Search Results

You are looking at 111 - 120 of 2,517 items for :

Clear All

Effects of scion inclination on root growth and distribution were studied on INRA GF 677 (Prunus persica × Prunus amygdalus) and apple/M.9 trees. At planting, central leaders were positioned vertically (0°) or inclined 45° or 60° to the north and south. Three years after planting, root total dry weight of inclined trees was lower than that of the control (0°, vertical central leader). Five years after planting, the isotropic distribution of the normal root systems was distorted by inclination in both species. Roots were more numerous and more elongated in the direction of inclination. Statistical analysis of root density data, using a polar coordinate system, confirmed that the trunk inclination reduced root development and redirected root distribution. The major effect was induced on GF 677 by 60° inclinations. Tree orientation did not seem to influence root distribution.

Free access

Chloroplast DNA (cpDNA) mutations in 7 cultivated Prunus species were compared to establish the phylogenetic relationship among them. Mutations were detected in 3.2 kb and 1.5 kb regions of hypervariable cpDNA, amplified and cut with 21 and 10 restriction endonucleases, respectively, to reveal polymorphisms. Parsimony and cluster analyses were performed. Two groups of species, P. persica and P. dulcis and P. domestica and P. salicina were completely monophyletic. The subgenus Cerasus was the most recently derived, while the subgenus Amygdalus was the most ancestral and somewhat separate from the rest of Prunus. The results also suggest that the rate of mutation in the Cerasus chloroplast genome is significantly greater than for the other subgenera sampled.

Free access

Tetraploid black cherry (Prunus serotina) is the only Prunus L. species that has commercial importance as a timber tree in North America and is well known in Europe for its invasive behavior. Inheritance studies have never been performed and it is not known whether the species is allo or autotetraploid. Six microsatellite nuclear markers were used to test the inheritance in progenies of controlled crosses. Inheritance was proven to be disomic at all loci and a typical diploid mendelian inheritance was found at two loci. A first screening of a population in the invasive range showed high number of alleles per locus (ranging from 6 to 16) and high level of observed heterozygosity (0.75 to 1). Knowing that inheritance is disomic at six microsatellite loci and that at least two of them can be treated as codominant, diploid markers will be beneficial for future genetic studies.

Free access

Abstract

Soil temperatures around roots of apple (Malus domestica Borkh.), peach (Prunus persica (L.) Batsch), and cherry (Prunus avium L.), were modified during anthesis. Cool (1.5 – 9°C) and cold (1 – 4.5°) soil temperatures in the field were achieved with white plastic covers over insulation over snow, and with coolant coils in the soil covered with insulation and clear plastic. Warm (5 – 19°) and hot (18 – 26°) soil temperatures were achieved with clear and black plastic covers over bare soil and with buried heat tapes under insulation and clear plastic. Potted peach seedlings were subjected to freezing (−3°) and warm (18°) soil temperatures in a growth chamber. No advance or delay of anthesis resulted from any of the treatments except delay in frozen soil.

Open Access
Author:

Abstract

Freezing injury to overwintering flower buds of apricot (Prunus armeniaca L.), European plum (P. domestica L.), Japanese plum (P. salicina Lindl.), peach (P. persica (L.) Batsch.), sweet cherry (P. avium L.) and sour cherry (P. cerasus L.) was found to be associated with an exothermic process detected on the time temperature profile. This exothermic process varied with seasonal fluctuations in the hardiness of 2 peach cultivars and was consistent with the hardiness of 5 cultivars tested on 3 dates during winter. No similar exotherm was detected in pear and apple. These results suggest that flower bud injury in some Prunus species was related to a specific event that involved freezing of a ‘bound’ or ‘supercooled’ fraction of water. This fraction of water remained unfrozen in the flower bud until the temperature fell below a critical level which in our studies was as low as -27°C. Exotherm flower bud hardiness in these fruit species.

Open Access

Paclobutrazol (PBZ), a triazole growth retardant known to harden various species to stress, was incorporated into the in vitro rooting medium of Prunus serotina var. virens at rates of 0.00, 0.15, 0.30, and 0.60 mg/L with and without 1.0 mg/L indolebutyric acid (IBA). PBZ significantly reduced shoot growth in vitro but increased/improved the quality and coloration. Although not significant, the roots appeared shorter, thicker, more numerous, and percentage was higher. The percent water loss from detached leaves of in vitro plantlets was significantly reduced by PBZ and IBA, Four weeks after transfer to the greenhouse, survival was significantly improved by PBZ, IBA, and the combination. The incorporation of PBZ in vitro better enables plantlets of Prunus serotina var. virens to withstand the stresses associated with acclimatization and offers the potential to benefit other more difficult-to-acclimatize plant species.

Free access

Abstract

In order to reduce the cost of fumigation and weed control in seedling nurseries of peach (Prunus persica (L.) Batsch.), a number of herbicides, used with and without Nemagon as a nematicide, were evaluated. While necessary for soil fumigation, the presence or absence of Nemagon did not effect weed control or seedling performance. The best and most economical herbicides were the spring application of simazine at 4.5 kg ai/ha or the fall application of diuron at 3.4 kg ai/ha.

Open Access

Performance of `Redhaven' peach [Prunus persica (L.) Batsch.] propagated on nine experimental Prunus rootstock was evaluated over 8 years beginning in 1984, in a randomized complete-block experiment with 10 replications on a Brookston clay loam soil type near Harrow, Ont. This experiment was part of an interregional NC-140 peach rootstock experiment. Significant rootstock-induced effects were noted for increase in trunk cross-sectional area, cumulative tree height and spread, cumulative number of root suckers, yield, average fruit weight, yield efficiency, winter injury, cold hardiness, and tree survival. None of the clonally propagated rootstock gave satisfactory overall performance. All trees on GF655-2, 80% on GF677, 60% Self-rooted, and 50% on GF1869 were dead by the eighth year. In addition, suckering was a major problem on GF1869 and a moderate problem on GF655-2. `Citation' induced the most scion dwarfing but had the lowest yields and low yield efficiency. When yield, yield efficiency, fruit size, and tree mortality were considered together, the four peach seedling rootstock performed better than the other Prunus rootstocks and were ranked as follows: Siberian C, Halford, Bailey, and Lovell. Of these, the first three could be recommended with the most confidence to commercial growers who grow peaches on fine-textured soils in northern regions.

Free access

Tissue osmotic potential(Ψπ) and solute constituents were evaluated in leaves and roots of well-watered and water-stressed Prunus avium L. × pseudocerasus Lindl. `Colt' and Prunus cerasus L. `Meteor'. Osmotic potential at full turgorΨπ,sat decreased in response to water stress for leaves and roots of both cultivars. For `Colt', a cultivar with an indeterminate growth habit,Ψπ,sat decreased by 0.56 MPa and 0.38 MPa for terminal expanding leaves and older expanded leaves, respectively. For `Meteor', a cultivar with a determinate growth habit,Ψπ,sat decreased by ≈0.47 MPa in both terminal and older leaves. RootΨπ,sat was alike for both cultivars and showed a similar decrease of 0.20 MPa in response to water stress. Roots had considerably higherΨπ,sat than did leaves in both cultivars, irrespective of irrigation treatment. Soluble carbohydrates and potassium (K+) were the major solute constituents in both cultivars. Of the soluble carbohydrates, sorbitol was found in the greatest concentration and accounted for the bulk of water stress-induced solute accumulation in both cultivars. Regardless of the irrigation treatment, mature leaves of `Meteor' consistently had lowerΨπ,sat (typically 0.4 MPa) than `Colt'. This variation in Ψπ,sat between Prunus cultivars suggests the potential for selection of cultivars with low Ψπ,sat and possibly superior drought resistance.

Free access

The most commercially grown peach [Prunus persica (L.) Batsch.] cultivars do not require cross-pollination for reasonable fruit set; however, self-incompatibility is a well-known feature within the Prunoideae subfamily. Isoelectric focusing and native polyacrylamide gel electrophoresis of S-ribonucleases; PCR analyses of S-RNase and S-haplotype-specific F-box genes as well as DNA sequencing were carried out to survey the self-(in)compatibility allele pool and to uncover the nature of self-compatibility in peach. From 25 cultivars and hybrids with considerable diversity in phenotype and origin, only two S-haplotypes were detected. Allele identity could be checked by exact length determination of the PCR-amplified fragments and/or partial sequencing of the peach S 1-, S 2-, and Prunus davidiana (Carr.) Franch. S 1-RNases. S-RNases of peach were detected to possess ribonuclease activity, and a single nucleotide polymorphism in the S 1-RNase was shown, which represents a synonymous substitution and does not change the amino acid present at the position in the protein. A 700-bp fragment of the peach SFB gene was PCR-amplified, which is similar to the fragment size of functional Prunus L. SFBs. All data obtained in this study may support the contribution of genes outside the S-locus to the self-compatible phenotype of peaches.

Free access