Reproductive partitioning and seed set efficiency in soybean,sunflower and maize

Seed number per plant (SNP) can be modelled as a function of plant growth rate during the critical period for seed set (PGR_C), the proportion of plant growth partitioned to reproductive organs (P_R) and the minimum assimilate requirement per seed (λ). In comparison to PGR_C, less attention has been given to P_R and λ. In this paper, we analysed reproductive partitioning and λ in three species of contrasting reproductive strategies, soybean (Glycine max L. Merrill), sunflower (Helianthus annuus L.) and maize (Zea mays L.). To study plant-to-plant variation and to characterise stability of the variables analysed, we focused on individual plants grown under a wide range of plant densities. In soybean and sunflower, reproductive partitioning comprised about 50% of shoot growth, was fairly stable in a wide range of plant growth, and only decreased in a few, very small plants. In comparison, reproductive partitioning in non-prolific maize showed an optimum, was generally below 50% and exhibited a strong variation and instability at plant growth rates ≅2 g/day. Among species, stability of reproductive partitioning correlated inversely with a PGR_C threshold for reproductive growth and positively with reproductive plasticity at high PGR_C. Consideration of reproductive partitioning improved estimation of seed number, particularly in maize, a species prone to barrenness. Seed number as a function of reproductive growth was adequately described through linear (soybean) and hyperbolic models with x-intercepts (sunflower and maize). Seed set efficiency in terms of seed number per unit of reproductive growth (Ef) was constant only in soybean. In sunflower and maize, Ef increased with decreasing reproductive growth and became highly variable and unstable when reproductive growth was close to the threshold for seed set. In maize, such threshold was higher than in soybean and sunflower possibly as a consequence of a higher minimum combined demand for assimilate, resulting from a higher λ and number of simultaneously developing sinks. Inclusion of parameters assessing (i) stability in reproductive partitioning at low plant growth rates, and (ii) the minimum assimilate requirement per seed might improve seed number estimation.     

Effects of high temperature and shading on grain abscisic acid content and grain filling pattern in rice (Oryza sativa L.)

ABSTRACT

Abscisic acid (ABA) is a key factor regulating starch biosynthesis genes and is involved in assimilate partitioning to individual spikelets. The objective of this study was to clarify the effects of high temperature and shading during grain filling on grain ABA content and the grain filling pattern of spikelets located at different positions in a panicle. We grew the rice cultivar ‘Koshihikari’ in pots in 2009 under two temperature regimes and two light conditions during grain filling. We periodically measured grain dry weight and grain ABA content (pmol per grain) and concentration (pmol per grain dry weight). Shading increased a grain weight difference between superior and inferior spikelets while high temperature decreased the difference regardless of light condition. High temperature decreased ABA content and concentration in grains. There was a close correlation between mean grain ABA content and mean grain-filling rate averaged over the first half of grain filling.     

Meta-analysis of environmental effects on soybean seed composition

The value of commodity soybean depends on the concentration of protein and oil in the seeds. While seed composition is primarily genetically determined, environmental conditions during seed development also affect seed component accumulation, and can result in protein and/or oil deficits for processing. To understand the general environmental effects on soybean composition, we conducted a meta-analysis of published data quantifying the effect of water stress, temperature, and/or nitrogen supply on seed protein and oil accumulation and their final concentrations. The meta-analysis showed that water stress reduced the content (mg per seed) of protein, oil and residual seed fractions. Protein accumulation, however, was less affected than were oil and residual accumulation, resulting in an increase in final protein concentration (% dry weight). Growth at high temperature also increased protein concentration in a manner similar to that observed for water stress. But in neither case was the increase in protein concentration due to an increase in protein synthesis per se. Increasing nitrogen supply to seeds cultured in vitro and to plants grown hydroponically increased both final seed protein concentration and content. But the magnitude of seed component response to experimental manipulation under field conditions was far less than that observed in the Uniform Soybean Regional Field Tests. Greater knowledge of the physiological processes that regulate these responses is essential to predict when and where future protein deficits might occur. Limitations of the meta-analysis approach and implications for future research on soybean seed composition are discussed.     

A crop model component simulating N partitioning during seed filling in pea

Seed N concentration is one of the main quality parameters in grain legume crops. Since few studies have aimed at modelling both seed and vegetative parts N concentrations, our objective was to model N partitioning between vegetative parts and filling seeds for pea (Pisum sativum L.) in field situations where both N nutrition and the plant genotype varied. A crop model component predicting the time courses of vegetative and seed N concentrations was built using knowledge concerning N partitioning during the seed filling period, which include a previously demonstrated relationship between the rate of individual seed N accumulation and the N availability within plants. A greenhouse experiment where assimilate availability was non-limiting was conducted with two genotypes. This experiment demonstrated the genotypic variability of one of the crop model component parameters, the maximum rate of individual seed N accumulation (SNR_max), allowing introduction of this parameter in the crop model component for the studied genotypes. Field experiments spanning 3 years and comprising various crop N nutrition and four genotypes were conducted to evaluate the crop model component. Observed seed and vegetative parts N concentrations ranged at harvest from 19.3 to 39.1 mg g⁻¹ and from 3.6 to 18.4 mg g⁻¹, respectively. N partitioning was well-simulated by the crop model component except when crops had deficient N nutrition. These results suggest that the parameter “NC_n-remob” (proportion of N in vegetative parts which is not available for remobilization to filling seeds), which is taken as constant in the crop model component, could depend upon the crop nutrition level. A sensitivity analysis highlights the need for a precise calibration of the parameters “NC_n-remob” and “SNR_max”. When the crop N nutrition level and further genotypic variability of these parameters are incorporated in the proposed crop model component, it will become a useful part of a pea crop model predicting yield and seed N concentration.     

覆膜红花单株种子产量相关性状的通径分析

以新红花1号、吉红1号等10个红花品种为材料,在地膜覆盖条件下进行单株种子产量相关性状通径分析.结果表明,10个相关性状对单株种子产量影响的顺序为:单株有效果球数＞单株总粒数＞每果球粒数＞百粒重＞一级分枝数＞单株无效果球数＞单株总叶片数＞株高＞主茎种子重量＞二级分枝数.单株总粒数与单株有效果球数的互作效应对单株种子产量的影响在所有的性状互作中为最大,单株有效果球数、单株总粒数、每果球粒数及百粒重是影响红花单株种子产量的4个主要因素.所研究的10个农艺性状中,两两性状间的互作效应对红花单株种子产量的影响极大,在红花育种、地膜栽培时应注意考虑这些性状间的影响.单株种子产量高的株型特征为单株无效果球数少,一级分枝数多,单株有效果球数多,单株总粒数和每果球粒数多,百粒重大等.     

Performance of high-protein mutant lines of Triticum aestivum (L.) under semi-arid conditions of Syria

The agronomical characters of nine high-protein mutant lines of T. aestivum produced by the IAEA were studied along with their mother line Mex22A and four local cultivars. The experiments were carried out under rainfed conditions in 1990 and 1991 in southern Syria. Statistical analysis revealed significant differences among the lines in all characters. Genotype by environment interaction was significant for all characters except for N yield. There was a negative correlation between grain nitrogen concentration (GNC) and yield. However, two of the check cultivars and seven mutant lines had similar yield to Mex22A with greater GNC. The other two mutant lines, 5074M and E296, were very late in heading and were characterized by low yield with extremely high GNC. Spikes per square meter contributed most to grain yield followed by number of seeds per spike and lastly seed weight. SDS sedimentation test values were negatively correlated with GNC.Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate (SDS-PAGE) was used to assay for high molecular weight (HMW) glutenin protein subunits of the grain endosperm. The results showed the presence of HMW glutenin GluD1 subunits 2 + 12 in Mex22A and all IAEA genotypes. Check varieties L92-6, Buhuth 4 and Cham 2 contain the good quality allelic GluD1 subunits 5 + 10. Nevertheless, 4 of 9 IAEA mutant lines were characterized by having higher SDS sedimentation values due to the presence of Glu-B1 subunits 17 + 18 when compared to those that had subunits 7 + 8.     

辽宁省部分中熟水稻品种穗部性状与结实特性分析

以辽宁省最新育成的水稻品种(品系)为试材,把参试品种分为高产品种、中产品种和低产品种三类,分析了不同产量水平水稻品种穗部性状及其结实特性,结果表明,高产品种具有较高的每穗粒数、二次枝梗粒数、一次枝梗粒数、以及较高的二次枝梗粒率,具有较高的结实率、二次枝梗结实率、一次枝梗结实率,具有较高的一次枝梗数、二次枝梗数,使穗粒结构得到较大程度的协调,以致其产量处于较高的水平。     

北部冬麦区旱地小麦品种的演变规律

为了给北部冬麦区旱地小麦育种提供参考,利用1986-2015年国家北部冬麦区旱地小麦长治区试点参试品种的试验资料,研究其演变规律,并对产量和主要农艺性状进行相关和通径分析。结果表明,28年间北部冬麦区旱地小麦品种产量呈逐年递增趋势,年平均遗传进展分别为68.163kg·hm~(-2)或1.57%。主要农艺性状演变的总趋势是,有效穗数和千粒重增加,穗粒数略有减少,株高降低,抽穗期和成熟期提前,灌浆期延长,其年平均遗传进展分别为0.18%、0.26%、-0.03%、-0.26%、-0.12%、-0.05%、0.17%。从产量及主要农艺性状变化趋势和变异情况及区域布局、气候条件和育种现状分析,选育抗旱节水性好、高产稳产适应性广的品种是北部冬麦区旱地小麦育种面临的挑战和最终目标。为了适应当前耕作制度、生产条件和气候变化的影响,北部冬麦区旱地品种选育应在加强品种抗旱节水性选择的基础上,通过适当降低株高增强抗倒性来进一步增加穗数,通过选育穗子较大、小穗数适中、结实性好的品种来提高穗粒数,通过选择灌浆期长且灌浆速率高的品种来提高品种的千粒重。     

北方杂交稻与常规稻籽粒灌浆特性的比较

以北方杂交稻和常规稻品种为试验材料,用Logistic方程对不同品种的籽粒灌浆过程进行了拟合。结果表明,杂交稻和常规稻的灌浆参数存在极显著差异,灌浆持续时间的不同是造成不同品种粒重差异的主要因素。灌浆阶段,渐增期短,启动灌浆速率大,灌浆快增期早,快增期和缓增期延长等特性有利于增加粒重。同一品种的粒重差异来源于灌浆速率的不同。在灌浆期杂交稻的光合同化物向籽粒运转率高,干物质由茎鞘源源不断地向籽粒输送,使杂交稻保持较长的高速灌浆期和缓增期,最终形成较大的粒重。     

Ecophysiological traits in maize hybrids and their parental inbred lines: Phenotyping of responses to contrasting nitrogen supply levels

Maize (Zea mays L.) breeding based primarily on final grain yield has been successful in improving this trait since the introduction of hybrids. Contrarily, understanding of the variation in ecophysiological processes responsible of this improvement is limited, especially between parental inbred lines and their hybrids. This limitation may hinder future progress in genetic gain, especially in environments where heritability estimation is reduced because grain yield is severely affected by abiotic stresses. The objective of this study was to analyze the genotypic variation between inbred lines and derived hybrids in the physiological determinants of maize grain yield at the crop level, and how differences among hybrids and parental inbreds may effect contrasting responses to N stress. Special emphasis was given to biomass production and partitioning during the critical period for kernel number determination. Phenotyping included the evaluation of 26 morpho-physiological attributes for 6 maize inbred lines and 12 derived hybrids, cropped in the field at contrasting N supply levels (N₀: no N added; N₄₀₀: 400 kg N ha⁻¹ applied as urea) during three growing seasons. Tested genotypes differed in the response to reduce N supply for most measured traits. Grain yield was always larger for hybrids than for inbreds, but N deficiency affected the former more than the latter (average reduction in grain yield of 40% for hybrids and of 24% for inbreds). We also found (i) a common pattern across genotypes and N levels for the response of kernel number per plant to plant growth rate during the critical period, (ii) a reduced apical ear reproductive capacity (i.e., kernel set per unit of ear growth rate) of inbreds as compared to hybrids, (iii) similar RUE during the critical period and N absorption at maturity at low N levels for both groups of genotypes, but enhanced RUE and N absorption of hybrids at high N supply levels, and (iv) an improved N utilization efficiency of hybrids across all levels of N supply. Results are indicative of a more efficient use of absorbed N by hybrids than by parental inbreds. Larger grain yield of hybrids than of inbreds at N₀ was associated to (i) enhanced dry matter accumulation due to improved light interception during the life cycle and (ii) enhanced biomass partitioning to the grain.     

Analysis of growth and yield of maize,sunflower and soybean grown at Balcarce,Argentina

The objectives of this study are: (1) to analyze the capacity of maize, sunflower and soybean to produce dry matter and seed yield, including the responses to shading during flowering, and shading and thinning during seed filling; and (2) to evaluate effects of plant density and sowing date on growth and yield. This report integrates data obtained during seven years of research at Balcarce Experimental Station, Argentina. In these experiments, nutrients and water were not limiting to growth. Maize produced the most biomass because of sustained ground cover and high light conversion efficiency. It also had the largest harvest index on a dry weight basis. When dry matter was expressed in glucose equivalents, differences among harvest indices for the three crops were smaller. Flowering in maize, seed filling in soybean and flowering and seed filling in sunflower were critical periods in determination of grain yield. Sunflower had more capacity than maize to compensate for fewer grains through greater grain weight. Maize and sunflower had low stability in grain number at less than optimal plant densities. Finally, delays in sowing date significantly reduced grain yields of the three crops. These reductions were due to decreases in number of grains per m² and in grain weight.     

Sulphur nutrition of sunflower (Helianthus annuus) as affected by nitrogen supply: Effects on vegetative growth,the development of yield components,and seed yield and quality

The effects of sulphur and nitrogen nutrition on the growth and yield components of a hybrid confectionery sunflower (cv. Kernel) were investigated in a glasshouse experiment using controlled S and N supplies that ranged from deficient to more than adequate, and in which the S supplies of some plants were changed at defined stages of growth. S deficiency delayed floret initiation and anthesis but not seed maturity; N deficiency delayed all developmental phases including seed maturity. S and N deficiencies reduced plant height and leaf area. N deficiency caused a reduction in leaf number, but S deficiency did not. Both S and N deficiencies reduced yield by reducing the number of seeds per plant and by decreasing single seed weight. Oil concentration in seeds was the same for all levels of S supplied, but it was reduced by increased N supply. Changing the S supply at the end of floret initiation and at anthesis indicated that floret number and therefore seed number per plant were mainly established by the S suplly before the end of floret initiation. Single seed weight responded positively to increased S supply after floret initiation but only if the N supply was adequate; there was no response to increased S supply after anthesis.Concentrations of S and N in plant organs increased with increasing S and Nsupplies, but seeds were much less responsive than vegetative organs. Plants grown on high N but low S had the highest concentrations of N in their tissues, but the highest S concentrations did not occur in high S low N plants. Cysteine and methionine decreased by 30% in seeds of S-deficient but N-sufficient plants, whereas arginine increased by 34% compared with nutrient-adequate plants.We suggest that an adequate supply of S to young sunflower plants is required, particularly up to floret initiation, to obtain large floret numbers and maximum leaf area. An adequate supply of S is also required between the end of floret initiation and anthesis to prevent floret abortion and allow development of large seeds. Sulphur stress in sunflower during seed filling results in kernels with low levels of essential S-containing amino acids.     

Environmental modification of hard red winter wheat flour protein composition

The intrinsic processing quality of wheat (Triticum aestivum L.) cultivars is modified significantly by cultural conditions and climate. In an attempt to understand the biochemical basis of such variation, environmental modification of flour protein content and composition was measured. Thirty hard red winter wheat cultivars and experimental lines were grown at 17 Nebraska environments during 1990 and 1991. Environmental conditions, including grain filling duration, temperature and relative humidity during grain filling, were monitored. Grain yield and test weight also were determined as environmental indicators. Significant linear correlations between flour protein content, as measured by near-infrared spectroscopy, were observed only with the duration of grain filling. Protein quality, as measured by SDS sedimentation volumes and size-exclusion high-performance liquid chromatography, was highly influenced by the frequency of high temperatures during grain filling and by the relative humidity. Observed ranges in genotypic responses (variance) at locations also were altered by environmental factors. Optimal protein quality, as determined by SDS sedimentation volumes, was observed with exposure to less than 90 h of temperature greater than 32°C during grain filling. Protein quality declined with exposure to a greater number of hours of elevated temperature.     

Morphological and physiological traits of roots and their relationships with shoot growth in “super” rice

Success in “super” rice breeding has been considered a great progress in rice production in China. This study aimed to test the hypothesis that an improved root system may contribute to better shoot growth and consequently to higher grain yield in “super” rice. Two “super” rice varieties Liangyoupeijiu (an indica hybrid) and Huaidao 9 (a japonica inbred) and two elite check varieties Yangdao 6 (an indica inbred) and Yangfujiang 8 (a japonica inbred) were field-grown at Yangzhou, China in 2006 and 2007. Root and shoot dry weight (DW) was significantly greater in “super” rice varieties than in check ones throughout the growth season in both years, so was the root length density. Root oxidation activity (ROA) and root zeatin (Z) zeatin riboside (ZR) content, in per plant basis, were significantly greater in “super” rice than check varieties before and at heading time. However, both ROA and root Z + ZR content, either in per plant basis or per unit root DW basis, were significantly lower in ‘super’ rice than in check varieties at the mid- and late grain filling stages. Grain yield of the two ‘super’ rice varieties, on average, was 10.2 t ha⁻¹ in 2006 and 11.4 t ha⁻¹ in 2007, and was 13% and 21% higher than that of check varieties, respectively. The high grain yield was mainly due to a larger sink size (total number of spikelets) as a result of a larger panicle. The percentage of filled grains of the two “super” rice varieties, on average, was 72.9% in 2006 and 79.0% in 2007, and was 19.4% and 12.9%, respectively, lower than that of the check varieties. The mean ROA and root Z + ZR content during the grain filling period significantly correlated with the percentage of filled grains. Collectively, the data suggest that an improved root and shoot growth, as showing a larger root and shoot biomass and greater root length density during the whole growing season and higher ROA and root Z + ZR content per plant at early and mid-growth stages, contributes to the large sink size and high grain yield in the “super” rice varieties. The data also suggest the yield of “super” rice varieties can be further increased by an increase in filled grains through enhancing root activity during grain filling.     

Characterization of physicochemical qualities and starch structures of two indica rice varieties tolerant to high temperature during grain filling

An extreme high temperature during grain filling is an important environmental factor that reduce the yield and quality of rice. In this study, we compared the grain appearance, composition and starch structure of four rice varieties response to high temperature during grain filling. The results obviously revealed that two indica AUS varieties Halwa and Jamir showed more tolerance to high temperature during grain filling than either the japonica Nipponbare or another AUS rice DJ24. The data showed that Halwa and Jamir presented less chalkiness, less grain weight loss, less change of endosperm components as well as starch structure than Nipponbare and DJ24 under high temperature treatment. Hence, the results implied that Halwa and Jamir might be useful targets to further identify genetic mechanism response to high temperature, at least during grain filling and endosperm development. Moreover, these AUS varieties have potential application value in further breeding of rice with good quality and heat tolerance.     

优良食味水稻品种籽粒蛋白质积累特征及其对氮素水平的响应

【目的】探讨优良食味水稻品种的籽粒蛋白质积累特征及其对氮素水平的响应。【方法】以食味值不同的常规粳稻和杂交稻为材料,在结实期设置不同氮素施用水平处理,分析不同类型品种在不同氮素水平下的蒸煮食味品质及其与稻米蛋白质及其组分含量的关系。进一步分析各品种在不同氮素水平下稻穗不同部位的氨基酸含量及籽粒蛋白质含量在结实期的动态变化,总结优良食味水稻品种的籽粒蛋白质积累特征及其对氮素水平的响应特征。【结果】优良食味水稻品种籽粒蛋白质含量较低,且随着氮素水平的增加而上升;优良食味水稻崩解值较高,消减值较低;蒸煮食味品质受氮素水平影响较小。优良食味水稻品种蛋白组分含量较低,且稻米蛋白质含量与食味品质呈显著负相关。在常规粳稻中,稻米食味值与清蛋白、球蛋白和醇溶蛋白含量均显著负相关;在杂交稻中,稻米食味值与醇溶蛋白和谷蛋白含量显著负相关。优良食味水稻品种籽粒充实过程中游离氨基酸含量较低,并呈现较低水平的蛋白质积累。而食味较差品种灌浆期籽粒的氨基酸含量较高,成熟籽粒蛋白质含量也较高,且氮素供应水平提升其籽粒蛋白质含量的效应更为显著。【结论】优良食味水稻品种的籽粒蛋白质含量较低,与其充实过程中蛋白质积累水平较低有紧密关系,且受氮素水平影响较小。     

不同自然脱水类型玉米品种子粒含水率变化与灌浆动态的关系

采用不同自然脱水速率的玉米品种为材料,分析其花后子粒含水量、粒重、体积和子粒灌浆的动态变化以及灌浆参数,研究玉米子粒含水量变化与灌浆动态的关系。结果表明,不同自然脱水类型玉米品种子粒含水量变化,以花后29 d和46 d为时间点,可划分为3个阶段。两种类型玉米品种46 d后自然脱水速率与蜡熟期(29~46 d)子粒含水量的变化趋势都正好相反。子粒体积和粒重变化趋势基本一致,花后46 d品种间差异逐渐加大。不同类型玉米品种灌浆动态变化差异较大,自然脱水快的品种(先玉335和桥玉8号)和自然脱水慢的品种(蠡玉16和中科4号)最大灌浆速率分别出现在花后29 d和36 d,二者最大灌浆速率差异达到显著水平,自然脱水快的品种平均灌浆速率低于脱水慢的品种,且活跃灌浆期较脱水慢品种短。两种类型玉米品种子粒含水量变化和灌浆速率呈正相关关系,其中脱水快的类型品种达到显著水平,相关系数为0.805(R0.05=0.755)。     

Alfalfa (Medicago sativa L.) seed yield and quality under different forage management systems and irrigation treatments in a Mediterranean environment

Alfalfa (Medicago sativa L.) is widely grown as a forage crop due to its good quality characteristics and high adaptability. However, seed yield is generally considered to be of secondary importance and is characterized by fluctuating yields with often poor seed quality. A field experiment using five alfalfa cultivars (Equipe, Iside, Lodi, Robot, Romagnola) was carried out in 1995, 1996 and 1997 at Foggia (southern Italy) to evaluate the effects of four defoliation practices (H1: crop mown during early plant growth; H2: plant desiccation by chemical agent at the end of February; H3: crop mown at early flowering; H4: never cut) and two irrigation treatments (I: irrigation applied from April to beginning of seed filling; NI: non-irrigated control) on seed yield, seed yield components and seed quality (as determined by seed germination with and without accelerated ageing (AA)). The relationships between yield components (stems per m², pods per stem, seeds per pod, 1000-seed weight) were determined by path-coefficient analysis. Irrigation significantly increased seed yield; on average doubling the control yield over the three seasons. However, the potential seed yield (calculated from seed yield components) was, on average, five times the actual seed yield. The two mowing treatments produced consistently higher seed yields than either desiccated or untreated swards. Cultivar differences were evident for seed yield, with Equipe having the highest value (40% higher than the mean of the other cultivars). Irrigation improved the yield primarily because it led on average a greater than four fold increase in the density of stems (the most influential yield component). By contrast, seeds per pod and 1000-seed weight increased in the absence of irrigation. Defoliation treatments had little effect on stems per m², seeds per pod and seed weight, whereas pods per stem were reduced by desiccation. Path analyses calculated across irrigation treatments and years revealed that stems per m² had the largest positive direct effect on alfalfa seed yield under each harvest management (path-coefficient values ≥0.89), and its indirect effects on seed yield via other traits were negligible. Seed quality, as measured by germination percentage both before and after AA, remained relatively consistent across both defoliation and irrigation treatments and cultivars, but was anomalously low in the 1997 irrigated crops. Overall, the highest seed yields were obtained under irrigated conditions when crops were mown during early growth or at early flowering. The potential seed yield of alfalfa varieties is sufficient to guarantee a profitable seed harvest. However, the harvest efficiency of the combine-harvester was low (20% of the potential seed yield); thus, more appropriate harvest techniques should be used.     

不同种植密度下小麦主要性状与产量和蛋白质含量的灰色评判

为了明确不同种植密度下小麦主要性状与产量和蛋白质含量的关系,以4种种植密度下4个小麦新品系(种)的11个性状为指标,运用灰色关联度分析其主要性状对产量和蛋白质含量构成的影响.结果表明,在不同密度下各主要性状对产量的关联度从大到小依次是:穗长＞可孕小稳数＞穗下节长＞株高＞蛋白质舍量＞整齐度＞不孕小穗数＞成穗数＞穗重＞千粒重＞穗颈长.在不同的密度下各主要性状对蛋白质含量的关联度从大到小依次是:株高＞可孕小穗数＞穗重＞千粒重＞穗长＞整齐度＞产量＞穗下节长＞不孕小穗数＞成穗数＞穗颈长.表明不同种植密度下影响产量和蛋白质含量的主要性状各有侧重,在高产优质新品种选育中应重视可孕小穗数和株高这两个主要性状.