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11.
红三叶再生草的生物学特性研究 总被引:15,自引:2,他引:15
对红三叶再生草的生物学特性进行了研究,发现随着刈割次数的增加,该牧草再生草达到相同生育期时的时间、株高、单株重和产草量等都有按一定规律逐渐减少或降低的趋势,作者拟把这种特性称之为“相同生育期再生草生长的序时递减规律”。 相似文献
12.
移栽密度对白三叶密度和生物量的影响 总被引:1,自引:0,他引:1
通过研究移栽密度对白三叶(Trifolium repens)密度和生物量的影响,筛选出适宜的移栽密度,为我国生态畜牧业饲粮生产提供基础依据。试验设置6组移栽密度,分别为16株·m-2、25株·m-2、36株·m-2、49株·m-2、64株·m-2和81株·m-2,进行6期处理分别记为D1,D2,D3,D4,D5,D6,测定其密度和生物量。结果表明:前期移栽密度对白三叶的生物鲜重、生物干重均有极显著影响(P<0.01),随密度增加而增加,但增加幅度随刈割次数增加而减小;中期生物鲜重、干重基本无显著差异,其中以49株·m-2的产量最高;第6次刈割时,密度对白三叶生物鲜重、干重有显著影响(P<0.05),但此时鲜重、干重产量最高的均是49株·m-2;白三叶生物总产量随移栽密度增加而增加,增加幅度先增大后降低,在49株·m-2时达到最大。因此,49株·m-2为白三叶最适宜的移栽密度。 相似文献
13.
14.
L.G. Lapchic A.J. Clark G.P. Lomonossoff M. Shanks 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(4):409-412
The relationship between red clover mottle virus (RCMV) isolated in the Ukraine (designated RCMV-Uk) and well-characterised strains from Sweden has been investigated. Nucleic acid hybridisation indicate that both RNAs from RCMV-Uk are highly homologous to their counterparts from RCMV strain S, a conclusion supported by protein sequence analysis of the two viral capsid proteins. Nucleic acid sequence analysis of a portion of RCMV-Uk RNA2 confirmed the high degree of similarity between RCMV-Uk and RCMV strain S. This information suggests that RCMV-Uk should be considered an isolate of RCMV strain S. 相似文献
15.
16.
Summary A collection of subterranean clover lines singled out from populations of the species Trifolium brachycalycinum and T. subterraneum collected in Sicily, Italy, was examined at two localities for flowering time and at one locality for oestrogen content and seed yield. The structure and variation of the populations of the two species were compared. The relationship between flowering time of the populations and some environmental features of their collection sites was examined to assess whether the maturity requirements of the two species were similar and to frame selection models focused on developing varieties of appropriate maturity. Populations of T. subterraneum were, on average, more complex than those of T. brachycalycinum, being characterized by higher number of lines per population and greater intra-population variation for flowering time, oestrogen content and seed yield. Furthermore, populations of T. subterraneum were, on average, about 15 days earlier than sympatric populations of T. brachycalycinum. Both the greater variation and the relative earliness of T. subterraneum occurred irrespective of the environments of origin of the populations. Inferences are drawn on the adaptive advantages that such features confer to T. subterraneum. Mean flowering time of the populations increased on increasing annual rainfall and altitude of the collection sites. However, the changes in maturity appeared almost exclusively related to variations in rainfall in T. subterraneum, while in T. brachycalycinum the effect of altitude was greater and that of rainfall less marked than in the former species. 相似文献
17.
Paolo Annicchiarico 《Euphytica》1993,71(1-2):131-141
Summary A set of Ladino white clover ecotypes including the last available landraces and some natural populations collected from old permanent meadows, together with some white clover varieties of various origins, were evaluated as monocultures for dry matter (DM) and seed yield assessed in separate field experiments. Other agronomic traits were also recorded. The best performing variety, Espanso, was significantly outyielded by some ecotypes for DM and seed production. Compared to landraces, natural populations yielded on average far less seed but as much DM and tended towards higher persistence indicating that domestication of the native Ladino at the farm level only improved seed yield of the crop. Natural populations showed, besides lower values of most seed yield components, a distinct canopy architecture characterized by smaller leaves, longer internodes and denser stolons. Seed weight proved the best character discriminating between the two ecotype groups. Significant variation for most traits was found both among landraces, in which it was mostly relatable to differences among provenances, and among natural populations. The relations between the main multivariate patterns of phenotypic variation and a set of environment collecting variables suggested that evolutive adaptation to different agronomic practices was a major determinant of the overall variation found in landraces. Evidence is provided that a relevant part of the variation observed among ecotypes for some important traits could be genetic.Abbreviations DM
dry matter
- DMY
dry matter yield
- NRH
number of ripe heads
- NFH
number of florets per head
- PL
petiole length
- LS
leaf size
- IL
internode length
- NS
number of stolons
- PRO
protein content
- SY
seed yield
- TSW
thousand seed weight
- NSF
number of seeds per floret
- PCA
principal components analysis
- PC
principal component 相似文献
18.
J. Hill 《Plant Breeding》1993,110(3):212-219
Analysis of a half diallel cross among four white clover cultivars, grown as monocultures and in mixtures (duocultures) with two separate perennial rye-grass cultivars, confirmed that for stolon and leaf number a higher proportion of the genetic variance in duocultures was non-additive. For canopy height and dry weight, however, this proportion was less affected by inter-specific competition. An additive-dominance model of gene action sufficed for all four characters in monocultures, but in duocultures epis-tasis was just one of the factors complicating the genetic picture. This, coupled with short-term reversals in the direction of dominance, merely illustrates the complexity of breeding white clover cultivars. Possible future developments in the breeding of white clover are discussed in the light of these results. 相似文献
19.
白三叶(Trifolium repens L.)作为优良牧草和地被植物具有重要的应用价值。但其耐盐碱、干旱能力差等原因致使应用受到广泛限制,转基因技术的快速发展为白三叶种质创新提供了有效技术手段,为开展白三叶分子育种奠定了基础。本文就近30年来有关白三叶组织培养、转化方法、转基因遗传改良方面的研究进展进行了综述,并对其应用进行了展望。 相似文献
20.
Red clover (Trifolium pratense L.) is one of the main forage species of temperate regions. Cultivars of red clover are heterogeneous which makes their genetic
analysis difficult. We applied RAPDs (Random Amplifed Polymorphic DNA) in order to assess the genetic relationship and levels
of genetic variability existing among a group of 16 elite red clover parents organised in four subsets of 4 parents each.
Out of 55 primers 21 provided reproducible results. A total of 135 reliable and polymorphic RAPD bands were detected which
were used to estimate genetic distances among pair-wise combinations of elite parents. Nei and Li's similarity values ranged
from 0.60 to 0.77, with a mean of 0.66, which reflects a rather high genetic variability among the genotypes evaluated. Lower
levels of genetic variability, as detected by polymorphic loci and mean heterogeneity values, were detected in a subset of
parents selected for resistance to the stem nematode. Cluster analyses resolved the different sets of parents in a manner
consistent with what is known from their breeding origins. An Analysis of Molecular Variance detected substantial levels of
variation within subsets of parents. RAPDs represent a valuable source of genetic information for red clover breeding programmes.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献