Effect of Biochar on Relieving Cadmium Stress and Reducing Accumulation in Super japonica Rice

It is of great importance to solve the threats induced by cadmium pollution on crops. This paper examined the effect of biochar on cadmium accumulation in japonica rice and revealed the mechanism underlying the response of protective enzyme system to cadmium stress. Biochar derived from rice straw was applied at two application rates under three cadmium concentrations. Shennong 265, super japonica rice variety, was selected as the test crop. The results indicated that cadmium content in above-ground biomass of rice increased with increasing soil cadmium concentrations, but the biochar application could suppress the accumulation of cadmium to some extent. Under high concentrations of cadmium, content of free proline and MDA （malondialdehyde） were high, so did the SOD （superoxide dismutase）, POD （peroxidase） and CAT （catalase） activity in the flag leaf of rice. However, the protective enzyme activities remained at low level when biochar was added.

Expression Characteristics and Borer Resistance of Bt Gene of Transgenic cry1C~* Super Japonica Rice

[Objective] The paper was to study the expression characteristics and borer resistance of Bt gene of Songjing 9 （1C^＊）. [Method] With super japonica rice Songjing 9 as the receptor, transgenic crylC^＊ super japonica rice Songjing 9 （1C^＊） regulated by ubi promoter was created by agrobacterium-mediated genetic transformation method. Ten strains of transgenic super japonica rice formed from different transformation events were planted in the field; the Tt-mRNA of leaf, stem-sheath and young spikelet at booting stage were detected by real-time fluorescent quantitative PCR; the Bt protein content of leaf, stem-sheath and young spikelet and harvested brown rice were detected by enzyme-linked immunosorbent assay （ELISA）; the white head rate damaged by Chilo suppressalis was manually investigated. [Result] The Bt-mRNA and Bt protein content of various organs and Bt protein content of mature brown rice at booting stage of Songjing 9 （1C^＊） significantly differed among strains; there was no correlation relationship in Bt-mRNA and Bt protein content between leaf and stem-sheath, between leaf and young spikelet, and between stem-sheath and young spikelet; there was no relation between Bt-mRNA or Bt protein content of leaf, stem-sheath and young spikelet and Bt protein content of brown rice; there was positive correlation between Bt-mRNA and Bt protein content in the same organ such as leaf, stem-sheath and young spikelet at booting stage; such strains as Songjing 9 （1C^＊）, whether the Bt gene expression was high or low, showed good resistance against C.suppressalis. This indicated that there were differences in Bt gene expression in different strains of transgenic cry1C^＊ super japonica rice or different organs of the same strain; there was no relation in Bt gene expression among different organs; the Bt-mRNA and protein content of the same organ usually had consistent expression; the Bt gene expression of various organs had nothing to do with the Bt protein content of brown rice. [Conclusion] The Bt gene and its expression cassette can meet the requirement of cultivating japonica rice varieties against stem borers.

Combined effect of shading time and nitrogen level on grain filling and grain quality in japonica super rice

There is limited information about the combined effect of shading time and nitrogen （N） on grain filling and quality of rice. Therefore, two japonica super rice cultivars, Nanjing 44 and Ningjing 3, were used to study the effect of shading time and N level on the characteristics of rice panicle and grain filling as well as the corresponding yield and quality. At a low N level （150 kg N ha^-1, 150N）, grain yield decreased （by 21.07-26.07%） under the treatment of 20 days of shading before heading （BH） compared with the no shading （NS） treatment. These decreases occurred because of shortened panicle length, decreased number of primary and secondary branches, as well as the grain number and weight per panicle. At 150N, in the treatment of 20 days of shading after heading （AH）, grain yield also decreased （by 9.46-10.60%） due to the lower grain weight per panicle. The interaction of shading and N level had a significant effect on the number of primary and secondary branches. A high level of N （300 kg N ha^-1, 300N） could offset the negative effect of shading on the number of secondary branches and grain weight per panicle, and consequently increased the grain yield in both shading treatments. In superior grains, compared with 150N NS, the time to reach 99% of the grain weight （T99） was shortened by 1.6 to 1.7 days, and the grain weight was decreased by 4.18-5.91% in 150N BH. In 150N AH, the grain weight was 13.39-13.92% lower than that in 150N NS due to the slow mean and the maximum grain-filling rate （GRmean and GRmax）. In inferior grains, grain weight and GRmean had a tendency of 150N NS〉150N BH〉150N AH. Under shaded conditions, 300N decreased the grain weight due to lower GReen both in superior and inferior grains. Compared with 150N NS, the milling and appearance qualities as well as eating and cooking quality were all decreased in 150N BH and 150N AH. Shading with the high level of 300N improved the milling quality and decreased the number of chalky rice kernels, but the eating and cooking quality was reduced with increased chalky area and overall chalkiness. Therefore, in the case of short term shading, appropriate N fertilizer could be used to improve the yield and milling quality of rice, but limited application of N fertilizer is recommended to achieve good eating and cooking quality of rice.

Research progress on the breeding of japonica super rice varieties in Jiangsu Province,China

In this study we report the results of a decade-long breeding program for japonica super rice made by Nanjing Branch of Chinese National Center for Rice Improvement in Jiangsu Academy of Agricultural Sciences. We concluded that selection of parents with good comprehensive traits and complementary advantages and disadvantages of both parents in the hybrid combination, and early selection of high heritability traits in earlier segregating generations could significantly improve the breeding efficiency. The use of closely-linked functional markers in pyramiding of multiple genes could greatly increase breeding efficiency, avoiding time-consuming and laborious steps that were used in traditional breeding program. It is also important to coordinate the yield components with variety characteristics such as yield stability, wide adaptability, lodging resistance, and an attractive grain appearance during late growth stage of rice.

Discussion on strategy of grain quality improvement for super high yielding japonica rice in Northeast China

japonica rice is mainly distributed in Northeast China and accounts for 44.6% of the total cultivated area of japonica rice in China. The comprehensive using of inter-subspecies heterosis is the main breeding mode of super japonica rice varieties in this region. Improving rice quality at relative high yielding level is the current research focus. Performing crosses between indica and japonica lines allows for the recombination of regulatory genes and genetic backgrounds, leading to complicated genetic rice quality characteristics, which can be used to explore patterns of quality improvement. In the present study, we utilize recombinant inbred lines （RILs） derived from indica-japonica hybridization to analyze the effect factors of rice quality derived from genetic factors, which contain both regulatory genes concerning rice quality and genetic backgrounds＇ random introduction frequency coming from indica （Di value）, and the improvement strategy was further discussed. The regulatory genes involved in amylase content （Wx） and nitrogen utilization efficiency （NRT1.1B） were the major factors affecting the amylose content （AC） and protein content （PC） in RILs, respectively. Both the Di value and the major grain width gene （GS5） had regulatory effects on milled rice width （MRW） in RILs, and their interaction explained the major variance of MRW in the RILs. With the mediation of MRW and chalkiness degree （C）, Di value had a further impact on head rice rate （HR）, which was relatively poor when the Di value was over 40%. In Northeast China, the Di value should be lowered by backcrossing or multiple crosses during the breeding of indica-japonica hybridization to maintain the whole better HR and further to emphasize the use of favorable genes in individual selection.

Advances and Prospects in Breeding Japonica Rice for Super High Yield inthe Northern China

In this paper, advances and prospects in breeding japonica rice for super high yield in the northern China were analyzed comprehensively in terms of breeding theories, techniques and practices. The author holds that developing and spreading super rice is an important way to enhance the overall yielding ability of japonica rice and attaining immense expansion of rice production. After theories and technical guidelines for super rice breeding were formulated, which involved the creation of new plant morphology and strong hybrid vigor through crossing indica with japonica subspecies, the optimization of combination of desirable traits via multiple crossing or backcrossing, the assemblage of favorable genes and the integration of ideal plant morphology with the utilization of vigor-major breakthroughs have been made in conventional breeding of japonica super rice. A batch of new super rice varieties marked by superior rice quality and high disease resistance, such as Shennong 265, Shennong 606, and Jijing 88, etc., have been developed and released. In comparison with the advancement in conventional breeding ef super rice, progress in hybrid japonica super rice breeding is slower because of climatic and ecological constraint in northern China. Therefore, solving the contradictions between vigor and growth duration, between yield and rice quality, and boosting vastly seed production are still serious challenges for breeders of hybrid japonica rice. Physiological and genetic problems in japonica super rice breeding are also discussed in this paper.

Breeding of New Japonica-indica Hybrid Rice Combination Chunyou 284

Chunyou 284 is a medium- japonica hybrid combination,as well as an indica-japonica subspecific hyrbid with super-high yield,which was developed from Chunjiang 23A,a thermo-sensitive CMS line with very early anthesis time,and C84,an indica-japonica intermediate type restorer line with wide compatibility.This combination has the advantages of high yield potential,early maturity,excellent comprehensive agronomic traits and wide adaptability.It was approved by Jiangsu Provincial Crop Variety Approval Committee in June,2018.The breeding process,main characteristics,cultivation techniques and seed production points of the combination were introduced.

不同产量水平寒地早粳稻品种的株型特征

为探明寒地早粳稻超高产株型特征,选用700~800 kg/667 m^(2)、600~700 kg/667 m^(2)、500~600 kg/667 m^(2)和400~500 kg/667 m^(2)4个产量水平的48个主栽品种和苗头品系,研究其穗型、叶片和茎秆特征的差异。结果表明,700~800 kg/667 m^(2)水平的早粳稻每穗干质量和着粒密度较高,剑叶、倒2叶和倒3叶叶基角及剑叶披垂度大,后4片叶的叶长序表现为倒2>倒3>倒4>剑叶,剑叶、倒2叶、倒3叶和倒4叶较宽,在合理范围内增加株高,但必须缩短倒4节间长度。相关分析表明,产量与每穗干质量、剑叶和倒2叶叶宽、倒3叶叶长和叶宽、倒4叶叶长和叶宽呈极显著正相关,与秆长、抽穗期和蜡熟期株高呈显著正相关。

氮肥施用量对超级粳稻新稻18号强、弱势籽粒灌浆和稻米品质的影响

以超级粳稻新稻18号为供试材料,2011年在7个纯氮水平,2012年在6个纯氮水平下,测定了结实期不同氮肥水平下水稻强、弱势籽粒灌浆速率、稻米品质及产量,分析了籽粒灌浆速率与稻米品质的关系,明确了强、弱势粒灌浆特性对稻米品质的影响。结果表明,低氮处理籽粒灌浆速率高于高氮处理;最大灌浆速率和平均灌浆速率强势粒快于弱势粒,平均比弱势粒快39.51%和20.34%,255.0kg/hm2纯氮处理的最大灌浆速率为1.14mg/(粒·d),比弱势粒快40.83%,平均灌浆速率N0处理最快,为0.74mg/(粒·d),比弱势粒快28.50%。活跃灌浆期粒重,强势粒明显高于弱势粒,无氮肥处理最高。相关分析表明,灌浆前中期强弱势粒粒重与其灌浆速率呈极显著正相关,成熟期籽粒充实度则表现为弱势粒籽粒充实度与其灌浆速率呈极显著正相关,强势粒相关不显著;灌浆前期强弱势粒灌浆速率与稻米的加工品质呈负相关,其中弱势粒达显著或极显著相关;灌浆后期强势粒灌浆速率与稻米外观品质呈显著负相关;灌浆高峰期(即花后24d)籽粒灌浆速率与加工品质呈正相关,与外观品质呈负相关,但相关不显著。说明增大灌浆前期弱势粒灌浆速率及提高灌浆高峰期和灌浆后期强弱势粒灌浆速率,可以同步改善稻米的加工和外观品质。

氮肥运筹对超级杂交粳稻产量、品质及氮素利用率的影响

在高产施氮量条件下(225 kg hm-2),按基蘖肥、穗肥不同施氮比例且穗肥依不同叶龄期追氮共设计了20种施氮模式,研究了其对超级杂交粳稻常优1号产量、氮素利用率及主要米质性状的影响。结果表明:氮肥运筹对常优1号产量影响极大,基蘖肥与穗肥施氮比例为58.34∶41.66,穗肥以叶龄余数4、2叶等量施氮时,产量最高;产量与总吸氮量、氮肥农学利用率、氮肥表观利用率、生理利用率呈极显著正相关关系,氮收获指数和百千克籽粒需氮量与产量呈二次曲线关系;随着穗肥施氮比例的下降,稻米整精米率、蛋白质含量、垩白率、垩白度逐渐下降;胶稠度、直链淀粉含量呈直线上升趋势;穗肥随追肥叶龄期推迟,整精米率、蛋白质含量提高,而直链淀粉含量下降。胶稠度、外观品质因基蘖肥施氮比例的不同而异。综合来看,基蘖肥、穗肥施氮比例为6∶4,穗肥以倒4、2叶期追肥可使该品种超高产、优质、高效得到较好的协调统一。

北方粳型稻超高产育种理论与实践

从育种理论、育种技术及育种实践等方面,综合评述了中国北方粳型稻超高产育种研究进展与前景,认为培育和推广超级稻是继株型育种和杂交稻之后,提高北方粳稻综合生产能力,实现北方水稻生产跨越式发展的重要途径。在“利用籼粳稻杂交创造新株型和强优势,通过复交优化性状组配,聚合有利基因,选育理想株型与优势利用相结合的超级稻”育种理论与技术路线确立之后,北方粳型超级粳稻在常规育种方面已取得重大突破,成功地培育出一批优质抗病的超级稻新品种并已广泛应用于生产,如沈农265、沈农606、吉粳88等。与常规超级稻育种相比,超级杂交粳稻育种研究进展则相对较缓慢。这一方面是由于北方气候与生态条件的限制,另一方面是育种技术相对落后。解决优势与生育期的矛盾、产量与品质的矛盾以及提高制种产量等问题,仍然是北方超级杂交粳稻育种所面临的严峻挑战。本文还讨论了与粳型超级稻育种有关的生理和遗传问题。

播插方式对超级粳稻宁粳3号产量及群体均衡性的影响

2009—2010年以超级稻宁粳3号为材料,设置小苗机插(MT)、手工撒播(BS)、条播(DS)、穴播(HS)、精量手栽(PT)、循环手栽(CT)和等距手栽(ET)7种种植方式,研究不同种植方式对水稻群体均衡性的影响,并分析水稻群体均衡性与产量的关系。结果表明,产量高低依次为精量手栽、机插、等距手栽、撒播、循环手栽、穴播、条播。宁粳3号穗粒数、一二次枝梗数和穗层分布整齐度与产量呈显著或极显著的正相关关系,表明群体均衡性差异是造成不同栽培方式产量差异的原因之一,群体均衡性越高产量越高。营养生长期的差异是造成宁粳3号机插、手栽和直播3种栽培方式间群体均衡性差异的主要原因。精量手栽方式分蘖营养生长时间长,穗层分布均匀、群体均衡。直播方式可利用分蘖叶位少,且各叶位发生的分蘖营养生长时间短,穗型小,群体均衡性较差。机插方式群体均衡性介于精量手栽与直播方式之间。2009—2010年以超级稻宁粳3号为材料,设置小苗机插(MT)、手工撒播(BS)、条播(DS)、穴播(HS)、精量手栽(PT)、循环手栽(CT)和等距手栽(ET)7种种植方式,研究不同种植方式对水稻群体均衡性的影响,并分析水稻群体均衡性与产量的关系。结果表明,产量高低依次为精量手栽、机插、等距手栽、撒播、循环手栽、穴播、条播。宁粳3号穗粒数、一二次枝梗数和穗层分布整齐度与产量呈显著或极显著的正相关关系,表明群体均衡性差异是造成不同栽培方式产量差异的原因之一,群体均衡性越高产量越高。营养生长期的差异是造成宁粳3号机插、手栽和直播3种栽培方式间群体均衡性差异的主要原因。精量手栽方式分蘖营养生长时间长,穗层分布均匀、群体均衡。直播方式可利用分蘖叶位少,且各叶位发生的分蘖营养生长时间短,穗型小,群体均衡性较差。机插方式群体均衡性介于精量手栽与直播方式之间。

超高产常规粳稻宁粳1号和宁粳3号群体特征及对氮的响应

2007—2008年对宁粳1号和宁粳3号的丰产示范方进行调查,2008年以宁粳3号为材料进行氮肥用量和前后比例试验,研究常规粳型超级稻超高产群体特征及对氮的响应。结果表明,常规粳型超级稻宁粳1号和宁粳3号抽穗后干物质积累占籽粒产量的70%～80%,茎叶等营养器官的表观转运率少,易高产稳产。足够的颖花量是高产稳产的保证,要达到11.0thm?2以上的产量,颖花数要≥42000m?2;要达到11.7thm-2以上的产量,颖花数要≥45000m-2,同时结实率≥90%,粒重≥26mg。超高产群体抽穗期适宜叶面积指数(LAI)为7.0～7.5,叶色呈"黑黄"节奏变化,后期生长速率(CGR)高,收获指数(HI)≥0.5。氮肥的适量施用和适当后移,不仅可以保证宁粳1号和宁粳3号生育期"黑黄"节奏变化,建立抽穗期适宜LAI的群体,还可以保持超高产株型特征,提高抽穗后LAI、叶面积维持期、CGR和HI,最终实现超高产量。

利用InDel和SSILP标记分析北方粳型超级稻的遗传组成

为明确籼稻血缘对北方粳型超级稻育种的贡献,利用89对籼粳特异性引物(34对InDel和55对SSILP)对15份粳型超级稻品种以及与其系谱密切相关的21份材料(12份1977-1999年育成的常规粳稻品种和9份1963-2000年育成的日本品种)的遗传组成进行分析。结果表明,15份粳型超级稻品种均含有一定的籼型血缘,且不同地区超级稻品种所含籼型基因频率(Fi)有所不同;对不同年代育成的参试材料的Fi进行比较分析,发现超级稻品种籼型基因型频率最高,Fi为0.068;12份常规粳稻品种次之,Fi为0.033;9份日本品种几乎不含有籼型血缘,Fi为0.011;表明随着时间的推进,近现代以来育成品种的籼型基因频率逐渐增加。

籼、粳超级稻氮素吸收利用与转运差异研究

【目的】目前我国选育和认定的超级稻品种很多,但如何发挥其高产潜力至关重要。氮素是影响水稻生长发育、产量和品质形成的最活跃因素之一,因此,深入分析籼、粳超级稻氮素吸收、利用与转运特征及其与产量形成的关系,从氮素营养层面上阐明超级粳稻高产形成机理,以期为超级稻品种的合理利用以及增产潜力的挖掘提供参考。【方法】2011~2012年在江苏苏中地区,以主体且具有代表性的5个超级杂交籼稻组合和5个常规粳型超级稻品种为试验材料,对稻-麦两熟制条件下籼、粳超级稻主要生育期植株含氮率和氮素积累量、氮素阶段吸收速率和阶段吸收量、氮素利用效率,以及抽穗至成熟期叶、茎、鞘氮素转运量、表观转运率和转运贡献率等进行了系统的比较研究。【结果】1)粳稻平均实收产量、氮素吸收总量和百公斤籽粒吸氮量分别达10.89 t/hm2、224.50 kg/hm2和2.79 kg,分别较籼稻高13.21%、32.74%和17.45%,差异极显著。2)移栽~有效分蘖临界叶龄期、拔节~抽穗期和抽穗~成熟期,粳稻氮素积累量显著或极显著高于籼稻,而有效分蘖临界叶龄期~拔节期粳稻极显著低于籼稻。氮素阶段吸收速率表现的趋势与氮素阶段吸收量一致。3)抽穗期和成熟期粳稻植株各器官以及整个生育期整株的含氮率均显著或极显著高于籼稻。4)粳稻氮素吸收利用率和农学利用率略高于籼稻,但氮素生理利用率、籽粒生产效率、干物质生产效率和氮肥偏生产力,除氮素生理利用率外,均显著或极显著低于籼稻。5)成熟期,粳稻叶、茎、鞘含氮量所占比例均极显著地高于籼稻,但穗中含氮量所占比例极显著低于籼稻,因此,籼稻氮素收获指数极显著高于粳稻。6)抽穗~成熟期,粳稻叶、茎、鞘氮素转运量、表观转运率和转运贡献率均小于籼稻,除鞘的氮素转运贡献率外其他指标均达显著或极显著水平。7)籼稻籽粒氮主要依靠抽穗前源器官中贮积的氮素的输出与转运,粳稻主要依靠生育中后期(拔节~成熟期)氮素的高速吸收。【结论】在稳定生育前期(移栽~拔节期)氮素吸收的基础上,大幅提高生育中期和后期(拔节~成熟期)氮素吸收速率和氮素积累量,是稳定形成较高的氮素吸收总量及粳稻高产形成的关键。

籼、粳超级稻产量构成特征的差异研究

为阐明籼、粳超级稻产量构成特征的差异,以当地主体且具有代表性的5个超级杂交籼稻组合和5个常规粳型超级稻品种为试验材料,对稻-麦两熟制条件下籼、粳超级稻产量及其构成因素、群体茎蘖动态特征、穗部构成特征、灌浆特性等方面进行了系统的比较研究。结果表明:粳稻产量、穗数、群体颖花量、结实率、库容量、总充实量、茎蘖成穗率、着粒密度、一二次枝梗数比值、一二次枝梗总粒数比值、每穗一次枝梗数、一次枝梗单枝梗着粒数、每穗一次枝梗总粒数、一次枝梗结实率、二次枝梗结实率、米粒终极生长量、到达最大灌浆速率的时间、灌浆速率最大时的米粒重、活跃灌浆期和有效灌浆时间均高于籼稻;籼稻每穗粒数、千粒重、穗长、单穗粒重、每穗二次枝梗数、二次枝梗单枝梗着粒数、每穗二次枝梗总粒数、起始生长势、最大灌浆速率和平均灌浆速率则高于粳稻,灌浆速率最大时的米粒重占米粒终极生长量的百分率则表现趋势不明显。籼、粳超级稻均为异步灌浆型,但籼稻两段灌浆现象更为明显,且籼稻灌浆启动快、充实快、持续时间短、呈速起速降的态势。粳稻弱势粒灌浆前、中、后期的灌浆充实量较籼稻分别高0.73%、2.59%、3.43%,随着籽粒灌浆的持续,粳稻灌浆优势不断加大。群体茎蘖稳升稳降、有效成穗数多、穗部构成合理、结实率高、灌浆速度稳定且持续时间长以及灌浆后期弱势粒较高的灌浆质量是粳稻扩库、促充实、稳产高产的关键。

光、氮及其互作对超级粳稻产量和物质生产特征的影响

大田条件下以超级粳稻南粳44和宁粳3号为材料,设置2种氮肥水平（N10：150 kg hm–2,N20：300 kg hm–2）和3种遮光处理（L1：不遮光,L2：抽穗前遮光20 d,L3：抽穗后遮光20 d）,研究光、氮及其互作对超级粳稻产量和物质生产特征的影响。结果表明,较之L1,L2不仅减少了有效穗数和每穗粒数,导致总颖花量下降,降幅达24.81%-35.63%,而且还显著降低了抽穗期茎蘖数和叶面积指数,降幅达2.90%-6.44%和19.02%-27.17%,导致抽穗至成熟阶段的光合势、干物质积累量显著下降,最终产量显著下降,降幅达27.23%-35.26%。较之L1,L3主要影响了抽穗至成熟阶段的光合物质积累,导致结实率和千粒重显著下降,降幅达1.49%-4.48%和5.54%-9.17%,最终产量显著下降,降幅达10.91%-18.47%。L2条件下,随着氮肥水平增加,抽穗期茎蘖数与叶面积指数均显著增加,导致抽穗至成熟阶段光合势、干物质积累显著增加,最终有效穗数、每穗粒数、总颖花量以及产量显著提高。L3条件下,随着氮肥水平增加,抽穗至成熟阶段的光合物质积累显著提高,其中茎叶干物质向穗部转运量显著增加,转运率和贡献率也进一步提高,最终产量显著提高。由此可见氮肥施用能部分弥补因弱光逆境对超级粳稻物质生产及其产量的影响。

籼、粳超级稻光合物质生产与转运特征的差异

为阐明籼、粳超级稻干物质积累及光合生产特征的差异,以江苏地区大面积推广种植的5个超级杂交籼稻组合和5个常规粳型超级稻品种为试验材料,对稻麦两熟制条件下籼、粳超级稻干物质积累、分配、运转及叶面积、光合势、群体生长率、净同化率、秧苗素质、叶型等方面进行了系统的比较研究。结果表明,粳稻生育前期(移栽至拔节期)干物质积累量、光合势、群体生长率、净同化率及上三叶叶长、叶基角、叶开角、披垂度和叶面积衰减率、收获指数均小于籼稻,而生育中后期(拔节至成熟期)干物质积累量、光合势、群体生长率、净同化率及有效叶面积率、高效叶面积率、粒叶比(颖花/叶、实粒/叶、粒重/叶)、最大叶面积指数、总充实量、实收产量、生物产量、茎鞘最大输出量和表观输出量及比率均大于籼稻,差异显著或极显著。虽然粳稻主要生育期单茎干物重均不及籼稻,但群体数量优势保证粳稻具有较高的群体干物质积累量和叶面积,且随着生长发育的持续,群体光合物质生产优势不断加大,群体干物质积累量于抽穗后25 d前后超过籼稻。粳稻灌浆后期(乳熟至成熟期)仍保持强劲生长优势,而灌浆初期(抽穗至乳熟期)茎鞘贮存物质合理输出,有效保障了高效光合层的安全支撑及高积累产量库的流畅充实。高生物学产量的稳定形成和叶面积"稳升缓降"态势以及拔节至成熟期较强的高效光合物质生产,是粳稻光合系统高效持续产出、灌浆充实多及高产形成的重要特征和原因。

籼、粳超级稻主要品质性状和淀粉RVA谱特征的差异研究

为了研究籼、粳超级稻品质特征差异及其形成的影响因素,采用大田试验,以5个超级杂交籼稻组合和5个常规粳型超级稻品种为试验材料,对稻-麦两熟制条件下籼、粳超级稻主要品质性状和淀粉RVA谱特征进行了系统的比较研究,并对米质性状与灌浆结实期的温光因子进行相关分析。结果表明,籼、粳超级稻主要品质性状年度间、类型间、品种间及其二因子间、三因子间的互作效应存在显著或极显著的差异。粳稻糙米率、精米率、整精米率、胶稠度、峰值黏度、热浆黏度、最终黏度和峰值黏度时间均高(长)于籼稻,垩白粒率、垩白大小、垩白度、长宽比、直链淀粉含量、蛋白质含量、崩解值和起始糊化温度均低(小)于籼稻,而消减值表现趋势不明显。相关分析表明,日平均温度、日最高温度和日最低温度对稻米加工品质和蒸煮食味品质具有负向作用,对稻米外观品质和营养品质具有正向作用,而日平均温差和日平均日照时数在米质性状的形成过程中作用不显著。可见粳稻具有稳定形成高出米率、低垩白、低蛋白稻米、高黏度淀粉以及蒸煮出可口米饭等品质特征,为实施"籼改粳"提供理论依据。

江淮下游地区籼粳超级稻生育期与温光资源利用特征的差异研究

为阐明籼粳超级稻生育期及温光资源利用特征的差异,以当地主体且具有代表性的5个超级杂交籼稻组合和5个常规粳型超级稻品种为试验材料,在稻麦两熟制条件下对籼粳超级稻主要生育期、干物质积累量、有效积温、温度生产效率、光合有效辐射、光能利用率等方面进行了系统比较。结果表明,大田生长阶段粳稻生育进程迟于籼稻,成熟期粳稻较籼稻迟16.2d,其中抽穗-成熟期较籼稻长25.82%,差异极显著。粳稻对低温具有较强的适应性,利于适当推迟抽穗结实,延长灌浆结实期与全生育期,加强对秋末温光资源的利用。粳稻经济产量、生物产量、日产量、全生育期天数、有效积温、光合有效辐射和光能利用率以及主要生育期、有效积温和光合有效辐射、抽穗-成熟期温度生产效率、拔节-成熟期干物质积累量和光能利用率均高于籼稻;而灌浆速率、全生育期温度生产效率以及播种-抽穗期温度生产效率、播种-拔节期干物质积累量和光能利用率均低于籼稻,差异显著或极显著。相关分析表明,水稻实收产量与全生育期天数、日产量和灌浆结实期天数均呈极显著正相关,而与灌浆速率呈极显著负相关;生物产量与全生育期有效积温、光合有效辐射和光能利用率均呈极显著正相关,而与全生育期温度生产效率负相关,且相关未达显著水平。因此,在稳定提高温光资源利用率、日产量和灌浆速率的基础上,通过延长生育期,尤其是灌浆结实期,来提高有效积温和光合有效辐射,进而提高干物质阶段积累量及生物学产量,是粳稻高生产力形成的重要途径与特征之一。