Analysis of Indica-Japonica Differentiation in Rice Parents and Derived Lines Using ILP Markers

Revealing the indica-japonica differentiation in parents of hybridization between indica and japonica rice and their derived lines can provide theoretical and practical bases for the breeding of practical inter-subspecific hybrid rice. Using subspeciesspecific molecular markers ILP （intron length polymorphism） and Cheng＇s index, the indica-japonica differentiation was analyzed with special materials including 18 indica-japonica hybrid parents and 39 derived lines, which accumulated different wide compatibility and restoring genes by convergent cross method in 21 years spanning four breeding phases. The indica-japonica differentiation was detected on all tested loci in 57 materials. Among the 18 parental lines, 4 were japonica type, 5 japonicaclinous type, 8 indicaclinous type and one indica type. The japonica proportion indexes in indica restorer lines Minghui 63 and 9308 were 12.50 and 33.33 %, respectively, while that in japonica restorer line C418 was only 31.25%. Among the 39 derived lines from indica-japonica hybridization, one was japonica type, 11 japonicaclinous type, 20 indicaclinous type and 7 indica type. The japonica proportion index in Minghui 502 was only 10.42%. The results of indica and japonica classification by ILP molecular markers and Cheng＇s index were relatively consistent. The correlation coefficient between the japonica proportion index and morphology index was 0.794＊＊, while that between the indica proportion index and morphology index was -0.7662＊＊. ILP markers could be used to accurately detect the proportion of indica/japonica content in the genome of a rice variety. The results of indica-japonica differentiation analysis could make reasonable explanation for that the hybrids obtained from indica-japonica type restorer lines had obvious heterosis. This conclusion would provide important guidance in efficient use of beneficial genes of inter-subspecific hybrid rice.

A Preliminary Study on the Relationship Between the Indica-Japonica RAPD Differentiation of Parents and Heterosisin Dian Type Hybrid Rice

The relationship between the indica-japonica differentiation of parents and heterosis of hybrid in rice was studied with 10 sterile lines, 10 maintainer lines of the sterile lines, 38 restorer lines of Dian type hybrid rice and 40 hybrids derived from the sterile lines and restorer lines. The results indicated that there was a parabolic correlation between the indica-japonica differentiation of parents detected by RAPD markers and heterosis of hybrid rice. When certain indica-japonica differentiation of parents exists, the percentage of combinations with positve heterosis and the mean heterosis of hybrids were high. But that didn't mean too much difference of parents could lead to stronger hetesosis, that meant overdiffernt parents seldom bring positve het-erotic hybrids. Suitable difference of percent of indica alleles of parents of stronger heterotic hybrid was 12 -16%.

Relationship of Parental Indica-Japonica Indexes with Yield and Grain Quality Traits of Japonica Hybrid Rice in Northern China

Taking the main parents （10 male sterile lines and 10 restorer lines） and their 100 combinations of japonica hybrid rice in northern China as materials, the relationships of parental indica-japonica indexes determined by the methods of the Cheng’s index as well as simple sequence repeat （SSR） markers with yield and grain quality traits of hybrid rice were studied. For the parents, the Cheng’s index （Chi） ranged from 13.5 to 19.3 and the indica index in SSR markers （ADi） were from 0.12 to 0.38. The classification of parents by Chi was not completely consistent with that by ADi. The Chi of male parent was more closely related to hybrid traits than that of female parent, as contrasted to ADi. At the same time, the difference between parents （PD） in Chi was more closely related to hybrid traits than that in ADi. The indica-japonica indexes of parents and their difference between parents appeared quadratic relationship to hybrid traits with the critical extremum. The directions of the correlation of indica-japonica indexes of parents and their differences with hybrid yield traits were on the opposition to those with hybrid grain quality traits. Therefore, the female parent should match the male parent moderately in indica-japonica index to obtain the optimum of hybrid traits, high yield as well as good quality.

Effects of chilling tolerance induced by spermidine pretreatment on antioxidative activity,endogenous hormones and ultrastructure of indica-japonica hybrid rice seedlings

Spermidine（Spd） is known to be involved in the regulation of plant responses to chilling stress and counteract the adverse effect of stress conditions.Antioxidant activities,endogenous hormones and ultrastructure change under chilling stress were investigated in indica-japonica hybrid rice seedlings.12-d-old seedlings were subjected to exogenous Spd（1 mmol L^（-1）） and then a chilling stress（6℃,4 d） was induced,followed by a subsequent recovery（25℃,4 d）.Results showed that malondialdehyde（MDA） and proline content were enhanced significantly,whereas shoot fresh and dry weights decreased during chilling stress and after recovery;chlorophyll content of chilling-stressed seedlings increased slightly but declined after recovery;additionally,total soluble sugar,sucrose,fructose and starch contents increased significantly during chilling stress,and only soluble sugar and fructose contents were observed in increase after recovery;chilling stress-induced increases in superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT） activities,but declined after recovery,and the level of ascorbate peroxidase was lower during chilling stress and after recovery;however,endogenous indole-3-acetic acid（IAA）,zeatin riboside（ZR）,gibberellic acid（GA_3）,and abscisic acid（ABA） levels were induced decreased compared with Spd pretreatment.The microscopic analysis revealed that chilling stress-induced destruction of the chloroplast envelope during chilling stress and increased the number of plastoglobuli along with aberrations in thylakoid membranes after recovery.In contrast,exogenous Spd protected rice seedlings from chilling-induced injuries in terms of lower malondialdehyde,proline and carbohydrates accumulation coupled with increased endogenous hormones metabolism.After recovery,Spd pretreatment chilling-exposed seedlings showed higher activities of antioxidant enzymes and normal physiological function of chloroplasts.These results suggest that Spd could promote effectively chilling tolerance which might be largely attributable to the integrity of cell structure and normal metabolism of endogenous hormones in indica-japonica hybrid rice seedlings.

SSR Marker Analysis on indica-japonica Differentiation of Natural Population of Oryza rufipogon in Yuanjiang, Yunnan Province

By using 19 pairs of primers that could identify two subspecies （indica and japonica） of cultivated rice （Oryza sativa L.）, the indica-japonica differentiation of 56 individuals from the natural population of common wild rice （Oryza rufipogon Griff.） in Yuanjiang was analyzed by SSR （microsatellite DNAs, or simple sequence repeat）. Of the 19 pairs of primers, 17 pairs （89.47%） could amplify only one kind of band type among all of the individuals, but primers RM251 and RM18 could amplify polymorphic band types. The bands amplified by 16 pairs of primers （84.21%） were identical to the indica-japonica diagnostic bands of relevant locus in cultivated rice, including 11 japonica-like loci and 4 indica-like loci. The bands amplified by the other three pairs of primers （RM18, RM202, RM205） were different from indica or japonica diagnostic bands of cultivated rice. The results showed that according to 19 loci analyzed, 84.21% of SSR loci in genomic DNA of common wild rice in Yuanjiang displayed indica-japonica differentiation and 13.79% of the loci still kept primitive, and most of the detected loci were homoaenetic in the natural population.

Studies on the Growth Habits and Characteristics of Two Polyploid Indica-Japonica Hybrid Rice with Powerful Heterosis

Based on a series of polyploid indica-japonica hybrid plant lines obtained from a new breeding strategy of using double predominance of wide cross and polyploidization to breed super flee, two polyploid indica-japonica hybrids, PSR073 and PSR120 were studied in their growth periods to show the powerful heterosis in a larger scale and to study the characteristics of polyploid indica-japonica hybrids more elaborately. The leaf age, tiller growth, flowering habits, and agronomic traits of them were observed to analyze their growth habits and characteristics. The results showed that the.agronomic traits of PSR073 and PSR120, such as the plant height, panicle length, grain length, grain width, and 1000-grain weight, all acquired obvious predominance of polyploidy, and that the seed setting rate was more than 83%. No significant difference was observed between the two tetraploids and common diploids in the leaf age, tiller growth, and flowering habits. It was concluded that the characteristics of the two powerful heterosis polyploid hybrids were different from those of the polyploid rice reported earlier. Wide cross and polyploidization had no negative effects on their growth habits and characteristics; on the contrary these had powerful heterosis. This had provided theoretic and practical evidences for their application to agricultural production.

Developmental Analysis of Genetic Behavior of Brown Rice Width in indica-japonica Hybrids

The developmental genetic behaviors of brown rice width （BRW） have been studied in indica-japonica hybrid rice （Oryza sativa L.）, in which seven indica male sterile lines and five japonica restorer lines were applied, by using the developmental genetic models and corresponding statistical approaches for quantitative traits of triploid in cereal crops. The BRW of indica-japonica hybrid rice was co-determined by gene expression of tdploid endosperm, cytoplasm, diploid maternal plant and their genotype × environmental interaction effects. Unconditional analysis showed that the endosperm additive and matemal additive effects were predominant for the development of BRW from early- to late-stage of the grain development, but the endosperm dominant effect together with matemal effect and cytoplasmic effect became the major factor determing the BRW at the ripening stage. Moreover, conditional analysis found that there were new onset and offset of gene expression at different developmental stages of BRW in indica-japonica hybrid rice. Maternal and cytoplasm general heritabilities and their interaction heritabilities were more important compared to other components of heritability for BRW at all the five developmental stages.

Genetic Analysis of Leucine Content in Indica-Japonica Hybrid Rice (Oryza sativa L.)

Genetic control of leucine content in indica-japonica hybrid rice (Oryza sativa L.) was studied in 35 crosses of F1 and F2 generations, which were derived from crossing 7 male sterile indica rice lines with 5 restorer japonica rice lines along with their parents. Two genetic models and their corresponding statistical methods for quantitative traits of triploid seeds in cereal crops were used for the analysis. The first was the unconditional genetic model, which refers to the analysis of cumulative measurements (from flowering to a specific time) along the developmental stages, while the second was the conditional genetic model, which relates to analysis from one developmental stage to another stage (t - 1→t). The results showed that leucine content of indica-japonica hybrid rice was controlled by the expression of triploid endosperm effect (endosperm additive effect and endosperm dominant effect), cytoplasm effect, diploid maternal plant effect (maternal additive effect and maternal dominant effect) and their environmental interaction effects. Of these effects, endosperm dominant effect and maternal dominant effect were more important at the earlier stages, while endosperm additive effect and maternal additive effect were more important at the later stages of rice grain development under both unconditional and conditional genetic analyses. Due to the high heritabilities, which came from endosperm, maternal and cytoplasm effects for leucine content at different developmental stages, selection for leucine content of indica-japonica hybrid rice would be more efficient at early generations in breeding programs.

Assessing indica-japonica differentiation of improved rice varieties using microsatellite markers

To assess the indica-japonica differentiation of improved rice varieties, a total of 512 modem varieties including 301 indica and 211 japonica accessions were analyzed using 36 microsatellites. The Fst coefficients ranged from 0.002 to 0.730 among the loci with an average of 0.315. Significant differentiation was detected at 94.4% of the loci studied （P 〈 0.05, pairwise Fst tests）, indicating that there was a high level of indica-japonica differentiation within the improved varieties. At 18 loci, about 74%-98% of the alleles of indica and japonica accessions were distributed in two ranges of amplicon length. Linkage disequilibrium analysis showed that the distribution trends were significantly nonrandomly associated. Using the differentiation trends at the 18 loci, microsatellite index （MI） was proposed for discrimination of the two subspecies. When rice accessions with MI value greater than zero were classified as indica, and those with MI value smaller than zero were classified as japonica, about 96.1% of the accessions could be classified. This result agrees with the classification based on morphological-physiological characters, indicating that this method is feasible and effective.

Differentiation of Indica-Japonica rice revealed by insertion/deletion(InDel)fragments obtained from the comparative genomic study of DNA sequences between 93-11(Indica)and Nipponbare (Japonica)

DNA polymorphisms from nucleotide insertion/deletions(InDels)in genomic sequences are the basis for developing InDel molecular markers.To validate the InDel primer pairs on the basis of the comparative genomic study on DNA sequences between an Indica rice 93-11 and a Japonica rice Nipponbare for identifying Indica and Japonica rice varieties and studying wild Oryza species,we studied 49 Indica,43 Japonica,and 24 wild rice accessions collected from ten Asian countries using 45 InDel primer pairs.Results indicated that of the 45 InDel primer pairs,41 can accurately identify Indica and Japonica rice varieties with a reliability of over 80%.The scatter plotting data of the principal compo-nent analysis(PCA)indicated that:(i)the InDel primer pairs can easily distinguish Indica from Japonica rice varieties,in addition to revealing their genetic differentiation;(ii)the AA-genome wild rice species showed a relatively close genetic relationship with the Indica rice varieties;and(iii)the non-AA genome wild rice species did not show evident differentiation into the Indica and Japonica types.It is con-cluded from the study that most of the InDel primer pairs obtained from DNA sequences of 93-11 and Nipponbare can be used for identifying Indica and Japonica rice varieties,and for studying genetic relationships of wild rice species,particularly in terms of the Indica-Japonica differentiation.

Two sequence alterations,a 136 bp InDel and an A/C polymorphic site,in the S5 locus are associated with spikelet fertility of indica-japonica hybrid in rice

The rice indica/japonica hybrid shows strong heterosis.However,such inter-subspecific hybrid can＇t be directly used in rice production due to its low spikelet fertility.The S5 locus was proved to be associated with fertility of indica/japonica hybrid and its S5n allele from wide-compatibility variety （WCV） is capable to overcome fertility barrier.In the present study,we reported the causal sites in the S5 locus responsible for compatibility of indica/japonica hybrid.Fine-mapping of the S5 locus using the 11 test-cross families pinpoints a candidate S5 locus encoding aspartic protease （Asp）.Intragenic recombination within the Asp gene happened in a number of recombinants,resulting in chimeric S5j-S5n alleles.Just like S5n,the chimeric S5j-S5n allele displayed higher spikelet fertility when combined with the S5i allele.In the complementary test,however,the S5n allele from WCVs failed to enhance fertilities of the indica/japonica hybrids.Compared to both indica and japonica varieties,all nine WCVs from different resources are characterized with a 136 bp deletion in the Asp N-terminus,which probably renders the S5n allele non-functional.Furthermore,an A/C polymorphic site is detected 1,233 bp downstream of the Asp start codon.The heterozygous A/C site of the Asp gene in indica/japonica hybrid is believed to be the casual factor to cause partial sterility.The functional makers based on the two polymorphic sites will be broadly used in developing wide-compatibility rice varieties.

超高产优质早熟籼粳杂交稻浙优915的选育与栽培技术

高产与优质是水稻产业的关键性目标,然而这2个性状存在明显的矛盾,运用常规育种技术在同一品种上集聚2个性状非常困难。本研究团队采用分子育种技术与籼粳杂种优势利用方法相结合,成功选育出超高产优质早熟籼粳杂交稻浙优915。该品种在区域试验和生产试验中,表现出超高产潜力。稻米品质符合食用稻部标三等,评价指标中除碱消值外,其余指标符合部标一等。全生育期为146.5~156.5 d,比嘉优5号早熟0.3~0.9 d。2023年通过国家品种审定,适宜在浙江、上海、安徽、湖北、苏南等南方粳稻种植区推广应用。根据浙优915品种特性,提出提高有效穗数和增加每穗粒数的关键性高产栽培技术。

不同灌溉模式对籼粳杂交稻甬优1540产量与水分利用效率的影响

旨在探讨不同灌溉模式对籼粳杂交稻甬优1540产量与水分利用效率的影响,并阐明其相关生理基础。本研究以甬优1540为材料,设置了3种灌溉模式,即长淹灌溉(continuous flooding,CF)、轻度干湿交替灌溉(alternate wetting and moderate drying, AWMD)以及重度干湿交替灌溉(alternate wetting and severe drying, AWSD)。研究结果表明,与CF相比, AWMD与AWSD均能显著提高水分利用效率,增幅分别为22.6%~25.6%与18.2%~23.1%;AWMD可以显著提高水稻产量,增幅为8.6%~10.0%,而AWSD则显著降低水稻产量,降幅为6.0%~7.5%。与CF相比, AWMD显著降低了拔节期水稻的茎蘖数、地上部干物质重、叶面积指数、移栽至齐穗期的光合势以及移栽至拔节期的作物生长速率,但显著提高了茎蘖成穗率、拔节至齐穗期的作物生长速率、主要生育期水稻根长密度、深根比、比根长、根系总吸收表面积与活跃吸收表面积,以及灌浆后2次土壤复水期的剑叶净光合速率、根系氧化力、根系与叶片中玉米素和玉米素核苷(Z+ZR)含量、籽粒中蔗糖-淀粉代谢途径关键酶活性等指标。以上结果表明, AWMD可以协同提高甬优1540产量与水分利用效率,优化根-冠生长发育特征,提高灌浆期植株生理活性,实现高产与水分高效利用,为本研究最佳水分管理模式。

甬优籼粳杂交稻作再生稻种植的再生特性及产量形成分析

为探究甬优籼粳杂交稻作再生稻种植时的再生特性及产量形成特点,以生产上应用广泛的甬优籼粳杂交稻品种甬优1540和甬优4949为试验材料、籼型杂交稻品种隆两优534为对照材料作再生稻种植进行了田间试验。结果显示:籼粳杂交稻和籼型杂交稻2个类型品种的再生特性存在显著差异;籼粳杂交稻甬优1540和甬优4949的优势再生节位为低节位的倒5节和倒4节,2个节位的再生苗有效穗占比之和分别为81.9%和68.9%,产量贡献率之和分别为89.6%和72.5%;2个节位再生稻的穗长、每穗粒数显著高于倒3节和倒2节,并呈现出从下往上节位逐步变小的趋势;而籼型杂交稻品种隆两优534的优势再生节位则是高节位的倒2节和倒3节,2个节位的有效穗占比和产量贡献率之和分别为71.5%和72.5%;甬优4949头季稻收割后1~7 d内的再生苗的成穗率、有效穗占比和产量贡献率分别为89.4%、74.6%和79.2%,均显著高于收割后8~12 d和12 d以上的再生苗;甬优1540和甬优4949再生稻的穗长、每穗粒数均要显著大于隆两优534,产量分别增产21.6%和17.3%。结果表明甬优籼粳杂交稻的低节位强再生力和再生苗穗大粒多的再生特性是其作再生稻种植时易获得高产的主要因素。

水稻籼粳中间型杂交组合若干性状的遗传效应分析

【目的】水稻籼粳亚种间杂交具有强大的杂种优势已成为当前水稻育种关注的焦点,本研究旨在为籼粳交水稻育种实践以及水稻关键性状的遗传研究提供理论依据。【方法】按照NC-II不完全双列杂交方式,选择14个亲本材料并配组48个杂交组合,采用植物数量性状的加性-显性遗传模型(A-D模型)分析生育期、株高与粒形相关性状等共计5个农艺性状的遗传效应、杂种优势及性状之间的相关性。【结果】籼粳亚种间杂交稻生育期、株高、粒长、粒宽及长宽比等的加性方差分量占遗传主效应比率(V_(A)/V_(P))比值分别为69.2%、 74.2%、 58.9%、66.0%和63.5%。广义遗传率(H^(2)B)和狭义遗传率(H^(2)N)的变幅分别为59.0%~99.6%和69.2%~98.9%,均达显著或极显著水平,主要受加性效应控制,且受环境影响小,在育种上早期选择有效。大多数的籼粳亚种间杂种一代的生育期、株高和粒形性状均呈负向中亲优势和负向超亲优势,杂交后代的生育期缩短、株高降低,长宽比介于双亲之间。籼粳亚种间杂交稻生育期是一个独立遗传的品种特性,株高与粒形具呈显著正相关。【结论】在籼粳交育种上应关注生育期、株高,粒形等性状间的协调,有效利用杂种优势,培育强优势亚种间杂交稻新组合。

优质高产籼粳杂交稻嘉禾优7245的选育及制种技术

嘉禾优7245是中国水稻研究所联合嘉兴市农业科学研究院等多家单位,以嘉禾212A(长粒型粳稻三系不育系)为母本与中恢7245(中籼迟熟型恢复系)为父本选育的三系杂交水稻新组合。该组合具有高产、优质、抗倒伏等优势,于2017年7月通过国家审定(国审稻20170064),2020—2022年先后通过了广西壮族自治区(桂审稻2020220号)、广西壮族自治区晚稻(桂审稻2022093号)、江西省(赣审稻20210016)的品种审定,2022年通过福建省:(闽)引种〔2022〕第1号的引种备案,适宜在长江中下游地区作中、晚稻种植。文章介绍了嘉禾优7245的选育过程、特征特性、高产栽培及制种技术等。

优质高产籼粳杂交稻嘉丰优3号的选育及制种技术

嘉丰优3号是嘉兴市农业科学研究院联合中国水稻研究所、浙江可得丰种业有限公司,以嘉禾112A(长粒型粳稻三系不育系)为母本与G1143(中籼迟熟型恢复系)为父本选育的三系杂交水稻新组合。该组合具有高产、优质、中抗稻瘟病等优势,于2021年4月通过浙江审定(浙审稻2021019),2021—2023年先后通过了江西省[(赣)引种〔2021〕第001号]、安徽省(皖引稻2021066)、福建省[(闽)引种〔2022〕第1号]、湖北省(鄂引种2022055)的引种备案,适宜在长江中下游地区作中稻种植。文章介绍了嘉丰优3号的选育过程、特征特性、高产栽培及制种技术等。

基于基因芯片的嘉禾系列长粒优质食味粳稻综合评价与比较

【目的】嘉禾系列长粒粳稻粒型(细)长,外观品质突出,食味优良,丰产性与主栽品种相近,抗病性较好。本研究旨在明确嘉禾系列长粒粳稻品种的特点与存在问题,解析嘉禾系列长粒粳稻品种优质性状形成的遗传基础,为长粒粳稻品种创新利用提供依据。【方法】以5份嘉禾系列长粒粳稻品种(系)为材料,利用GSR40K水稻高密度芯片分析品种籼粳属性、相似度,鉴定育种相关功能基因,同时比较嘉禾系列长粒粳稻品种(系)与东北长粒粳稻稻花香2号遗传基础差异。【结果】嘉禾系列长粒粳稻品种(系)和稻花香2号基因组中,粳稻区段数占比84.20%~88.38%,均为典型粳稻类型;嘉禾系列长粒粳稻品种(系)间遗传相似度超过92%,基因组相似度为77.59%~91.73%,与稻花香2号遗传相似度为84.55%,基因组相似度为49.52%~53.68%;嘉禾系列长粒粳稻含有长粒优势功能基因gs3和GW7,嘉禾香1号还含有大粒型基因qSW5/GW5和多穗粒数基因LAX1;嘉禾系列品种的品质性状形成主要是ALK^(c)/Wx^(b)/OsAAP6等优势功能基因组合所致,嘉禾香1号香味是由Badh2第2外显子突变所致;嘉禾系列长粒粳稻品种(系)含有较多的抗稻瘟病基因,如抗病基因组合Pizt+Pii/HIT7/pi5-1、Pizt+Pi-ta、Pizt+Pii/HIT7/pi5-1+Pi-d2/Pid2+Pid3+Pi-ta,抗白叶枯基因只有Xa26/Xa3。【结论】嘉禾系列长粒粳稻食味优、丰产稳产、抗病抗逆的突出优点,是品种含有较多的产量、品质、抗性、株型、生育期等优势等位基因变异综合影响的结果,但也存在品种相似度较高、白叶枯抗性基因单一的不足。本研究结果也为后续嘉禾系列长粒粳稻品种遗传改良提供了依据。

安徽省稻米品质综合评价方法研究

为定量化评价稻米品质综合性状,利用安徽省2008—2021年中籼和中粳水稻区域性试验稻米品质资料,根据食用稻品种品质行业标准,以整精米率、垩白度、透明度、碱消值、胶稠度、直链淀粉含量作为稻米品质评价指标,采用分级赋值、线性加权求和等方法以及计算机数值模拟技术,确定中籼和中粳稻米品质各项评价指标权重系数,并构建稻米品质指数(rice quality index,I_(RQ),中籼和中粳稻米品质指数分别用I_(RQ1)和I_(RQ2)表示)以及中籼和中粳稻米品质综合评价方法。结果表明,中籼稻米品质评价指标中整精米率、垩白度、透明度、碱消值、胶稠度、直链淀粉含量权重系数分别为0.20、0.26、0.06、0.22、0.10、0.16,中粳稻米中分别为0.23、0.28、0.10、0.08、0.15、0.16,其中垩白度是影响中籼和中粳稻米品质的主要因素。中籼优质稻米一至三等和普通稻米对应的稻米品质指数阈值分别为:I_(RQ1)≥3.94、3.94>I_(RQ1)≥3.47、3.47>I_(RQ1)≥3.17、I_(RQ1)<3.17,中粳优质稻米一至三等和普通稻米对应的品质指数阈值分别为:I_(RQ2)≥3.82、3.82>I_(RQ2)≥3.33、3.33>I_(RQ2)≥3.04、I_(RQ2)<3.04。经验证,构建的中籼和中粳稻米品质综合评价方法对于安徽省多品种样本检验的准确率分别为81.4%和80.0%,单品种样本检验的准确率分别为85.7%和92.9%;对于其他部分省份多品种样本检验的准确率均在80%以上,该方法可用于不同区域中籼和中粳稻米综合品质的定量化评价。

江苏省滨海盐碱地籼粳杂交稻产量优势形成特征

旨在探明滨海盐碱地大田条件下籼粳杂交稻产量优势形成特征。2021—2022年,在江苏省滨海盐碱地择取中度盐碱地(medium saline-alkali soil,MS,土壤电导率平均2.7 dSm^(-1))和重度盐碱地(high saline-alkali soil,HS,土壤电导率平均7.2 dSm^(-1))两类典型田块,以籼粳杂交稻(甬优2640和甬优4949)、常规粳稻(南粳9108和淮稻5号)、杂交籼稻(丰优香占和Y两优372)3种类型水稻品种为试材,探究实地条件下盐胁迫对不同类型品种产量及其形成特征的影响。与中度盐碱地相比:(1)重度盐碱地下各类型品种的穗数、每穗粒数、结实率和千粒重均显著低于中度盐碱地。中度和重度盐碱地下,籼粳杂交稻的产量均显著高于常规粳稻和杂交籼稻,这主要是由于其较高的每穗粒数。(2)重度盐碱地下各类型品种关键生育期(拔节、抽穗和成熟期)的群体茎蘖数及茎蘖成穗率均显著下降。中度和重度盐碱地下,常规粳稻和杂交籼稻关键生育期的群体茎蘖数及茎蘖成穗率均高于籼粳杂交稻。(3)重度盐碱地下各类型品种关键生育期的干物重均显著下降。中度及重度盐碱地下,籼粳杂交稻抽穗期和成熟期干物重、拔节期—抽穗期和抽穗—成熟期作物生长速率均显著高于常规粳稻和杂交籼稻。重度盐碱地下各类型品种的收获指数呈上升趋势。籼粳杂交稻在重度盐碱地下的收获指数高于常规粳稻和杂交籼稻。(4)重度盐碱地下各类型品种关键生育期的叶面积指数、播种期—拔节期、拔节期—抽穗期和抽穗期—成熟期光合势均显著下降。中度和重度盐碱地下,籼粳杂交稻成熟期叶面积指数和抽穗期—成熟期光合势均显著高于常规粳稻和杂交籼稻,抽穗期—成熟期叶面积指数衰减率则呈相反趋势。(5)重度盐碱地下各类型品种株高、上三叶叶长和叶宽、叶片SPAD值和光合速率均显著下降。中度和重度盐碱地下,籼粳杂交稻上三叶叶长和叶宽、叶片SPAD值和光合速率均高于常规粳稻和杂交籼稻。本研究结果表明,滨海盐碱地实地条件下,盐胁迫显著影响水稻产量及其形成特征。与常规粳稻和杂交籼稻相比,籼粳杂交稻在滨海盐碱地仍具有较高的产量优势,这主要得益于其较高的每穗粒数;此外,较高的作物生长速率、较大的上三叶叶面积及其较强的叶片持绿性也是籼粳杂交稻在滨海盐碱地具有较好产量优势的重要特征。