直干桉生长性状的遗传效应分析

对直干桉的树高，胸径，材积，冠幅，枝下高，弯曲度和枝径比等7个性状的一般配合力（GCA），特殊配合力（SCA），母本效应（FEM），父本效应（MAL）和特殊正反交效应（SRE）进行了分析。重点讨论了树高，胸径和材积3个性状的遗传效应。这些性状主要受SRE和MAL的控制，GCA仅对树高和枝下高有较澌上的影响。有两个亲本数量性状的GCA值高，可用于建立种子园，直干桉自交衰退非常严重，有8个组合的数量性状显著高于平均值。对直干桉进行遗传改良的最好途径是，通过杂交育种，从中再选出优异个体进行无性繁殖。培养出优良无性系后应用于生产。若要以建立种子园来改良直干桉，必须引进或引变新的育种材料才有效果。     

Analysis of diallel cross for some physical-quality traits in peanut (Arachis hypogaea L.)

The combining abilities for physical-quality traits in peanut were examined to understand the type of gene action governing these traits, and to identify peanut genotypes suitable for use as parents in breeding for quality improvement. The F₁ hybrids including reciprocals from a six-parent diallel cross along with the parents were evaluated in a randomised complete block design. Data were recorded on five quality traits in peanut viz., shelling outturn, 100-pod weight, 100-seed weight, Count and proportion of sound mature seeds. Substantial genetic variability was observed among the hybrids for the traits studied. Diallel analysis indicated that expression of majority of the quality traits is regulated predominantly by additive gene action suggesting possibility of early-generation selection, while non-additive gene action also plays an equally important role in the control of seed size. Significant reciprocal effect for all the traits denoted role of maternal parent in the expression of quality traits and importance of parental selection in quality breeding. Genotypes ICGV 86564 and TPG 41 were good combiners for seed size, while J 11 was a good combiner for improvement of shelling outturn and proportion of mature seeds. Association between general combining ability (GCA) effects and mean performance suggested that the performance per se of the genotype should be a good indicator of its ability to transmit the desirable quality attributes to its progenies. Though performance of crosses was found to be independent of parental GCA status, it is evident that at least one of the parents used in hybridisation should have large pods and seeds for obtaining better segregants.     

小麦茎秆特性的配合力与环境互作研究

随机选用7个亲本,连续3年组配成21个双列杂交组合,研究了小麦茎秆特性的配合力与环境互作。结果表明,倒一、二和基部第一、二节间长以及倒一节间茎粗的一般配合力与环境互作显著,各节间长和基部节间茎粗的特殊配合力与环境互作均显著;上部节间长与倒一、二和基部第一、二节间茎粗的遗传以加性效应为主,而基部节间长和中部茎粗环境效应作用最大,加性效应次之。一般配合力年际间具有较高的稳定程度。特殊配合力年际间的稳定程度相对较低。最后讨论了配合力的测度和茎秆特性的遗传改良。     

玉米籽粒含油量的配合力、方差成分和遗传力及其应用的研究

用11个玉米自交系（其中2个高油自交系,9个普通自交系）作完全双列杂交,产生55个正交组合,按Griffing（1956）的双列杂交设计方法2进行配合力、方差成分和遗传力的研究。结论指出：1.含油量的基因型差异显著;2.所有自交系的一般配合力效应均达到0.01的显著水平;3.特殊配合力效应只有11个组合达到显著或极显著水平;4.一般配合力效应与特殊配合力效应无关,即一般配合力高未必特殊配合力也高;5.含油量的一般配合力效应高低与自交系本身含油量的高低趋势一致,二者之间表现线性关系。一般配合力效应值Y依含油量X的直线回归方程为y=0.5X-2.4,其回归标准误为0.12;6.含油量的加性方差比显性方差重要得多,加性方差占98.5%,而显性方差只占1.5%,表明含油量有很高的遗传力。文章还对配合力和遗传力对高油玉米育种的指导意义进行了讨论。     

5个玉米自交系数量遗传分析

选用5个玉米优良自交系按双列杂交设计,对其株高、穗位高、茎粗等7个主要性状进行遗传分析.结果表明各个性状广义遗传力达到29%以上,其中穗长的遗传力最大,达到 59%;在杂种优势率方面,Suwan3×Suwan1、Suwan3×下层云优78、NS1×下层云优78、台南 17×Suwan1、台南 17×下层云优78组合较好.其中Suwan3×下层云优78、台南 17×下层云优782个组合鲜重的中亲优势率均为正值,最高迭 13.05%.其超亲优势率分别为 4.86%和 3.12%;在配合力方面,穗长一般配合力并不显著,而特殊配合力却达到极显著水平,表现出较强的非加性效应.可见,5个自交系的遗传力均达到中等及以上强度,下层云优 78、Suwan1 表现出较高的遗传力.在育种中具有一定的利用价值.     

大豆品种抗锈病遗传的研究

本研究利用4个对锈病抗性反应不同的大豆品种,配制双列杂交,并采用离体叶片人工接种鉴定F_1、F_2、B_1C_1、B_1C_2、杂种抗性的方法,研究了大豆抗锈病的遗传。研究结果表明,4个品种的抗锈性遗传基础显著不同,抗病品种PI459025的抗锈性受一个显性基因控制,耐病品种的耐病性受多基因控制,并有超显性作用存在。抗性的回交效应明显,受细胞核基因控制。抗性的一般配合力和特殊配合力均重要,抗性的广义遗传力和狭义遗传力均较高。     

Protein quality and endosperm modification of quality protein maize (Zea mays L.) under two contrasting soil nitrogen environments

Quality protein maize (QPM) breeding involves the combined use of the opaque-2 (o2) gene and the genetic modifiers of the o2 locus to develop cultivars with modified kernel endosperm, and increased concentrations of lysine and tryptophan. This study was designed to assess grain yield performance, endosperm modification, and protein quality and quantity under two contrasting soil nitrogen environments. A 15-parent diallel cross was evaluated under one low nitrogen stress and one optimal nitrogen environment each at Harare (Zimbabwe) and Bako (Ethiopia). Most QPM hybrids showed higher protein quality levels than the best non-QPM check under both conditions. Protein concentration tended to vary across nitrogen levels, but not endosperm type. Significant differences were found for the test of main effect (nitrogen-level) for endosperm modification and tryptophan concentration. This indicated that QPM maintains quality even under low soil nitrogen, a widespread condition in Africa. General combining ability (GCA) mean squares were highly significant for most protein quality traits for each environment and across environments whereas specific combining ability (SCA) mean squares were not significant in most cases. This indicated that additive gene effects were primarily responsible for variation of most traits evaluated and hence progeny performance can adequately be predicted on the basis of parental performance. Inbred lines P2, P4 and P12 had desirable GCA effects for endosperm modification while P1 and P3 had the best GCA for tryptophan concentration in grain. The current study suggests that hybrids with desirable endosperm modification, protein quality and stable performance under low nitrogen stress and optimal conditions can be produced with careful selection.     

Increased resistance to <Emphasis Type="Italic">Ustilago zeae</Emphasis> and <Emphasis Type="Italic">Fusarium verticilliodes</Emphasis> in maize inbred lines bred for <Emphasis Type="Italic">Fusarium graminearum</Emphasis> resistance

Preliminary field observations in our maize breeding nurseries indicated that breeding for improved resistance to gibberella ear rot (Fusarium graminearum) in maize may indirectly select for resistance to another ear disease, common smut (Ustilago zeae). To investigate this, we compared the disease severity ratings obtained on 189 maize inbreds, eight of which included our inbreds developed with selection for gibberella ear rot resistance after field inoculation and breeding for 8–10 years. No correlation was found between disease severities for the 189 inbreds but the eight gibberella-resistant lines were consistently more resistant to smut. To further examine this relationship and to determine if these eight inbreds would be useful for developing inbreds with either common smut or fusarium ear rot (F. verticilliodes) resistance, we conducted a Griffing’s diallel analysis on six inbreds of maize, four with high levels of gibberella ear rot resistance representing all of the pedigree groups in our eight gibberella lines, and two with very low levels. Our most gibberella ear rot resistant inbreds, CO433 and CO441, had the lowest disease ratings for all three diseases, the consistently largest general combining ability effects and several significant specific combining ability effects. It was concluded that some inbreds bred specifically for gibberella ear rot would also be useful in breeding for resistance to common smut and fusarium ear rot.     

小麦冠层叶片性状配合力与环境互作分析

为了研究小麦冠层叶片性状的配合力与环境互作．随机选用7个亲本．连续3年组配成21个双列杂交组合进行试验。结果表明．旗叶的开张角、长、宽、叶鞘长和倒二叶的宽、叶鞘长的一般配合力与环境互作显著,冠层各叶片性状的特殊配合力与环境互作均显著;各叶角性状和旗叶鞘长以加性效应为主;叶长和倒二叶鞘长环境效应作用最大．加性效应次之;叶宽环境效应作用最大。各性状的一般配合力都具有较高的稳定程度．而特殊配合力的稳定程度相对较低。最后讨论了配合力的测度和冠层叶片性状遗传改良的亲本选配与后代选择的原则。     

小麦叶片水分利用效率生理性状遗传相关分析

为了明确小麦叶片水分利用效率与相关生理性状的遗传相关关系，为小麦水分利用效率遗传育种提供信息，本实验选用了4个抗旱和高产小麦品种，组成4×4完全双列杂交试验。通过对亲本和杂交后代的表型相关和遗传相关分析结果表明，在小麦灌浆早、中、晚期，叶片水分利用效率（WUE）和光合速率(Pn)与呈显著或极显著正相关；与胞间CO2浓度（Ci）和蒸腾速率（Tr）成负相关，且达到极显著水平；与叶温（Tl）呈负相关，且在灌浆后期达到极显著负相关；与气孔导度（Cond）呈现二次曲线的趋势。说明叶片WUE和相关性状间在灌浆期间有很好的遗传相关关系，可以在小麦WUE生理遗传育种中进行应用。