Mineral Nitrogen Availability and Isoflavonoid Accumulation in the Root Systems of Soybean (Glycine max (L.) Merr.)

Isoflavonoids, as plant-to-bacteria signal molecules, play an important role in the establishment of the soybean ( Glycine max (L.) Merr.)– Bradyrhizobium japonicum nitrogen (N) fixing symbiosis. They are essential to the development of effective root nodules and responsible for inducing the nod genes of B. japonicum . Because N affects a broad range of infection events, especially the symbiotic events occurring within 18 h of inoculation, it is reasonable to hypothesize that mineral N disrupts the interorganismal signal exchange between soybean host plants and B. japonicum . High performance liquid chromatographic (HPLC) analysis of root extracts of soybean, inoculated with B. japonicum or not, grown with various levels of mineral N in the rooting medium were performed to test this hypothesis. The results of these studies indicated that: (1) at early plant growth stages (before the onset of N fixation), a strong negative relationship between N application and soybean root isoflavonoid (genistein and daidzein) concentrations existed; (2) although isoflavonoid (genistein and daidzein) concentrations in both inoculated and non-inoculated soybean root systems were generally decreased by N application, at very low N levels (10 mg N l⁻¹) genistein in the non-inoculated plant roots was not decreased relative to the 0 N plants; (3) averaged over all mineral N treatment levels and sampling times, inoculation of soybean with B. japonicum increased root daidzein concentrations (P > 0.05), but did not affect genistein. Overall, N application reduced the isoflavonoid concentration of soybean root systems, which probably plays a part in the regulation of soybean nodule formation by available N.     

不同熟期及产量类型的大豆生殖生长期生理特性的比较研究

通过分析不同熟期、不同产量类型的大豆，特别是高产品种（系）的群体生理特性，为栽培措施的合理运用及生态育种指标的有效选择提供理论参考。连续2年的试验结果表明，高产大豆应具有株高适宜，节数相对较多，产量形成的空间较大，生殖生长期LAI和LAD较高，R5期后叶片衰减慢，叶片在各个方向上的分布均匀，干物质积累量大，     

Differential Response of Soybean Cultivars Promiscuous to Native Rhizobia to Split Application of Fertilizer N in Nigerian Savanna

Field experiments were conducted to ascertain the differential response of promiscuous soybean cultivars to split application of fertilizer N during 1984 and 1985 at Yandev Agricultural Experiment Station, Nigeria. The cultivars were grown with and without 205 kg N/ha and was applied into equal splits at 20, 40, 60 and 80 days after planting in 1984. In 1985, however, graded doses of 0, 50, 100 and 200 kg fertilizer N/ha were equally split into 3 and applied at 30, 50 and 70 days after planting.
In both years, averaged over all cultivars, split application of N increased the grain yield and total N content of shoot and decreased the nodulation significantly. Cultivars X N interaction existed in affecting the grain yield and total N content wherein cultivars like TGX 297-35C, TGX 536-02D, TGX 713-011D and TGX 306-036D showed significant increase in grain yield and total N content as against no effect on these attributes of other cultivars. This probably proves our hypothesis that, though some promiscuous cultivars yield moderately better without inoculation with R. japonicum or fertilizer; they are incapable of fixing sufficient quantity of atmospheric N symbiotically for maximum soybean yields and therefore require fertilizer N to be applied into splits at several growth and development stages of crop.     

Genistein and Daidzein Concentrations and Contents in Seedling Roots of Three Soybean Cultivars Grown under Three Root Zone Temperatures

Daidzein and genistein are plant-to-bacterium signal compounds involved in soybean nodule formation. They can induce nod gens expression in Bradyrhizobium japonicum. The objective of this study was to determine whether the production of signal molecules was affected by low root zone temperatures (RZTs) in a manner that varied among soybean cultivars. Daidzein and genistein concentrations of soybean seedling roots were measured at three RZTs by high performance liquid chromatography (HPLC). The results indicated that daidzein content and concentration per plant were higher at 15 and 17.5°C than those at 25°C. AC Bravor had higher daidzein contents and concentrations than did Maple Glen and KG20. At 17.5°C. KG20 had higher genistein content and concentration levels than Maple Glen, and no difference existed for the two cultivars at 15 and 25 C. Daidzein contents and concentrations of Maple Glen and AC Bravor increased with harvest time. However, for cultivar KG20, the content and concentration decreased at 19 days after inoculation. Genistein contents and concentrations of the three cultivars increased under each RZT up to the last harvest. There was an interaction between soybean cultivar and RZT for root genistein and daidzein contents and concentrations. The content and concentration of daidzein in soybean seedling roots were much higher (more than five times) than those of genistein.     

Evaluation of the Effect of SoyaSignal Technology on Soybean Yield [Glycine max (L.) Merr.] under Field Conditions Over 6 Years in Eastern Canada and the Northern United States

Previous studies showed that inoculation of soybean [ Glycine max (L.) Merr] with Bradyrhizobium japonicum preactivated with plant-to-bacteria signal molecules increased nodule number, particularly at low root zone temperatures, thereby improving plant seasonal nitrogen fixation and final grain and protein yield under cool spring conditions. Two products carrying this technology, SoyaSignal^TM and Affix+^TM, were designed and tested at 127 locations in Canada and the United States from 1994 to 1999. A summary of the field test results shows that preincubation of B. japonicum with genistein and daidzein, as well as directly increasing the genistein and daidzein concentration in the soybean root rhizosphere, gave an average final grain yield increase of 7 %. The success of SoyaSignal technology was temperature dependent. The plants responded better to the SoyaSignal products when grown under cool soil conditions. Application of SoyaSignal to early planted soybean (before the soil temperature rose above 17.5 °C) increased yields by an average of 10 %. The responses declined with delayed planting dates. Soybean genotypes with high yield potential had greater yield increases than those with low yield potential. As the ratio of return to cost for SoyaSignal technology was 5.3 : 1 over the 127 site-years, SoyaSignal technology can be used as a tool to improve soybean yield in production areas with cool springs.     

三江平原不同年代大豆主栽品种粒茎比和主要病害抗性分析

为了研究三江平原不同年代大豆主栽品种粒茎比与主要病害（灰斑病、根腐病）的变化规律,选用不同年代18 个同熟期的主栽品种为试验材料,采用田间小区试验方法,深入系统的开展研究工作。结果表明：随着年代的推进,粒茎比的变化趋势为逐年累加提高,变化幅度为0.44~0.88,极差为0.44,增长速度为0.73%,是品种产量提高的关键因素之一。品种对灰斑病抗性水平存在着较大的差异,抗病能力总体呈逐步增强的趋势,说明灰斑病危害得到了有效的控制。其中20 世纪50、60 年代品种均表现感灰斑病,70 年代品种抗感交替过渡,到80 年代以后的品种全部表现为中抗或抗灰斑病。品种对根腐病的抗性除个别品种（‘绥农4’、‘合丰45、55’、‘黑农48’）抗性水平突出外多数品种抗病性较差,抗病能力总体呈阶段性提高的趋势,其中抗病品种占22.22%,感病品种占77.78%。说明根腐病没有得到有效的控制,是当前育种与生产亟待解决的病害。     

Effect of Foliar Fertilizers on the Growth of Soybean Cultivars1

Foliar fertilizers (FF) applied at the reproductive growth stage was reported to increase soybean (Glycine max L. Merr.) yield in field trials. But yield increases have not been consistent. Field experiments were conducted on Calloway silt loam soil in 1981—1982 to determine the effect of two foliar fertilizer (FF) formulations, 16N + 4P + 4K + 1 S (Hanway) and 12 N + 4 P + 4 K + 0.5 S (Folian), and time of application, 0800- and 1900-h, on the growth of seven soybean cultivars from maturity groups V, VI, and VII. Foliar fertilizers were applied at a rate of 187 L/ha^?1 in water by a backpack CO₂ pressure sprayer at R5 to R6 growth stages. Foliar fertilizers caused no crop injury (leaf burn) when applied at 1900-h but caused moderate injury at 0800-h, which caused a yield reduction. The most significant crop injury was caused by Hanway formulation when applied at 0800-h. Yields were significantly reduced by FF in 1981 but not in 1982. Generally, Folian formulation treatments had higher yields than Hanway formulation treatments, but neither formulation increased yield above that of the untreated plants. The Bragg cultivar exhibited the least amount of crop injury and the most positive yield response to FF. Plant height, 100-seed weight and lodging rates were not adversely affected by the foliar applications. Due to the general lack of consistent yield increases or in some instances yield reduction from FF applications, the formulations used cannot be recommended for use by soybean producers.     

The effects of simulated weed pressure on early maturity soybeans

Breeding for increased weed suppression would be a sustainable contribution to improved soybean weed management, because weed infestation is a major constraint to soybean production world-wide and in organic farming in particular. However, genetic variation in the soybean–weed interaction would be necessary to enable plant breeders to select soybean genotypes based on a superior weed suppression behavior. As there is a lack of information on variation between soybean cultivars in their competitive ability against weeds, the effects of weed pressure on ten early maturity soybean genotypes were studied in a controlled field experiment over three years in Austria. Winter oilseed rape was sown into the soybean stand to simulate pressure from a seed-propagated type of weed. Weed pressure significantly affected soybean yield as well as other agronomic, phenologic and seed quality characters. In two seasons, strong competition from weeds caused a soybean yield reduction of 370 and 560 kg/ha, respectively. In a third season a significant yield increase over weed-free controls was observed at relatively low levels of weed pressure which is explained by non-competition effects of a weak weed ground cover on soybean growth. Yield loss due to weed pressure was lower in early than in late maturity genotypes which appears to be the effect of a better weed tolerance rather than weed suppression. Genotype by weed treatment interaction was not significant, and genetic variation in ground cover development or leaf area was low or not significant in the early maturity soybean cultivars investigated. As such characters are considered important for weed suppression, their variation needs to be increased to enable selection for improved weed suppressive ability.     

Breeding aspects of clustering winter wheat cultivars for yield response

The objective of this study was to compare the yield response of several present day winter wheat cultivars of different origin with the aim of broadening breeders' information from multi-year/location tests by using an appropriate cluster procedure. Yield response of 18 cultivars was analysed using data from two series of official yield performance tests in Germany. Similarity of yield response between two cultivars is defined by a positive correlation coefficient (nearly one) for the yields over all test environments. A hierarchical agglomerative procedure was used to establish clusters of similarly responding cultivars. The smallest distances in yield response were established between closely related cultivars of equal maturity. Clusters of cultivars with distinct maturity and also the groups of East and West German cultivars tested exhibited clear differences in yield response.     

Characterization of genotype by environment interactions in soybean breeding programmes of southeast Europe

Southeast Europe is Europe's major production area of soybean of maturity groups (MG) 0, I and II, but genotype by environment interaction (GEI) for soybean traits in this region is still not characterized. The objective of this study was to characterize GEI in soybean grown in Croatia for seed yield, protein and oil content. Fourteen soybean cultivars of MG 0 and I were evaluated at 15 environments. In the combined anova , genotypes, environments and GEI were significant. All three seed traits were more affected by year than by location and seed yield and protein content were more sensitive to environmental changes than oil content. Genotype by environment interaction is generally of less importance than effects of genotypes and years, especially for oil content. High‐yielding genotypes had values of regression coefficient (b) close to 1, indicating that they were not responsive to extreme environments, either positive or negative. Means and b values were not correlated for yield and negatively correlated for protein and oil content, probably because of low‐input practice in the region. The absence of recognizable differences in means, b values and principal component scores of ammi analysis between two MGs for all traits indicated that soybean cultivars of MG 0 may be recommended for growing in the region because they responded similarly to environmental changes as do full‐season genotypes of MG I.     

Screening for Drought Resistance: Evaluation of Drought Susceptibility Index of Legume Plants under Natural Growth Conditions

Eighteen cultivars of legume species (field bean, soybean, field pea, lupine) were screened for drought tolerance in 3 year-long field experiments. The aim of the investigations was to evaluate the generic variation of drought susceptibility of the tested varieties. The experimental plots were equipped with an installation which enabled the limitation of the water content in soil and soil irrigation. The applied drought susceptibility index (DSI) considered the relations between seed yield of plants under drought conditions (Y_D) and that under conditions of good soil watering (Y_IR) as well as their dependence on the drought severity index (D_S). The use of the index divided the cultivars into two groups of different drought tolerances. The group of drought resistant cultivars characterized by mean values of the DSI index < 0.31 comprised field bean cultivars Bourdon, Gobo and Nadwislanski, soybean cultivars Aldana, Polan and Progres, field pea cultivars Miko and Solara and lupine cultivars Popiel and Bac. To the drought sensitive cultivars with DSI > 0.44 belonged Victor and Bronto of field bean species, Bareness and Mige of field pea species and Emir of lupine species. In general, the resistant cultivars when compared with the susceptible ones were characterized by lesser yield of seeds, which, however, was more stable both under conditions of drought and moistured plots. Any dependence of the degree of drought tolerance on the duration of the particular periods of plant growth was not observed in the experiments, however, both in’ drought susceptible and drought resistant cultivars there appeared the tendency to shorten the development phases under drought and to prolong them under artificial irrigation. In general, based on the results obtained, it can be concluded that legume plants belong to the species sensitive to water supply. The observed decrease of plant seed yield under moderate natural soil dryness in the year 1993 differed only a little from that found in experiments in the years 1994 and 1995, when soil dryness was much more severe.     

Variation in the photoperiodic response on several characters in soybean,Glycine max (L.) Merrill

Summary The photoperiodic response on 12 characters in 40 soybean, Glycine max (L.) Merrill, cultivars were investigated using 10-hour (short day) and 16-hour (long day) photoperiods. Seventeen cultivars showed no significant difference between photoperiods for all 12 characters. Seven cultivars showed significant difference for only one trait. Phenotypic changes in 17 cultivars may be due to factors other than photoperiod. Number of pods per plant, days to maturity, and number of nodes per plant were highly correlated with yield per plant in both photoperiods. Invariably, the cultivars which had significant differences in the numbers of flowers produced per plant between the two photoperiods also had significant differences in the numbers of pods per plant and yield. First node to flower, plant height at flowering, days to flowering, nodes at flowering, and the 100-seed weight were least influenced by the photoperiods in most of the cultivars, while the height at maturity, number of nodes at maturity, number of days to maturity, and yield were most influenced.AVRDC Journal paper 46 (78–88).     

Root and Rhizosphere Colonization of Soybean [Glycine max (L.) Merr.] by Plant-Growth-Promoting Rhizobacteria at Low Root Zone Temperatures and under Short-Season Conditions

Co-inoculation of plant-growth-promoting rhizobacteria (PGPR) with B. japonicum has been shown to increase soybean [ Glycine max (L.) Merr.] nodulation, nitrogen fixation, growth and physiological activity at suboptimal root zone temperatures (RZTs). We studied the survival and growth of seven PGPR inoculated on soybean in a sterile rooting medium at three RZTs (25, 17.5 and 15 °C) on a growth bench. The survival of the two most promising strains ( Serratia liquefaciens 2-68 and S. proteamaculans 1-102) was studied under field conditions in methyl bromide fumigated and non-fumigated soils. In general, population densities varied with temperature. PGPR strains generally colonized the rhizosphere and root surface effeciently at higher RZTs; however, S. proteamaculans 1-102 colonized best at a low RZT (15 °C). The population of PGPR applied to the rhizosphere either with or without addition of B. japonicum increased over time in fumigated soil as compared to non-fumigated soil, indicating that the PGPR survive and proliferate better under fumigated conditions. S. liquefaciens 2-68 had higher population densities both on the root and in the rhizosphere, demonstrating, their ability to colonize under short-season conditions. The possible interactions between the two cultivars (Maple Glen and AC Bravor) and the PGPR were generally not significant, despite observations that growth and yield of AC Bravor respond more strongly to PGPR inoculation.     

滨海盐碱地不同抗虫棉品种的产量和熟相及去早果枝的效应

 为探讨不同抗虫棉品种在滨海盐碱地的产量和熟相及其对去早果枝的反应,以早发型（鲁棉研17、21）、晚发型（鲁棉研18、22）抗虫棉和两者的F₁杂交种（01H00、01H01）为材料,于2006－2007年在东营市盐碱棉田进行了试验观察。结果表明,早发型和晚发型抗虫棉品种间的早熟性和熟相存在显著差异,两者的杂交种在2006和2007年分别比常规种增产5.7%~14.5%和4.7%~6.8%,并表现出较好的熟相。早发型常规抗虫棉去早果枝增产5.6%~8.4%,早衰得到延缓;晚发型常规抗虫棉去早果枝减产9.3%~13.1%,表现晚熟。利用不同熟相类型的常规抗虫棉配置杂交组合以及对早发抗虫棉品种去早果枝都是延缓早衰、提高盐碱地棉花产量的有效途径。     

大豆重组自交家系群体动态株高及其相对生长速率与产量的关系

提高产量潜力始终是大豆育种的重要目标,研究产量相关性状是解析产量重要途径之一。大豆株高影响产量,但存在不确定性。本研究利用一套包含212个家系的大豆重组自交家系(RIL),于2008—2009年连续2年测定各家系动态株高,并计算相对生长速率,研究与产量的关系,以期为大豆产量改良中对株高的选择提供参考信息。试验结果表明,(1) 产量和株高变幅分别为1 000~5 000 kg hm^–1和38~103 cm,说明样本有较大代表性。(2) 出苗后20 d的株高即与产量具极显著正相关,随生长进程,相关系数逐渐增大,至株高生长停止达到最大。株高生长速率前期与产量呈显著正相关,后期与产量具负相关,说明后期过快增加株高不利于产量。(3) 在试验范围内,株高与产量呈负指数回归关系,随株高增加,产量逐渐增加,当株高为80 cm时,随株高增加,产量的增加逐渐缓慢。发现株高的变异在70~90 cm之间时,均能获得4 000 kg hm^–1产量。本文还简要讨论了重组自交家系用于表型分析的优势,以及在大豆产量育种中如何对株高进行选择。     

干旱胁迫对不同生态型大豆生理生化特征的影响

为了研究干旱胁迫对大豆生理生化特征和产量的影响,选用22份不同生态型大豆品种为研究材料,用盆栽称重法与大田试验结合的方法,研究花期不同生态型大豆抗旱生理生化特征。结果表明：干旱胁迫下,不同生态型大豆品种的叶片相对含水量、过氧化物酶(POD)、超氧化物歧化酶(SOD)活性、叶绿素a含量、总叶绿素含量和净光合速率都有一定程度的降低,与大豆品种的抗旱性均呈正相关,表现为抗旱性强的品种下降幅度较小,而抗旱性弱的品种下降幅度较大;而丙二醛含量、相对电导率和可溶性糖都有一定程度的增加,与抗旱性均呈极显著负相关,表现为抗旱性强的品种增加的幅度较小,而抗旱性弱的品种则相反;脯氨酸含量与抗旱性呈极显著正相关,表现为抗旱能力强的品种脯氨酸含量增加幅度大。这一结果说明,在干旱胁迫环境下,水分亏缺降低了大豆叶片相对含水量,膜脂过氧化伤害加重,引起丙二醛的累积,相对电导率升高,游离脯氨酸及可溶性糖含量升高,而丙二醛含量的升高导致保护酶活性降低,同时水分亏缺导致叶绿素含量降低,净光合速率下降,最终导致产量下降。     

Implications of selecting improved strains of soybeans for dry-matter accumulation and grain yield

Summary Three maturity groups of soybeans (Glycine max L.) were used to investigate the relationship between dry-matter accumulation (DMA) and grain yield (GY), and the prospects for selection of high seed yielding strains among the existing soybean cultivars in a tropical environment. The positive and significant association between DMA and GY (r=0.888^***) indicated that selection for high DMA could give gains in GY. However, the higher harvest index (HI=37.5%) for the low seed yielding early maturing genotypes than the more vegetatively endowed and higher seed producing late maturity group, is an indication that excessive DMA could be disadvantageous. Total seed yield per land area for the three maturity groups of soybeans showed that the genotypes with high harvest index and low seed yield could be as good as those ones with high seed and dry-matter yields with low harvest index. The high coefficient of variation which ranged between 18.1 and 59.8% and the heritability estimations which also ranged from 34.4 to 82.2% are indicative of the presence of substantial genetic diversity and there are good prospects for the improvement of the crop through selection.     

Genotypic Variation for Nitrogen Fixation in Soybean

Twenty soybean cultivars from maturity groups IV, V, VI, VII and VIII were screened in the growth chamber study to determine their response to two Rhizobium strains through N-fixation rates. Cultivars Lee 74, Essex and Bay showed high nitrogenase activities of 201.00, 93.75 and 74.86 nM C₂H₂/pl/hr, respectively. Braxton, Hutton and Bragg showed low nitrogenase activity rates of 4.73, 4.20 and 3.0 nM C₂H₂/pl/hr, respectively. A range of variation was found among the cultivars in shoot fresh and dry weights, nodule number and nodule weight.     

Genetic diversity in soybean genotypes from north‐eastern China and identification of candidate markers associated with maturity rating

Random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) markers were used to estimate the genetic relationships among 101 soybean cultivars developed in north‐eastern China. Fifty‐three fragments of the 100 RAPD markers and 35 SSR markers tested were polymorphic across the 101 soybean cultivars. Similarity values among these soybean cultivars ranged from 45.2% to 100% for RAPD data, and ranged from 36.1% to 100% for SSR data. The similarity matrices for SSR data and RAPD data were moderately correlated (r = 0.31, P < 0.05). Cluster analyses indicated that the cultivars released from the same seed company were mostly grouped together. A principal component analysis, based on the combined RAPD and SSR data, yielded a good separation of soybean varieties with different maturity ratings [represented by soybean Heat Unit (HU)]. The varieties with HU < 2200 were well separated from those with HU > 2200. Four RAPD markers and eight SSR markers were significantly associated with the maturity ratings of soybean.     

三江平原不同年代大豆主栽品种主要农艺性状及产量变化分析

为了研究三江平原60 余年大豆生产主栽品种更替过程中主要农艺性状与产量的改进与变化规律,指导当前或今后的品种改良与创新,采用田间小区试验的方法,选用三江平原不同年代同熟期组的18 个主栽品种为试验材料。试验结果表明,主要农艺性状随年代的推进,株高与有效分枝数呈降低趋势;底荚高度变化不大,总体呈增加趋势;主茎节数呈增加趋势;抗倒伏能力逐渐增强;生育日数逐年延长;品种单株荚数、每荚粒数、单株粒数、单株粒重均呈不断增加的趋势;百粒重呈波动增加趋势。产量随着年代的推进逐年累加提高,产量变化幅度为2509.20~3311.25 kg/hm2,年平均产量增加13.35 kg/hm2,增长速度为0.53%。由于品种主要农艺性状的改进与变化,特别是品种生育日数延长和产量性状的改进,不断的提高品种产量水平,所以导致了生产主栽品种不断更替与变化,这一结论对当前或今后品种改良与创新具有重要的指导与借鉴意义。