Evaluation of Heterosis in Cultivated Barley Varieties

大麦品种间杂交的障碍主要有：杂交脆性、杂交弱性和杂交致死性等。因此，在本研究中，大麦杂种优势试验是在较窄的杂交范围内进行的。本研究共进行了七种实验。(1)东亚六棱大麦品种配合力的研究；(2)二棱大麦品种的杂种优势；(3)大麦双列杂交配合力的评价；(4)野生大麦与天然大麦之间f_1 -杂种茎长杂种优势的表达；(5)栽培二棱大麦f_1 -杂种茎长杂种优势的研究；(7)两种不同种植密度下杂种优势效应的比较研究。试验(1)、(2)、(4)、(5)采用顶交制，分别以1个或2个品种为供体亲本。本研究中，f_1杂交品种在较窄的杂交范围内，如六行型、二行型和uzu型或半短穗型，分别获得了较高的生产性能杂种优势。然而，在远处收集的品种间，f_1杂种的杂种优势有较大表达的趋势。f_1杂交植株茎长普遍有伸长的趋势。因此，本研究对短茎显性基因或短茎显性基因进行了搜索，但在150个或更多的杂交中，没有发现一个短茎显性基因。10个品种的双列分析表明，在产量和大部分产量组成性状上存在显著的加性和显性效应，部分杂交组合表现出一般配合力或特定配合力。此外，f_1杂交植株和品种的生长分析结果表明，植株的主要生长指标或总干重、相对生长速率、净同化速率和叶面积比与最终籽粒产量的关系不显著。少

It has been known that there are several barriers to hybridization between barley varieties: hybrid brittleness, hybrid weakness and hybrid lethal etc. In this study, therefore, experiments on heterosis in barley was made within the limit of rather narrow crossing. Seven kinds of experiments are carried out in this study. (1) Studies on combining ability between six-rowed barley varieties originated in East Asia, (2) heterosis in two-rowed barley varieties, (3) evaluation of combining ability by means of diallel crosses in barley, (4) expression of heterosis in stem length of F_1-hybrids between wild barley, Hordeum spontaneum, (5) heterosis in stem length of F_1-hybrids in cultivated two-rowed barley, (6) relation between heterosis in mature and juvenile plants and (7) comparative investigation of heterosis effect under two different planting densities. In the Experiments(1), (2), (4) and (5), top cross system was used in which one or two varieties were taken as the donor parents, res … More pectively.In present study, high heterosis for yielding performance was obtained in F_1-hybrids within comparatively narrow range of crossing such as six-row type, two-row type and also uzu or semi-brachytic type, respectively. However, there were some tendencies to become larger expression of heterosis in F_1-hybrid between varieties collected from further distant. F_1-hybrid plants generally tended to elongate in stem length too much. So, dominant gene or genes for short stem were searched in this study, but no one dominant gene for short stem was found so far as 150 or more crosses were tested. Diallel analysis using 10 varieties showed significantly additive and dominant effects in yield and most of yield component characters, and some of cross combinations represented general or specific combining ability. Furthermore, results of growth analysis, made by F_1-hybrid plants and varieties, showed that major indications of growth or total dry weight, relative growth rate, net assimilation rate and leaf area ratio, have had non-significant relation with final grain yield of the plants. Less