用STS标记检测春化基因Vrn-A1在中国小麦中的分布

在证实Vrn-A1春化基因的STS标记与CAPS标记结果一致的基础上,用STS标记检测了全国主要麦区历史上大面积推广和当前主栽的250份品种的春化基因Vrn-A1。结果表明,中国品种Vrn-A1基因平均分布频率为36.8%,不同麦区的分布频率不同,依次为东北春麦区=北部春麦区=西北春麦区（100%）＞新疆冬春麦区（42.9%）＞西南冬麦区（35.3%）＞黄淮冬麦区（19.8%）＞长江中下游冬麦区（17.4%）＞北部冬麦区（3.0%）,这与冬春特性有关。在长江中下游冬麦区和西南冬麦区品种中,Vrn-A1基因分布频率随着时间推移呈降低趋势;在黄淮冬麦区品种中,20世纪50到70年代呈上升趋势,随后呈下降趋势。在年最大推广面积大于66.7万hm²的58份品种中,Vrn-A1基因的频率为27.6%。这些信息有助于改良小麦品种的适应性和提高产量潜力。     

Genetic improvement of grain yield and associated traits in the southern China winter wheat region: 1949 to 2000

To understand the genetic gains of grain yield in the Southern China Winter Wheat Region (SCWWR), two yield potential trials, i.e., YPT 1 including 11 leading cultivars from the Middle and Low Yangtze Valley (Zone III) and YPT 2 including 15 leading cultivars from the Southwestern China Region (Zone IV) from 1949 to 2000, were conduced during the 2001–2003 cropping seasons. A completely randomized block design of three replicates was employed with controlled field environments. Molecular markers were used to detect the presence of dwarfing genes and the 1B/1R translocation. Results showed that average annual genetic gain was 0.31% (P < 0.05) or 13.96 kg/ha/year and 0.74% (P < 0.01) or 40.80 kg/ha/year in Zones III and IV, respectively. In YPT 1, changes of all other traits were not significant, but plant height was significantly reduced. In YPT 2, the genetic improvement of grain yield was primarily attributed to the increased thousand kernel weight (TKW) (0.65%, P < 0.01) and kernel weight/spike (0.87%, P < 0.01), reduced plant height and increased harvest index (HI). The dwarfing gene Rht 8 was most frequently present (46.1%), Rht-B1b was observed in three genotypes in Zone III, and Rht-D1b was present in only one genotype in Zone IV. The 1B/1R translocation was present in four genotypes. Utilization of Italian germplasm and development of landmark cultivar Fan 7 were the key factors for grain yield improvement in SCWWR. The future challenge of wheat breeding in this region is to continue improving grain yield and disease resistance, and to develop cultivars suitable for the reduced tillage of wheat/rice double cropping. Utilization of Mexican germplasm could provide opportunities for future yield improvement.     

Profiling peanut (<Emphasis Type="Italic">Arachis hypogea</Emphasis> L.) accessions and cultivars for oleic acid and yield in Botswana

The ratio of monounsaturated oleic fatty acid to polyunsaturated linoleic fatty acid (O/L) and the associated agronomic traits were profiled for local peanut (Arachis hypogaea L.) cultivars and accessions in Botswana. The research was tested on 16 entries planted in four localities across the country. The average total oil yield of the genotypes studied was about 42.1% and there was no significant difference in total oil yield (P < 0.05) across the four research sites and among all entries (accessions). The average mean O/L ratio for all entries was about 1.47. The highest was that of the locally improved variety, Peolwane (2.58), which was significantly different (P < 0.05) from all other accessions, and the lowest is that of the local accession GO 63 (1.23). This study also profiled the agronomic yield traits to identify genotypes that have both high oil quality and high yielding potential. No correlation was detected between pod yield and O/L ratio among the tested genotypes. The station with little rainfall but adequate repartition showed a very high O/L ratio for some genotypes, and future work is recommended to test this interesting observation on the correlation between moisture stress and oil quality.     

Genetic Analysis of Grain Yield and Other Traits of Early‐Maturing Maize Inbreds under Drought and Well‐Watered Conditions

Maize (Zea mays L.) is an important staple food crop in West and Central Africa (WCA). However, its production is constrained by drought. Knowledge and understanding of the genetics of hybrid performance under drought is invaluable in designing breeding strategies for improving maize yield. One hundred and fifty hybrids obtained by crossing 30 inbreds in sets using the North Carolina Design II plus six checks were evaluated under drought and well‐watered conditions for 2 years at three locations in Nigeria. The objectives of the studies were to (i) determine the mode of gene action controlling grain yield and other important agronomic traits of selected early inbred lines, (ii) examine the relationship between per se performance of inbreds and their hybrids and (iii) identify appropriate testers for maize breeding programmes in WCA. General combining ability (GCA) and specific combining ability (SCA) mean squares were significant (P < 0.01) for grain yield and other traits under the research environments. The GCA accounted for 64.5 % and 62.3 % of the total variation for grain yield under drought and well‐watered conditions, indicating that additive gene action largely controlled the inheritance of grain yield of the hybrids. Narrow‐sense heritability was 67 % for grain yield under drought and 49 % under well‐watered conditions. The correlations between traits of early‐maturing parental lines and their hybrids were significant (P < 0.01) under drought, well‐watered and across environments. Mid‐parent and better‐parent heterosis for grain yield were 45.3 % and 18.4 % under drought stress and 111.9 % and 102.6 % under well‐watered conditions. Inbreds TZEI 31, TZEI 17, TZEI 129 and TZEI 157 were identified as the best testers. Drought‐tolerant hybrids with superior performance under stress and non‐stress conditions could be obtained through the accumulation of favourable alleles for drought tolerance in both parental lines.     

Genome-wide association study of differences in 14 agronomic traits under low- and high-density planting models based on the 660k SNP array for common wheat

One hundred and ninety-seven wheat accessions from Yellow and Huai Winter Wheat Region (YHW) were evaluated for differences of 14 agronomic traits under low- and high-density plantings. Compared with the high-density plantings, plant height, neck length, uppermost internode length, flag leaf angle and number of sterile spikelets under the low-density plantings reduced, while heading date, flowering date, flag leaf length and width, spike length, number of fertile spikelets, grain number per spike, thousand-kernel weight and grain weight per spike increased. A total of 1,118 markers were detected based on GWAS, and seven QTLs were confirmed. One QTL on chromosomes 5BL and two other QTLs on 5Dl were all tightly associated with flowering date difference. Bioinformatics analysis revealed that two haploblocks in 5Dl were involved, and the Vrn-D1 locus was located in this interval. A region on chromosome 5B at around 531.5 Mb was significantly associated with plant height difference. Two QTLs including AX-94840438 (7BL) and AX-94563647 (7DS) were responsible for neck length or uppermost internode length difference.     

Effect of recombination in the maize breeding population with exotic germplasm on the yield stability

A little knowledge exists about the probability that recombination in the parental maize populations will enhance the chances to select more stable genotypes. The synthetic parent maize population ((1601/5 × ZPL913)F₂ = R₀) with 25% of exotic germplasm was used to assess: (i) genotype × environment interaction and estimate stability of genotypes using nonparametric statistics; (ii) the effect of three (R₃) and five (R₅) gene recombination cycles on yield stability of genotypes; (iii) relationship among different nonparametric stability measures. The increase of mean grain yield was significant (P < 0.01) in the R₃ and R₅ in comparison to the R₀, while it was not significant between R₃ and R₅. Analysis of variance showed significant (P < 0.01) effects of environments, families per set, environment × set interaction, family × environment interaction per set on grain yield. The non-significant noncrossover and significant crossover (P < 0.01) G × (E) interactions were found according to Bredenkamp procedures and van der Laan-de Kroon test, respectively. The significant (P < 0.01) differences in stability were observed between R₀-set 3 and R₅-set 3 determined by S_i⁽³⁾ S_{i}^{(3)} , R₃-set 1 and R₅-set 1 determined by S_i⁽³⁾ S_{i}^{(3)} (P < 0.05), and R₀-set 3 and R₅-set 3 determined by S_i⁽⁶⁾ S_{i}^{(6)} (P < 0.05). The significant parameters were those which take into account yield and stability so the differences could be due to differences in yield rather than stability. Findings can help breeders to assume the most optimum number of supplementary gene recombination to achieve satisfactory yield mean and yield stability of maize genotypes originating from breeding populations.     

Effect of terminal water stress on leaf epicuticular wax load,residual transpiration and grain yield in barley

The effect of drought on barley leaf epicuticular wax load (EWL), residual transpiration rates (RTR) and grain yield was examined by subjecting 12 barley genotypes to controlled irrigation and terminal water stress conditions. The mean leaf epicuticular wax load was found to be 9% greater in the plants subjected to terminal water stress than in those provided irrigation, while the mean residual transpiration rate of the irrigated plants was 20% higher than in those subjected to water stress. Under these stress conditions, the correlation between grain yield and the epicuticular wax load was positive (P < 0.01), while that between the grain yield and the residual transpiration rate was negative (P < 0.05). Under the water stress conditions, the breeding lines studied showed a greater mean epicuticular wax load than the commercial varieties, while the residual transpiration rate was greater in these varieties than in the breeding lines. The greater epicuticular wax load of the breeding lines favoured their tolerance of drought, improving their yields over those of the commercial varieties.     

Diversity in a pea (<Emphasis Type="Italic">Pisum sativum</Emphasis>) world collection for key agronomic traits in a rain-fed environment of Southern Europe

The marked underutilization of pea ecotype and old cultivar genetic resources need be reversed by producing information on elite germplasm and diversity patterns for key agronomic traits. This study generated such information for a world collection of 223 ecotypes or old cultivars of P. sativum subsp. sativum subdivided into 19 regional pools (each represented by 9–15 entries) and one reference pool of 11 locally-adapted varieties from France, Spain and Germany. The collection was evaluated for grain yield, seed protein content, straw biomass, phenology and other agronomic and morphological traits in a spring-sown, water-limited environment of Northern Italy. Variation within ecotype/old cultivar germplasm pools was at least two-fold greater for seed size and protein content and seven-fold greater for other traits relative to variation between pools, and was particularly large within pools from Central Europe, Near East and United Kingdom. The traditional germplasm, compared with improved variety material, tended to display higher dry grain yield (1.11 vs. 0.85 t/ha) and straw biomass, later crop maturity, smaller seed, and similar protein content. Traditional germplasm from Central Europe combined outstanding grain yield and total biomass with high seed protein content. High grain yield characterized, inter alia, the germplasm pools from Ukraine and Spain, the latter also featuring high protein content. Several ecotype/old cultivar accessions out-performed (P < 0.05) the best-ranking varieties for grain yield or protein content. Patterns of phenotypic variation were poorly related to geographic origin of germplasm pools, while highlighting the distinctness of improved variety germplasm.     

用AMMI模型分析作物区域试验中的地点鉴别力

为了比较不同试验点在区域试验中鉴别力的大小,利用AMMI模型中地点的得分向量长度衡量地点鉴别力,并与传统的联合线性回归模型中的斜率进行了比较。以1995~96和1997~2000年度黄淮南片春水组小麦区域试验4年的产量数据为例进行了地点鉴别力分析。结果表明, AMMI模型比联合线性回归模型能更好地解释基因型与环境互作效应;多     

Nitrogen and water-use efficiency of Australian wheat varieties released between 1958 and 2007

We used a collection of Australian wheats released between 1958 and 2007 to probe for time trends in evapotranspiration and nitrogen uptake, and the efficiencies in the use of water and nitrogen to produce grain yield. Yield increased linearly with year of cultivar release at a rate of 18 kg ha⁻¹ y⁻¹; this rate aligned with the relationship between rate of genetic gain and environmental yield from breeding programs worldwide. No time trend was apparent for seasonal evapotranspiration, hence the linear increase in yield per unit evapotranspiration with year of release which was fully accounted for by yield improvement. Under our experimental conditions, yield per unit transpiration of current varieties was ∼24 kg ha⁻¹ mm⁻¹, highlighting the need to update the 20 kg ha⁻¹ mm⁻¹ ratio commonly used in agronomic benchmarking.Yield per unit nitrogen uptake was largely unchanged as a consequence of increased nitrogen uptake that paralleled the increase in yield, and a secondary contribution of reduced grain protein concentration particularly under environmental conditions that favoured high protein. The nitrogen nutrition index, accounting for the effect of biomass on nitrogen uptake, increased linearly with year of cultivar release, hence supporting the conclusion that breeding for yield improved the nutrition status of wheat in association with an increased capacity to uptake nitrogen in equal-sized crops.     

Effect of Rainfall Collecting with Ridge and Furrow on Soil Moisture and Root Growth of Corn in Semiarid Northwest China

A plastic‐covered ridge and furrow farming of rainfall collecting (RC) system were designed to increase water availability to corn for improving and stabilizing agricultural production in the semiarid Loess region of northwest China. This system comprised two elements: the ridge mulched by plastic film that acts as a rainfall harvesting zone and the furrow as a planting zone. To adopt this system for large‐scale use in the semiarid region and bring it into full play, it is necessary to test the appropriate rainfall range for RC farming. A field study (using corn as an indicator crop) combined with rainfall simulation was conducted to determine the effect of RC on soil moisture, root characteristic parameters and the yield of corn under three different rainfall levels (230, 340 and 440 mm) during the growing seasons of 2006 and 2007. The results indicated that with the rainfalls ranging within 230–440 mm, the soil moisture at 0–100 cm depth for RC system in furrows was significantly higher (P < 0.05) than that of conventional flat (CF for control) practice. At 100–200 cm soil depth, there was no significant difference (P > 0.05) between soil moisture in the RC₂₃₀ plots and in the CF₂₃₀ plots during the corn growing seasons, while the soil moisture both in the RC₃₄₀ and RC₄₄₀ plots were significantly higher (P < 0.05) than those in the CF₃₄₀ and CF₄₄₀ plots. The root length, root surface area, root volume and root dry weight for RC₂₃₀ and RC₃₄₀ plots all significantly increased (P < 0.05) compared with CF₂₃₀ and CF₃₄₀ plots, but these root characteristic parameters at 440 mm rainfall slightly decreased compared with those of CF practice. Compared with the CF_230–440 pattern, the increasing amplitude of grain yield under the RC_230–440 pattern diminished with the rainfall increase and there was no obvious yield‐incrementing effect (P > 0.05) between two patterns at 440 mm rainfall in 2006. In comparison with these two farming practices, the RC system not only improved soil moisture of dry farmland, but also promoted the development of corn root systems when the rainfall ranged between 230 and 440 mm. Thus, it could be concluded that the optimal upper rainfall limit for the RC system is below 440 mm in the experiment. For corn, the adoption of the RC practice in the 230–440 mm rainfall area will make the system more effective during the whole growth period and offer a sound opportunity for sustainable farming in semiarid areas.     

Yield enhancement by short‐term imposition of severe water deficit in the vegetative growth stage of grain sorghum

Water deficit is generally thought to negatively impact crop yields, including grain sorghum (Sorghum bicolor L.), but a small body of literature reports changes in crop physiology and growth in plants with short‐term imposition of water deficit during vegetative development that could lead to increased yield. In a replicated and repeated pot experiment in which water deficit was imposed for 10‐day periods in grain sorghum plants that were otherwise well‐watered, we tested the hypothesis that relatively severe, short‐term water deficit imposed during early vegetative development could enhance grain sorghum yield. The results showed that severe water deficit (~30% of control ET) imposed during two vegetative periods enhanced grain yield compared to continuously well‐watered plants by 21% (p = .0356). Grain yield was correlated with average grain weight, grain number per head and shoot‐to‐root ratio. Yield enhancement was associated with a substantial shift in resource partitioning, as water deficit reduced root mass (p = .0032), stem/leaf mass (p < .0001) and total biomass (p = .0005), resulting in a 60% increase in harvest index. Imposition of water stress during vegetative growth in sorghum can increase grain yield.     

高产夏玉米产量性能特征及密度深松调控效应

以现代高产玉米品种中单909和郑单958为试验材料, 于2010-2011年在河南新乡设置种植密度与耕作方式田间试验, 研究夏玉米高产群体产量性能参数变化及主要栽培措施调控效应。结果表明, 中单909相比郑单958显著增产11.36%, 穗粒数(KN)、千粒重(KW)极显著增加(P<0.01), 生育天数(D)、收获指数(HI)和收获穗数(EN)无明显差异(P>0.05); 平均叶面积指数(MLAI)、光合势在灌浆后期增加更为显著, 平均净同化率(MNAR)显著增加(P<0.05), 而干物质积累最大生长速率、生长速率最大时的生长量、平均生长速率、活跃生长期均明显提高。进一步分析产量性能参数间相互关系, EN与MLAI呈极显著正相关(P<0.01), KN和KW与MNAR呈极显著正相关(P<0.01), 而MNAR、KN、KW与MLAI呈极显著负相关(P<0.01)。中单909比郑单958增产可能是产量性能参数差异补偿的结果。中单909在高密度下具有较高的MLAI、MNAR和KN, 获得最高产量的群体密度比郑单958高27.3%; 深松耕作方式下, 中单909和郑单958分别增产13.0%和8.7%, 主要表现为, MNAR和KN显著增加, MLAI和D无明显变化, HI、EN、KW增加幅度在不同品种间表现不一致, 表明土壤深松条件下密植(9.50×10⁴株 hm^-2)是目前夏玉米高产重要技术途径之一。综上, 密植夏玉米高产群体产量性能特征参数为MLAI 3.05~3.55、MNAR 4.80~6.27 g m^-2 d^-1、D 109~111、HI 0.50~0.52、EN 9.60~10.38×10⁴穗 hm^-2、KN 352.0~370.1粒、KW 314.7~315.9 g, 可以实现11 250~12 000 kg hm-2以上的产量。     

建国以来我国黄淮棉区棉花品种的遗传改良Ⅰ. 产量及产量组分的改良

本文是我国黄淮棉区棉花品种遗传改良和系列研究之一, 目的在于探讨建国以来我国黄淮棉区棉花品种在产量和产量组分性状(株铃数、 铃重、 衣分)上的遗传改良成效。 对不同历史时期10个代表性品种2年5点的试验资料和30多年的区域试验资料的研究表明, 建国以来, 我国黄淮棉区棉花品种产量性状的遗传改良成效显著, 品种的产     

高油大豆新品种淮豆8号的选育研究

大豆新品种“淮豆8号”是利用淮89-15为母本,菏84-5为父本通过有性杂交,采用单籽传法育成的高油高产夏大豆新品种。于2005年通过全国农作物品种审定委员会审定。该品种丰产性、稳产性好,产量水平2700~3000 kg/hm2。株型紧凑,叶片上部披针形,有利于通风透光。品质优良,突出表现在脂肪含量高,超过22%。抗倒伏,高抗大豆花叶病毒病。适应性较广,适宜在山东西南部、河南南部、江苏和安徽两省淮河以北地区种植。     

Heterosis and combining ability of seven maize germplasm populations

Understanding the combining ability and heterosis of available germplasm is a prerequisite for successful maize improvement and breeding. The objectives of this study were to analyze the combining ability and heterosis of seven representative maize germplasm populations, and further, to evaluate their potential utility in germplasm improvement. A total of 21 crosses were made among these seven populations in a complete diallel without reciprocals. The parental populations and 21 crosses were evaluated for days to silking (DS), ear height (EH), and grain yield (GY) in the Northeast and Yellow and Huai River maize growing areas in China in 2012. Csyn5, Csyn7, Cpop.11, and Cpop.12 had desirable general combining ability (GCA) effects for DS and EH in both the Northeast China mega-environment (NCM) and the Yellow and Huai River Regions of China mega-environment (YHCM). Cpop.11 possessed a favorable GCA effect for GY in the NCM, as did Csyn5, Cpop.17, and Cpop.18 in the YHCM. Csyn6 and Csyn7 exhibited tremendous yield-enhancing potential in both mega-environments. Additionally, six combinations including Csyn7 × Csyn6, Csyn5 × Csyn6, Cpop.11 × Cpop.18, Cpop.12 × Cpop.17, Csyn7 × Cpop.17, and Csyn5 × Csyn7 exhibited better specific combining ability effects for GY, yield performance, and mid-parent heterosis in the appropriate mega-environment. These results indicated that the seven populations would be very useful for the improvement of related agronomic traits, and the six candidate combinations possessed great potential for further improvement and utilization.     

Heterosis of purple blotch (<Emphasis Type="Italic">Alternaria porri</Emphasis> (Ellis) Cif.) resistance,yield and earliness in tropical onions (<Emphasis Type="Italic">Allium cepa</Emphasis> L.)

Five open pollinated onion cultivars Red Creole, Kaharda, Koumassa, Sokoto local and Ori were crossed in a complete diallel and their progenies were evaluated in replicated trials, at Sokoto and Talata Mafara, Nigeria, during the 2004/2005 and 2005/2006 seasons. The experiments were randomised as complete block design with three replications. 30 mls of 10⁻¹ cfu of spore suspension of Alternaria porri prepared by serial dilution was poured into the centre of each plot (sunken bed) immediately after irrigation at 2 weeks after transplanting. Combined analysis across seasons and locations indicated significant (P < 0.05) differences between the populations with respect to all the characters under study. Crosses Ori × Koumassa and Koumassa × Ori recorded highly significant (P < 0.01) positive high parent heterosis for bulb diameter. Crosses Ori × Sokoto local and Ori × Koumassa recorded highly significant (P < 0.01) negative high parent heterosis for days to maturity. Cross Sokoto local × Koumassa exhibited highly significant (P < 0.01) positive high parent heterosis for number of leaves/plant. Crosses Red Creole × Kaharda and Kaharda × Red Creeole recorded highly significant (P < 0.01) positive high parent heterosis for disease incidence. Red Creole × Kaharda and Kaharda × Red Creeole also recorded highly significant (P < 0.01) positive high parent heterosis for fresh bulb yield. Cross Kaharda × Ori recorded highly significant (P < 0.01) positive high parent heterosis for bulb weight. The cross Kaharda × Sokoto local recorded significant (P < 0.05) negative high parent heterosis for days to maturity while the cross Red Creole × Kaharda recorded highly significant (P < 0.01) positive high parent heterosis for number of leaves/plant. Bulb diameter and bulb weight recorded highly significant (P < 0.01) and significant (P < 0.05) environmental correlation with days to maturity.     

Genotype × environment interaction for yield and reaction to leaf spot infections in groundnut in semiarid West Africa

Capitalizing on the yield potential in available groundnut germplasm, and high stability of kernel yield are important requirements for groundnut producers in semiarid environments. Forty-seven groundnut genotypes were evaluated from 2003 to 2005 at 4 locations representative of the Guinea and Sudan savanna ecologies in Ghana. The objectives were to assess genotypic differences in reaction to early and late leaf spot infections under natural field conditions, assess the extent of genotype × environment (G × E) interaction for kernel yield, and determine the relationship between yield potential and yield stability. Genotypes differed significantly in their reaction to leaf spot infections indicated by the area under disease progress curve (AUDPC). Genotypic AUDPC was negatively correlated with maturity period (P < 0.01), with kernel yield (P < 0.05) at each of the 3 locations in the Guinea savanna ecology but not in the Sudan savanna ecology and with each of four stability parameters (P < 0.05). High or low yielding genotypes were grouped based on Dunnett’s test at P < 0.10. High yielding groups had significantly low AUDPC, high biomass, high partitioning of dry matter for kernel growth, and were later in maturity compared to low yielding genotypes. Significant G × E interaction effect for kernel yield was dominated mainly by the lack of correlation among environments variance (76–78%) relative to the heterogeneity of genotypic variance component (22–24%). Stability of yield assessed through the among-environment variance, Wricke’s ecovalence, and Finlay-Wilkinson regression coefficient revealed that genotypes in the higher yielding group were relatively unstable compared to the low yielding group. Indicated by the Kataoka’s index of yield reliability, however, relatively unstable genotypes in the high yielding group are expected to be more productive even under assumptions of high risk aversion (P = 0.75–0.95) compared to the more stable, low yielding genotypes. The findings indicate that deploying these recently developed germplasm in semiarid regions in West Africa provides a better match to farmers’ risk-averse strategies compared with the use of existing earlier maturing cultivars.     

Combining ability,maternal, and reciprocal effects of elite early-maturing maize population hybrids

Choosing germplasm based on elite and diverse genetic sources is essential for the genetic improvement of maize (Zea mays L.) hybrids. The objectives of this research were to evaluate the agronomic and economic potential of maize population and single-cross hybrids and whether significant maternal (ME) and reciprocal effects (RE) reside in elite population hybrids for seed production purposes. Seven elite maize populations currently under recurrent selection at North Dakota State University (NDSU) [NDSCD(M-S)C11, NDSAB(MER-FS)C14, BS21(R)C7, BS22(R)C7, LEAMING(S)C4, CGL(S₁-S₂)C5 and CGSS(S₁-S₂)C5] were crossed in a diallel mating design to form 42 population hybrids, including their reciprocals. The 42 population hybrids with eight single-cross hybrids were evaluated at six U.S. North Central locations in 2005. Data collected across locations indicated that differences across genotypes were significant (P ≤ 0.05) for all traits observed, except for grain yield ear components. General combining ability (GCA) effects were on average larger than specific combining ability (SCA) effects. ME and RE were not significant for all traits, except for ear height. The large grain yield differences between macro-environments were reflected in the ranking of genotypes, with BS21(R)C7 × BS22(R)C7 being the top performer in eastern environments and CGSS(S1-S2)C5 × NDSAB(MER-FS)C14 being the top one across western environments where drought is the major limitation. The increased ethanol production and demand from maize make test weight (and grain quality), earliness, lodging resistance, and drought tolerance as important as grain yield for maintaining a sustainable maize-ethanol relationship. Part of the thesis submitted by McDonald B. Jumbo in partial fulfillment of the requirements for a MS degree at North Dakota State University.     

Effects of reduced height (<Emphasis Type="Italic">Rht</Emphasis>) and photoperiod insensitivity (<Emphasis Type="Italic">Ppd</Emphasis>) alleles on yield of wheat in contrasting production systems

Near isogenic lines (NILs) varying for reduced height (Rht) and photoperiod insensitivity (Ppd-D1) alleles in a cv. Mercia background (rht (tall), Rht-B1b, Rht-D1b, Rht-B1c, Rht8c+Ppd-D1a, Rht-D1c, Rht12) were compared for interception of photosynthetically active radiation (PAR), radiation use efficiency (RUE), above-ground biomass (AGB), harvest index (HI), height, weed prevalence, lodging and grain yield, at one field site but within contrasting (‘organic’ vs. ‘conventional’) rotational and agronomic contexts, in each of 3 years. In the final year, further NILs (rht (tall), Rht-B1b, Rht-D1b, Rht-B1c, Rht-B1b+Rht-D1b, Rht-D1b+Rht-B1c) in Maris Huntsman and Maris Widgeon backgrounds were added together with 64 lines of a doubled haploid (DH) population [Savannah (Rht-D1b) × Renesansa (Rht-8c+Ppd-D1a)]. There were highly significant genotype × system interactions for grain yield, mostly because differences were greater in the conventional system than in the organic system. Quadratic fits of NIL grain yield against height were appropriate for both systems when all NILs and years were included. Extreme dwarfing was associated with reduced PAR, RUE, AGB, HI, and increased weed prevalence. Intermediate dwarfing was often associated with improved HI in the conventional system, but not in the organic system. Heights in excess of the optimum for yield were associated particularly with reduced HI and, in the conventional system, lodging. There was no statistical evidence that optimum height for grain yield varied with system although fits peaked at 85 and 96 cm in the conventional and organic systems, respectively. Amongst the DH lines, the marker for Ppd-D1a was associated with earlier flowering, and just in the conventional system also with reduced PAR, AGB and grain yield. The marker for Rht-D1b was associated with reduced height, and again just in the conventional system, with increased HI and grain yield. The marker for Rht8c reduced height, and in the conventional system only, increased HI. When using the System × DH line means as observations grain yield was associated with height and early vegetative growth in the organic system, but not in the conventional system. In the conventional system, PAR interception after anthesis correlated with yield. Savannah was the highest yielding line in the conventional system, producing significantly more grain than several lines that out yielded it in the organic system.