Search Results
Abstract
Paclobutrazol applied at 37 mg per plant to container-grown, own-rooted peach [Prunus persica (L.) Batsch ‘Redhaven’] trees reduced vegetative growth (compared with no treatment) as measured by shoot extension, leaf size, and shoot dry weight. All paclobutrazol treatments (foliar and/or soil) increased root tip diameter and reduced unsuberized root length. Paclobutrazol increased the size of the cortex parenchyma cells and resulted in radial rather than longitudinal elongation of the innermost layer of cortex cells. These changes in cell shape and size were primarily responsible for increasing root tip diameter. Chemical name used: (R*,R*)-(±)-β-[(4-chlorophenyl)methy]-α-(l,l-dimethylethyl)-1H-1,2,4-triazole-l-ethanol (paclobutrazol).
Planting treatments were evaluated for their influence on shoot development and root distribution of own-rooted `Redhaven' peach [Prunus persica (L.) Batsch] trees planted to high density (5000 trees/ha). Planting in fabric-lined trenches (FLT) or narrow herbicide strips (NHS) reduced the diameter and length of primary shoots, the number and combined length of second-order shoots, and the total length of shoots. Flower density, the number of flowers per node, and the percentage of nodes containing one or more flowers were increased for FLT trees but not for NHS trees when compared with controls. The length of primary shoots increased quadratically for all treatments with increasing limb cross-sectional area (LCA). The total length of shoots increased more with increasing LCA for controls than for FLT trees. The number of flowers per shoot increased linearly for all treatments with increasing LCA values. Root concentration decreased with increasing soil depth and distance from tree rows for all treatments. Reduced widths of weed-free herbicide strips had little effect on root distribution. Roots of FLT trees were reduced in number and restricted vertically and laterally when compared with other planting treatments. The FLT treatment modified shoot development by reducing the length of total shoots and length of primary shoots across LCA values measured when compared with NHS and control-treatments.
Abstract
Black, purple, and tan discolorations have been found within red-pigmented areas of the peach fruit skin. Scanning electron and light micrographs show damage caused by defuzzing and roller drying, which could facilitate entry of causal agents associated with peach skin discoloration. Comparisons of reflectance and transmittance spectra (380-700 nm) of discolored (purple) and nondiscolored (red) peaches show the mean reflectance value for discolored peaches is 100% darker than nondiscolored peaches. However, transmittance spectra of acidified extracts of discolored and nondiscolored peach skins are similar throughout these wavelengths. Extracted pigment color was altered by pH changes and metallic ion concentration. At low pH, discoloration may be caused by ion complexing with anthocyanin pigment. At high pH, discoloration may result from alkaline hydrolysis of the pigment molecule.
The low density, free-standing Open Center (OC) training system for peach production is inexpensive to establish and maintain. However, a lengthy establishment period is required before profitable yields are obtained and uneven distribution of fruiting wood within and between trees reduces potential fruit production and quality. Redhaven/Lovell trees were planted in 1985 to evaluate four peach training systems: OC, Central Leader (CL), Y-Trellis (YT), & Meadow Orchard (MO) planted at 278, 1111, 2222, & 3333 trees/ha, respectively. YT trees were trained with two scaffold limbs oriented across the row, each supported at the top by one wire (8 feet above ground). MO was managed as the Intensive System described by Erez. Irrigation was not available. Crop was reduced by drought in 1988 and by frost in 1990 & 92. YT produced profitable yields in the third season, with good light distribution throughout the canopy. OC trees required seven years to reach yields of YT. Excessive shoot growth following spring frosts has been difficult to manage in CL and MO, resulting in shading out and loss of fruiting zone. Training system has affected fruit number more than fruit size or quality.
Abstract
Semihardwood peach [Prunus persica (L.) Batsch] cuttings were successfully rooted when the bases and tops were misted intermittently with water. Rooting was not affected by cultivar or type of cutting (basal vs. terminal). Closer proximity of the bases of the cuttings to the mist line and overhead misting improved rooting percentage.
Abstract
The ethylene-releasing agent CGA-15281 (2-chlorethyl-methylbis (phenylmethoxy) silane) effectively thinned fruit of several cultivars of peach [Prunus persica (L.) Batsch.]. Thinning varied with cultivar, stage of development, concentration, and application technique. Negligible (<1%) leaf injury and drop occurred even at the higher (720 ppm) concentration over the 8-year period.
Abstract
In vitro propagation of ‘Nemaguard’ peach rootstock [Prunus persica (L.) Batsch] was obtained on a modified Murashige and Skoog (MS) medium using shoot tips as primary explants. Shoot proliferation was induced on MS medium supplemented with 50 mg/liter L-ascorbic acid, 20 ml/liter Staba vitamin mixture, 2.0 mg/liter 6-benzylamino purine (BA), and 0.1 mg/liter naphthaleneacetic acid (NAA). Rooting was induced by subculturing plantlets on a similar medium without the Staba vitamins and without BA. When the Staba vitamin mixture was present, rooting was reduced; the inhibition resulted from the presence of riboflavin.
Abstract
An inexpensive chamber for controlled freezing of large container-grown plants up to 2 m in height was constructed using liquid nitrogen as a refrigerant. A microcomputer-based system was developed to control the cooling sequence and to collect data on tissue temperature, air temperature, and exotherms. Versatile software was written that allowed the programmed rate of temperature drop to be based on either tissue temperature or air temperature.
Abstract
Application of 960 ppm (2-chIoroethyl)methylbis(phenylmethoxy)silane (CGA-15281) substantially inhibited carbon transport into young fruit of peach [Prunus persica (L.) Batsch] 4 to 5 days before visual symptoms of senescence occurred. Carbon transport was unaffected 4.25 hours after treatment, but was greatly reduced after 24 hours. Reduced carbon transport continued through 144 hours following CGA-15281 application.