in rice genotypes with varying degrees of heat tolerance, and the response of spikelet water status to HT, involving increased total expression of aquaporins and soluble sugar content, thereby improved pollen fertility,anther dehiscence, and spikelet fertility, especially in heat-resistant genotypes. The heat-resistant genotypes N22 and SY63 may adopt different approaches to reduce heat damage.

Bulked Segregant RNA-Seq Analysis of Pollinated Pistils Reveals Genes Influencing Spikelet Fertility in Rice

Prezygotic isolation is important for successful fertilization in rice, significantly affecting yield. This study focused on F_(5:6) generation plants derived from inter-subspecific crosses(Nipponbare × KDML105) with low(LS) and high seed-setting rates(HS), in which normal pollen fertility was observed. However, LS plants showed a reduced number of pollen grains adhering to the stigma and fewer pollen tubes reaching the ovules at 4-5 h post-pollination, compared with HS plants. Bulked segregant RNA-Seq analysis of pollinated pistils from the HS and LS groups revealed 249 and 473 differentially expressed genes(DEGs), respectively. Kyoto Encyclopedia of Genes and Genomes analysis of the HS and LS-specific DEGs indicated enrichment in metabolic pathways, pentose and glucuronate interconversions, and flavonoid biosynthesis. Several of these DEGs exhibited co-expression with pollen development genes and formed extensive clusters of co-expression networks. Compared with LS pistils, enzyme genes controlling pectin degradation, such as OsPME35 and OsPLL9, showed similar expression patterns, with higher levels in HS pistils pre-pollination. Os02g0467600, similar to cinnamate 4-hydroxylase gene(CYP73), involved in flavonoid biosynthesis, displayed higher expression in HS pistils post-pollination. Our findings suggest that OsPME35, OsPLL9, and Os02g0467600 contribute to prezygotic isolation by potentially modifying the stigma cell wall(OsPME35 and OsPLL9) and controlling later processes such as pollen-stigma adhesion(Os02g0467600) genes. Furthermore, several DEGs specific to HS and LS were co-localized with QTLs and functional genes associated with spikelet fertility. These findings provide valuable insights for further research on rice spikelet fertility, ultimately contributing to the development of high-yielding rice varieties.

药隔期倒春寒对小麦主茎穗不同穗粒位结实数与粒重的影响

在大田盆栽条件下利用智能超低温光照培养箱,对烟农19(YN19,抗倒春寒性强)和新麦26(XM26,抗倒春寒性弱)两个小麦品种于幼穗分化的药隔形成期进行4h·d-1的倒春寒模拟试验。设置2℃和-2℃两个低温胁迫水平,对照(CK)为10℃,以明确不同程度倒春寒胁迫对不同抗倒春寒性品种小麦主茎穗各穗粒位结实粒数及粒重的影响。结果表明:(1)各处理主茎穗不同小穗位的结实粒数和粒重均呈先升后降的二次曲线变化。(2)倒春寒胁迫导致小麦主茎穗不同穗粒位结实粒数显著降低,且降幅随胁迫程度的加重而增大。2℃和-2℃胁迫处理下YN19主茎穗的下、中、上部小穗总粒数分别显著降低40.74%、18.75%、35.00%和70.37%、32.50%、15.00%(P<0.05);XM26分别显著降低62.50%、7.87%、20.00%和100%、42.22%、100%(P<0.05)。(3)轻度倒春寒胁迫(2℃)导致小麦主茎穗粒重降低,重度倒春寒胁迫(-2℃)下粒重反而会因穗粒数的大幅降低而有所上升。与对照相比,2℃胁迫处理下YN19主茎穗各小穗粒重降幅在2.93%~47.53%,XM26降幅为19.72%~49.96%(P<0.05);-2℃胁迫处理下YN19主茎穗各小穗粒重增幅在20.57%~60.84%,XM26增幅为1.20%~42.78%(P<0.05)。(4)倒春寒胁迫导致两品种小麦主茎穗不同小穗位总粒重较CK降低。YN19在2℃和-2℃胁迫处理下,下部和中部小穗总粒重较CK分别显著降低49.49%、28.99%和65.76%、29.47%,上部小穗在-2℃胁迫处理下总粒重较CK显著降低23.09%(P<0.05);XM26下、中、上部小穗总粒重较CK分别显著降低69.76%、28.61%、20.02%和100%、42.33%、100%(P<0.05)。综上所述,倒春寒对小麦主茎穗不同穗粒位结实粒数和粒重均会产生不利影响,对小麦穗位的危害表现为下部>上部>中部,对小麦粒位的危害表现为第3粒位>第1粒位>第2粒位。本试验分析认为,倒春寒对小麦主茎穗结实粒数的影响大于对粒重的影响,影响程度随倒春寒胁迫程度的加重而增大。无论是结实粒数还是粒重均表现为下部小穗受害程度最大,即弱势小穗和弱势粒受倒春寒影响更大。药隔期倒春寒主要通过减少主茎穗上部小穗和下部小穗的穗粒数,降低弱势粒粒重,最终导致小麦减产。综合比较,品种YN19的受害程度轻于XM26,YN19抗倒春寒能力更强,所以选用抗倒春寒性强的小麦品种是生产中降低倒春寒危害的重要措施。

秸秆全量还田对冬小麦不同小穗位和粒位结实粒数和粒重的影响

【目的】研究小麦玉米秸秆连续全量还田对小麦穗部不同小穗位和粒位结实粒数及粒重变化的影响。【方法】通过设置3年定位试验研究小麦玉米秸秆全量还田对小麦不同小穗位结实粒数、粒重的小穗位和粒位的影响效应。【结果】小麦玉米秸秆连续全量还田提高了小麦的公顷穗数、穗粒数、千粒重和产量。各处理小麦不同小穗位结实粒数、小穗重、小穗平均单粒重均呈现二次曲线变化趋势,不同粒位的粒重也随小穗位的变化呈二次曲线形式。结实小穗越多、各小穗结实粒数或单粒重差异越小,空间分布模拟曲线的弧度越平缓。秸秆还田提高了小麦主茎穗和分蘖穗的结实小穗数与小穗结实粒数,降低了不孕小穗数,且下部小穗的结实粒数增加幅度较大;秸秆还田还提高了小麦不同粒位的单粒重,以第3、4粒位提高幅度较大。【结论】小麦玉米秸秆连续全量还田提高了小麦不同小穗位的结实粒数和粒重,进而提高了籽粒产量。

水稻籼粳杂种不育性及其类型

克服栽培稻不同亚种间杂种F1的不育性是有效利用亚种间杂种优势的前提。本研究选择了籼粳两亚种不同生态型的 19个水稻品种作为试验材料 ,研究了它们之间杂种不育性的表现特点及遗传特性。试验按p×q设计进行 ,以籼稻作为母本 ,共配置了 90个籼粳交组合。调查了各组合F1的小穗育性和花粉育性。研究结果表明 :(1)各组合的小穗育性和花粉育性都存在显著的差异。 (2 )花粉育性和胚囊育性分别由不同的遗传系统所控制 ,两者共同决定小穗育性的高低。 (3)起源于我国华南的籼稻品种比具有国际稻血缘的籼稻品种与粳稻的分化更远。 (4 )根据花粉育性和小穗育性为指标的聚类分析结果可知 :本研究中 90个籼粳交F1可分为 4个类型 ,即花粉育性和小穗育性都高 ;小穗育性高 ,但花粉育性低 ;小穗育性低 ,但花粉育性高 ;小穗育性和花粉育性都低。

施氮量和穗粒肥比例对稻米营养品质及中微量元素含量的影响

通过田间试验研究了施氮量和穗粒肥比例对稻米氨基酸和蛋白质含量及Fe、Zn、Cu、Mn、Mg、Ca含量的影响。结果表明,稻米氨基酸和蛋白质含量均随着施氮量和穗粒肥比例的提高而增加,但施氮量和穗粒肥比例对氨基酸含量的影响程度因品种和氨基酸种类而异。合系39的氨基酸含量受施氮量和穗粒肥比例的影响较滇屯502的大;His、Val、Gly、Pro和Lys受施氮量和穗粒肥比例的影响较大,Ile、Arg、Asp和Glu受施氮量和穗粒肥比例的影响较小。稻米中Fe、Zn、Cu、Mn、Mg、Ca的含量和产量均随着施氮量的增加先上升后下降;从稻谷和蛋白质的产量、6种矿质元素的含量和产量看,供试粳型品种合系39的适宜施氮量较籼型品种滇屯502高。

氮素穗肥对水稻幼穗细胞分裂素和生长素浓度的影响及其与颖花发育的关系

以粳稻品种武育粳3号和2401为研究材料,在盆栽条件下,设高(HN)、低(LN)两个穗肥施氮水平,对幼穗发育过程中(颖花分化至抽穗后7d)细胞分裂素(ZRs、iPAs)和生长素(IAA)含量及其动态分别进行测定和比较分析。结果表明,幼穗发育过程中穗中细胞分裂素和生长素含量均表现先降后升的趋势,穗肥的施用(HN处理)提高了各个时期细胞分裂素的含量,尤其是颖花分化期效果最为明显。而生长素的变化情况较为复杂,从颖花分化期到花粉母细胞减数分裂期前LN处理稍高于HN处理,之后HN处理又逐渐超过LN处理。穗发育期间HN处理的ZRs/IAA和iPAs/IAA均高于LN处理,颖花分化期差距最大,随后逐渐减小,到花粉母细胞减数分裂期差异最小,抽穗时比值差距又再次扩大,两个品种表现相似。水稻氮素穗肥的施用具有延长颖花分化时间、增加每穗颖花数的作用,这可能与其提高幼穗分化期尤其是颖花分化期的细胞分裂素含量及其与生长素的比值有关。

高温下水稻开花习性对受精率的影响

以籼稻Ⅱ优7954(中等敏感)和Ⅱ优7号(耐高温)为材料采用人工气候箱在水稻抽穗开花期进行38℃高温处理,研究高温下颖花开放特性对受精率的影响。结果表明,高温下Ⅱ优7号与Ⅱ优7954花时较对照提前,Ⅱ优7号花时集中,而Ⅱ优7954花时分散;Ⅱ优7954处理温度与高温处理时间之间存在互作,随着高温处理时间延长受精率下降;高温处理时段和变温模式直接影响水稻的开花习性,对受精率的影响很大。

水稻特定位颖花结实率作为孕穗开花期耐冷性鉴定指标

以十和田与昆明小白谷的重组自交系(RIL)F8和F9群体为研究材料,在4种海拔条件下连续两年进行孕穗期耐冷性鉴定,采用方差分析、相关分析和多元逐步回归分析等方法对单株结实率与单株特定位颖花结实率间的相关性进行了研究.结果表明,单株结实率与特定位颖花结实率呈极显著相关(r=0.9011～0.7364),在低温冷害条件下,单株结实率与特定位颖花结实率间的相关系数高于无冷害条件;单株结实率和特定位颖花结实率与穗抽出度均呈极显著正相关.遗传分析表明,特定位颖花结实率可以替代单株结实率作为孕穗开花期耐冷性鉴定指标,而穗抽出度可作为孕穗开花期耐冷性鉴定的一个辅助指标.

水稻亚种间广亲和性鉴定标准的研究

对受测品种与籼、粳测验种测交 F_1的黑染花粉率与小穗结实率的分析表明,两者相关不显著,建议在广亲和性品种筛选中宜以 F_1小穗结实率作为亲本亲和性鉴定的主要指标。提出当某品种与籼、粳测验种测交 F_1的平均结实率显著高于测验种间籼粳交 F_1的平均结实率而与测验种的平均结实率无显著差异时,可视为亲和性品种;在与籼、梗广泛测交中全部或绝大多数组合的结实率都在正常水平范围内的品种,可视为广亲和性品种。本研究筛选和验证了一批亚种间杂交具有亲和性的品种:皖9024、T984、Pecos、六千辛、中国91、秀水117、L201和 Douradaprecoce。其中 T984和中国91被进一步鉴定为广谱型的亲和性品种。