Genetic variation in chilling requirement was investigated over three growth periods using clonal progenies of six apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] families derived from crosses of high and low chill requiring cultivars. Two quantitative measurements related to chilling requirement, viz., the time of initial budbreak (vegetative and reproductive) and the number of breaking buds over a specified time interval, were used as evaluation criteria. Genetic and environmental variances of the traits are presented as intra-class correlation coefficients for clones within and between families. For budbreak time, reproductive and vegetative, broad-sense heritability averaged around 75% and 69% respectively, indicating a high degree of genetic determination in this material. For budbreak number, moderate to low genetic determination was found with broad-sense heritabilities around 30%. Estimates of genetic components of variance between families were generally very low in comparison to the variance within families and predict potentially favorable responses to truncation selection on the traits within these progeny groups. Analysis of the data showed that distribution of budbreak time is typical of quantitative traits with means distributed closely around midparent values. Skewed distributions towards low budbreak number were obtained in varying degrees in all families.
preservation of plant resources and to selection of wild fruit genotypes from natural populations ( Ercisli et al., 2007 ; Tosun et al., 2009 ). The cornelian cherry is a semi-domesticated plant that can be used as both food and medicine. In folk tradition, it
( Goldblatt and Manning, 2008 ). There are ≈70,000 known Iris cultivars, and more than 1000 new cultivars are produced by selection and hybridization every year ( Hu and Xiao, 2012 ). Few of those cultivars bloom in early spring (late March to mid-April in
compounds present in minor quantities in eggplant are numerous, and apart from their potent antioxidant activity, they also include free radical scavenging and antitumoral activities ( Sawa et al., 1998 ; Triantis et al., 2005 ). The selection of eggplant
In Dec. 1990, sweet cherry (Prunus avium L.) selections varied in floral bud kill from 9% to 92% following exposure to severe cold. In the following winter, the hardiness of two hardy and two tender selections was analyzed by differential thermal analysis (DTA) to screen selections for hardiness. In a mild winter, when buds remained at their minimum hardiness level, the hardy selections consistently were > 2C hardier than the tender selections. About one-half of that hardiness difference was associated with differences in tissue water content, the other half with unknown factors. Buds of the tender selections began to develop earlier and bloomed earlier than the hardy selections. DTA analysis of floral bud populations separated selections that clearly differed in floral bud hardiness.
H. L. de Vilmorin, in 1900, wrote “selection is the surest and most powerful instrument that man possesses for the modification of living organisms”. This early estimate of selection’s importance would probably be accurate today. While many techniques have since been developed as effective tools for the plant breeder-irradiation, colchicine, tissue cluture-his reward more frequently comes from selection pressure applied to population variation, natural or created.
evaluated as ‘Selection 19-20’ after being grafted on five seedling—trees planted at 10 × 10 m distance in the 1980s at INIFAP’s Experiment Station of Zaragoza Coahuila (lat. 28°29′30″ N; long. 100°55′10″ W). ‘Norteña’ has been registered in the Servicio
fluctuate depending on the development stage of shoots evaluated and on environmental conditions such as temperature and humidity. Selection using molecular markers that identify a genotype can be done accurately with low cost and time expenditure
. Breeding line selection The 20 F 1 hybrid combinations from crosses involving the four snap bean breeding lines and five snap bean cultivars were generated in July 2008 ( Fig. 1 ). F 1 phenotypes were visually compared with phenotypes of the corresponding
In 1987, `Starkspur Supreme Delicious' and `Melrose' were planted on eight apomitic apple selections made in Germany by Dr. Hanna Schmidt for use as rootstocks and compared to trees on M.7. Selection 2, was the most precocious, followed by trees on M.7, with selections 1 and 7 being less precocious than M.7. Selections 2 and 8 were 25% larger than M.7, while 1, 3, 4, and 7 were similar in size and 5 was 15% smaller than trees on M.7. Selections 2 and 8 had the highest cumulative yields/tree, followed by trees on M.7, with all other selections having lower yields. Internal bark necrosis (IBN) developed on the `Delicious' trees, with the most-severe symptoms on selections 1, 3, 4, 5, 6, and 7, with less-severe symptoms on 8 and very little present on trees on M.7. IBN was correlated with leaf Mn levels. In 1995, the highest density of flowering spurs occurred on M.7 and selections 3 and 7, with lower densities in selections 2 and 5. Selection 2 had the highest density of non-fl owering spurs, followed by selection 5, with all others having lower densities similar to trees on M.7.