[Objective]The aim of this study was to explore the effects of nitrogen fertilizer management on rice yield and quality under rice shrimp rotation mode.[Method]Using Yexiangyou Mingyuesimiao and Nongxiang 42 as experimental materials,different nitrogen application mounts and ratios at different stages were designed.[Result]With a 15%or 30%reduction based on the conventional nitrogen application amount(195 kg/hm2),the yield of Yexiangyou Mingyuesimiao did not significantly decrease,while the yield of Nongxiang 42 significantly increased.When the ratio of basal fertilizer:tillering fertilizer:panicle fertilizer was 4∶4∶2,the number of grains per panicle,seed setting rate and 1 000-grain weight of Yexiangyoumingyuesimiao were the highest,and the yield was the highest.When the ratio of basal fertilizer:tillering fertilizer:panicle fertilizer was 5∶3∶2,the effective panicle number per unit area,grain number per panicle,seed setting rate and 1 000-grain weight of Nongxiang 42 were the largest,and the yield was the highest.With the decrease of nitrogen application rate,the milled rice rate of Yexiangyou Mingyuesimiao and amylose content was significantly increased,while the protein content was significantly reduced.The peak viscosity and breakdown viscosity showed a trend of first increasing and then decreasing,reaching their maximums with the nitrogen application amount of 165.8 kg/hm2.When the ratio of basal fertilizer:tillering fertilizer:panicle fertilizer was 4∶4∶2 for Yexiangyou Mingyuesimiao and 5∶3∶2 for Nongxiang 42,the milled rice rate,head milled rice rate,gel consistency,peak viscosity and breakdown viscosity were the highest,while chalky grain rate,chalkiness degree,and amylose content were the lowest.[Conclusion]Under the rice-shrimp rotation system,reducing nitrogen application rate by 15%-30%and applying nitrogen at a ratio of 4∶4∶2 or 5∶3∶2 is beneficial to rice nitrogen efficiency,high quality and high yield.

Cadmium (Cd) pollution and uptake into the grains of developing rice plants represent a major threat to human health. Studies of specific genes can offer new insights into the functional roles of particular genes, highlighting candidate alleles that can be leveraged as DNA markers. Accordingly, the identification of novel Cd-related traits and sequence variants can provide new molecular markers for Cd resistance in rice. In the present study, a genetic diversity analysis was carried out on 85 rice varieties exhibiting varied Cd accumulation, and 436 single polymorphic sites (SNP) corresponding to 43 haplotypes were detected across 12 Cd-associated genes (CAL1, OsCADT1, Oscd1, OsHMA4, OsHMA9, OsNRAMP1, OsNRAMP2, OsNRAMP5, OsHMA2, OsHSMA3, OsPCR1, and OsABCG43). By utilizing the information of the SNPs, 85 rice varieties was classified the into 2 clusters with different source categories and Cd contents. Among the variants, 45 sites in 5 genes were significantly associated with the Cd content in rice grains, of which 8 alleles in OsPCR1, CAL1, and Oscd1 were negatively correlated with Cd accumulation. The results of haplotype aggregation analysis for OsPCR1, Oscd1, and CAL1 showed that 85 rice varieties were divided into 5 clusters. Interestingly, most of the varieties in Cluster A belonged to tropical type, which contained the aggregation of three favorable alleles, whereas the temperate varieties constituted the majority of Cluster B lacking favorable alleles. This observation suggests that the allelic combination found in tropical rice varieties may hold promise for reducing Cd accumulation levels in rice grains. The Cd-associated alleles identified in the present study can not only be used to check the Cd tolerance of rice varieties, but also serve as functional molecular markers to differentiate the source of the rice varieties, which provides a better understanding of the relationship between the sequence variation in Cd-related genes and Cd accumulation in rice.

: Plant architecture is a compound trait integrated with multiple morphological and physiological traits, and it is closely related to rice yield. Deciphering excellent plant architecture alleles or QTLs is of great significance for high-yield rice breeding. In this study, we constructed a set of Changhui 121/Koshihikari chromosome segment substitution lines (CSSLs) with the size of 208 in our laboratory. QTLs controlling plant height, flag leaf morphology, and tiller numbers were detected under three environments. A total of 35 QTLs for rice architecture were identified on 11 chromosomes except chromosome 9, and the range of the phenotypic variation explaining was 2.00%–22.86%. It was worth noting that qPH-1-1 , qFLW-6 , and qFLA-3 could be detected in three environments, among which qFLW-6 was a newly identified QTL of the flag leaf width. Phenotypic identification verified that the additive effects and environmental stability of the two locus alleles by the replacement lines carrying qPH-1-1 and sites. The results of this study laid the foundation for further fine mapping and cloning of QTLs for rice plant architecture and the molecular marker-assisted selection (MAS) in rice breeding.

稻米蒸煮特性和感官食味品质是稻米品质的重要评价指标,其遗传复杂.为挖掘与利用优异的稻米品质基因,本研究利用籼稻昌恢121为受体亲本和优质粳稻越光为供体亲本构建的一套染色体片段置换系(CSSL),对稻米的吸水率(WA)、延伸率(CRE)和膨胀率(VE)3个蒸煮特性进行QTL定位.共检测到4个QTL,分布于第8和第11号染色体上.qWA-8、qCRE-8、qCRE-11和qVE-11的表型贡献率和加性效应值分别为25.05％、25.94％、27.95％、41.16％和-25.68、-8.00、8.30、30.31,其中位于第11号染色体上分子标记RM287附近的qCRE-11和qVE-11为新鉴定的QTL.对稻米蒸煮特性与感官食味品质性状进行相关性分析,发现两者之间无相关性,稻米蒸煮特性WA、CRE与VE之间两两呈极显著正相关,米饭外观(AP)、香味(ARM)、味道(TA)、口感(TE)和感官评分(SS)之间两两呈极显著正相关.本研究结果为了解稻米蒸煮特性与感官食味品质性状间的相互关系,挖掘优异等位基因以及稻米品质的遗传改良提供了一定的理论依据.

[目的]水稻纹枯病的抗性鉴定易受环境中温度、湿度及水稻株高和生育期等的影响,不同学者在水稻抗纹枯病遗传研究中采用的接种鉴定方法不同,寻找一种科学的水稻抗纹枯病接种鉴定方法至关重要.[方法]以已知抗、感纹枯病差异明显的8个水稻品种为试验材料,比较评价了前人研发的8种水稻抗纹枯病接种鉴定方法:离体叶片法、苗期微室法、苗期雾室法、苗期Parafilm小袋法、成株期谷壳散布法、成株期田间嵌入法、成株期雾室法、成株期铝箔包裹法.[结果]水稻纹枯病主要是叶鞘病害,离体叶片法虽操作简单,但基于叶片部位接种的离体叶片法和Parafilm小袋法的鉴定结果与其它6种方法的结果不具有显著相关性,这2种方法不能真正反应水稻品种对纹枯病的抗性,不适用于水稻纹枯病的抗性鉴定.成株期谷壳散布法操作粗放,发病不一致,重复性较差,可作为前期大规模品种抗病的初步筛选,但不适合表型鉴定等要求准确量化的抗病QTL定位研究.成株期雾室法和铝箔包裹法虽然纹枯病抗性鉴定结果较准确,但操作繁琐,需要精确的控温、控湿和光照设备,同样不适合大规模的表型抗性鉴定.苗期微室法、苗期雾室法和成株期田间嵌入法操作相对简单,接种后抗性鉴定结果差异显著,与品种的实际抗性水平吻合,结果重复性好,3种方法之间的相关性均达极显著水平.[结论]苗期微室法、苗期雾室法和成株期田间嵌入法3种水稻纹枯病接种鉴定方法适合大规模水稻抗性鉴定和遗传分析,研究结果明确了简便、准确、客观、适用的水稻抗纹枯病鉴定方法,为水稻抗纹枯病鉴定和抗性遗传育种育种提供便利.

The panicle apical abortion (PAA) causes severe yield losses in rice production, but details about its development and molecular basis remain elusive. Here, we detected PAA quantitative trait loci (QTLs) in three environments using a set of chromosome segment substitution lines (CSSLs) that was constructed with indica Changhui121 as the recurrent parent and japonica Koshihikari as the donor parent. First, we identified a novel major effector quantitative trait locus, qPAA7, and selected a severe PAA line, CSSL176, which had the highest PAA rate among CSSLs having Koshihikari segments at this locus. Next, an F2 population was constructed from a cross between CSS176 and CH121. Using F2 to make recombinantion analysis, qPAA7 was mapped to an 73.8-kb interval in chromosome 7. Among nine candidate genes within this interval, there isn't any known genes affecting PAA. According to the gene annotation, gene expression profile and alignment of genomic DNA, LOC_Os07g41220 and LOC_Os07g41280 were predicted as putative candidate genes of qPAA7. Our study provides a foundation for cloning and functional characterization of the target gene from this locus.

稻米是我国三分之二以上人口的主食,其质量安全直接关系到人民的健康.镉污染是严重威胁我国稻米质量安全的重要因素,如何降低水稻籽粒中的镉积累已成为当前水稻产业发展中的重点问题之一.利用作物本身对镉积累的遗传差异,选育籽粒镉含量低的水稻品种,是减少稻米镉超标的经济有效途径.本文简要概述了稻米镉积累的一般特性,从稻米镉积累相关基因的鉴定及其功能以及QTL定位分析等方面较系统地综述了目前关于稻米镉积累的遗传调控研究进展,并对进一步的研究进行了展望,旨在为降低稻米镉含量、减少食品安全问题提供参考.

粒形及千粒重是水稻产量的重要影响因素,通过挖掘这些性状的优异基因,对水稻超高产育种具有重要意义.本研究利用1套以籼稻恢复系昌恢121为背景亲本,粳稻越光为供体亲本构建的染色体片段代换系为材料,在3个环境下对水稻粒形及千粒重进行QTL检测及稳定性分析,共检测到59个QTL,分布于1号、2号、3号、4号、5号、6号、7号、10号、11号和12号染色体上,贡献率为0.77％～36.26％,其中发现10个QTL多效位点.值得关注的是qGW2-1、qGW2-2、qGW3-1、qGW3-2、qGL3和qGL12这6个QTL能在3个环境中重复检测到,其中qGW3-1为新鉴定的QTL位点.这些结果为进一步开展水稻粒形基因的精细定位、克隆和分子辅助育种奠定了一定的理论基础.

为进行水稻苗期耐镉胁迫QTL的定位研究,以籼稻品种昌恢121为轮回亲本、粳稻品种越光为供体亲本构建的染色体片段代换系(CSSL)群体,共97个家系为试验材料,利用质量浓度为17 mg/L的CdCl2溶液,采用水培方法进行水稻幼苗镉胁迫处理,以不加CdCl2的水培液作为对照,以苗长、根长、苗鲜重、根鲜重、苗干重、根干重等6个性状的耐镉胁迫指数为耐镉指标,检测到7个LOD＞ 2.5的耐镉胁迫相关QTL,分别分布在水稻的第1、4、7、8、10号染色体上,贡献率在9.84％～24.50％.其中包括2个根长耐镉胁迫QTL,3个根鲜重耐镉胁迫QTL,根干重、苗干重QTL各1个.贡献率最大的是位于7号染色体上的根鲜重耐镉胁迫QTL,贡献率为24.50％,LOD值为4.82.不同形态性状间未检测到相同的QTL区域.