A testcross procedure for selecting exotic strains to improve pure-line cultivars in predominantly self-fertilizing species

Methods for identifying germplasm carrying alleles with the potential to improve a particular single-cross hybrid have been proposed and discussed in recent years. There is a need for similar methods to be used in breeding crops for which pure-line cultivars, rather than hybrids, are the goal. The objective of this research was to develop a method to identify germplasm lines with the potential to contribute favorable alleles not present in a specified pure line or set of pure lines. Given a set of adapted pure lines (A ₁, A ₂ ..., A _m) to be improved and a set of germplasm lines (P ₁ P ₂ ..., P _f), the procedure consists of producing all f x m possible hybrids and evaluating them along with the parents. The testcross statistic T _ij is defined by T _ij=(F _ij–A _j)+(1–) (F _ij–P _i), where A _j, P _i, and F _ij represent the performance of thej ^th adapted line, the i ^th germplasm line, and their hybrid, respectively. The statistic is the mean value of T _ij over all adapted parents A _j. If =(1/2)(1+d), where d = the mean degree of dominance, then T _ij measures the potential for alleles from P _i to improve A _j and measures the potential for alleles from P _i to improve the set A ₁, A ₂ ..., A _m. Use of data on soybean and peanut hybrids published by other researchers suggests that the value assumed for d has little effect on the P _i chosen. The ability of the T _ij and statistics to identify germplasm strains carrying rare favorable alleles should be assessed in empirical studies.Joint contribution: OARDC (Journal Articale No. 161-94), USDAARS, Iowa Agriculture and Home Economics Expriment Station (Journal Paper No. J-16109; Project 2985), and Agreculture and Agri-Food Canada. Salaries and research support for S. K. St. Martin Provided by state and federal funds appropriated to the Ohio Agricultural Research and Development Center, Ohio State University     

Long term lily scale bulblet storage: effects of temperature and storage in polyethylene bags

Collections of lily genotypes are usually maintained by yearly planting, harvesting and storage of the bulbs. To facilitate this maintenance, a storage method has been developed for a collection of lily genotypes, including Asiatic hybrids, Oriental hybrids, Lilium longiflorum and L. henryi. Scale bulblets were stored either dry, sealed air-tight in polyethylene bags, or in moist vermiculite in open polyethylene bags for a period of 2 yr. The decrease in mass, sprouting proportion and ion leakage or sprouting proportion alone were determined for treatments carried out at -2°C, °C and 17°C. Sealing scale bulblets in polyethylene bags at -2°C resulted in the smallest decrease in mass, the least ion leakage and the highest sprouting proportion after 2 yr of storage.     

畜禽遗传资源系统保存的理论与模拟实验研究──I．畜禽遗传资源系统保存的理论分析

本文提出了畜禽遗传资源系统保存的概念、基本思想及其群体遗传结构变化的数学模型。该理论是将一定时空内某一畜种所拥有的全部基因作为保存对象,既将活体保存作为基本方法,又将其有机地与高新生物技术结合在一起;既追求系统地保存控制畜种特性的基因资源,又可达到保存地方品种的目的。在假定无世代重叠,群体内存在选择、突变、迁移,且考虑漂变效应的情况下,本文所构建的两个数学模型可分别用来描述一个座位上多个主基因频率或数量性状群体均数的动态变化。     

绞股蓝的林下栽培

近年来由于绞股蓝的过度采收,野生资源面临枯竭危险,为了扩大绞股蓝植物的资源,人工栽培势在必行。１９９０－１９９３年在皖东琅琊山进行林下人工栽培试验,结果表明,在粗放管理的条件下,林下种植绞股蓝是可行的,选择适合的种源及林分郁闭度是关键因子,在刺槐林下栽培产量可到３３００ｋｇ／ｈｍ＾２。     

江苏野菜资源的利用与开发

江苏野菜资源丰富,共计１９２种,隶属４４科１０８属,其中蕨类植物７科１５属５１种,种子植物３７科９３属１４１种。江苏野菜利用历史悠久,近年已发展成为规模种植,产生良好的经济效益和社会效益。     

植物资源与化学数据库系统（DPRC）的功能与应用

由中国科学院昆植物研究所和云南省机械研究设计院的植物资源化学数据库系统是一个将植物资源,植物化学成分及化学结构的多种信息、数据和图象融为一体的、开和式多功能软件系统、,包括植资源检索系统、植物化学成分检索系统及天然产物化学结构检索系统等三个子系统。     

根瘤菌资源数据库（RRDB）的建立

在总结我室多年对根瘤菌资源调查与分类研究的基础上,建立了根瘤菌资源数据库（ＲＲＤＢ）。此库依据根瘤菌研究特点而设计,包括：基本信息、采集信息、保藏信息、回接信息、参考文献、性状信息、菌株说明等七个子库。目前收录了来自国内２１个省或地区及国外部分研究单位提供的;并经全面性状分析与分类研究的２８６个菌株的信息,每个菌株设有寄主来源、固氮酶活性、碳源、氮源的利用等３２１个数据项。该库具有数据维护、查询检索、数据统计、输出打印等功能,引入并连接了聚类分析软件包－ＭＩＮＴＳ系统,可以满足当前研究的需要。     

Implications of the variance effective population size on the genetic conservation of monoecious species

The concept of variance effective population size [Ne_(v)] and other expressions are reviewed and described for specific sampling steps in germplasm collection and regeneration of monoecious species. Special attention is given to procedures for computing the variance of the number of contributed gametes [V(k)] to the next generation. Drift, as it occurs between generations, was considered to contain a component due to the sampling of parents and a subsequent component due to the sampling of gametes. This demonstrates that drift, caused by reduction of seed viability, damages the genetic integrity of accessions stored in germplasm banks. The study shows how mating designs, such as plant-to-plant or chain crossings with additional female gametic control, can partially alleviate this problem. Optimal procedures for increasing Ne_(v) when collecting germplasm in the field are also discussed. The effect of different female and male gametic control strategies on Ne_(v) is considered under several situations. Practical examples illustrating the use of V(k) and Ne_(v) expressions are given.     

Introgressions fromLycopersicon pennellii can improve the soluble-solids yield of tomato hybrids

RFLP-defined chromosome segments covering the entire tomato genome were introgressed from the wild green-fruited speciesLycopersicon pennellii into the cultivated tomato (L. esculentum cv M82; Eshed et al. 1992). SixL. pennellii chromosome segments were selected for a detailed evaluation based on previous observations of their effects on the two yield components, fresh tomato yield and total soluble-solids content (Brix). Differences in the quantitative traits measured between M82 and the introgression lines, or their hybrids with different inbred parents, can be attributed to the alien chromosome segments. Replicated field trials, grown at wide and dense spacing, identified three quantitative trait loci (QTLs) for solublesolids content on chromosomes 1, 5 and 7. In plants heterozygous for the chromosome-5 locus there was a 50% increase in soluble-solids yield in wide but not in dense spacing. Plants heterozygous for the chromosome-1 QTL/s were tested over a 2-year period, in three genetic backgrounds, and showed a significant 16% elevation in soluble-solids yield only in dense spacing. These results demonstrate that wild tomato germplasm can be used to improve the yield of the cultivated crop.