不同栽插密度下嘉糯Ⅰ优721的分蘖动态及成穗规律

以三系杂交糯稻嘉糯Ⅰ优721为试验材料,研究了不同栽插密度下的分蘖动态变化及成穗规律,分析了穗粒结构特点及其对水稻产量的影响,结果表明,栽插密度为22.5万穴/hm~2时最高茎蘖数适宜,成穗率最高,较好地协调个体和群体之间的关系,能充分发挥该品种的高产潜力。     

Lead accumulation and distribution in different rice cultivars

This experiment was conducted to investigate the characteristics of lead (Pb) accumulation and distribution among rice organs in 35 rice cultivars of different genotypes. The 35 rice cultivars of four cultivar groups (temperate japonica, tropical japonica, tongil-type, and Indica) were grown with irrigation water containing 10 ppm throughout all growing seasons at the experimental farm of Seoul National University, Korea. Rice plants were sampled and analyzed for Pb accumulation and distribution in each rice organ at harvest. The results showed that Pb concentration, accumulation, and distribution in rice organs except roots were significantly different among 35 rice cultivars. Pb levels in different rice organs followed the order: root > shoot > grain. Grain Pb concentration and accumulation ranged from 0.05 to 0.22 mg kg^-1 and from 0.016 to 0.127 mg m^-2, respectively. The lowest and highest grain Pb concentration and accumulation were observed in a temperate japonica cultivar ‘Hwajin’ and a tropical japonica cultivar ‘IR71204’, respectively. Grain Pb concentration showed highly significant correlations with the shoot-grain redistribution ratio among 35 cultivars. However, it was not correlated with shoot Pb concentration and accumulation, root Pb concentration, and the root-shoot translocation factor. Significant differences in Pb concentration, accumulation, and distribution in rice organs among four cultivar groups were only found in shoot Pb accumulation. Indica showed the highest Pb accumulation in shoots, while temperate japonica was the lowest. Grain Pb concentration for four cultivar groups was found to be significantly correlated with the shoot-grain redistribution ratio in common.     

镉胁迫对不同抗性水稻品种幼苗生长和生理特性的影响

以耐镉性不同的两个水稻品种（水稻秀水63和秀水09）为试验材料,采用溶液培养方法,研究不同浓度镉（0、1、5、10、25、50、100μmol/L-1）对水稻幼苗生长和生理特性的影响。结果表明：随Cd浓度增加水稻幼苗生长明显受抑,株高、叶绿素含量、叶片干重明显下降,且秀水63的下降幅度大于秀水09。总体上,脯氨酸含量、超氧化物歧化酶（SOD）、过氧化物酶（POD）活性均呈上升趋势,其中,在较低浓度Cd胁迫下,秀水63叶片中脯氨酸含量、POD活性增加幅度较大,而在较高浓度Cd胁迫下,秀水09的增加幅度较大。过氧化氢酶（CAT）活性表现为先上升后下降。丙二醛（MDA）含量随着Cd胁迫浓度的提高而增加, 且增加幅度秀水63大于秀水09。从实验结果表明,秀水09对Cd胁迫的抗性大于秀水63。     

不同施肥水平与抛栽密度对优质稻玉美占生长及产量的影响

试验采用2因素3水平随机区组试验设计,设3个施肥水平处理和3个不同抛栽密度处理。结果表明:玉美占在低、中氮肥水平条件下,有效穗数和产量随着抛栽密度的增加而增加,但在高氮水平条件下,高密度却会导致群体的恶化和产量的下降;玉美占要获得良好的群体结构、较高的产量,其适宜施氮水平为210kg/hm2,适宜抛栽密度为30万穴/hm2,低氮水平下其密度可增加至36万穴/hm2。     

再生稻次适宜区迟播栽对不同杂交籼稻淀粉RVA谱的影响

为探讨再生稻次适宜区播栽期对杂交籼稻淀粉RVA谱的影响,以2个杂交籼稻品种,川优6203和宜香优2115为材料,在四川的隆昌和犍为2个生态点,研究不同生态条件下推迟播栽期对籼稻淀粉RVA谱特征值的影响。结果表明,播栽期的主效应对籼稻淀粉RVA谱特征值存在明显的影响。在再生稻次适宜区,推迟播栽期会导致水稻灌浆期温度降低,日照时长缩短,降雨量减少,从而降低了籼稻淀粉RVA谱的峰值黏度、热浆黏度、冷胶黏度和崩解值,提高了消减值以及峰值时间;与再生稻相比,迟播栽期处理具有较大的峰值黏度、崩解值以及较小的冷胶黏度、消减值、回复值、峰值时间和糊化温度。播栽期对籼稻淀粉RVA谱特征值的影响在不同生态点具有差异,与隆昌生态点相比,犍为生态点处理间的峰值黏度、消减值和崩解值差异更为显著。播栽期对不同品种淀粉RVA谱的影响程度不同,宜香优2115的峰值黏度和崩解值比川优6203更容易受到播栽期的影响。从淀粉RVA谱的变化趋势来看,迟播栽期处理的籼稻淀粉RVA谱表现与再生稻更为接近,蒸煮食味品质更高。     

Isolation and linkage mapping of disease-resistance-like sequences from various rice cultivars, containing different recognition specificities

Degenerated oligonucleotide primers identified from the nucleotide‐binding sites of known disease resistance (R) genes were used from rice cultivars harbouring different recognition specificities to amplify and clone homologous sequences of R genes. A total of 68 non‐redundant clones, which showed various degrees of sequence homology to R genes, were obtained from 18 rice cultivars. These clones had a high degree of sequence diversity both in the nucleotides and in the predicted amino acids, and were classified into five groups using clustal analysis. Fifteen of the 68 clones were mapped to 17 loci on chromosomes 3, 5, 11 and 12 in the rice molecular linkage map. The loci of the mapped clones correlated with the locations of known rice R genes for blast resistance and bacterial blight resistance on chromosomes 11 and 12. Other mapped loci occurred in cluster on chromosome 3, and correlated with the position of a quantitative trait locus for bacterial blight resistance. The mapping of the R gene homologues may aid the identification and isolation of R gene candidates.     

水稻生态化种植高产栽培技术

水稻种植在农业生产中具有举足轻重的作用。做好粮食安全生态化生产,对于我国水稻种植再上新台阶具有重要现实意义和历史意义。从基地的生态环境条件要求、水稻获得高产的合理种植密度、田间的平衡施肥管理、病虫害和杂草的综合生态防治、优良品种的选择和培育壮秧等方面,分析了水稻生态化种植的高产栽培技术。     

Assessment of quantitative resistance of rice cultivars to Xanthomonas campestris pv. Oryzae: a comparison of inoculation methods

Summary Lesion size and lesion number were measured on cultivars of rice inoculated by clipping or spraying with virulent isolates of Xanthomonas campestris pv. oryzae. Mean percentage diseased leaf area (%DLA) gave a similar ranking for the two inoculation methods but differences in lesion size among cultivars were much more evident after clip than after spray inoculation. Correlation between the methods was high (r=0.82^**), but some cultivars responded differently with the two techniques. Cultivars which had low scores following spray inoculation showed low disease progress during the first nine weeks after transplanting into a screen-house experiment. Assessment after clip inoculation measures resistance due to spread of bacteria within the leaf xylem system, an important component of quantitative resistance. Assessment after spray inoculation measures all resistance, including resistance to entrance of bacteria into the leaf. In order to select rice entries with improved quantitative resistance to X. c. oryzae based on both components, a screening based on lesion length after clip inoculation, followed by a test for lesion number after spray inoculation, is advised.     

Assessment of quantitative resistance of rice cultivars to Xanthomonas campestris pv. oryzae: A comparison of assessment methods

Summary Lesion length, leaf length, and leaf width were measured on infected leaves two weeks after clip inoculation of 64 rice cultivars with two virulent isolates of Xanthomonas campestris pv. oryzae (X.c. pv. oryzae). No significant correlation was found between the lesion length and the leaf dimensions, indicating that physical leaf size does not affect the spread of the bacteria once these have entered the leaf. Lesion length is therefore an acceptable parameter for assessing resistance to (X.c. pv. oryzae), and is to be preferred above the parameter percentage diseased leaf area (% DLA), especially when small differences between genotypes are to be assessed. The confounding influence of differences in leaf length can cause large changes in the ranking order of cultivars when assessed by the % DLA. For this reason lesion length is a better assessor of the value of a quantitative resistance for breeding and research purposes than % DLA.     

我国水稻超大规模种植品种分析

分析了年推广面积高峰时过千万亩的44个水稻品种的育种方法、亲本血缘和育种单位,清楚地看出我国水稻育种经历了系统育种、国外引进、矮化育种、辐射育种、三系育种、两系育种的历程;所分析品种几乎都来源于南特号、矮仔占、IR8、农垦58等4个系列或其中2系列的杂交。除南特号外,其他3个品种都是国外引进,正是这3个品种催生了我国水稻育种技术上的3次突破:矮化育种、三系育种、两系育种。由此发现,水稻育种技术的重大进步都是从新的基因资源的发现和利用开始的,只有新的基因资源和新的育种技术结合,才会有育种实践的重大突破。作者预测,我国水稻育种的第4次重大突破是分子育种,下一轮超大规模种植品种将是转基因抗螟虫水稻,育种中心可能在湖北。     

Genetic and phytochemical analysis of Indonesian black rice cultivars

Journal of Crop Science and Biotechnology - There are many local black rice cultivars spread throughout Indonesia and are only a few of these which formally describe their genetic diversity and...     

Effect on leaf photosynthetic rate by leaf blast for rice cultivars with different types and levels of resistance

Summary The effect of an inoculation with Pyricularia oryzae (isolate P06-6) on net leaf photosynthetic rate of rice (Oryza sativa) was studied with four cultivars. Measurements were taken on the sixth leaf of the main culm of plants in the early tillering stage. On cultivars CO39, IR50 and IR64 a susceptible infection type developed, but a clear difference in relative infection efficiency of the cultivars was observed. The highest number of lesions developed on leaves of CO39, whereas the lowest number was found on leaves of IR64. For all three cultivars the effect of a single lesion on the reduction in net leaf photosynthetic rate was found to be equal to a reduction in leaf area of three times the area occupied by the visible lesion. On IR68, a cultivar with complete resistance, brown specks of pinpoint size appeared without any effect on net leaf photosynthetic rate.     

不同氮水平下水稻钾吸收及全基因组关联分析

以业已完成深度重测序的134份水稻地方种质资源为材料,在大田栽培条件下按不施氮(N0),施96kg hm^–2纯氮(N1)和施192kg hm^–2纯氮(N2)3种氮肥水平,检测了分蘖盛期植株的钾含量、植株干重和钾积累。结果表明,水稻钾含量、植株干重和钾积累在N0、N1、N2三种氮肥处理下均呈正态分布,表型变异丰富。植株干重和钾积累与施氮量呈极显著正相关,钾含量与施氮量相关性不显著;钾含量与植株干重呈负相关,钾含量与钾积累相关性不显著,而植株干重与钾积累呈极显著正相关。在3个施氮水平下,籼稻的钾含量极显著低于粳稻,籼稻的干重和钾积累都极显著高于粳稻。全基因组关联分析发现,在3个氮肥水平下检测到12个显著相关位点,其中钾积累、钾含量和植株干重的显著相关位点分别有2、5和5个。在N1水平下,位于第6染色体上与钾含量相关的SNP(Chr6_1,524,776)的显著性峰候选区包含与钾离子转运蛋白互作的RUPO基因。根据钾含量的差异,鉴定出3个钾含量与低氮响应有关的SNP位点,1个位点与高氮响应有关,而位于第10染色体上的显著性位点Chr10_2,822,026对低氮和高氮均有响应,该区域的4个候选基因的表达在不同氮水平间存在差异。     

Localization of salt-tolerant QTL in rice germination stage under different salinity concentrations

Euphytica - Determination of nuclear DNA content, genome size, and ploidy level and, information on cytogenetic characteristics are all prerequisite of modern plant breeding. However,...     

Variations of the vascular bundle system in Asian rice cultivars

Summary The capacity of vascular bundle system transporting assimilates from source to sink is one of the limiting factors for rice (Oryza sativa L.) yield. Genetic variation in vascular bundle system should be investigated for improvement of transporting efficiency. A total of 531 Asian rice cultivars were studied for vascular bundles in the peduncle and its relation to spike morphology. A few difference was detected for the number of primary rachis branches of the spike among the cultivars from various countries. However, the number of vascular bundles significantly differed among the cultivars; those from Nepal, Bangladesh and India bore more vascular bundles than those from Japan. Therefore, the ratio of vascular bundles to rachis branches (V/R ratio) was nearly 1.0 in cultivars from Japan, while those from Nepal, Bangladesh and India ranged from 1.3 to 2.2. Chinese and Indonesian cultivars incuded two types of high and low V/R ratios. Cultivars with high V/R ratio showed positive reactions to the phenol solution, while those with low V/R ratio were negative reactions, suggesting that the former cultivars are of Indica type and the latter of Japonica type. It was concluded that the relationship between vascular bundles and rachis branches differentiated among the ecotypes of Asian cultivated rice.     

Quantitative trait loci for whiteness of cooked rice detected in improved rice cultivars in Hokkaido

Improving the eating quality of cooked rice has been one of the most important objectives in rice breeding programs. Eating quality of cooked rice is a complex trait including several components, such as external appearance, taste, aroma, and texture. Therefore, dissection of these components followed by marker-assisted selection of detected QTL(s) may be a useful approach for achieving desirable eating quality in rice breeding. Whiteness of cooked rice (WCR) is an important factor related to the external appearance of cooked rice. WCR is known to be associated with the amylose and protein contents of the endosperm. However, the genetic basis of WCR remains unclear. In this study, we evaluated phenotypic variation in WCR among recently developed rice cultivars from Hokkaido, Japan. Then, we developed doubled haploid lines (DHLs) derived from a cross between two cultivars from Hokkaido, Joiku No. 462 (high WCR) and Jokei06214 (low WCR). Using the DHLs, we detected two QTLs for WCR, qWCR3 and qWCR11, on chromosomes 3 and 11, respectively. We also examined the dosage effect of the two QTLs based on both the categorized segregants in the DHLs and the relationship between the WCR phenotype and inheritance around the QTL regions in cultivars from Hokkaido.     

Comparative analysis of different methods revealing the involvement of proteins during ageing of rice seeds

Seed longevity is a very important characteristic controlling seed quality. However, the mechanism underlying this characteristic is poorly understood. In this study, 'FH7185', a storable rice variety, the germination rate of which was 66.63%, much higher than the control after artificial ageing under relative humidity 88% and 42°C for 21 days. Different methods were applied to reveal the involvement of proteins during ageing of rice seeds. In total, 35 differential proteins were identified from 2D‐PAGE, and 3,719 proteins from iTRAQ analysis. A comparison of these two methods showed that not all protein types could be detected on the 2D‐PAGE gels, and the dynamic range was somewhat limited. So the comprehensive proteome map from the iTRAQ analysis was used to identify the quantitatively regulated proteins that played roles in seed longevity, and found that the most marked change was the increased abundance of many metabolic enzymes, especially the ones involved in α‐linolenic acid metabolism in the embryos during ageing. OsLOX2 and OsLOX3 had a negative effect on seed longevity, which were lower in FH7185 than the control. The dehydrogenase (LOC_Os07g44430) which played a major catalytic role in lipid peroxidation, also changed significantly during ageing. Therefore, OsLOX2, OsLOX3 and Loc_OS 07G44430 may be involved in the regulation of seed longevity with a synergistic effect.     

不同施氮水平对超级稻源库特性的影响

摘 要 以超级杂交稻Q优6号和金优527为材料,在不同施氮水平下研究超级杂交稻源库特性。研究结果表明,随着施氮量的增加,作物群体生长率、最大叶面积指数、有效叶面积指数和高效叶面积指数、叶面积比率、光合势、拔节期-孕穗期叶源总量值均逐渐增加,而有效叶面积率、高效叶面积率、净同化率、孕穗期单茎茎鞘重逐渐降低随氮肥的增加而减少。在施氮量0～315 kg/hm2的范围内,随着施氮量的增加,总颖花数、总库容量逐渐增大,而饱粒千粒重、颖花数/叶、实粒数/叶、粒重/叶逐渐降低。颖花数/叶、实粒数/叶和粒重/叶均与饱粒千粒重、结实率达显著的正相关,总库容量与总颖花数呈极显著正相关。     

Effect of rhizosphere microbiome on different crop growing fields in various rice cultivars and its molecular approaches for sustainable agro-ecosystem

Journal of Crop Science and Biotechnology - The present investigation was carried out to investigate the effects of rhizosphere bacteria on growth and rice yields. Also, isolation and...