Sources of Resistance to Phytophthora Pod Rot at the International CocoaGenebank, Trinidad

The International Cocoa Genebank, Trinidad (ICG,T) contains about 2000 cacao (Theobroma cacao L.) accessions. The purpose of the collection is to provide a source of genes for the genetic improvement of cacao through breeding. In fulfilling this objective, it is imperative that this collection be evaluated to identify major sources of genes for the genetic improvement of important agronomic–economic traits. In this study, 816 cacao accessions were evaluated for resistance to Phytophthora pod rot (black pod disease), which causes enormous loss of yield in cocoa production throughout the world.The study identifies promising resistant genotypes that could be exploited in cacao breeding programmes. It further compares the levels of resistance to Phytophthora pod rot among two cacao types (wild and cultivated types), three major groups (Forastero, Trinitario and Refractario) and 11 accession groups (B, AM, CL, ICS, IMC, JA, LP, MOQ, NA, PA and TRD) . The distribution of scores for the 816 accessions showed skewness towards the susceptible end of the disease rating scale, indicating that a large proportion (68.9%) of the sample was susceptible (disease rating 6–8) to Phytophthora pod rot. However, 12.9% of the sample population was found to be resistant (disease rating 1–3) and 18.2% moderately resistant (disease rating 4–5). Significant differences were observed between the wild and cultivated accessions and among the Forastero, Refractario and Trinitario groups. Marked differences were also observed among 11 accession groups, each of which was represented by at least 20 genotypes. Higher proportions of resistant (17.7%) and moderately resistant (22.6%) genotypes were observed in the wild accessions than in the cultivated varieties (9.4% resistant and 14.4% moderately resistant). The Forastero group, consisting of many wild accessions, was found to contain more resistant (18.0%) and moderately resistant (23.1%) genotypes than either the Trinitario (4.8% resistant and 13.6% moderately resistant) or Refractario (11.3% resistant and 15.4% moderately resistant). Among 11 accession groups, the largest percentage of resistant (24.2%) and moderately resistant (28.8%) genotypes were found in the PA (Forastero). Different accession groups had varying proportions of resistant and moderately resistant genotypes. This is not unexpected in an out-breeding crop such as cacao with a high level of heterogeneity. This finding reinforces the idea of a pre-breeding programme (germplasm enhancement) to accumulate resistance genes over several populations as a strategy for improving the genetic base of resistance in national cacao breeding programmes. One hundred and five promising resistant genotypes were identified among the 816 accessions evaluated. These accessions are potential sources of resistance genes for the development of high-yielding resistant varieties in cacao.     

4JH-220型秸秆粉碎还田机的研制

针对棉花秸秆机械化粉碎还田作业中存在的问题,通过对比分析国内外棉花秸秆回收还田技术与装备的特点,综合考虑新疆棉花种植模式以及秸秆粉碎还田作业要求,研制出了基于新型自适应摆动尾轮与螺旋排列刀轴刀片结构的4JH-220型秸秆粉碎还田机,实现了秸秆粉碎还田的机械化作业。试验结果表明:装备结构合理、工作平稳、性能可靠。经检测,茎秆粉碎长度合格率达97.3%,留茬高度仅为71mm,抛撒不均匀度为15.6%,工作幅宽为2.2 m,生产率达到0.7 hm2/h,相关指标均优于国家标准。     

Does the Honeybee (Hymenoptera: Apidae) Reduce the Blooming Period of Canola?

The aim of this study was to determine if and how the honeybee reduces the blooming period of canola (Brassica napus). Colonies were installed in different fields of canola in the Chaudiere‐Appalaches (two replicates) and Quebec City (one replicate) regions to create a density gradient of zero to three colonies per hectare. To calculate the blooming period under these conditions, 10 labelled plants were caged in the field, out of the reach of pollinators, and 10 others were labelled in the field and exposed to foragers. The number of flowers found on each plant was recorded daily. This study also aims at demonstrating that the canola plant will produce new flowers as long as it does not reach its maximum carrying capacity, thereby extending the blooming period. To simulate the fall of unfertilized flowers, a predetermined number of flowers from 20 randomly selected plants in one of the replicates were cut off every day. The plant, when it reaches its maximum carrying capacity, stops producing new flowers. With three colonies per hectare, the blooming period was reduced by 3.8 days, or 17 % compared with in the absence of pollinators. Because of the efficient pollen transfer to the stigma, the honeybees do not only cause the flower to live for a shorter period of time, but they also bring about a decrease in the number of flowers produced by the plant, thereby reducing the duration of blooming period.     

渐近模型在优化花生种植密度上的应用

种植密度是影响作物生产效率的关键因素之一，因此将渐近模型（方程1）应用到阿根廷的花生种植密度决策中，试验采用2个品种（分别属于西班牙型和兰娜型），方式为3种行间距（分别为0.70m、0.50m和0.30m）和2种株间距（分别为0.06m和0.12m）的组合，株行距比值较低（介于0.1和0.4之间）。模型的适用范围取决于种植密度和相应的株行距比值。各方式的密度分别为12，17，24，28，33和56株/m^2，模型（方程1）恰当地描述了两个品种单产和密度之间的关系。由此模型我们可以得出花生最佳种植密度为25和30株/hm^2之间。再加大种植密度并不能取得更高的荚果产量和经济效益。     

大豆抗大豆食心虫机制研究初报

在抗虫鉴定的基础上,对大豆抗食心虫品种(系)的抗性机制进行了研究。发现豆荚硅元素含量高是抗虫的主要原因之一;豆荚表皮细胞呈近圆形突起、直径小或表皮细胞下小细胞层数多、表皮下有特长形细胞者;豆荚隔离层细胞呈短椭圆形、直径小、排列紧密者均有较强抗性。抗性与荚皮厚度、隔离层厚度及隔离层细胞排列方向无关。     

花生每荚种子数相关性状QTL的定位

【目的】花生是重要的油料作物和经济作物,高产一直是花生育种的主要目标,决定产量的因素是单位面积的种子数和仁重。单位面积种子数是种植密度、每株荚数和每荚种子数的乘积。因此,对花生每荚果种子数相关性状进行QTL分析,有助于发掘该性状相关基因/位点,为花生产量相关性状分子育种提供重要的理论依据。【方法】以四粒红×冀农黑3号构建的RIL群体为研究材料,于2018年（E1）和2020年（E2）在河北省保定市河北农业大学清苑试验站（115°30′E,38°40′N）种植鉴定,收获时调查统计单仁果数、双仁果数以及多仁果数表型值,利用河北农业大学花生创新团队实验室构建的高密度遗传图谱,采用QTL Icimapping V4.2中的完备区间作图法对2个环境下的每荚种子数相关性状进行QTL定位与分析。【结果】单仁果率与双仁果率均呈正态分布,多仁果率呈偏正态分布。3个性状的QTL定位分析结果表明,共检测到11个QTL,可解释4.66%—22.34%的表型变异,加性效应为-9.35—9.42。其中,定位到5个多仁果率QTL,可解释3.19%—22.34%的表型变异,有1个QTL的加性效应为负值（-4.77）,来自冀农黑3号,其余4个QTL的加性效应为正值（3.59—9.42）,均来自母本四粒红;定位到2个单仁果率QTL,可解释4.97%—6.43%的表型变异,加性效应均为负值（-4.45和-4.54）,均来自冀农黑3号;定位到4个双仁果率QTL,可解释3.46%—20.87%的表型变异,加性效应均为负值（-9.35—-3.84）,均来自冀农黑3号。这些QTL中,6个为主效QTL,其中,qRMSPA05被重复检测到,且可遗传表型变异为16.58%—17.34%,加性效应为7.69—8.12。【结论】定位6个主效QTL和1个主效稳定的多仁果率QTL,有助于改良花生产量性状,可以作为遗传改良的重要候选区段,用于分子标记辅助选择与精细定位研究。     

常规与非常规粗饲料在奶牛瘤胃中的降解特性研究

旨在探讨非常规粗饲料(玉米芯、毛豆荚壳)与奶牛常用粗饲料(苜蓿干草、玉米青贮)在奶牛瘤胃中的降解规律,试验选用3只装有永久性瘤胃瘘管的荷斯坦奶牛,采用尼龙袋法测定4种粗饲料的干物质(DM)、粗蛋白(CP)、中性洗涤纤维(NDF)和酸性洗涤纤维(ADF)的瘤胃降解规律。结果表明:1)苜蓿干草和毛豆荚壳的CP含量分别为17.55%和11.10%,且苜蓿干草显著高于毛豆荚壳(P<0.05);玉米芯和玉米青贮的CP含量分别为2.97%和8.41%,且玉米芯显著低于玉米青贮(P<0.05);玉米芯的NDF和ADF含量显著高于其他3种粗饲料(P<0.05),达到79.98%和43.35%。2)苜蓿干草的DM有效降解率最高(P<0.05),由高到低依次为苜蓿干草、毛豆荚壳、玉米青贮和玉米芯。毛豆荚壳的CP有效降解率显著高于其他3种粗饲料(P<0.05),由高到低依次为毛豆荚壳、苜蓿干草、玉米青贮和玉米芯。苜蓿干草的NDF有效降解率显著高于毛豆荚壳(P<0.05),玉米青贮和毛豆荚壳无显著差异(P>0.05);玉米芯的ADF有效降解率最高(P<0.05),苜蓿干草、玉米青贮和毛豆荚壳无显著差异(P>0.05)。综上所述,玉米芯和毛豆荚壳可作为非常规粗饲料资源加以开发利用。     

等离子体浸没离子注入豌豆种子的表面形态研究

用等离子体浸没离子注入设备对食荚青豌种子进行了氩离子注入。卢瑟福背散射方法证实了经这种离子注入后,的确有一定数量的氩离子进入了食荚青豌种子,并发现注入种子的氩离子的相对浓度与注入的时间有关。用扫描电子显微镜对经过注入和未经注入离子的食荚青豌种子的表面形态进行了研究,发现等离子体浸没氩离子注入对种子有刻蚀作用。本文还探讨了这种注入方式引起种子细胞损伤的机制。     

大果干制朝天椒“湘辣762”的选育

摘要：湘辣762是以702a不育系为母本,以自交系簇生朝天椒RC17-580为父本配制的杂交一代中熟品种。 果实小羊角形,单生朝天,果长9.8 cm、果宽1.6 cm、果肉厚0.12 cm,青果深绿色,熟果鲜红光亮,一致性 好,单果质量8.64 g;果实中维生素C含量1.509 g/kg,辣椒素含量2.167 g/kg,干物质含量27.56%,味香辣, 丰产性好,易干制、油分高、干物质含量高,适合作鲜椒、剁酱或干制加工;综合抗性和适应强,抗疫 病,中抗炭疽病及病毒病;耐寒性和耐旱性强。平均鲜椒667 m2 产量高达1 794.4 kg,干椒667 m2 产量高达 394.0 kg,鲜干比例为4.55。适合在贵州、河南及安徽等地区春夏季露地栽培。     

菜用大豆品种花荚粒形成的初步研究

通过对24个菜用大豆品种花荚及籽粒形成的比较,认为不同熟期类型品种间发育规律存在差异。早熟品种较晚熟品种花、荚形成发育快,时间短,脱落也快。籽粒形成主要集中在三个时期:籽粒重在中后期,荚皮重在中前期,荚重在中期。中期的生殖生长是籽粒形成的基础,也是影响产量的关键。因此在江苏徐淮地区的生态条件下,鼓粒前的花荚期长短是选择菜用大豆品种生育指标的重要因素。菜用大豆鼓粒前的花荚期以20d左右为宜。