Evaluation of drought tolerance for Atlas fescue,perennial ryegrass,and their progeny

Primitive cottons (Gossypium spp.) represent resources for genetic improvement. Most primitive accessions are photoperiod sensitive; they do not flower under the long days of the U.S. cotton belt. Molecular markers were used to locate quantitative trait loci (QTLs) for node of first fruiting branch (NFB), a trait closely related to flowering time in cotton. An F₂ population consisted of 251 plants from the cross of a day neutral cultivar Deltapine 61, and a photoperiod sensitive accession Texas 701, were used in this study. Segregation in the population revealed the complex characteristics of NFB. Interval mapping and multiple QTL mapping were used to determine QTLs contributing to NFB. Three significant QTLs were mapped to chromosome 16, 21, and 25; two suggestive QTLs were mapped to chromosome 15 and 16. Four markers associated with these QTLs accounted for 33% of the variation in NFB by single and multiple-marker regression analyses. Two pairs of epistasis interaction between markers were detected. Our results suggested that at least three chromosomes contain factors associated with flowering time for this population with epistasis interactions between chromosomes. This research represent the first flowering time QTL mapping in cotton. Makers associated with flowering time may have the potential to facilitate day neutral conversion of accessions. Contribution of USDA-ARS in cooperation with the Mississippi Agric. and Forestry Exp. Stn. Journal paper J-11131 of Mississippi Agric. and Forestry Exp. Stn. Mention of trademark, proprietary product, or vendor does not constitute a guarantee or warranty of the product by USDA, ARS and does not imply its approval to the exclusion of other products or vendors that may also be suitable.     

青花菜与甘蓝近缘野生种‘B2013’杂交后代对根肿病抗性的遗传分析

以高感根肿病的青花菜自交系‘93219’和高抗根肿病的甘蓝近缘野生种（Brassica macrocarpa Guss.）自交系‘B2013’为亲本配制的6个联合世代（P1、P2、F1、BC1、BC2和F2）群体为试材,采用主基因 + 多基因混合遗传模型对根肿病抗性进行了遗传分析。结果表明：青花菜 × 甘蓝近缘野生种‘B2013’后代对根肿病抗性的最适遗传模型为B-1模型,即由两对加性―显性―上位性主基因控制。BC1、BC2和F2世代主基因遗传率分别为81.22%、78.36%和80.00%,遗传变异平均值占表型变异的79.86%,环境变异平均值占表型变异的20.14%,表明抗病性以主基因遗传为主,同时受环境影响较大,应在早期世代进行选择,BC1、F2世代主基因选择效率较高。     

药用植物Andrographis paniculata中硝酸盐累积和硝酸还原酶活性随其基因、生长阶段及时间的变异研究

There is a growing concern over the presence of high concentrations of nitrate in orally consumed herbal remedies. Since nitrate accumulation in the plant body can vary with spatial location and plant development and temporally with photoperiod, understanding the relations between these factors and nitrate contents in the consumed herbs are vital for the development of agrotechnical strategies for nitrate avoidance. Therefore, the distribution profiles of nitrate concentration and nitrate reductase activity were analyzed in 14 accessions of Andrographis paniculata (Burm.f.) Wall. ex Nees., a medicinal plant widely used as a component of many herbal teas and medicinal infusions. Significant variation in nitrate accumulation in the plant was observed between the accessions, and most contained nitrate levels beyond the safety limit recommended according to the European Commission’s Scientific Committee on Food. Nitrate content increased with plant development and leaf age, and that in leaf segment was higher in the center of the leaf than at its tip or base; the nitrate concentration in plant organ followed the order of petiole > leaf > stem, and it was lower at mid-day than in the early morning or evening. Gradients of NR activity negatively correlated with nitrate content in all studied temporal and spatial profiles. Identification of the characteristic spatial and developmental profiles of nitrate accumulation and NR activity in A. paniculata can guide the development of harvest strategies aimed at minimizing nitrate contents in the consumed herbal tissue.     

抗炭疽病柱花草空间育种新品系的多目标决策评价筛选

为选育综合性状优良的柱花草(stylosanthes SW.)新品种1系,运用多目标决策法中的差值加权法(RE-VAWEA)、简单加性加权法(SAVA)、逼近于理想解的排序法(TOPSIS)及集结技术将85个空间辐射柱花草株系的7个指标以其贡献率为权重计算得出综合评价指数,据此评价各株系综合性状的优劣。结果表明:85个株系中2001-71,2001-28,2001-15,2001-24及2001-2等综合性状最佳;2001-22,2001-82,2001-57,2001-18等表现中等;而2001-50,2001-85,2001-32及2001-78等最差。随后将多目标决策评价结果与一维有序聚类相结合,得到聚类图,以此选育出能取代其亲本‘热研2号’柱花草并能在生产上推广利用的新品系。     

40个决明品系牧草在闽北红壤山地的适应性

引进 Chamaecrista rotundifolia、C.nictitans、C.serpens、C.pilosa4种决明种的 4 0个品系 ,在闽北红壤山地进行引种筛选试验并测定其对山羊的适口性 .概述了各品系建植、生长与生育特性、越冬性及次年种子自然萌发情况 .筛选出适于刈割—搬运系统牧草的羽叶决明品系 ATF2 2 17、ATF2 2 19(C.nictitans) ,适于热带、亚热带红壤山地果园套种的圆叶决明品系 ATF2 2 30、ATF2 2 31、ATF2 2 2 4、ATF2 2 2 5、ATF2 2 2 8(C.rotundifo-lia) .     

Weed-Suppressing Effect and Mechanism of Allelopathic Rice Accessions

Two allelopathic rice accessions, PI312777 and Allelopathyl, significantly suppressedthe growth of associated weeds in the field. Moreover, their weed-suppressing effectswere correlated with the cultivation patterns. The weed-suppressing effects of throwingand transplanting were more effective than that of direct seeding. Furthermore, theamounts of allelochemicals (resorcinols, flavones and hydroxamic acids) produced andreleased from two allelopathic rice accessions were much higher than that from a non-allelopathic rice variety Hua-Jing-Xian 1, and reached the maximum concentration at the6th leaf stage. Differences in the weed-suppressing effects of rice accessions appear toresult from the accessions producing and releasing different amounts of allelochemicalsin the field. Further research confirmed that in PI312777 plants, allelochemicals weresynthesized by the above-ground parts, and then secreted through the root tissues. Roottissues of PI312777 plants never produced the allelochemicals. Root exudates fromPI312777 could significantly inhibit the growth of E. crus-galli surrounding rice plantsin water culture. However, when activated carbon was added to the culture solution, whichcould absorb allelochemicals from root exudates, the growth of E. crus-galli was nolonger significantly inhibited. Weed-suppressing effects of rice accessions depended onallelopathy, cultivation patterns and other factors in rice fields, while allelopathywas one of important factors. Interestingly, the amounts of allelochemicals produced andreleased from allelopathic rice plants may be induced by the presence of E. crus-galli.This suggests that there is a possible chemical recognition between rice and E. crus-galli.     

Herbage yield and quality of Gliricidia sepium under different cutting heights and defoliation frequencies

The browse shrub Gliricidia sepium, introduced into the subhumid zone of Nigeria to serve as a supplementary-forage source for ruminant during the dry season, has the undesirable characteristic of shedding its leaves during its flowering phase which coincides with the early dry season. This report relates a management practice undertaken to maintain G. sepium in vegetative growth through the dry season. Evaluation was undertaken on the influence of cutting to different heights and defoliation at different frequencies. Eight different accessions of the species were involved in the study. Cutting generally ensured vegetative growth during the early dry season, with greater shoot development observed at a cutting height of 0.7 m than at two lower heights. Under the double harvest regime, dry matter yield was generally highest at first harvest and significantly (P < 0.05) so at a cutting height of 0.3 m than at 0.5 or 0.7 m. Accession HYB yielded more dry matter than three other accessions harvested once. Cutting to 0.7 m yielded more leaves than cutting at lower heights. The foliage contained adequate levels of organic matter, crude protein and the minerals, Ca and P while the accession HYB consistently maintained a higher dry matter yield than the other accessions.     

大豆抗锈种质的评价

对14个国内外大豆抗锈种质在福建地区的抗锈性及农艺性状进行了评价。结果表明:抗锈基因Rpp1、 Rpp2、Rpp3和Rpp4 (屏南豆)的抗性已被克服,抗锈种质樟子乌、九月黄和日向可能含有新的抗锈基因。来自国外 的抗锈种质在福建地区未能表现出对锈病的抗性,农艺性状较差,不适宜直接利用。     

引进春播啤酒大麦品种生育时期及产量性状鉴定与筛选

对从法国引进的7个春播啤酒大麦品种,进行了生育时期及产量相关性状的鉴定与评价,旨在筛选适宜河北保定地区种植的优良啤酒大麦品种,并为育种改良提供种质来源。结果表明:7个外引品种在产量水平上存在显著差异,其中SB1和SB3品种表现生育期较短、分蘖能力强、成穗率高、产量高及抗倒伏性能好等特点,适宜在该地区种植,且具有可直接利用于生产的可能性。此外,7个引进品种的产量性状遗传基础较为丰富,可作为种质材料利用。     

Genetic relationship between Litopenaeus setiferus (L.) and L. schmitti (Burkenroad) determined by using 16S mitochondrial sequences and enzymatic analysis

Genetic differentiation and variability data of two populations of two species of shrimp (Litopenaeus setiferus (L.) and L. schmitti (Burkenroad)) have been obtained by electrophoretic analysis and by analysis of 16S mitochondrial DNA. Using eight polymorphic enzymes, the genetic distance (GD) between the two species was 0.165. The GD between L. setiferus populations was 0.0057 and between L. schmitti populations it was 0.0034. The greatest differentiation was found within, rather than between, populations, although the differentiation value between Mexican and Cuban populations varied in accordance with the geographic distance and ecological characteristic of each. We found a high similarity between these two species with a bimodal distribution of the loci with respect to genetic identity. The homology percentages for gene 16S fragments were compared with those from six different shrimp species (L. vannamei, L. stylirostris, Farfantepenaeus notialis, Metapeneopsis lamellata) and Artemia salina. Ninety‐seven percent of identity was found by analysis of a 409 bp of 16S mitochondrial DNA. With these values a phylogenetic tree was made using parsimony criteria. The GDs obtained with this method confirm the classification proposed by Pérez‐Farfante & Kensley (1997) .