晚籼稻抽穗期冷害生态适应性评价

选择生育期相近的迟熟高产杂交稻组合或水稻品种（品系）,在自然条件下分期播种,寻找水稻抽穗期冷害相关的形态评价指标,并对参试材料进行抽穗期耐冷生态适应性评价。抽穗期遭受低温冷害胁迫后,主要农艺性状中受冷害程度大小顺序依次是每穗实粒数、单蔸产量、结实率、每穗总粒数、株高、穗长、千粒重;单蔸产量相对受害率（ＲＤＰ）与每穗实粒数ＲＤＰ、结实率ＲＤＰ、剑叶叶色分、抽穗期延尺天数分成极显著正相关。在低温冷害胁迫条件下,水稻不同基因型的抽穗期耐冷能力存在明显的差异。将判别水稻抽穗期耐冷能力的形态指标－－每穗实粒数ＲＤＰ、结实率ＲＤＰ、剑叶叶色、抽穗期延迟天数、苞穗率增加值进行量化,综合判别参试材料抽穗期对低温冷害的生态适应性。研究结果表明：籼穗交材料９５ＬＲ１０２后期耐冷能力强;带有部分粳稻血缘、正在生产中大面积种植的杂交稻     

不同生态区籼粳稻杂交F2代亚种属性与株型性状的特点

两个籼粳稻杂交F₂群体(F₂-A：晚轮422/沈农265、F₂-B：泸恢99/沈农265)分别在辽宁和四川种植,研究生态环境对亚种属性及其与株型性状相互关系的影响。结果表明,不同生态环境下F₂代植株籼粳属性均呈接近正态的连续变异,相对于四川,辽宁呈现明显的偏籼分布,生态环境对程氏指数六性状的影响并不完全一致。生态环境对株型特性也有较明显的影响,从四川到辽宁,株高和穗弯曲度显著提高,而穗长、剑叶长、剑叶宽及剑叶张角则表现降低趋势。不同地区株高的类型间差异没有明显规律性,剑叶长表现为籼型显著大于其他类型的趋势,剑叶张角地区和类型间大多无显著差异,不同地区剑叶宽的类型间差异因组合而异。总之不同地区从籼型到粳型,均有穗长递减而穗弯曲度递增的趋势。籼粳稻杂交F₂代植株个体籼粳属性与株型性状表现出一定的相关性,但相关的方向和程度在不同地区和组合间不完全一致。     

Genotypic association between grain yield and six agronomic traits in a cross between rice varieties of contrasting plant type

Summary Phenotypic and genotypic correlation coefficients as well as path analysis were computed to evaluate the genetic association between six agronomic traits and rice grain yield and also among the traits in a representative sample of F₇ lines in the tall Peta × semi-dwarf I-geo-tze cross maintained as an unselected bulk from F₃ through F₅. Data were taken on grain yield, duration from seeding to heading, panicle number, ratio of panicles to tillers, angle of the flag leaf, angle of the leaf below the flag leaf, and plant height on the two parents and 139 F₇ lines. The F₇ lines were divided into three groups based on plant height: tall, intermediate, and short (semi-dwarf).Differences in grain yield were highly significant among lines in the tall and short groups, and significant among the intermediate lines. Significant to highly significant differences among lines were obtained in each of the height groups for all of the agronomic traits except for the ratio of panicles to tillers in the intermediate and tall groups.Path analysis showed that among the semi-dwarf progenies, erect flag leaf angle made the largest positive contribution to grain yield, followed by high panicle number and early maturity. Among the intermediates, the erectness of the leaf below the flag contributed most to high yield and was closely followed by earliness in maturity. For the tall lines, erect leaves below the flag leaf and high panicle number contributed positively to yield, whereas tallness and late maturity had a negative effect.Phenotypic and genotypic correlation coefficients indicated that low grain yield was closely associated with tall stature, drooping leaves, and low panicle number in the tall lines. In the intermediate lines, low grain yield was associated with late maturity and drooping leaves. Among the semi-dwarf lines, high grain yield was correlated with erect flag leaves and a high ratio of panicles to tillers. When the lines in different height groups were combined, highly significant phenotypic correlations were obtained between high yield levels and erect leaves, a short plant stature, early maturity, or a high panicle number. Erect flag leaves and high yield levels were associated at a significant level. The genotypic correlation coefficients of the above paired traits were identical in sign and generally greater in value than the corresponding phenotypic correlation coefficients.Mail address: P. O. Box 583, Manila, Philippines.     

RFLP facilitated analysis of tiller and leaf angles in rice (Oryza sativa L.)

Plant type is an important composite trait associated with the yield potential in rice and other cereal crops. Several characters associated with the plant type of modern rice cultivars including tiller angle, leaf and flag leaf angle, were investigated using a complete linkage map with 115 well distributed RFLP markers and progeny testing of 2418 F₂ derived F₄ lines from a cross between O. sativa ssp. japonica cv. ‘Lemont’ and spp. indica cv. ‘Teqing’. One major gene (Ta) and 11 QTLs were largely responsible for the tremendous variation of the three plant type characters in the Lemont/Teqing F₂ population. The major gene, Ta, located between RZ228 and RG667 on chromosome 9, accounted for 47.5% of the phenotypic variation in tiller angle and had large pleiotropic effects on both leaf and flag leaf angles. This gene plus four QTLs accounted for 69.1% of the genotypic variation in tiller angle. Eight additional QTLs for leaf and flag leaf angles were also identified, which collectively explained 52.0 and 66.4% of the genotypic variation of these traits. Ta and three QTLs ( QFla2, QFla5 and QFla7) apparently affected the related plant type characters differently, suggesting their possible differential expression in different developmental stages of rice plants or possibly clustering of different genes affecting these traits. Plant type, and consequently grain yield of rice, may be improved by deliberately manipulating these QTLs in a marker-assisted selection program. This revised version was published online in July 2006 with corrections to the Cover Date.     

一个具有主效晚抽穗基因的水稻染色体片段代换系的鉴定、形态分析及Ehd4-2定位

抽穗期是决定水稻品种种植地区和季节适应性的重要农艺性状,鉴定抽穗期基因对水稻生产具有重要意义。本研究采用高代回交和SSR标记辅助选择相结合的方法获得了1个以日本晴为受体亲本、西恢18为供体亲本的含有1个控制晚抽穗表型的主效单基因的水稻染色体片段代换系Z315。Z315携带来自西恢18的5个代换片段,分布于第1、第3、第6和第7染色体上,平均代换片段长度为7.39 Mb。Z315的叶绿素含量、株高、穗长、倒一节间长、倒二叶长、倒三叶长、有效穗数、每穗实粒数和总粒数均显著高于受体日本晴,暗示其代换片段可能携带这些性状的QTL。进一步利用日本晴与Z315杂交产生的F1和F2群体对晚抽穗基因进行遗传分析和分子定位。该晚抽穗表型受1对隐性核基因控制,最终将该基因定位于第3染色体RM14283和RM6349之间,物理距离为233 kb。对该区间进行候选基因预测和测序,发现1个与抽穗相关的编码锌指蛋白的基因LOC_Os03g02160在日本晴和Z315间存在差异,该基因可能与Ehd4等位,称作Ehd4-2。由于染色体片段代换系除代换片段外与受体亲本一致,因此本研究无论对进一步分离其他QTL还是进行基因聚合育种均具有较大利用价值。     

水稻中胚轴伸长特性的遗传分析

以长中胚轴/短中胚轴杂交组合的两个亲本、F₁、B₁、B₂和F₂为试验材料，在小型人工气候箱黑暗条件下培养幼苗，对水稻中胚轴伸长特性的遗传规律进行了研究。结果表明，中胚轴伸长特性受两对隐性基因控制。F₂群体中长、短中胚轴植株在节间长度、穗长、株高和剑叶长等性状上均存在较明显的差异，而中胚轴伸长特性与节间粗、剑叶宽、单株穗数、每穗总粒数、结实率、千粒重和单株产量等性状关系不明显。还对水稻中胚轴伸长特性的遗传改良以及长中胚轴材料在直播稻育种上的利用进行了探讨。     

Analysis of ATPase and succinic dehydrogenase in F1 hybrids of rice (Oryza sativa L.)

Summary Activities of ATPase and succinic dehydrogenase were assessed in three F₁ hybrids of rice and their parental lines during boot leaf stage, flowering, on 10th and 20th days after flowering. ATPase activity showed increase at the flowering and on 20th day after flowering. Succinic dehydrogenase activity continued to rise till 10th day after flowering and declined on 20th day after flowering. Hybrids with high yield were generally endowed with more positive heterosis for these two enzymes. Correlation coefficient of grain yield per panicle was significantly positive with ATPase activity at all the stages studied. Heterosis for ATPase activity might serve a reliable criterion for the selection of efficient F₁ combinations.     

氮肥用量与运筹方式对晚籼稻产量及花后干物质积累与转运的影响

旨在建立晚籼稻合理氮肥施用技术,探究了氮肥用量与运筹方式对晚籼稻产量及干物质积累与转运的影响。以‘益9优447’和‘益9优651’为试验材料,设置2个氮肥用量和3种氮肥运筹方式,并以不施氮处理为对照,测定产量及其构成因素、干物质积累量和剑叶SPAD值等指标。与不施氮处理相比,施氮可增加晚籼稻有效穗数12.3%~61.9%,降低花后剑叶SPAD值衰减率5.9~8.5个百分点,增大花后干物质转运量0.8~1.1倍,提高花后干物质转运率5.5~10.2个百分点和增加产量23.5%~35.6%。氮肥运筹方式对晚籼稻产量及干物质积累与转运的影响较小。氮肥用量270 kg/hm²与运筹方式基肥:分蘖肥:穗肥:粒肥=40%:20%:25%:15%组合处理的产量及干物质转运量与转运率最高。氮肥用量180 kg/hm²与氮肥运筹方式基肥:分蘖肥:穗肥=60%:20%:20%组合处理的氮肥农学利用率最高。氮肥用量为180 kg/hm²时,应增加氮肥基肥使用比例;氮肥用量为270 kg/hm²时,可适当增加氮肥后期追肥次数和比例。     

同源四倍体水稻农艺性状的遗传分析

与二倍体水稻相比,同源四倍体水稻杂种具有强大的生物学优势,目前对同源四倍体水稻数量性状的遗传规律及存在较强优势的遗传基础还不清楚。此研究利用一套4×12不完全双列杂交的亲本和F1 2个世代的同源四倍体材料,采用加性-显性模型和统计分析方法,分析同源四倍体水稻农艺性状的遗传规律。结果表明,同源四倍体农艺性状受到遗传主效应与基因型×环境互作效应共同控制;其中株高、穗长以显性效应为主,剑叶宽以加性效应为主,有效穗数和剑叶长性状以显性×环境互作效应为主;株高、穗长和剑叶宽的HN和HB均分别比HNE和HBE大,表明这3个性状的选择效果受环境的影响较小;有效穗数和剑叶长的HN相对较小,HNE相对较大,说明这两个性状的选择效果因环境而不同。此研究为在杂种配制和后代选择中有效地利用同源四倍体新种质提供理论依据。     

The mode of gene action in flue-cured tobacco

A study was made on the quantitative inheritance of seven characters viz., flowering time, plant height, leaf length, leaf width, number of curable leaves, green weight and cured weight for two crosses of flue-cured tobacco Chatham x Delcrest and 232 x Hicks. Six genetic populations P₁, P₂, F₁, F₂, B₁ and B₂ were observed in each cross.Small and significant values of heterosis were observed for almost all the characters for the two crosses. Significant average inbreeding depression was found for all the characters in both the crosses.Significant additive and dominant effects were found for the various characters in the cross Chatham x Delcrest in which the dominance gene effects were high. While in 232 x Hicks cross, additive gene effects contributed much in controlling the characters studied.Significant epistatic effects were found for leaf length and number of leaves in the cross Chatham x Delcrest, flowering time and plant height in 232 x Hicks by ² test. Indications of exploiting these above two characters in plant breeding were revealed by these studies and a systematic approach in planning for such exploitation would be possible by further investigations.     

Detection of quantitative trait locus for leaffolder (Cnaphalocrocis medinalis (Guenée)) resistance in rice on linkage group 1 based on damage score and flag leaf width

Rice leaffolder (RLF) (Cnaphalocrocis medinalis (Guenée) is a destructive and widespread insect pest throughout the rice growing regions in Asia. The genetics of resistance to RLF in rice is very complex and not thoroughly explored. The present study was conducted to detect the quantitative trait loci (QTL) associated with RLF resistance involving 176 recombinant inbred lines (RILs) of F₈ generation derived from a cross between IR36, a leaffolder susceptible variety and TNAULFR831311, a moderately resistant indica rice culture. Simple sequence repeat (SSR) markers were used to construct specific linkage groups of rice. All the RILs were screened to assess their level of resistance to RLF by measuring the leaf area damaged. Besides this, the length and width of the flag leaf of each RIL were measured since these two parameters were considered as correlated traits to the RLF resistance in rice. All the above parameters observed across the RILs showed quantitative variation. Correlation analysis revealed that damage score based on greenhouse screening was positively correlated with length and width of the flag leaf. Out of 364 SSR markers analysed, 90 were polymorphic between the parents. Multi-point analysis carried out on segregating 69 SSR marker loci linkage group wise resulted in construction of linkage map with eleven groups of 42 SSR markers. Through single marker analysis, 19 SSR markers were found to have putative association with the three phenotypic traits studied. Of these markers, RM472 was identified as a locus having major effect on RLF resistance trait based on length of the flag leaf. Interval mapping detected two QTLs on linkage group 1. Among these QTLs, the QTL flanked by RM576–RM3412 were found to be associated with width of the flag leaf and RLF resistance. The putative SSR markers associated with leaffolder resistance identified in the present study may be one of the loci contributing resistance to RLF in rice.     

Genetical studies on the difference of anther length among common wheat cultivars

Summary Anther and pistil lengths of 61 cultivars and experimental strains of common wheat were measured just before flowering. Anther length varied from 3.0 to 5.1 mm, and pistil length varied from 3.8 to 5.2 mm. A specific correlation was observed between anther length and flowering date among the parental strains, as well as in the F₁ generations of 13 cross combinations; Anther length on flowering date fitted well to a curvelinear regression of the second order in parental and F₁ generations. The reduction of anther length in both early and late flowering cultivars was attributed to the worse environmental conditions for their floral development, compared to the intermediate types. Such relationship between anther length and flowering date was not found in the F₂ generation. This indicates that most of the genes controlling the two characters are different. Heritability of anther length estimated from the regression coefficient of the F₁s on the midparents was greater than 0.65.Contribution from the Laboratory of Genetics, Faculty of Agriculture, Kyoto University, Japan, No. 430. The work was supported in part by a Grant-in-Aid (no. 439016) from the Ministry of Education, Science and Culture, Japan.     

氮肥运筹对湘南双季杂交稻生长发育与稻米品质的影响

为明确湘南双季杂交稻适宜的氮肥运筹方式，以早稻品种陆两优996和株两优819、晚稻品种H优518和盛泰优018为材料，比较研究3种分蘖肥、穗肥、粒肥比例（7:2:1,N1;6:3:1,N2;5:4:1,N3）对双季杂交稻产量形成与稻米品质的影响。结果表明，氮肥运筹对双季稻产量及其构成因素有显著影响，早、晚稻实际产量均以N2处理最高，且显著高于N1处理，其增产的原因主要是有效穗数与穗粒数较高。与N1和N3处理相比，N2处理茎蘖数居中，但成穗率最高，且孕穗之后的叶面积指数、叶片叶绿素含量与干物质积累量最高。各品种糙米率、精米率和整精米率均以N2处理最高；N3处理直链淀粉含量显著低于N1处理，但与N2处理无显著差异；胶稠度随穗肥比例增加呈下降趋势；各品种垩白粒率和垩白度均以N2处理最低，处理间粒长、粒宽和长宽比均无显著差异。从稻米RVA谱特征参数来看，N1处理稻米食味品质最好，略优于N2处理，N3处理米质最差。综合考虑产量与稻米品质，N2处理（分蘖肥:穗肥:粒肥=6:3:1）是湘南双季杂交稻较理想的氮肥运筹方式。     

Interactions between different genotypic tissues in citrus graft chimeras

The heritability of tolerance of wheat F₃ lines to competition from annual ryegrass (Lolium rigidum), and its relationship to morphological traits, were determined using crosses between wheat cultivars with good and poor competitive ability. Forty F₂-derived F₃ lines from a cross between two late flowering varieties (Machete × Spear) and 40 from a cross between early flowering varieties (Wilgoyne × Gutha) were grown in the field with and without annual ryegrass. There was significant genetic variation between lines within each of the two populations in a number of aspects of plant growth and development, including yield in monoculture. The estimates of heritability for % yield loss due to competition were 0.25 and 0.57 in the two crosses respectively, indicating that selection for high tolerance to competition in the F₃ generation or later should be effective. Fairly strong relationships between height and % yield loss and between leaf length and % yield loss suggest that these may be useful auxiliary traits when selecting for low % yield loss. However, differences between crosses in the magnitude and sign of genetic and phenotypic correlation between traits indicate that competitive ability is a complex character influenced by many factors. This revised version was published online in August 2006 with corrections to the Cover Date.     

Genetic variation in F<Subscript>2</Subscript> populations and their potential in the improvement of grain yield in tef (<Emphasis Type="Italic">Eragrostis tef</Emphasis>)

Tef is a staple cereal of Ethiopia in high demand by consumers. In order to cope up with this high consumer demand, productivity per unit of land must increase through the development and use of high-yielding varieties. To this effect, the National Tef Research Project has long been striving towards the development of high yielding varieties through direct selection from germplasm and concentrating favourable alleles through hybridization and selection, despite the tedious crossing technique. The objective of this study was to assess the degree of genetic variation in F₂ populations of tef as a basis for improving grain yield. F₂ populations from 12 crosses and their parents were grown at the Debre Zeit Agricultural Research Center, Ethiopia, and assessment was made on eight traits on individual plant basis. Eleven of the 12 crosses showed substantial genetic variation for grain yield and its components, indicating the potential for improvement through selection. Moreover, grain yield, plant weight and yield related traits showed moderate to high heritability values (17–80%). In all the crosses, tiller number, panicle weight, yield per panicle and panicle length showed significant (P ≤ 0.05) and positive association with grain yield. Considering the degree of genetic variation and heritability values, emphasis should be given to selected crosses in an effort to developing high-yielding tef varieties.     

Gene action and heritability for photosynthetic activity in two wheat crosses

Summary Gene action and heritability for photosynthetic activity were estimated from generation means in two wheat crosses during two stages (5 ^th leaf and flag leaf between 2 and 5 days after anthesis). Six generations were available for each cross: parents (P₁ and P₂), F₁, F₂ and backcrosses (BC₁ and BC₂).Correlations between some morphophysiological characters and photosynthetic activity of the flag leaf was also determined. The joint scaling test described by Mather & Jinks was used to determine the gene action. It showed that them; [d]; [h]; [i], [l] (mean, additivity, dominance, additive x additive interallelic interaction effects, dominance x dominance interallelic interaction effects) model fits the two crosses at both measurement times. All the model genetic components were significant for the flag leaf, however for the 5 ^th leaf only [h]; [i] and [l] were significant. The presence of additive and additive x additive effects suggested the possibility of selecting for this character using the flag leaf so as to obtain pure inbred lines. Dominance effects [h] were negative and dominance x dominance effects [l] were positive. Broad sense heritability values were medium to low. There were no correlations between the studied morphophysiological characters and the photosynthetic activity.     

豫南稻茬小麦生长发育特点研究

摘 要：豫南稻茬小麦的生产在河南省小麦生产中占有重要地位。然而,历史上稻茬麦产量不是太理想,除了自然障碍因素外,小麦生长发育规律还没有真正掌握、栽培技术不配套是重要原因之一。针对当前该区生产上小麦主导品种,研究分析了稻茬麦分蘖成穗规律、幼穗分化规律、籽粒灌浆规律。结果表明：（1）分蘖消长的特点是两个盛期、一个高峰、冬季不停、集中死亡,栽培管理上应走主茎成穗为主,争取部分分蘖成穗的途径。（2）幼穗分化早、分化期长,前期慢、后期快,茎、蘖、叶发生重叠进行,普遍存在同伸关系。栽培上要注意促使一、二分蘖赶主茎,提高分蘖成穗率,促进分蘖幼穗发育,提高结实率,争取大穗多粒,增加产量。（3）抽穗后3-5d开花,籽粒灌浆全过程短,从开花到成熟只有35d左右,呈慢-快-慢的S型曲线生长,籽粒发育经历形成、灌浆、成熟三个阶段;腊熟末期粒重最大,此时收获产量最高。提出了稻茬麦育种注意事项。     

Fine mapping of a major quantitative trait locus, <Emphasis Type="Italic">qFLL6.2</Emphasis>, controlling flag leaf length and yield traits in rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.)

Fine mapping of a quantitative trait locus, qFLL6.2, controlling flag leaf length (FLL) and yield traits in rice was conducted using four sets of near isogenic lines (NILs) that were developed from a common residual heterozygote at F₇ generation of the indica rice cross Zhenshan 97/Milyang 46. Each of the NIL sets consisted of 40 lines that are S₁ progenies of ten maternal homozygotes, ten paternal homozygotes, and 20 heterozygotes differing in a portion of the 1.19-Mb interval RM3414–RM6917 on the short arm of rice chromosome 6. Analysis of phenotypic differences among the three genotypic groups in each NIL set delimited qFLL6.2 to a 62.1-kb region flanked by simple sequence repeat marker RM3414 and sequence-tagged site marker Si2944. This QTL explained 52.73% of the phenotypic variance, and the Zhenshan 97 allele increased FLL by 2.40 cm. Based on data collected from homozygous lines of three of the NIL sets, qFLL6.2 was shown to have major effects on all the three yield traits analyzed, including the number of spikelets per panicle, the number of filled grains per panicle, and grain weight per panicle. A comparison of the different groups revealed that the effect of qFLL6.2 was highly consistent across different genetic backgrounds and environments, providing a good candidate for map-based cloning and investigating the source–sink relationship in rice.     

Evaluation of three sources of pollen fertility restoration genes and natural outcrossing of cytoplasmic male-sterile wheat

Summary Fertility restoration genes in Triticum aestivum L. in Texas Restorer Composite (TRC), D6301, and four CIMMYT restorer lines were studied, and selection was made for higher fertility in TRC. Mean-while, outcrossing percentages of seed set for 27 spring habit cytoplasmic male sterile (cms) varieties were evaluated for 3 to 5 years at Davis. The winter-habit TRC material did not restore reasonably good fertility, and the response to selection for higher fertility seemed to be slow. This poor fertility could be partly due to its late winter growth habit causing flowering at a period of high temperature and low humidity at Davis. The highest F₁ fertility was 46.6% in the cross cms Ramona x TRC-6, and its F₂ segregated into the ratio of 15 fertile to 1 sterile, with fertility ranging from 3.2 to 100%. Suggested for its improvement was intensive selection in the original TRC material and in the segre-gating F₂ population, followed by intercrossing. D6301 has 2 fertility restoration genes with different strengths which restore fertility up to 45.2% when both genes are heterozygous. D6301 is quite likely heterogeneous for these genes. Four CIMMYT restorer lines, D7464, D7465, D7466, and D7467, had satisfactory F₁ fertility restoration after crossing with cms Ramona 50. In 1975, the fertilities of the F₁'s ranged from 71 to 85% and were over 90% in 1976. The F₂ population of the cross cms Ramona 50 × D7464 segregated into a ratio of 3 fertile to 1 sterile, indicating that D7464 has a single dominant gene for fertility restoration. The F₂'s of crosses cms Ramona 50 × D7465, cms Ramona 50 × D7466, and cms Ramona 50 × D7467 gave a ratio of 15 fertile to 1 sterile, indicating that two gene pairs in these three lines were responsible for the fertility restoration. The best of this group was D7467 which restored fertility fully after being crossed with cms Ramona 50 (T. timopheevi cytoplasm).The early-flowering cms male-sterile varieties had higher outcrossing rates (16 to 38%) than late varieties (6 to 30%) over a 5-year period. This was due to hot and dry weather during the late growing season as well as to the rarity of windborne pollen. In 1970, 1971, 1972, and 1976, the variation among varieties was rather great. Some of them such as Roque 66 and Bajio 67, had consistently high outcrossing rates. This outcrossing ability seemed to be inherited and probably associated with the open-flowering characteristics of each variety.     

穗肥运筹对不同秧龄机插超级稻宁粳1号产量及群体质量的影响

以超级稻宁粳1号为材料,研究穗肥施用时间对不同秧龄机插水稻产量及其群体质量的影响。结果表明,相同穗肥施用条件下,机插水稻在适龄移栽时其产量、各生育阶段的群体生长速率、茎蘖动态、叶面积指数、光合势等均优于超秧龄移栽水稻。适龄移栽并于叶龄余数4、3 (D4-3)等量施用穗肥时,其产量、拔节至抽穗和抽穗至成熟阶段的群体生长速率、茎蘖成穗率、抽穗后的叶面积指数和群体光合势、抽穗期有效叶面积及其比率、高效叶面积及其比率、上三叶的叶片披垂度均高于叶龄余数5、3 (D5-3)和叶龄余数5、4 (D5-4)时等量施用穗肥的处理。而超秧龄移栽时,D5-4处理的产量、抽穗至成熟阶段的群体生长速率、拔节后各生育时期的群体茎蘖动态、群体叶面积指数、有效分蘖临界叶龄期(N-n)后的群体光合势、抽穗期有效叶面积和高效叶面积、基部3节间长度及3节间总长占秆长比例均优于D5-3和D4-3处理。说明机插水稻适龄移栽对水稻高产的获得尤为重要。适龄移栽时,穗肥于叶龄余数4、3等量施用可以形成良好的群体获得高产,而在超秧龄移栽时,将穗肥施用时间适当提前到叶龄余数5、4,可以促进部分动摇分蘖转化为有效分蘖并最终成穗,适当弥补秧苗因超秧龄移栽而造成的生长量不足,但穗肥的提前施用也使得基部节间过度伸长,增加了倒伏的风险。