Evaluation of grain yield and its components in wheat cultivars and landraces under near optimal and drought conditions

In a 2-years experiment, 30 wheat cultivars and 21 landraces from different countries were tested under near optimum and drought stress conditions. Plant height, number of sterile spikelets per spike, spikelets per spike, number of kernels per spike, kernel weight per spike, 1000 kernel weight and grain yield were evaluated. The number of kernels per spike, 1000 kernel weight and especially yield were more sensitive to drought stress in the cultivars than plant height and number of spikelets per spike, while in the landraces these traits did not differ under drought stress compared to near optimum conditions. The average yield of cultivars was significantly better than the average yield of landraces under near optimum as well as drought stress conditions. Path coefficient analysis showed that for cultivars under near optimum conditions there was no significant direct association of any of the analysed characters with yield, while under drought stress conditions, number of kernels per spike had a significant positive direct effect. Under drought stress conditions, the number of sterile spikelets displayed a negative direct effect, while kernel weight per spike had a positive direct effect on yield. Hierarchical cluster analysis was used as a tool to classify cultivars and landraces according to their yield ability under near optimum and drought stress conditions. Among the cultivars, two groups out of five and among one of three in the landraces were characterised by high yields in both near optimum as well as under drought stress conditions. These genotypes may serve as sources of germplasm for breeding for drought tolerance. This revised version was published online in August 2006 with corrections to the Cover Date.     

Ontogenetic analysis of yield components and yield stability of durum wheat in water-limited environments

Summary One main reason for the slow improvement of durum wheat in water-limited environments is the lack of clear understanding of the interrelationships among yield components and their compensatory changes under low and erratic moisture availability. Five cultivars, varying in many physiological attributes, were tested under different drought-stress conditions in field and greenhouse experiments. The cause-effect relationships of duration of vegetative period, duration of grain-filling period, number of spikes per m², kernels per spike, kernel weight and grain yield per m² were assessed. Furthermore, yield stability was evaluated. Yield reduction was largest under mid-season stress (58%), followed by terminal stress (30%) and early stress (22%). Cultivar Po was very sensitive to terminal stress.Path-coefficient analysis revealed a complex pattern of relationships among the six variables. An increase in vegetative period reduced the grain-filling period under all conditions. It increased number of kernels per spike under non-stress conditions. The direct effect of spikes per m² on grain yield was significantly positive. However, more spikes per m² resulted in fewer kernels per spike and a low kernel weight and, as a result, a negative relationship with grain yield under early stress. Grain-filling period had a strong influence on grain yield via kernel weight. Kernels per spike had the largest direct effect on grain yield. However, it was negatively correlated with kernel weight, especially under terminal stress. Grain yield heavily depended on kernels per spike under early stress and grain-filling period and kernels per spike under terminal stress.Variation in drought susceptibility index among cultivars was significant under early and terminal stress conditions, but not under mid-stress conditions. Yield potential and stability were not correlated for the different drought-stress conditions.Longer grain-filling period, increased number of kernels per spike and limited spike number per m² can be used as selection criteria for sustainable yield in water-limited environments.     

37个玉米新品种（组合）耐旱性评价

为评价37个玉米新品种（组合）的耐旱性潜力,采用4种控水处理对玉米植株性状和产量性状进行了分析评价。结果表明,水分胁迫对穗长、秃尖长、行粒数、百粒重、ASI和单株产量6个性状有显著或极显著影响。水分胁迫使玉米品种抽丝散粉间隔期延长,秃尖变长,结实率降低,行粒数减少,籽粒变小,百粒重下降,单株产量降低。应用模糊数学隶属函数法综合评价分析,‘帮豪玉509’、‘忠玉9号’、D36、BH0310和D30综合耐旱性较强,D23、D3、D26和BH3404综合耐旱性较差。     

Selection response for carbon isotope discrimination in a Triticum polonicum×T. durum cross: Potential interest for improvement of water efficiency in durum wheat

This study has been conducted to evaluate the usefulness of carbon isotope discrimination (δ) in mature kernels as a criterion for the improvement of water-use efficiency and yield under drought in durum wheat. For this purpose, Triticum durum‘Om Rabi 5’ was crossed with T. polonicum pseudochrysospermum 9 (Tp9) which has been found to be more drought tolerant and to have a lower carbon isotope discrimination value of the grain. The F₂ population showed a wide segregation for carbon isotope discrimination. Further, divergent selections (selection of plants most different in carbon isotope discrimination) were made among individual F₂ plants, and for carbon isotope discrimination in F₃ progenies under field conditions. Selected F₃ and F₄ progenies were evaluated under field conditions for morphological and agronomical traits. Broad-sense heritability (h²_b), response to selection and realized heritability (h²_r) were high. The narrow-sense heritability (h²_n= 0.37 ± 0.047) indicated that additive and dominance effects were involved in the genetic control of carbon isotope discrimination. Negative correlations were noted between carbon isotope discrimination and grain yield and between carbon isotope discrimination and biomass yield within years and generations. An explanation of this result is attempted by analysing the relationships between carbon isotope discrimination and several phenological and morphological traits influencing the water-use efficiency. The divergent groups selected for low and high carbon isotope discrimination exhibited significant differences for days to heading, plant height, shape of the spike and number of spikelets per spike. Correlations were also found between carbon isotope discrimination and plant height, harvest index, shape of the spike, spike length, and number of spikes per plant. The potential use of carbon isotope discrimination as a criterion for the improvement of water-use efficiency in durum wheat is discussed by considering the genetics of this trait (variability, heritability, response to selection) and also the associations with phenological and morphological traits.     

Variance components and heritability of traits related to root: shoot biomass allocation and drought tolerance in wheat

Enhanced root growth in plants is fundamental to improve soil water exploration and drought tolerance. Understanding of the variance components and heritability of root biomass allocation is key to design suitable breeding strategies and to enhance the response to selection. This study aimed to determine variance components and heritability of biomass allocation and related traits in 99 genotypes of wheat (Triticum aestivum L.) and one triticale (X. Triticosecale Wittmack) under drought-stressed and non-stressed conditions in the field and greenhouse using a 10?×?10 alpha lattice design. Days to heading (DTH), days to maturity (DTM), number of tillers (NPT), plant height (PH), spike length (SL), shoot and root biomass (SB, RB), root to shoot ratio (RS), thousand kernel weight (TKW) and yield (GY) were recorded. Analyses of variance, variance components, heritability and genetic correlations were computed. Significant (p?<?0.05) genetic and environmental variation were observed for all the traits except for spike length. Drought stress decreased heritability of RS from 47 to 28% and GY from 55 to 17%. The correlations between RS with PH, NPT, SL, SB and GY were weaker under drought-stress (r?≤???0.50; p?<?0.05) compared to non-stressed conditions, suggesting that lower root biomass allocation under drought stress compromises wheat productivity. The negative association between GY and RS (r?=???0.41 and ??0.33; p?<?0.05), low heritability (<?42%) and high environmental variance (>?70%) for RS observed in this population constitute several bottlenecks for improving yield and root mass simultaneously. However, indirect selection for DTH, PH, RB, and TKW, could help optimize RS and simultaneously improve drought tolerance and yield under drought-stressed conditions.     

冬小麦水旱品种间杂交主要性状的遗传分析

利用水地和旱地两种生态型的品种 ,采用 4× 4不完全双列杂交试验 ,对水旱品种间杂交主要性状的配合力和遗传表现进行了研究。结果表明 ,水地亲本的一般配合力效应对杂种后代主要性状的影响 ,除千粒重外 ,均达到显著或极显著水平 ;旱地亲本的一般配合力效应主要对株高、穗下节长、单株穗数、收获指数等与抗旱性有关的性状影响明显 ,且除株高和收获指数外 ,其余性状P1的方差均大于P2 的方差。说明水地亲本对杂种后代产量性状影响大 ,旱地亲本主要影响抗旱性状 ,水旱两种生态型杂交 ,实现了抗旱与丰产的有机结合。株高、穗下节长、穗粒数、单株产量、单株生物产量和收获指数以加性效应为主 ,而显性基因对单株穗数、千粒重、单穗重的影响较大。旱地小麦产量性状遗传力均较低 ,而株高、穗下节长、收获指数等与抗旱性有关的性状遗传力较高     

小麦抗倒性影响因子和产量因子的遗传与相关研究

旨在为小麦育种和生产上预防倒伏、提高稳产能力提供参考.以来源于野生二粒小麦远缘杂交组合的82个高代系为试材,在西北农林科技大学试验站测定并分析抗倒性影响因子和产量性状的相关性.结果表明,(1)株高与抗倒性呈负相关关系,成熟期茎壁厚与抗倒性呈正相关关系,各个性状的抗倒性排序为株高＞成熟期茎壁厚度＞单穗重＞单株重;(2)粒...     

Mass selection of wheat for grain filling without transient photosynthesis

Summary Post-anthesis chemical desiccation of wheat (Triticum aestivum L.) plants in the field eliminates transtent photosynthesis by killing all green tissues, thus revealing the plant's capacity for grain filling from stored stem reserves, as the case is for post-anthesis stress such as drought or leaf diseases. This study was conducted to investigate whether mass selection for large kernels under chemical desiccation would lead to the improve ment of grain filling in the absence of transient photosynthesis.Six crosses of common spring wheat were subjected to three cycles of mass selection from F₂ through F₁ when selection was performed for large kernels by sieving grains from plants that were erther chemically desiccated after anthesis, or not (controls). The resulting 36 bulks (six crosses by three selection cycles by two selection environments) were compared with their respective F₂ base populations, when tested with and without chemical desiccation.Selection for large kernels under potential conditions (without chemical desiccation) did not improve kernel weight under potnetial conditions, evidently because these materials were lacking in genetic variation for kernel weight under potential conditions. In four of the crosses, 3rd cycle selection for large kernels under potential conditions decreased kernel weight under chemical desiccation. On the other hand, selection for large kernels under chemical desiccation was effective in improving kernel weight and test weight under chemical desiccation, depending on the cross and the selection cycle, with no genetic shift in mean days to heading or mean plant height. Selection for large kernels under chemical desiccation was also effective in some cases in increasing kernel weight under potential conditions. The results are interpreted to show that selection under potential conditions and under chemical desiccation operate on two different sources for grain filling, namely transient photosynthesis and stem reserve utilization, respectively. In order to expose genetic variability for stem reserve utilization to selection pressure, transient photosynthesis must be eliminated, as done by chemical desiccation in this study.     

不同土壤条件下追施硼肥对小麦产量和品质的影响

试验于2018-2019年在中国农业科学院作物科学研究所温室内进行,采用两因素随机区组设计,以土壤类型和追施硼肥为调控因素,研究不同土壤条件下硼肥对小麦产量和品质的影响。供试土壤分别为黑土、潮土及红土,供试小麦品种为来自埃及的春小麦品种Egypt New。结果表明：黑土条件下小麦的株高、穗长、穗粒数、千粒重和子粒产量均极显著高于潮土和红土条件下的小麦;黑土条件下小麦的蛋白质及其组分产量最高,潮土次之,红土最低,差异显著;拔节期追施硼肥显著提高了子粒产量。不同处理组合条件下,以黑土和拔节期追施硼肥处理的小麦株高、穗长、穗粒数、千粒重和蛋白产量最高。     

高产小麦品种冠层形态生理性状的研究

对河南省及部分黄淮麦区种植的小麦高产品种的冠层形态、生理和产量性状相关分析和遗传分析的结果表明,小麦旗叶面积与主茎粒重、主茎粒数和每穗粒重呈显著正相关.穗下节长度和粗度与主茎粒重有显著的正相关.千粒重、旗叶长度、面积、基角、开张角和鞘长,穗下节长、颈长、穗长以及旗叶持续光合面积的遗传符合简单的加性显性模型.穗下节粗度和主茎粒重存在“互补型”的非等位基因互作.株高、旗叶宽、比叶重、叶绿素含量和主茎粒数似有基因的非随机分布.净光合速率的遗传则可能存在复杂因素.此外,对30个高产小麦品种的旗叶和穗下节形态作了分类.     

小麦品种抗旱性鉴定指标遗传规律研究

依据Griffing方法I配制种植不同类型的复合双列杂交组合,在人工模拟干旱棚和田间自然干旱条件下,分别设水、旱2种水分条件。在不同生育时期测定株高、株穗数、株粒重、穗粒数、黄叶片数、SOD、POD、MDA等农艺、生理生化性状,研究不同组合类型对杂交后代的遗传力影响及其与抗旱性的关系及遗传规律。结果表明,可采用抗旱指数(DRI)作为评价小麦品种抗旱性强弱的指标。旱地株粒重、旱地穗下节长、旱地黄叶片、籽粒饱满度、落黄、旱地成穗数、旱地株高等7个质量性状和数量性状与抗旱性关系密切且遗传力较强,可作为高产种质杂种后代的早期抗旱性鉴定指标。SOD活性和MDA含量由于广义遗传力和狭义遗传力均较高,可以在杂种后代早期世代进行选择,OA能力和POD活性广义遗传力较高但狭义遗传力低,适宜在杂种后代的晚期世代进行选择。     

Effects of dwarfing genes on yield and yield components under irrigated and rainfed conditions in wheat (Triticum aestivum L.)

Summary Near-isogenic tall (no dwarfing gene), semidwarf (Rht1 or Rht2) and dwarf (Rht1 + Rht2 or Rht3) spring wheat lines were evaluated for yield and yield components under irrigated and rainfed conditions. Under irrigated conditions, the dwarf and the semidwarf lines exhibited a significant yield advantage over the tall lines. Under rainfed conditions, the semidwarf lines outyielded the tall as well as the dwarf lines. Percent yield reduction in response to drought stress was highest with the dwarfs and lowest with the tall lines. Dry matter production of the tall lines and that of the semidwarf lines did not differ significantly and both produced significantly more dry matter than the dwarf lines under irrigated as well as rainfed conditions. Plant height and kernel weight decreased with increasing degree of dwarfness while number of kernels per spikelet, harvest index and days to heading increased under both moisture regimes. The dwarfing genes did not have any significant influence on number of tillers/m² and spikelets per spike in either moisture regime.     

大麦种质资源成株期抗旱性鉴定及抗旱指标筛选

干旱是影响大麦生产的主要因素之一。在鉴定大麦种质资源成株期抗旱性的基础上,筛选抗旱指标,可为培育抗旱品种提供依据。本研究在2016和2017年在大麦生长主要需水期平均降雨量不足40 mm的甘肃省武威市进行田间试验,以30份大麦种质资源为研究对象,设置正常灌水和干旱胁迫处理,测定大麦株高、穗长、分蘖数、单株粒数、单株粒重、穗粒数、千粒重和产量,采用抗旱性度量值(D)、综合抗旱系数(CDC)、加权抗旱系数(WDC)、相关分析、频次分析、主成分分析、灰色关联度分析、隶属函数分析、聚类分析和逐步回归分析相结合的办法,对其进行抗旱性鉴定及抗旱指标的筛选。干旱胁迫对测定的各指标均有极显著影响。频次分析表明,各指标对干旱胁迫反应的敏感程度依次为产量、株高、单株粒重、穗长、单株粒数、分蘖数、穗粒数和千粒重。相关分析表明,产量与株高、穗长、分蘖数、单株粒数和单株粒重呈极显著正相关,与穗粒数呈显著正相关、与千粒重呈不显著正相关。主成分分析表明,5个主成分可以代表大麦抗旱性86.39%的原始数据信息量。基于D值、CDC值和WDC值的大麦种质资源抗旱性排序基本一致。灰色关联度分析表明,各指标单项抗旱系数值与D值间的关联度依次为产量、单株粒重、单株粒数、穗长、株高、分蘖、穗粒数和千粒重,各指标DC值与WDC值间的关联大小依次为单株粒重、产量、单株粒数、分蘖、穗长、穗粒数、株高和千粒重。根据D值进行聚类分析,将供试大麦种质资源依据抗旱性从强到弱分为5个抗旱等级,其中1级5份、2级1份、3级11份、4级10份、5级3份。除分蘖和千粒重外,其余指标的隶属函数值、CDC值、D值和WDC值均随着抗旱级别的升高而增大。回归分析表明, 5个测定指标均与D值密切相关。干旱胁迫对大麦种质资源成株期各指标均有极显著影响。确定了D值为适宜的抗旱鉴定指标。筛选出成株期抗旱性强的大麦种质资源甘啤7号、Z06-278-9、MERIT、NEVADA和西藏25,可为大麦抗旱育种、抗旱机制以及干旱调控缓解机制的研究提供技术支持。穗长、单株粒数、单株粒重、穗粒数、产量可作为大麦种质资源成株期简单、直观的抗旱评价指标。     

大麦杂种优势利用研究Ⅰ.F1杂种的离中亲优势和超优亲优势

以7个细胞质雄性不育系及相应保持系和4个恢复系,按NCⅡ交配设计配成7×4=28个F1杂种,研究了12个数量性状,即株高(PH)、穗长(SL)、穗下节间长(IL)、每株穗数(SP)、主穗粒数(KMS)、每株粒数(KP)、每株粒重(KWP)、每株干重(DWP)、千粒重(KW)、籽粒产量(KY)、籽粒蛋白质含量(PC)和赖氨酸含量(LP)的杂种优势表现。以杂种离中亲     

小麦产量与农艺性状的相关分析和通径分析

以23个小麦品系为研究对象,采用随机区组试验,设3个重复,对不同农艺性状与产量进行相关性和通径分析,分析参试品系的农艺指标与产量的关系。结果表明,产量三要素与产量的相关系数和通径系数都为穗数>穗粒数>千粒重,穗数与产量之间呈显著正相关,穗粒数、千粒重与产量之间关系呈负相关,但相关性不显著。收获指数、生物产量与子粒产量分别呈极显著和显著正相关,所有品系都有较高的生物产量和收获指数;供试品系的产量与株高和株高构成指数呈正相关,穗长、单穗重与产量之间呈负相关,但相关性不显著。     

新疆冬小麦品种农艺及产量性状遗传多样性分析

Grain yield is one of the most important goals in wheat breeding, and agronomic or yield-related traits can directly reflect the characteristics of varieties. In order to determine the evolution of genetic diversity in agronomic traits of Xinjiang winter wheat varieties and their adaptabilities to different ecological environments, 134 winter wheat landraces and 54 moderns bred varieties from Xinjiang were selected for agronomic trait investigation. They were planted in three different ecological environments (Urumqi and Yining in Xinjiang province, and Tai’an in Shandong province) for two consecutive growth seasons, and nine agronomic and yield-related traits were surveyed and analyzed. The estimated broad sense heritability of nine agronomic and yield traits was in descending order: plant height > grain width > grain length/width ratio > spike length > spikelet number > thousand- kernel weight > grain number per spike > grain length > fertile spikelet number. Correlation analyses of nine agronomic and yield traits showed that these traits were correlated with each other. It was found that the plant height, spike length and grain length/width ratio of landraces were higher than that in modern bred varieties, but the grain number per spike, thousand kernel weight, grain length and grain width in landraces were less than that in modern bred varieties. However, the correlation coefficient of these nine traits was higher in modern bred varieties than that in landraces. These variations reflected the evolution of Xinjiang winter wheat varieties in agronomic traits in recent years. This study may provide important information for breeders to select the breeding parents in different winter wheat regions.     

大麦杂种优势利用研究,Ⅲ.大麦异棱型和同棱型F1杂种的杂种优势特征

研究了大麦4种杂交类型（含二棱×二棱、二棱×六棱、六棱×二棱和六棱×六棱）的F₁杂种的性状表现和优势特征，比较了同棱型相配组（二棱×二棱和六棱×六棱）和异棱型相配组（二棱×六棱和六棱×二棱）的超高亲优势（H_h）组合数及其出现率。研究性状包括株高、穗长、穗下节间长、穗数、粒数、粒重、籽粒产量、籽粒蛋白质含量和赖氨酸含量等13个.结果表明,(1)二棱×二棱杂种的穗长较长、每株穗数较多、千粒重较高；六棱×六棱杂种的每穗粒数、每株粒数较多、籽粒产量较高；而异棱型相配杂种则比同棱型相配组有较高的株高、穗下节间长和千粒重。（2）4种杂交类型杂种的类型内杂种间变异，在大多数性状上均为同质，仅有株高、穗长和主穗粒数在六棱×六棱杂种中变异增大，有较大的选择潜力。（3）在13个数量性状中，有9个性状的H_h优势出现率与杂交类型显著关联；株高、穗下节间长和千粒重的H_h优势出现率在二棱×六棱和/或六棱×二棱杂种中最高，而主穗粒数、每穗粒数、每株粒数、每粒重和每株干重的H_h优势出现率则在六棱×六棱和/或六棱×二棱杂种中最高。（4）异棱型相配组杂种的株高、穗下节间长和千粒重的Hh优势率显著高于同棱型相配组杂种，依次为20/30对8/33、30/30对18/33和22/30对5/33；但同棱型相配组杂种籽粒产量的H_h优势率显著高于异棱型相配组杂种，为10/33对2/30。说明异棱型杂种易产生生物量和千粒重优势，而同棱型杂种易产生籽粒产量优势。     

A comparison of yield and yield component selection in winter wheat

Summary Three populations of winter wheat were formed by crossing Avrora to Sage, TAM W-101, and Danne. Approximately 10% of the F₂ plants from these crosses were selected for high and low levels of number of tillers per plant, number of kernels per spike, 1000-kernel weight, and grain yield. Forty-eight solid seeded F₃ lines obtained from the selected F₂ plants were then selected for high and low expressions of yield components and grain yield. Realized heritabilities were estimated. Indirect responses of yield to yield component selection and direct response to selection for grain yield were measured. Heritabilities were low for tiller number, number of kernels per spike and kernel weights but were high or intermediate for grain yield when selection occurred in the F₂ generation. When selection was practiced in the F₃ generation, heritabilities for tiller number and yield were low, but were intermediate to high for number of kernels per spike and kernel weight and high heritabilities were found for kernel weight. Selection for kernel weight often increased grain yield; however, direct selection for grain yields was usually as effective.Journal article no. J-4488 of the Oklahoma Agri. Exp. Stn., Stillwater, Oklahoma 74074.     

矮秆超大穗小麦亲本与多抗丰产小麦主要农艺性状的配合力评价及遗传分析

为了进一步挖掘矮秆超大穗小麦亲本在遗传育种中的应用潜力,为小麦高产、超高产育种选择优良亲本和最优杂交组合提供理论依据,选用5个矮秆超大穗小麦品种（系）作为父本,8个多抗丰产小麦品种（系）作为母本,按NCII遗传交配设计,采用8×5不完全双列杂交法,配制了40个杂交组合,对小麦亲本及杂种F1的株高、主穗长、单株穗数、结实小穗数、主穗粒数、主穗产量、单株产量、千粒重8个性状进行了考察,并在基因型方差分析显著的基础上进行了配合力评价及遗传力分析。结果表明：父本中A1、A3、A4是综合性状优良的亲本,其多数性状的一般配合力均较高,特别是穗长、主穗粒数、结实小穗数、主穗产量、单株产量的一般配合力高,而株高的一般配合力效应值较低,是很理想的矮秆超大穗多粒亲本材料。母本中B5、B6单株穗数一般配合力较高,株高的一般配合力效应值较低,可作小麦高产杂交育种的矮秆多穗型亲本使用。结合特殊配合力效应分析：组合B5×A3单株穗数、主穗产量、单株产量、千粒重特殊配合力效应最高,株高特殊配合力效应较低,可作为的矮秆、多穗、粒重高且高产的重点杂交组合。B2×A4主穗长、单株产量、单株穗数特殊配合力效应都较高,而株高特殊配合力效应低,可作为矮秆大穗高产的重点杂交组合。遗传力分析表明：单株产量、千粒重、主穗长、主穗产量皆在70%以上,表明这4个性状的广义遗传力较大,受环境影响较小,而狭义遗传力的分析除主穗长、主穗粒数、主穗产量、株高大于50%,其余4个性状均低于50%,说明受环境影响大,不宜早期选择,应该适当推迟选择的代数。     

Single and Multiple Traits Selection in a Segregating Population of Wheat, Triticum aestivum L.

The breeding materials used in this study were the F₃, F₄ and F₅-generations of the cross between Giza 158 × Sonora 64 (Triticum aestivum L.). The objective of this study was to compare the relative merits of Smith-Hazel, desired gain selection indices, independent culling levels and single trait selection in improving grain yield, heading date and several agronomic traits. Highly significant differences among F₃ families and a satisfactory genotypic coefficient of variability were obtained for all the traits studied. The genotypic correlations were high between yield and each of spike weight, kernels/spike and spikes; plant, intermediate with 1000 kernel weight and very low with heading date, plant height and spike1 length-After two cycles of selection, the results of the gains realized indicated that the most effective method for improving yield was the Smith-Hazel index (SH₇) of seven traits followed by the desired gain index of seven traits (DG₇), SH₅, independent culling levels, DG₅ and direct selection (or grain yield/plant. Direct selection for heading date, plant height and spike length was the best method for improving these traits, but undesirable correlated responses in the other traits were obtained.