四川不同生态区高产栽培条件下的杂交籼稻的稻米品质

郫县、汉源、射洪、邻水是四川具代表性的4个生态区,郫县位于成都平原区,土壤肥沃但受弱光限制;汉源位于攀西高海拔地区,温光充足;射洪位于川中丘陵区,受地形制约而气温日差较小;邻水则位于川东丘陵区,水资源缺乏且受干旱等灾害制约。本文以位于这4个典型生态区实施的水稻高产示范片为研究对象,分别对4个生态区及各生态区不同栽培方式、不同高产水平的杂交籼稻稻米碾米品质、外观品质、蛋白质含量、直链淀粉含量及淀粉RVA谱特征值进行比较研究。结果表明:(1)生态条件与稻米品质有密切关系,受气温和土壤肥力影响较大,郫县的稻米品质最优,邻水相对较劣;齐穗前后气温略高及较高的土壤全氮、全钾、速效磷含量有利于高碾米品质的形成;土壤全磷含量的降低可显著增加米粒长宽比;灌浆成熟期的高温会增加稻米的垩白粒率和垩白度,而土壤速效磷含量高则有利于降低垩白粒率和垩白度;灌浆结实期的高温也会降低稻米蛋白质含量;直链淀粉含量随土壤有机质含量的升高而升高;峰值黏度与土壤全钾含量显著负相关,崩解值与土壤全钾、速效磷显著负相关,还与齐穗前8~21 d的日最高气温显著正相关,回复值、峰值时间与齐穗前14~21 d日最高气温、抽穗至成熟期日最高气温呈显著或极显著负相关,与土壤碱解氮呈显著正相关。(2)各栽培方式间,机直播的碾米品质较优,优化定抛的直链淀粉含量较高,而机插的峰值黏度、崩解值较高,消减值较低,蒸煮食味品质较好。(3)高产及超高产田块的碾米品质整体较优,而外观品质和蒸煮食味品质相对较差。本研究可为四川杂交中籼稻高产优质栽培技术提供理论参考。     

美国稻在水稻杂种优势利用中的地位

对１３个美国稻（Ａ）与籼稻（Ｈ）、粳稻（Ｋ）的Ｆ１杂种优势的研究结果表明，Ａ×Ｈ的各性状的杂种优势与Ｋ×Ｈ（亚种间）比较一致，但一般稍低于Ｋ×Ｈ，单株产量、单株穗数和主穗颖花数优势较强，且是可利用的杂种优势，株高也有较强的优势，但是非利用的杂种优势，单株产量的优势大小与美国稻的亲和性有密切关系；在Ａ×Ｋ中，单株产量和单株穗数有较强的杂种优势，表现了与Ｋ×Ｋ较一致的趋势。千粒重无论在Ａ×Ｈ或Ａ×Ｋ中都表现了较低的正向优势。另外，根据试验结果提出了美国稻中的广亲和品种（ＷＣＶＳ）与籼稻杂交或美国稻与粳稻杂交均为水稻杂优利用中较好的高产组合模式，其中Ａ×Ｋ更为切实可行。     

穗重差异型两系法杂交水稻灌浆期若干源库指标动态变化的比较

从单茎水平上比较了重、中、轻3种不同穗重型两系法杂交水稻灌浆期若干源库及其相互关系指标的动态差异.结果表明,相时于中、轻型两系法杂交稻,重型具有如下特点:单穗粒多、实粒数多、千粒重重、单茎库容量大;抽穗后叶绿素含量前期高、中期衰减慢、后期较迅速;籽粒灌浆速度快,持续期长;抽穗后前期比叶重大,后期持续缓慢衰减;粒叶比高、物粒比和颖花茎鞘重较低.     

Suppressing Weeds in Direct-seeded Lowland Rice: Effects of Methods and Rates of Seeding

High weed infestation is a major constraint to widespread adoption of direct seeding of rice (Oryza sativa L.) The experiments were conducted in 1998 wet and 1999 dry seasons in the Philippines to examine the effects of seeding methods and rates on suppressing weeds in direct-seeded lowland rice. Treatments consisted of four seeding methods: conventional and modified broadcast seeding, drill seeding with east–west and north–south row orientations; three seeding rates: 40, 80 and 160 kg seed ha⁻¹ as well as two weed control levels: weed control with herbicide and no weed control. Among the seeding methods drill seeding with east–west row orientation had the lowest rice grain yield loss caused by weeds (38 % in the wet and 20 % in the dry season), whereas the highest losses because of weeds were observed with conventional broadcast seeding (59 % in the wet and 27 % in the dry season). Seeding rate was inversely correlated to weed interference. Severe rice yield reduction (71 %) caused by weeds was found at a seeding rate of 40 kg seed ha⁻¹ in the wet season. Using seeding rates of 80 and 160 kg seed ha⁻¹, respectively, lowered yield loss to 47 and 26 % in the wet season, 32 and 18 % in the dry season. Therefore suitable method and/or rate of seeding can significantly suppress weeds in direct-seeded lowland rice.     

Comparison of fertility between the F1, F2 and anther derived lines in the crosses of indica/japonica and japonica/indica in rice (Oryza sativa L.)

Summary Response of anthers in in vitro culture was examined in the indica-japonica hybrids of rice (Oryza sativa L.). Significant genotypic differences were observed for callus induction and regeneration among the different interracial hybrids of indica-japonica races. Induction frequency of haploids ranged from 57.7 to 72.9 per cent and doubled haploid androgenic lines ranged from 27.1 to 42.3 per cent in the anther culture of the different hybrids. The indica-japonica hybrids recorded partial pollen grain and spikelet fertility in F1 (29.9 to 41.5% and 19.4 to 48.7% respectively) as well as in F2 (42.7 to 50.6% and 37.1 to 54.4% respectively). In contrast, the androgenic doubled haploid lines recorded significant increase and the pollen grain and spikelet fertility was 76.3 and 78.6 per cent respecitively. The results suggested that the sterility barriers for realising genetic recombinants and fixation of fertile homozygous lines in indica-japonica hybridization programme could be overcome through F1 anther culture technique.Abbreviations BAP Benzyl Amino Purine - 2,4-D 2,4-Dichlorophenoxy acetic acid - MS Murashige & Skoog medium - IAA Indole Acetic Acid     

Genetics of fertility restoration of ‘Wild Abortive’ cytoplasmic male sterility in rice,Oryza sativa L.

Summary Genetics of fertility restoration in six varieties and breeding lines of rice was studied in Wild Abortive cytoplasmic genetic male sterility system using cytoplasmic male sterile lines V 20 A and IR 54752 A. Fertility evaluation of the plants in F₂ and testcross populations of the crosses of V 20 A with PR 103, PR 106 and PAU 502-94-1, and IR 54752 A with PAU 1124-36-1 and PAU 1126-1-1 revealed that fertility restoration in PR 103, PR 106, PAU 502-94-1, PAU 1124-36-1 and PAU 1126-1-1 was controlled by two independently segregating dominant genes. The two genes appeared to have additive effects; one of them being stronger than the other in imparting fertility restoration. Data on spikelet fertility of the plants in F₂ and testcross populations of V 20 A/UPR 82-1-1 cross showed that fertility restoration in UPR 82-1-1 was controlled by two independently segregating dominant genes which exhibited recessive epistatic interaction.

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A DNA Probe for Rapid Screening of Sugar Beet (Beta vulgaris L.) Carrying Extra Chromosomes from Wild Beets of the Procumbentes Section

Genes from wild species of the Procumbentes section can be transferred to sugar beet chromosomes via translocations. Since large translocations, including for example a gene for nematode resistance, generally result in meiotic disturbances, there is a need to select new diploid resistant beets from progenies of monosomic wild beet addition lines. A dispersed repetitive DNA probe, which is closely correlated with the resistance gene and hybridizes exclusively with wild beet DNA, appears to be highly superior to selection based on isozyme markers. Characteristic ‘fingerprints’ on the available monosomic addition lines reveal the existence of at last 5 different chromosomes in the wild species each housing a gene for nematode resistance. This probe can be used advantageously to identify individuals carrying the intact or fragmented wild beet chromosomes, or even various amounts of translocated chromatin. Strategies are discussed for the identification of new translocation types using straightforward squash dot or Southern hybridization techniques in combination with the wild beet DNA probe.     

Chromosome localisation of genes for resistance to Heterodera schachtii, Cercospora beticola and Polymyxa betae using sets of Beta procumbens and B. patellaris derived monosomic additions in B. vulgaris

Beet cyst nematodes (BCN, Heterodera schachtii), Cercospora beticola, and rhizomania, caused by the beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae, are the most serious diseases of sugar beet ( Beta vulgaris subsp. vulgaris). The wild Beta species of section Procumbentes are known to be completely resistant to H. schachtii, C. beticola and P. betae. Alien monosomic additions (2n=19), plants of cultivated beet (2n=18) carrying different individual chromosomes of B. procumbens (2n=18) or B. patellaris (2n=36), were tested in greenhouse experiments for resistance to these pathogens. Gene(s) conferring full resistance to the beet cyst nematode in B. patellaris are located on chromosome 1.1, and the other tested chromosomes of B. patellaris are not involved in the expression of resistance. Artificial inoculation under greenhouse conditions, with in vitro produced inoculum of C. beticola and spot-percentage rating of the disease intensity, showed that the high level of resistance that was observed in the wild species B. procumbens and B. patellaris was not found in any of the monosomic additions tested. It was suggested that genes on various chromosomes of the wild species are needed to express full resistance, and that the chromosomes of group 7 of B. patellaris and chromosome 7 of B. procumbens have the largest effect. The greenhouse tests for resistance to P. betae in B. patellaris derived monosomic additions showed that the addition families of group 4.1 have a strong partial resistance, while the addition families of group 8.1 appeared to be completely resistant to the pathogen. Resistance to P. betae in the two wild species as well as in the two resistant addition types did not exclude infection with BNYVV, but resulted in a considerable reduction of the virus concentration. It was concluded that resistance to the vector would complement virus resistance, and may provide a more effective and durable control of rhizomania. This revised version was published online in July 2006 with corrections to the Cover Date.     

南方稻区早籼区试品种产量分析及育种刍议

通过对“六五”至“八五”期间南方稻区早籼区论资料分析表明，南方稻区早籼育种取得了明显进展，产量水平大约每5年提高4％～6％。产量水平得以提高的主要因素是每穗粒数和粒重的增加。但优质品种产量水平偏低，其主要原因是粒重偏低。     

Orientation and integration of the classical and molecular genetic maps of chromosome 11 in rice

Summary The classical genetic map and molecular map of rice chromosome 11 were oriented to facilitate the use of these maps for genetic studies and rice improvement. Three morphological markers (d-27, z-2, and la) were crossed to a rice breeding line, IRBB21, which has the Xa-21 gene for bacterial blight resistance. Three F₂ populations were analyzed with RFLP markers known to be located on chromosome 11. Segregation analysis of molecular markers and morphological markers was used to construct an RFLP map for each population. The recombination frequency between markers varied from population to population although the marker order on the maps was the same for all three populations. Based on a common set of markers mapped in the three populations, an integrated map was generated consisting of both RFLP and morphological markers. The genetic distance between markers on this map was determined by taking a weighted average of the data from the three populations. The oriented map serves as a bridge to understand the relationship between the classical and molecular linkage maps. Based on this information, the location of several genes on the classical map can be approximated with respect to RFLP markers without having to map them directly.