Peach Shoots Research Articles

Ice Propagation in Peach Shoots and Flowers

Abstract The linear propagation of ice in peach [Prunus persica (L.) Batsch] shoots was measured during and after bloom. The mean rate of ice propagation was 9.3 ± 2.3 mm·s-1 at — 3C, with no significant differences observed among ‘Redskin’, ‘Reliance’, and ‘Redhaven’ cultivars. No barriers to the spread of ice were observed. Flowers froze within 30 sec from the time the advancing ice front passed their location on the stem. No ice-nucleation active bacteria were detected on the shoots or flowers.

Ingress and Spread of Pseudomonas in Stems of Peach and Apricot Promoted by Frost-Related Water-Soaking of Tissues

A freezing-thawing cycle created a water-soaked condition in the bark of shoots of peach and apricot that induced a quick (1 min) ingress and a noticeable spread (15-35 mm) of bacteria and dyes in tissues. This phenomenon may explain the decisive effect of low temperature on several diebacks and cankers of fruit trees caused by pseudomonads

Nonbacterial Ice Nucleation in Peach Shoots

Abstract Experiments were conducted to determine the relative contributions of bacterial and nonbacterial ice nuclei to freezing of peach [Prunus persica (L.) Batsch] shoots. Exposure to 33°C for 3 hr eliminated bacterial ice nuclei active at −3° on inoculated shoot pieces, but controls were not affected. In another experiment, ice nucleation temperatures and ice nucleation-active (INA) bacterial populations of field-collected shoots were determined. Mean freezing temperatures of 20 g (fresh weight) shoots were not significantly different in the presence or absence of INA bacteria (detection limit of 10 cells/g fresh weight). INA bacteria were detected on 19% of the shoots with a maximum natural population of 180 cells/g fresh weight. Inoculation studies indicated that 20 g fresh weight peach shoots contained a mean of 1.0 nonbacterial (−3°) ice nuclei, while shoots with 180 INA cells/g fresh weight averaged 1.4 (−3°) ice nuclei per 20 g. Most ice nuclei active at −3° were of nonbacterial origin.

Cold Resistance in Peach, Apricot, and Cherry as Influenced by Soilapplied Paclobutrazol

Abstract Low temperature injury to flower buds of peach [Prunus persica (L.) Batsch.] and sweet cherry [Prunus avium L.] and to one-year-old shoots of peach and apricot (Prunus armeniaca L.) during fall and winter was more severe on trees treated with paclobutrazol (PP 333) than on those not treated. Paclobutrazol had no measurable effect on cold resistance of apricot buds or cherry shoots. The average date of 1st bloom was advanced by one to 2 days in all 3 species by paclobutrazol.

Hydraulic Conductivity and Ethylene Production in Detached Flowering Peach Shoots.1

Abstract Hydraulic conductivity decreased logarithmically over an 8-day period in detached flowering peach stems [Prunus persica (L.) Batsch]. Decreased hydraulic conductivity was negatively correlated (r = - 0.96) with an increase in the number of plugged vessels and positively correlated with a decrease in the percentage of functional vessels (r = 0.97). Ethylene production from flowering shoots peaked after 7 days in the holding solution but decreased rapidly thereafter. Addition of 1% ethanol to the holding solution increased xylem hydraulic conductivity and delayed the surge in ethylene production.

Factors Affecting Establishment and Growth of Peach Shoots in Vitro1

Abstract Contamination was reduced from 100 to 3.3% if surface-sterilized forced lateral shoots of peach (Prunuspersica (L.) Batsch), dissected to 0.5–1.0 cm, were cultured rather than similarly sterilized dormant lateral buds which had met their chilling requirement. Optimum shoot tip growth was obtained on a liquid Murashige and Skoog salts medium supplemented with 0.01 mg/liter indolebutyric acid (IBA) and 0.2 mg/liter 6-benzylamino purine (BA). Growth on liquid media was significantly greater than on solid media. Survival of shoot tips at 21° – 24°C was significantly greater than at 26° or 30°. Peach cultivars differed significantly in their survival in vitro.

Opening and Vase Life Extension of Peach Flowers on Detached Shoots with Sucrose and Ethanol1

Abstract Detached shoots of double-flowered peach [Prunus persica (L.) Batsch] selections Fla. 6-1 and Fla. 0-5 were successfully opened in floral solutions containing 1 to 10% sucrose in deionized water. Addition of 8-hydroxyquinoline citrate (8-HQC), gibberellic acid (GA3), or 6-benzylaminopurine (BA) to solutions did not extend vase life. Solution uptake rate decreased over the 8-day life of the shoots and was influenced by solution molarity. Xylem plugging by pectic-type materials increased with time in solution. Addition of 1% ethanol to the floral solution hastened time of first opening, decreased the extent of xylem plugging, and extended vase life. Ethanol at 2% extended vase life and increased solution uptake rate over solutions containing sucrose alone.

Water Soluble Extracts from Peach Plant Parts and Their Affect on Growth of Seedlings of Peach, Apple and Bean1

Abstract Water suspensions from seeds, root and shoots of peach (Prunus persica (L.) Batsch) influenced growth of peach, apple and bean seedlings when applied to soil of potted plants. Different levels of amygdalin were found in plant parts of peach and apple. Synthetic amygdalin applied to potted peach seedlings was not toxic. Certain nutrient elements were altered due to the soil treatment. Disposal of plant parts is suggested as a practical sanitation practice to possibly reduce peach tree decline on old soil.

Protection of Peach Shoots Against Species of Leucostoma with Benomyl and Captafol

Protection of Peach Shoots Against Species of Leucostoma with Benomyl and Captafol

Properties of syringomycin, a wide spectrum antibiotic and phytotoxin produced by Pseudomonas syringae, and its role in the bacterial canker disease of peach trees

Methods were devised for the large-scale production of syringomycin using stainless steel trays which were poured with agar medium, and then covered with cellophane. The bacteria were grown on the surface of the cellophane. Syringomycin was then extracted from the cellophane and purified by ion exchange column chromatography and partition chromatography; it was a single, low molecular weight, ninhydrin-reactive compound. Nine ninhydrin-reactive spots were detected in the acid hydrolysate of syringomycin by two-dimensional chromatography. Eight of the spots corresponded in R F and color to amino acids tentatively identified as aspartic acid, d-glutamic acid, serine, glycine, α-alanine, valine, d-phenylalanine and d-lysine. Investigation of some of the properties of syringomycin showed that its antibiotic activity was labile in alkaline solutions, especially above pH 8. Syringomycin is soluble in water and the lower alcohols, and insoluble in ether and chloroform. Its isoelectric point is about pH 7. Syringomycin has a wide spectrum of antibiotic activity. A species of each of six genera of bacteria, four different fungal species, a unicellular algal species and a Daphnia species were all inhibited by low levels of syringomycin. The growth of Geotrichum candidum, the most sensitive of the organisms surveyed, was completely inhibited by 24 μg syringomycin per ml. Syringomycin produced phytotoxic symptoms in the leaves of peach shoots when the stems were immersed for 24 h in a water solution of syringomycin containing 600 μg syringomycin per ml. The stems of peach shoots became brown and necrotic after being immersed for one week in a solution containing 6 μg syringomycin per ml. Inoculations of peach shoots with Pseudomonas syringae showed that the symptoms produced by the bacterium were very similar to the phytotoxic symptoms produced by syringomycin. Inactivation of the antifungal activity of syringomycin by mild pH manipulation also decreased its phytotoxicity proportionately. An antibiotic which was indistinguishable from syringomycin was isolated from diseased host tissues. It was concluded that syringomycin is probably the major phytotoxin in the bacterial canker disease of peach trees.

14C Translocation patterns in peach and apricot shoots

14CO2 was supplied under laboratory conditions to the terminal leaves of peach and apricot shoots taken from orchard trees over the period from flowering to fruit maturity. The distribution of 14C assimilates along the shoot, and the patterns of deposition within the developing fruit were recorded on X-ray film. In both peach and apricot shoots, the terminal leaves, soon after emergence, exported assimilates to adjacent fruit which competed successfully with nearby expanding leaves, although isolated leaves (in peach) were capable of importing. At a more advanced stage only the fruits imported assimilates from the terminal leaves, and the labelled substrates were deposited in both flesh and inner seed structures despite the hardened stone. The fruit continued to accumulate 14C photosynthate even when completely ripe. Following fruit removal, export from the terminal leaves on the peach shoot was minimal, and labelled photosynthate was detected only in the main stem; whereas in apricot shoots, mature lower leaves showed extensive import of current assimilates.

Gibberellin-like substances in peach tissue: Separation by thin-layer electrophoresis and chromatography

Thin-layer electrophoresis in conjunction with thin-layer chromatography proved an excellent method for separating gibberellin-like compounds extracted from small quantities of peach tissue. Eleven compounds active in the barley-endosperm gibberellin bioassay were separated from peach shoot tips. Two of these were possibly identical with known gibberellins but the remainder were distinctly different. Of the latter, five were acidic, one was neutral, and three were basic. The most active compound in shoot tips may have been GA1 or GA3 but in seeds the most active compound resembled no known gibberellin.

"Die-Back" of Peach Shoots

"Die-Back" of Peach Shoots