小麦穗粒数形成的基因型差异及增粒途径分析

以27个穗粒性状不同的小麦品种为材料,对小麦穗粒数形成过程中的各构成因素进行了相关、通径和聚类分析。结果表明：不同穗粒性状基因型在分化小穗数、结实小穗数、分化小花数和可孕小花数上均有明显差异。特大穗型小麦的小花分化速率最快,分化持续时间最短。穗粒数对小麦产量提高的贡献最大,穗粒数与千粒重之间不存在负相     

播种密度对冬小麦不同穗位与粒位结实粒数和粒重的影响

利用重穗型小麦品种兰考矮早八和中间型品种周麦18,研究了不同播种密度对结实粒数与粒重的小穗位和粒位效应的影响。结果表明,不同穗型冬小麦品种小穗位结实粒数、小穗重及不同粒位粒重均随着小穗位自基部至顶部呈先增后降的二次曲线变化;不同穗型冬小麦品种穗部籽粒的分布差异显著,主茎穗的结实特性及粒重均优于分蘖穗;随着播种密度的下降,穗部结实特性和粒重有优化的趋势,重穗型品种兰考矮早八对密度的反应更为敏感,中间型品种周麦18小穗位和粒位对播种密度的调节效应较强;不同部位小穗粒重因结实粒数的差异表现出不同的粒位效应,下部和中部小穗位的第2粒位粒重较大,而位于上部和顶部小穗位第1粒位粒重较大,第3粒位粒重次于第1和第2粒位,第4粒位粒重最小。在小麦栽培中,应在保证主茎穗的基础上适当增加分蘖穗的比例。并在保证结实粒数的基础上提高粒重,尤其是下部小穗的结实粒数和粒重。同时,在保证第1、2粒位粒重的前提下最大限度地发挥第3、4粒位的粒重潜力,可以使小麦实现高产稳产。     

Nitrogen Fertilizer Effects on the Duration of the Pre-anthesis Period and Spikelet Number per Spike in Barley

The effects of increased yield and grain number per unit area in barley in response to nitrogen application are well known. However, the influence of applied nitrogen on the rates and durations of developmental phases in barley are less well understood. Our objective was to investigate the effect of applied nitrogen on the duration of pre-anthesis development in barley and the number of spikelets per spike in two barley cultivars, Franklin and Schooner, in two studies. We found no effect of nitrogen on the duration of the pre-anthesis period in Schooner, when applied to pots at a rate of 0 or 55 kg N ha^-1, or when applied in the held at 0, 40 or 160 kg N ha^-1. However, this duration was extended in Franklin in the first study by an application of 55 kg N ha^-1. Both plant biomass and grain yield at maturity were increased between 0 and 55 kg N ha^-1, and 0 and 160 kg N ha^-1. Meld increase was largely associated with an increase in the number of tillers per plant.     

Analysis of Wheat Cultivar Differences in Grain Yield, Grain Nitrogen Yield and Nitrogen Utilization Efficiency.

More detailed information on the causes of yield variability among wheat cultivars is needed to further increase wheat yield. Field studies were conducted in Northern Greece over the two cropping seasons of 1985—1986 and 1986—1987 to assess the effects of nitrogen fertilizer and application timing of the various component traits that determine grain yield, grain nitrogen yield and nitrogen utilization efficiency of two bread ( Triticum aestivum L.) and two durum ( Triticum durum Desf.) wheat cultivars, using yield and yield component analysis. Nitrogen at a rate of 150 kg ha^-1 was applied before planting or 100 N kg ha^-1 before planting and then 50 N kg ha^-1 top dressed at early boot stage. Nitrogen and cultivars affected all traits examined, while split nitrogen application affected only some of the traits. Grain yields in the most cases were correlated with number of grains per unit area and grain weight and grain nitrogen yields in all cases with grain number per unit area. The contribution of the number of grains per spike to total variation in grain yield among cultivars was almost consistent (37 to 55 %), while the contribution of grain weight was more significant (up to 55 %) in high yields (>6.500kg ha^-1) and number of spikes per unit area (>500). The number of grains per spike contributed from 60 to 83 % to the total variation in grain nitrogen per spike. Increased grain nitrogen concentration resulted in a reduction of its contribution in grain nitrogen yield variation. Nitrogen utilization efficiency was higher during grain filling than during vegetative biomass accumulation. The contribution of nitrogen harvest index to the variation of utilization efficiency for grain yield was higher in plants receiving nitrogen application.     

The Effects of Ethephon, Chlormequat Chloride and Mixtures of Ethephon and Chlormequat Chloride Applied at the Beginning of Stem Elongation on Spike-Bearing Shoots and other Yield Components of Spring Barley (Hordeum vulgare L.)

Effects of chlormequat chloride (CCC), ethephon and mixtures of CCC and ethephon, applied at Zadoks growth stage (ZGS) 30 (the beginning of stem elongation) on the number of spike-bearing shoots and their contribution to grain yields of four spring barley ( Hordeum vulgare L.) cultivars were studied in 1987 and 1988 at McGill University, Quebec, Canada. The results varied between years and among cultivars. The mixtures of CCC and ethephon or ethephon alone, produced significant increases in the number of spikes m⁻² in cultivars Joly and Laurier , in both years, and in Leger only in 1988. Ethephon and ethephon containing mixtures reduced the yields of Joly and Leger in 1988. In both years CCC had no effect on spikes m⁻² for all cultivars. Increases in spikes m⁻² were accompanied by decreases in 1000-grain weight, and/or grains per spike, which offset or more than offset potential benefits from increased spikes m⁻². These results indicate that under continental climatic conditions such as those prevalent in Quebec, Canada, application of PGRs to spring barley at ZGS 30 does not increase grain yield through an increased number of spikes m⁻².     

Yield determination in triticale as affected by radiation in different development phases

The critical period for grain yield determination has not been determined for triticale. We aimed to identify it, determining the relative importance of both the major yield components and the dry matter acquisition by the spikes at anthesis. A field experiment was carried out with two triticales, differing in tillering capacity, subjected to shading treatments at five different timings from early tillering to maturity. Results showed that reductions in grain yield were more significant when shading was imposed during 3 weeks before and 1 week after anthesis. Reductions in grain yield by shading treatments were associated with lower number of grains per m² more than with changes in the average grain weight. Reductions in grains per m² were due to reductions in the number of fertile florets per spike, affecting grains per spike. The assimilate acquisition by the spikes during the critical period was a key determinant of floret survival. Grain number per m² was related with photothermal quotient during 30 days before anthesis and spike dry weight at anthesis, though the goodness of the prediction compared with wheat, was lowered by poorer grain setting percentage.     

Effects of Elevated Ultraviolet-B Radiation on Productive Tillers, Spikelet Sterility and Grain Characteristics of Southern US Rice (Oryza sativa L.) Cultivars

Depletion of the stratospheric ozone layer is leading to an increase in ultraviolet-B (UVB) radiation (280–320 nm) reaching the Earth's surface, which can alter crop productivity. The objective of this study was to determine the effects of elevated UVB radiation on rice production with special emphasis on grain characteristics in southern US rice cultivars (six inbred cultivars and three hybrids). Due to the spectral characteristics of the greenhouse glass, plants received no natural UVB radiation; hence, plants were provided with supplemental UVB lighting. Plants were exposed to UVB radiation of 0, 8 (ambient) or 16 (twice ambient) kJ m⁻² day⁻¹. There was no significant effect of elevated UVB radiation on the number of productive tillers in any cultivar except 'Sierra'. All the cultivars except 'Sierra' showed increased spikelet sterility with an increase in UVB radiation. There were decreases in main-stem panicle length, number of primary branches per panicle, and grain width with an increase in UVB radiation in most of the inbred cultivars. Elevated UVB radiation decreased plant grain yield in all the cultivars, however the per cent decrease in plant grain yield varied among the cultivars (31–79 %). The hybrid 'Clearfield XL729' performed best among the selected southern US rice cultivars under an elevated UVB environment.     

Physiological Genetics of Salt Tolerance in Wheat (Triticum aestivum L.): Performance of Wheat Varieties, Inbred Lines and Reciprocal F1 Hybrids under Saline Conditions

Four bread wheat cultivars were studied at two salinity levels. Tobari 66 had the lowest uptake of Na⁺ and Cl⁻, and the highest K⁺/Na⁺ ratio; Pato had the highest uptake of these ions and Lyallpur 73 was intermediate. Intervarietal differences were greater at higher salinity, suggesting that they were not caused by variation at the Kna1 locus. There were significant differences between inbred lines for Na⁺, particularly in Blue Silver, suggesting the possibility of selecting genotypes with enhanced tolerance from within existing cultivars. Pato, Tobari 66 and their reciprocal F₁ hybrids were further evaluated at four salinity levels. The hybrids exhibited similar relative grain yield to Tobari, with better Na⁺ and Cl⁻ exclusion and higher K⁺/Na⁺ ratios than Pato. Overall, Tobari had the highest absolute yield under salinity, and the hybrids were closer to Tobari than to Pato. Tiller and grain numbers, 100-grain weight and yield were more affected by salinity than were height, spike length and spikelet number. We conclude that intervarietal variation for salt tolerance in wheat is controlled by genes which could be transferred to sensitive genotypes to improve their tolerance, and that the K⁺/Na⁺ ratio of the youngest leaf could be used to screen for salt tolerance.     

Allocation of Photosynthates and Grain Growth of Two Wheat Cultivars with Different Potential Grain Growth in Response to Pre- and Post-anthesis Shading

Grain yield in wheat is dependent on photosynthate production and allocation. Light intensity is one of the main factors affecting photosynthate production and allocation, and grain yield. This study was conducted to determine whether cultivars varying in grain number per spike and grain weight respond differently to pre‐anthesis shading (PRE) and post‐anthesis shading (POST), and to characterize the responses in production and allocation of photosynthate, yield and yield components, and spike traits. Both PRE and POST caused a decrease in both dry matter (DM) accumulation and allocation to grain. Cultivar Lumai 22, which has a large spike and large grains, was more sensitive to either PRE or POST. PRE reduced photosynthate production and partitioning to the spike in Lumai 22 at anthesis. In contrast, PRE had little influence on these parameters in the small‐spike, small‐grain cultivar Yannong 15. POST reduced the partitioning to the grain, especially in Lumai 22, for which marked reductions in biomass and grain yield were found for both the PRE and POST treatments. Changes in yield components attributable to shading varied with cultivars. The number of spikes m^?2 was not affected by either PRE or POST. Lumai 22 was more seriously affected by shading than Yannong 15 in terms of grain number per spike and weight per grain. The decreases in grain number or weight per spikelet in both the PRE and POST treatments took place mainly in the upper and basal spikelets, especially in Lumai 22. We concluded that the adaptability of the small‐spike, small‐grain cultivar Yannong 15 to either PRE or POST was much greater than that of the large‐spike, large‐grain cultivar Lumai 22 in terms of many characteristics closely related to grain yield. Hence, we suggest that, in areas where low light intensity often occurs, the small‐spike, small‐grain cultivar would be more likely to produce high, stable grain yields.     

Translocation of 14C-sucrose within the Ear in Durum and Aestivum Wheat Varieties

Excised ears of Triticum durum (HD 4502 and B 449) and T. aestivum (Kalyansona and Kundan) varieties were cultured in ¹⁴C-sucrose, and the uptake and distribution of ¹⁴C within the ear was examined. Species-level differences in the distribution of ¹⁴C to spikelets at basal, middle and apical positions in the wheat ear (vertical distribution) were observed. T. aestivum var. Kalyansona and Kundan showed no limitation in vertical translocation of ¹⁴C-sucrose, whereas in T. durum there was a decrease in the distribution of ¹⁴C to apical spikelets. Within a spikelet, the distribution of ¹⁴C-sucrose to distal grains was significantly less than that to proximal grains in all the genotypes.     

Spring Barley Responses to Nitrogen Fertilizer and Ethephon in Regions with a Short Crop Growing Season

Aspects of intensive management practices such as high N fertilization inputs and plant growth regulator use could potentially increase cereal yields in regions with a short crop-growing season and occasionally dry and hot weather. A field experiment was carried out for four years (1987 to 1990) at Agronomy Research Centre of McGill University, Canada to evaluate the response of spring barley ( Hordeum vulgare L.) cv. Cadette, Laurier and Leger to N rates (0, 70 and 140 kg N ha⁻¹) and ethephon (2-chloroethyl phosphonic acid) growth regulator treatment. The application of higher than conventional N level (70 kg N ha⁻¹) did not increase barley yields under dry weather conditions and when the soil N resources were high. The high levels of N did increase the grain crude protein concentration by 2 to 10 g kg⁻¹, as did ethephon treatment. The feed quality of spring barley was improved. Ethephon treatment reduced grain yield due to a severe reduction in the number of grains spike⁻¹, and/or 1000-grain weight, although the number of spikes m⁻² was increased. Thus, the overall effect of ethephon treatment on yield was inconsistent and was influenced to a large extent by the prevailing weather conditions.     

Response of Yield Attributes of Isogenic Tall, Semidwarf, and Doubledwarf Winter Wheats to Nitrogen Fertilizer and Seeding Rates

Relationships between grain yield attributes and response to agronomic practices of dwarf and tall genotypes in the major U.S. wheat region were investigated. Isogenic tall, semidwarf, and doubledwarf (Norin 10/5/Pawnee) 'Pawnee' winter wheat ( Triticum aestivum L.) lines were planted in a split-split-plot design with nitrogen fertilizer rates of 0, 50, and 100 kg ha⁻¹ as main plots and seeding rates of 30, 60, and 90 kg ha⁻¹ as subplots in four replications at Hutchinson and Manhattan, Kansas, during 1980–1981. There was no evidence that dwarf lines responded better than the tall line to nitrogen fertilizer; however, percentage fertile spikelets, spike length, harvest index, and kernel number per spike of the semidwarf line were favored by high nitrogen rates. Grain yield was more responsive to seeding rate in the doubledwarf line than in the other lines, and test weight and spike number per unit area were more responsive to seeding rate in one or both dwarf lines than in the tall line. Grain yield of each genotype depended highly on the predominant yield attributes — usually spike number per unit area and/or kernel weight — at one or both locations.     

Availability and Utilization of Assimilates in Relation to Grain Growth Within the Ear of Wheat

The development of grains of different positions in the apical, middle and basal spikelets of wheat var. Kaly-ansona showed that beyond first two basal grains, the more distal a grain in a spikelet the lower its weight. The distal grains received less assimilates than the proximal grains as revealed from sugar concentration in the grains. The eflficiency of distal grains of kalyansona to synthesize reserves was, however, not inferior than the proximal grains in a spikelet. The depression in grain weight lowards extreme spikelet was lower compared to the depression in weight of individual grams towards a distal position in a spikelet. The study seems to suggest that in order to ensure better grain uniformity while maintaining a higher grain number per ear, the spikelet number per ear should be increased instead of increasing the grain number per spikelet.     

播期和密度对江苏淮北强筋小麦籽粒产量和品质的影响

旨在为江苏淮北地区小麦优质高产栽培提供参考,以优质强筋品种‘瑞华麦506’为材料,研究了播期（10月5日、15日、25日、11月4日和14日）和密度（2.1×10⁶、2.7×10⁶和3.3×10⁶/hm²）对温光利用、籽粒产量和籽粒品质的影响。结果表明,播期延迟减少了出苗至越冬始期累积积温和日照时数以及花后累积日照时数。迟播显著降低了茎蘖数和穗数,但不同程度增加了每穗粒数和千粒重,籽粒产量以10月15日播种最高。每晚播种10天,生育期、积温、日照时数和穗数分别减少8.5天、108℃、38 h和3.85×10⁵/hm²,产量损失700 kg/hm²。推迟播期降低了面粉吸水率,但增加了籽粒容重、蛋白质含量、湿面筋含量和面团稳定时间。增加密度对籽粒品质影响不显著。综合而言,10月15日播种、采用2.7×10⁶/hm²密度是江苏淮北强筋小麦协同高产优质的适宜组合。     

30余年来北部冬麦区小麦品种产量改良遗传进展

采用1965年以来北部冬麦区育成的10个主栽品种,在水、肥供应充足、病、虫、倒伏得到有效控制条件下,连续两年共进行4个点次试验;同时对1B/1R易位系和矮秆基因进行分子鉴定。结果表明,品种产量年遗传进展为64.63 kg hm^-2 或1.20%,其较大幅度的提高出现在1980年丰抗号品种育成时期。丰抗2号和丰抗8号是该地区最早育成的含有1B/1R染色体和Rht-D1b矮秆基因的品种。主要农艺性状演变的总趋势是抽穗期提前、株高显著降低、生物学产量基本保持稳定、单位面积穗数减少、每穗粒数有所增加、千粒重和收获指数大幅度提高,其年遗传进展分别为－0.1%、－0.70%、0.35%、－0.50%、0.63%、1.12%和0.79%。通过减少不孕小穗和小花数来增加每穗粒数,通过提高灌浆速率来提高千粒重,再把高穗粒重与较多的单位面积穗数结合在一起,是北部冬麦区进一步提高产量的重要途径。     

Breaking Uniculm Growth Habit of Spring Cereals at High Latitudes by Crop Management. II. Tillering, Grain yield and Yield Components

Long days at high latitudes inhibit tillering of cereals and hence seeding rates of 500–700 seeds m⁻² are commonly used for spring wheat, barley and oats in Finland. Costs could be reduced by using a lower seeding rate in combination with crop management to produce more head-bearing tillers m⁻². This study was designed to assess possibilities of breaking the uniculm growth habit of spring cereals by (1) lowering the seeding rate from 600 to 300 seeds m⁻² and (2) manipulating tiller growth with early mechanical treatments to the crop (rolling, cutting) or chemical applications (foliar urea, CCC and GA). A low seeding rate and early application of foliar CCC at high latitudes, under good moisture conditions prior to heading, promoted 20% more head-bearing tillers and 6% higher grain yield than standard management practices. However, cultivars differed in their response to CCC. The advantageous effects of CCC at a low seeding rate were attributed to increase, over the controls, in contribution of head-bearing tillers to grain yield in wheat (cultivar Heta ), but more grains per head in oats (cultivar Veli ). Varietal recommendations for use of low seeding rate in combination with early CCC spraying should be examined further.     

Grain Weight Reductions in Wheat Associated with Semidwarfism: an Analysis of Grain Weight at Different Positions Within the Spike of Near-isogenic Lines

Semidwarf genes have made a major contribution to grain yield gains in wheat during this century. These genes have frequently been reported to increase grain number but decrease grain size. To analyse possible causes of this negative association between number of grains per head and mean grain weight, grains from different positions within the spikes were individually weighed in three isolines (standard-height, SH; semidwarf, SD; and dwarf, DD) of the spring wheat cultivar Maringa grown under field conditions. Dwarfing genes affected both grain number and grain weight. Increasing doses of Rht genes resulted in a decreased average grain weight (ca. 22 %) but in a greater increase in number of grains per m² (ca. 40%). Since the isogenic lines did not differ in either the number of spikes per m² or number of spikelets per spike, the frequencies of appearance of grains in the distal positions (florets 3 and 4) of the central spikelets and in the top spikelets of the spike was much higher for the SD and DD lines than for the SH line. Averaging across spikelets, basal grains (grains 1 and 2) of SH, SD and DD lines represented ca. 82, 73, and 69 %, respectively, of the total number of grains. On the other hand, grain 4 was almost absent in the SH line but represented around 10 % of the grains in the DD line. Averaging across lines and spikelets, basal grains weighed ca. 30 mg, which is approximately 20 % heavier than grain 3 (ca. 25 mg) and 85 % heavier than grain 4 (ca. 16 mg). Although there was a clear trend for a greater grain weight in the SH line (with no major differences between the SD and DD line) when basal grains were considered, grains 3 and 4 did not show any clear difference between lines. The fact that genotypes with Rht alleles had grains in the distal positions with a much higher frequency of appearance than in the SH line could be the main reason for their lower average grain weight. Therefore, the negative relationship between grain number and average grain weight might be not reflecting that competition for assimilates among grains of the DD and SD lines is stronger than that in the SH line.     

基于顶端发育的小麦产量结构形成模型

小麦产量由单位面积穗数、每穗粒数与粒重构成。本研究以试验资料为基础,通过定量分析小麦茎顶端发育过程及其与环境因子和品种特性的动态关系,构建了小麦穗粒发育与结实的模拟模型,包括对叶原基数、叶片数、小穗原基数、小穗数、籽粒数及籽粒重的预测;进一步结合茎蘖发生与穗数决定模型,最终建立了小麦产量结构形成的模     

钾肥对西藏垂穗披碱草种子产量的影响

垂穗披碱草作为西藏种植面积最广的优质牧草之一,其种子生产问题在当地畜牧业生产中显得尤为重要。研究表明,不同时期施钾均可影响垂穗披碱草生殖枝数/m2、小穗数/生殖枝、小花数/小穗、种子数/小穗和千粒重。施钾可增加垂穗披碱草的实际种子产量。其中拔节期施钾种子实际产量为221.8 kg/hm2,与对照(ck)差异显著(p0.05)。分蘖期施钾潜在种子产量和表现种子产量均最高,为2 803.8 kg/hm2和1 040.2 kg/hm2,与对照(ck)差异极显著(p0.01)。     

冬小麦不同穗位籽粒淀粉粒差异及其与粒重的相关性

为研究小麦不同穗位籽粒淀粉粒差异及其与粒重相关性, 以露天池栽冬小麦济麦20, 测定不同小穗位成熟颖果胚乳细胞大小、淀粉粒的数目、体积和表面积分布及胚乳发育过程中淀粉体数量变化。结果表明, 小麦胚乳淀粉粒发育具有显著的粒位、穗位效应, 相同小穗位, 强势粒淀粉体起始时间比弱势粒早4~5 d。相同粒位, 中部小穗籽粒淀粉体最先发育, 上部小穗次之, 下部小穗最晚。淀粉体数量在中部小穗籽粒最多, 随着灌浆进程, 下部小穗逐渐赶上并超过上部小穗。成熟籽粒淀粉粒数目分布总趋势为B_L型>B_S型>A型; B_S型淀粉粒表现强势粒>弱势粒, 且随小穗位的升高而呈增加趋势; B_L型则相反。淀粉粒的数目分布导致其体积与表面积分布表现出相同的变化趋势。粒重与大、小淀粉体数目相关系数随灌浆进程逐渐增大, 且前者大于后者; 成熟期分别达到0.88^**和0.78^**。粒重增加与大、小淀粉粒数目增长的相关系数分别高于0.96^**和0.93^**, 前者在穗位间差异不显著, 后者表现为下部小穗>上部小穗>中部小穗。小麦胚乳淀粉粒形成及粒度分布既具有强弱势籽粒间的粒位效应, 也具有显著的小穗位效应; 弱势籽粒仍有通过增加淀粉粒数量以减小其与强势籽粒间粒重差异的调控空间。