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- Author or Editor: G.A. Couvillon x
- Journal of the American Society for Horticultural Science x
Abstract
Dormant ‘Redhaven’ peach [Prunus persica (L.) Batsch.] cuttings with flower, lateral vegetative, and terminal vegetative buds were exposed to either 7.2°, 3°, or 2°C for 600, 1340 or 2040 hr. Terminal vegetative (TV) buds had the shortest chilling requirement and showed less differential response to the various temperature levels than the other bud types. ‘Redhaven’ lateral vegetative (LV) and flower buds (FL) had similar chilling requirements. In general, 7.2° was more effective in releasing buds from rest than 3° or 2°. Prolonged chilling (2040 hr) decreased the growing degree hours (GDH°C) required for vegetative bud opening regardless of temperature. However, the GDH°C required for flower bud opening was decreased only by prolonged chilling at 7.2°C.
Abstract
The chilling enhancement effect of moderate temperature (15°C) on rest completion in ‘Redhaven’ peach was verified and observed only when the moderate temperature occurred followed exposure to chilling temperatures. Chilling efficiency rose with temperatures between 0° and 8° if no moderate temperatures were interspersed. Although 0° was an inefficient chilling temperature, cycling between 0° and 15° resulted in as efficient bud rest release as 6°. The most efficient moderate temperature level was 13°, and the effect of moderate temperatures on rest completion seemed to increase when received during the latter stages of rest. Leaf and flower buds reacted similarly, although the reaction of the former was more prominent. A two-step scheme is proposed for the effect of temperature on bud rest. The first step involves the conversion from the unchilled to the chilled state by chilling temperatures. This stage can be reversed by high temperatures. The second stage is not reversible and involves the conversion by moderate temperatures of the unstable intermediate formed by step 1 to a stable material, which, when accumulated to a certain level, will result in rest completion.
Abstract
Fruits on uniform peach shoots selected from the periphery of trees were thinned to leave only those nodes of the terminal, intermediate, or basal regions of the shoot, or at 6” spacings along the shoot. The control consisted of unthinned shoots. During one year of the study the date of 90% bloom of buds at the various node positions and size of the subsequent fruit was determined. During the second year fruit volume and mean ovule length were determined for each thinning treatment.
Flower buds from the terminal nodes were the first to bloom the resulting fruit were the largest at harvest. Conversely, buds at the basal nodes were the last to bloom and produced the smallest fruit. In treatments that included fruit from all node positions, the mean fruit volume was smaller than for shoots having fruit only at the terminal nodes. Mean ovule length was also influenced by node position.
Abstract
The “after-rest” and “post-rest” quiescent periods of flower buds of 2 peach cultivars of different chilling requirements were characterized by a period of reduced inhibition during which the degree of inhibition decreased each succeeding week. Buds within this reduced period of inhibition appeared to be quiescent since they broke and grew during 2 weeks in a greenhouse. However, during this period the buds responded to GA3 and chilling temp. The “post-rest” quiescent period was not reached until mid-February, at which time the buds no longer responded to GA3 or additional chilling and bud break occurred within 72 to 84 hours after exposure to the greenhouse environment.
The degree of inhibition of buds of the 2 cultivars varied throughout this study. ‘Redhaven’ buds were more inhibited than buds of ‘Redskin’ throughout the period studied.
Abstract
‘Concord’ grapes were harvested at weekly intervals from vines trained to either the Modified Munson (M.M.) or 4-arm Kniffin (4-A.K.) training systems. Total pectic substances and protopectin increased until about 7-9% soluble solids was reached and then decreased during further maturation. As maturity approached, water and oxalate soluble pectins increased. The M.M. system gave higher values for total pectic substances, protopectin, and water soluble pectins than the 4-arm Kniffin system.
Abstract
The effect of exposure of small peach plants (Prunus persica (L.) Batsch cvs. Redhaven and Redskin) to daily fluctuating temperatures (16 hours low: 8 hours high) of 6-15°, 6-18°, 6-21° and 6-24°C was examined in comparison with continuous chilling at 4° and a non-chilled control. Even though all chilling treatments received the same amount of chilling (weighted chilling hours), good leaf bud break was obtained only in the continuous 4°, 6-15° and 6-18° treatments. No lateral leaf buds opened in the 6-21°, 6-24° or the non-chilJed controls of both cultivars. The 6-15° temperature regime was more efficient than continuous chilling in breaking bud rest on a weighted chilling hour basis. ‘Redskin’ lateral buds were shown to have a higher chilling requirement than ‘Redhaven’. Terminal buds especially of ‘Redhaven’ showed a very low chilling requirement. Treating plants with 50 or 150 mg/liter GA3 slightly advanced bud break but did not affect the level of sprouting.
Abstract
Leaf bud break of ‘Redhaven’ and ‘Redskin’ peach (Prunus persica (L.) Batsch) following exposure of plants to temperature cycles of 1, 3, 6 and 9 days was examined. During each cycle the plants were exposed to 4°–6°C for 2/3 of the cycle length and 24° for the remaining 1/3 with all cycles repeated until the plants were exposed to a designated number of chilling hours. Thus, all plants within each treatment were exposed equally (in total) to chilling and heat. No lateral bud (LB) break occurred with ‘Redskin’ in the 1-day cycle, a low level was obtained in the 3-day cycle and good bud break occurred in the continuous chilling control and the 6 and 9 day cycles. With ‘Redhaven’ no LB break was evident in the 1 day cycle while the 3, 6, and 9 day cycles responded similar to the continuous chilling control. From these data it was concluded that chilling (4°-6°) accumulated during the 20 to 40 hrs prior to the onset of high temperature was susceptible to high temperature negation.
Abstract
[14C-ethyl] labeled (2-chloroethyl)methylbis(phenylmethoxy)silane (CGA-15281) was applied to fruit and leaves of 4-year-old ‘Bicentennial’ peach trees [Prunus persica (L.) Batsch]. Virtually none of the parent material moved into the fruit or was taken up and transported in vegetative tissue. Of the small amount found within the vegetative tissue, there was equal distribution between acropetal and basipetal movement. The compound appears to act through the release of ethylene which penetrates the tissue rather than uptake of the parent molecule and subsequent release.