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1.
Summary Several thousand apple and pear seedlings of many progenies were studied in connection with their juvenile period (J.P.). The initially significant inverse relation between the vigour (stem diameter) and the J.P. of the seedlings became insignificant as the trees grew older, due to a retardation of growth occurring when the seedlings become generative. This relation can be used effectively in pre-selecting for vigour in the nursery. Cumulative yields were higher when the J.P. was shorter, but there was no evident link between the J.P. and annual yield in full bearing, that is to say, precocity and preductivity are not directly connected. Better growing conditions and pre-selection have shortened the mean progeny J.P. of either crop by three years since the 1950's. Generally, the pear seedlings appear to grow faster, to become generative slower and to yield lower than comparable apple seedlings. The mean J.P. of apple and pear progenies averaged 4.2 and 6.0 years respectively. The difference between apple and pear may be attributable to a greater selection pressure on both precocity and productivity with apple than with pear.This possibly also led to a smaller tree in the productive phase on the assumption that tree size at first flowering-small at a short, large at a long J.P.-expresses reproductive efficiency and as such is reflected in the size of the adult tree.Also presented at the Juvenility Symposium held at West-Berlin, November 1976. 相似文献
2.
Precocity and productivity of propagated apple and pear seedlings as dependent on the juvenile period 总被引：1，自引：0，他引：1
Summary Adult apple and pear seedlings varying in juvenile period were propagated on rootstocks. They were subsequently found to be more precocious and more productive when the juvenile period had been shorter. In view of the significant relation between vigour measured by stem diameter) and precocity of both seedlings and propagated trees, it is possible to pre-select for the potentially more precocious seedlings on the basis of vigour.Samenvatting
De vruchtbaarheid van vegetatief vermeerderde appel- en peerzaailingen in verband met hun jeugdperiode
Reeds vruchtdragende appel- en perezaailingen, waarvan de voormalige jeugdperiode sterk varieerde, werden op onderstam geoculeerd. Het bleek dat de bomen gemiddeld vroeger vruchtbaar en productiever waren naarmate de voormalige jeugdperiode korter was geweest.De al eerder geconstateerde relatie tussen groeikracht en jeugdperiode (kortere jeugdperiode naarmate de bommen dikker zijn), bleek ook na vermeerdering te bestaan, d.w.z. de dikkere bomen bloeiden eerder dan de dunnere. Daar deze samenhang erfelijk bepaald is, biedt dit de mogelijkheid om de potentieel vroeg-vruchtbare zaailingen reeds in het kwekerijstadium op basis van groeikracht te selecteren. 相似文献
3.
T. Visser 《Euphytica》1970,19(3):293-302
Summary The stem diameter of apple seedlings, either measured in the nursery or later, is associated with both the duration of the juvenile period (the thicker, the shorter) and initial productivity (the thicker, the higher) of the seedlings. The relation between vigour and juvenile period, or precocity in general, is probably largely inherent, and thus remains valid for the propagated clone.No significant relation existed between stem diameter and size or season of ripening of the fruits, nor between the latter two characteristics and the duration of the juvenile period. The stem diameter is therefore an effective parameter of selection for fertility alone during the nursery stage. Provided growth conditions are uniform, selection for vigour may enhance breeding efficiency in three ways:- it shortens the first screening period of seedlings on their own roots in the orchard;- it shortens the second screening period of the seedlings selected and propagated after the first period;- it improves the chances of finding precocious varieties.Samenvatting
Het verband tussen groei, jeugdperiode en vruchtdracht van appelzaailingen en zijn gebruik om de veredelingsefficiëntie te verbeteren
De lange duur van de jeugdperiode (tijd in jaren tussen zaadkieming en eerste bloei) bij fruitgewassen, zoals appel, vormt een belangrijke hinderpaal voor de veredeling. Verkorting van deze periode verhoogt de doelmatigheid. Eén van de middelen hiertoe is het toepassen van voorselectie in de kwekerij op basis van groeikracht. Het is nl. gebleken, dat de stamdiameter, gemeten na twee of meer groeiseizoenen, in sterke mate gecorreleerd is met de duur van de jeugdperiode; d.w.z. de dikkere zaailingen blijken gemiddeld eerder te bloeien en beter te dragen dan de dunnere. De relatie is goeddeels erfelijk bepaald en handhaaft zich na vermeerdering op onderstam. Selectie van de dikste zaailingen verkort dus de omlooptijd van een nakomelingschap. Een zodanige selectie blijkt geen nadelige invloed te hebben op de grootte of rijptijd van de vruchten, maar biedt wel het extra voordeel dat de kansen op het vinden van vruchtbare rassen worden vergroot. 相似文献
4.
T. Visser 《Euphytica》1965,14(2):125-134
The following observations were made on the inheritance of the juvenile period (elapsing between seed germination and first flowering) of apple seedlings.
- 1.Highly significant correlations (0.52 and 0.78 at n=382 and 71) were found between the length of the juvenile period and the degree to which seedlings or progenies as a whole show juvenile symptoms. This relation may provide a basis for the early elimination of seedlings with a relatively long juvenile period (and which are possibly late-bearing). 相似文献
5.
The length of the juvenile period was found to be associated with the degree of juvenility (degree to which seedlings show juvenile symptoms) and with the time leaf buds break in spring. The time of bud break was also related to time of flowering; bud break and juvenility were not interrelated. The observations suggest that preselection on the basis of a low degree of juvenility and early bud break together would substantially increase the proportion of early-bearing and, to a smaller extent, that of early-flowering seedlings in the selected material. The shift towards earlier flowering was not accompanied by an advance of the date at which flowering ended, at least when the selection limit is based on the progeny mean. The degree of leaf fall (colour) during autumn appeared to be closely related to the time the fruits become picking ripe; no significant relation existed between this parameter and juvenility or bud break. The degree or time of leaf fall (colour) is a possible pre-selection criterion of the time of picking. 相似文献
6.
泥鳅早期形态发育研究 总被引：1，自引：0，他引：1
【目的】为了解泥鳅仔、稚鱼生长发育规律,同时为规模化苗种培育工作提供基础数据。【方法】通过对0~23日龄的泥鳅仔稚鱼连续取样,系统观察了泥鳅仔稚鱼各发育分期的形态特征和发育时间。【结果】研究结果表明,在水温(19.5~22)℃下,泥鳅胚胎发育时间需要24~28 h。初孵仔鱼平均体长为3.04 mm,鱼体透明,全身无黑色素,口和消化管均未形成;初孵仔鱼至孵化后6日龄为卵黄囊期仔鱼,4日龄仔鱼开口,仔鱼进入混合营养期;7~9日龄为前弯曲期仔鱼,7日龄仔鱼卵黄囊吸收完毕,此时完全进入外源营养期;10~14日龄为弯曲期仔鱼;15~22日龄为后弯曲期仔鱼;至23日龄,出现细小圆鳞,已与成鱼具有相似的外观和生活习性,此时进入稚鱼期。【结论】研究泥鳅早期形态发育将为泥鳅自然资源繁殖保护和养殖业苗种培育提供理论依据。 相似文献
7.
Summary The vase-life in tulip (Tulipa L.) is an important character. Research was done on the possibilities of selecting for keeping quality. It was found that the keeping quality of undetached flowers was strongly correlated with the keeping quality of cut flowers at 17°C in a glasshouse. The period from flowering date till 50% discoloration appeared to be highly correlated with days to perianth drop. For practical reasons the latter trait has preference in selection work. The number of days to discoloration is also an effective selection criterion. Flower longevity in the field in April/May and in the glasshouse were significantly correlated; thus, already in the field a first selection on keeping quality can be carried out. The increase in height for flowering (adult) and non-flowering (juvenile) plants during forcing did not appear to be significantly correlated with flower longevity, so preselection on this character is not promising. Flower longevity was positively correlated with forcing period. This poses some problems in selection, as a long forcing period is considered an undesirable character. The daily water uptake of cut flowers was significantly correlated with flower longevity. 相似文献
8.
R. Blaak 《Euphytica》1972,21(1):22-26
Summary Precocity in the oil palm (Elaeis guineensis Jacq.) is defined, for the purpose of this study, as the percentage of palms bearing female or hermaphrodite inflorescences 36 months after germination. A method of calculating breeding values for precocity is described and it is shown that the character is predictable. An upper limit for heritability (h2) of 0.68 and a correlation between observed and predicted values of r=+0.77 (significant at P=0.01) have been calculated from the available data. The available information suggests that precocity could easily be adjusted to the desired level by breeding and selection. 相似文献
9.
养殖与野生大刺鳅不同生长阶段肌肉脂肪酸组成的比较研究 总被引：1，自引：1，他引：0
为比较人工养殖大刺鳅与野生大刺鳅肌肉脂肪酸组成的差异,采用气相色谱分析法对养殖和野生大刺鳅幼鱼、鱼种、成鱼肌肉脂肪酸组成及其相对含量进行了检测与分析。结果表明,养殖和野生大刺鳅肌肉中共检出24种脂肪酸,其中不饱和脂肪酸含量较均最高,平均含量分别达到(65.63±1.88)%和(59.03±2.11)%,特别是含有丰富的C18:2、二十二碳六烯酸、二十碳五烯酸和 ,花生四烯酸等多不饱和脂肪酸;ΣUFA/ΣSFA比值从幼鱼到成鱼阶段显上升趋势,且养殖大刺鳅(2.45±0.21)高于野生大刺鳅(1.98±0.15);养殖大刺鳅成鱼阶段的P/S比值达到1.0,超过一般的淡水鱼类。综合分析表明,养殖大刺鳅肌肉品质在脂肪酸组成及均衡性略优于野生大刺鳅,但差异不明显。 相似文献
10.
梨杂交后代童期和童程的研究 总被引：1，自引：0，他引：1
以八个梨杂交组合后代492株实生树为试材,调查了其童程、始花节位数、节间长度和树干直径,探讨了童期和童程以及二者的关系。结果表明：在调查所有杂交组合中,有68.7%的杂种实生后代童期为3-5年,平均童程为214.26cm;节间长度与童程存在正相关性,始花节位数和干径都与童程存在极显著的正相关;童期与童程存在极显著的正相关,表明矮化的植株具有早结果的潜力。 相似文献
11.
Summary Eight controlled crosses were made between seven different sweet-kerneled almond cultivars (Prunus dulcis [Mill.] D. A. Webb), and five crosses were made between sweet x highly floriferous bitter almond clones. Sweet x bitter progenies out-yielded the sweet x sweet matings by more than three to one in the first year of production. This was attributable to greater cropping efficiency rather than to tree size or precocity. There was no pleiotropic association or association due to linkage between bitterness and yield. The selected Alnem (bitter) clones appear to be potentially useful progenitors for increasing almond yield capacity by conventional breeding methodology. 相似文献
12.
The transition time from the juvenile phase to the adult phase differs in soybean cultivars ‘Enrei’ and ‘Peking’ 
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下载免费PDF全文 Suguru Ozawa Katsunori Hatakeyama Yoshihito Takahata Shuji Yokoi 《Plant Breeding》2017,136(3):386-392
Plants develop juvenile phase to adult phase in vegetative stage. Although soybean is a very important crop worldwide, there has been only one study of the juvenile–adult phase change. In this study, we determined that the juvenile–adult phase change occurred at different stages in two soybean cultivars that differ in their photosensitivity. Cultivar ‘Enrei’ (E1e2e3E4) is weakly photosensitive and cultivar ‘Peking’ (E1E2E3E4) is strongly photosensitive. In ‘Enrei’, the leaf size gradually increased at a constant leaf position regardless of the difference in day length. In ‘Peking’ plants transferred to short‐day conditions at several leaf development stages, leaf size gradually increased at different leaf positions. Expression of miR156 by ‘Enrei’ transferred to short‐day conditions had nearly the same pattern as that of ‘Enrei’ grown under long‐day conditions. In ‘Peking’, the expression of miR156 had different patterns in younger leaves of plants subjected to either a short‐day treatment or long‐day conditions. These results indicate that the E2 and E3 loci that regulate photosensitivity also regulate the expression of miR156 and the juvenile–adult phase change in soybean. 相似文献
13.
M. Guadalupe Arenas‐Corraliza M. Lourdes Lpez‐Díaz Víctor Rolo Gerardo Moreno 《Journal of Agronomy and Crop Science》2021,207(1):100-119
Agroforestry systems are reported as climate‐resilient productive systems, but it is yet unclear how tree shade affects crops performance. The aim of this work was to assess how the phenology, plant traits and grain yield of wheat and barley were affected by shade. In an open greenhouse experiment, we cultivated in pots nine cultivars differing in precocity for each species and imposed three artificial shading levels (S0 ~ 0%, S1 ~ 25%, S2 ~ 50%) at the start of cereal booting. Our results showed that shade speeded up first growth stages in both species, until the starting of milk development. Barley showed consistent phenological responses to the three irradiance levels among cultivars, but not wheat that showed larger phenological differences among cultivars at moderate shade. Deep shade prolonged the time needed for wheat grain ripening. Both species increased grain yield by 15%–20% with shade, driven by shade‐acclimations of plant traits that differed among species. For wheat, grain yield was determined by the assemblage of traits that contribute to yield, such as grain weight, precocity and non‐photochemical quenching, while, for barley, SPAD value, precocity to reach phenological stages, grains per spike and plant height had the strongest influence. These traits varied widely among cultivars and seem of interest to identify best suited cultivars for shading conditions of Mediterranean agroforestry systems. 相似文献
14.
It was investigated whether and to what extent the duration of the juvenile phase of pear and apple seedlings is related to their vegetative growth. The juvenile phase was defined as the period in years that the seedling remains vegetative; the trunk diameter served as a measure of vegetative vigour. The following observations were made:
-
1)
A significant negative correlation exists between the duration of the juvenile phase and the vigour of the seedling (as measured by trunk diameter).
-
2)
Environmental conditions with respect to weather, soil and cultural practices which promote or restrict growth, tend to shorten or lengthen the juvenile phase accordingly by their influence on the time required for the attainment of a certain minimum size which at least partly determines the attainment of the flowering condition.
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3)
The weak rootstock M. IX significantly accelerated the onset of flowering of apple seedlings by about 1 1/2 years; this rootstock appears to combine a retarding effect on growth with a specific influence on flowering.
15.
S. H. Hjeltnes 《Euphytica》1994,77(1-2):55-58
Summary In the Norwegian pear breeding programme selection is based on evaluation of 20 fruit samples together with field observations
of precocity, productivity and resistance to biotic and abiotic factors. Fruit weight is recorded in grams, and then transformed
to a scale of 20 gram classes. Appearance, shelf life and flavour are recorded on a 0 to 9 scale, and observations of shelf
life and flavour are made at 4 defined intervals following ripening at 20 °C. The final index is made by summarizing the scores
of fruit size and appearance, mean score of internal breakdown, mean score of flavour, maximum score of flavour and scores
of precocity, productivity and resistance. All parameters, except mean flavour, are given a weighting of one, mean fruit flavour
is given a weighting of 2. Data for 160 seedlings evaluated in 1992 is presented. 相似文献
16.
Dionysia A. Fasoula 《Euphytica》1990,50(1):57-62
Summary This study was undertaken to explore the relation between auto-, allo- and nil-competition using a long established pure line cultivar of bread wheat, where genes controlling yielding and competing ability co-exist and co-interact. The investigation lasted three growing periods, the first two with trials grown at nilcompetition (100 cm), and the third with trials grown at the three conditions of competition. In the first growing period, divergent single plant honeycomb selection for high and low yield was applied in the cultivar Siete Cerros, to continue in the second growing period with divergent line honeycomb selection. In the third growing period, top and bottom lines selected under nil-competition were compared with the mother variety Siete Cerros under auto-, allo- and nil-competition.Correlation coefficient estimates between auto-, allo- and nil-competition demonstrated that auto-competition and nil-competition are correlated positively interse and negatively with allo-competition. In general, the results suggest that yielding and competing ability are correlated negatively.The implications of the findings are discussed in relation to the possibility of (1) selecting for heritable high yield on a single plant basis, (2) avoiding biased results due to interplot competition, (3) substituting cultivar degeneration for cultivar improvement. 相似文献
17.
《Netherlands Journal of Sea Research》1991,27(3-4):423-432
Analyses of the 1985 to 1989 juvenile flatfish survey data from the Grand Bank off the east coast of Newfoundland has delimited two major areas of juvenile American plaice, Hippoglossoides platessoides, concentrations: one on the northern slope and one on the southern edge of the bank. A major concentration of juvenile yellowtail flounder, Limanda ferruginea, was distributed in the area of the Southeast Shoal on the southern Grand Bank. Juveniles of both species shared their distribution with their adult population and there was some overlap by juveniles of both species on the southern Grand Bank. These areas of concentrations are hypothesized to be oceanic nursery sites for both Grand Bank species.The northern plaice nursery area is fished heavily by the Canadian otter-trawler fleet because the majority of the adult population is located in this area. The southern nursery area for plaice is fished heavily by many otter-trawl fleets of other nations since it is located outside of Canada's 200-mile fishing boundary. The southern nursery area for juvenile yellowtail flounder straddles the 200-mile boundary and, consequently, is fished heavily by Canadian (inside) and non-Canadian (outside) fleets. The implications of these dual fisheries on the southern Grand Bank is discussed in terms of discarding of under-sized fish by the Canadian fleet inside the 200-mile boundary and the directed effort on juveniles outside the boundary. 相似文献
18.
旨为查找建鲤(Cyprinus carpio var.jian)胰岛素样生长因子结合蛋白1(Insulin-like growth factor binding pro-teins 1,IGFBP1)基因上与增重相关的SNP位点。利用基因克隆,Clustal W比较8个个体的DNA序列,筛选SNP位点。并采用PCR-RFLP方法检测了其中2个位点(1b-E1-A210G,1b-E3-C108T)在913尾建鲤(♂469,♀444)中的基因型分布。成功分离得到了建鲤IGFBP1的2条DNA序列,并在1a、1b上分别找到7个和24个SNPs位点,其中,1a外显子上有2个,1b外显子上有4个。检测的2个位点与增重的相关性分析表明:2位点均与雄鱼增重呈极显著相关(P<0.01),其中,增重快的基因型在鱼种阶段分别为GG型和CC型,在成鱼阶段分别为AG型和CC型。与雌鱼鱼种阶段增重相关的位点为A210G,其AG型增重极显著快于AA型(P<0.01),与雌鱼成鱼阶段增重相关的位点为C108T,其CC型、CT型增重极显著快于TT型(P<0.01)。对组合成的9种双倍型与增重的相关性分析表明:雌雄鱼中双倍型D4、D5、D7个体生长显著(P<0.05)或极显著(P<0.01)快于双倍型D6、D9个体,D4、D5、D7双倍型个体在整个样品中占60%,还存在改良空间。试验检测的2个位点A210G、C108T可作为建鲤增重相关的分子标记应用于育种实践。 相似文献
19.
20.
Carlos A. Cairo Juliana Stein Luciana Delgado Santiago Bortolotti Sebastián A. Guelman Juan Pablo A. Ortiz Eligio N. Morandi 《Euphytica》2002,124(3):387-395
Soybean cultivars carrying the `long juvenile trait' show a delayed flowering response under short day conditions. The incorporation
of this character into genotypes of agronomic interest may allow a broader range of sowing dates and latitudes for a single
cultivar adaptation. The objective of this work was to identify molecular markers linked to the juvenile locus in soybean.
Experiments were carried out using two pairs of near isogenic lines(NILs) differing in the presence of the long juvenile trait,
and RAPD markers. Four hundred primers were first screened to find polymorphism associated with the trait. Additional differences
between NILs were sought by digesting the genomic DNA with five restriction enzymes. Polymorphic fragments detected between
NILs were tested for linkage to the juvenile locus in the corresponding F2 segregating populations. Marker bc357-HaeIII was linked (χ2L = 46.316) to the juvenile locus with an estimated recombination frequency of 0.13 ± 0.03in one of the genetic backgrounds
studied. The fragment was cloned, sequenced and converted into a SCAR marker. Moreover,bc357-HaeIII was used as RFLP probe. Both, SCAR and RFLP generated markers linked to the juvenile locus in the two genetic backgrounds
analysed. Results presented in this work can be utilised for both, the localisation of the gene associated with the character
and for tagging the juvenile trait in soybean breeding programs.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献