Flower Bud Density Research Articles

The Effect of Soil Volume on Young Peach Tree Growth and Water Use

An experiment designed to study the effects of different root volumes was installed in Fall 1991. `Golden Queen' peach trees [Prunus persica (L.) Batsch.] were planted into different isolated soil volumes (0.025, 0.06, 0.15, 0.4, and 1.0 m3), which were essentially individual drainage lysimeters. Trunk cross-sectional area (TCA) increased from 5.76 to 14.23 cm2 for the smallest and largest volumes, respectively, while leaf area was 4.56 and 21.32 m2 for the respective treatments. Leaf size was not affected by soil volume. Soil volume was positively related to the number of lateral shoots produced, lateral shoot density, and internode length. Total flower bud number and flower bud density were inversely related to soil volume. Fruit set was similar among treatments despite an almost 4-fold difference in tree size. Tree water use (liters·mm-1 pan evaporation) increased with soil volume; however, when adjusted for tree size (tree water use per TCA), there were no consistent differences between treatments for tree water use over the season. These results suggest that trees planted in the smaller soil volumes were more efficient reproductively per unit of tree size and would be easier to manage in an ultra-high-density planting.

Flower initiation and node development of axillary buds, growth partitioning, and bleeding sap production of young apple trees as affected by fertigation

SUMMARYNode and flower development in axillary buds of one year old 'Elshof trees, growth and dry-matter partitioning, and bleeding sap production were examined in unfertigated field-grown trees as well as in fertigated field- and pot-grown trees. Flower initiation in axillary buds was delayed by approximately 40 d as compared with spur buds, and the critical node number within the bud was only 14 or 15 against 19 nodes in spur buds. Fertigated trees exhibited increased node development, axillary flower-bud densities, extension shoot growth and trunk increments, and decreased root/top ratios. The seasonal shoot development was markedly hastened in fertigated trees, and the amount of bleeding sap was increased. Especially, trees fertigated in pots, using a nitrogen application range of 14 to 420 ppm N, had high bleeding sap concentrations of nitrogen, phosphorus and calcium. Flower-bud initiation of apple is discussed in terms of bud development, shoot growth and root activity.

Hedgerow Orientation Affects Canopy Exposure, Flowering, and Fruiting of `Anjou' Pear Trees

Mature hedgerows of `Anjou' pear (Pyrus communis L.) trees, planted north(N)-south (S) or east (E)-west (W), were used to study the effect of hedgerow orientation on fruiting and canopy exposure. In 1990, flower bud density tended to be lower on the E-W rows, especially on their N sides. Fruit set (FS) was highest on the S side of E-W rows and lowest on the N side, while the E and W sides of the N-S rows were intermediate. Crop density (CD) had a similar pattern as FS, with more fruit on the S than on the N side of the E-W rows. CD was more evenly distributed between the sides on the N-S hedgerows. Differences in FS and CD between sides were related to different levels of sunlight interception. Light exposure was lowest on the N sides of the E-W rows and highest on the S sides throughout the growing season and especially toward the equinoxes. Increased exposure to the sun on the S and W sides late in the season led to more fruit with solar injury. Fruit from E–W rows were larger and less firm. Accumulated yields over 11 years showed a 21.4% increase in the N-S rows over those of the E-W rows.

Irrigation Schedules and Annual Ryegrass as a Ground Cover to Conserve Water and Control Peach Tree Growth

Irrigation schedules were evaluated on `Cresthaven' peach [Prunus persica (L.) Batsch.] to determine if water application could he reduced or omitted without affecting fruit size or yield. Tensiometers were used to schedule trickle irrigation during 1984-M. Treatments were no irrigation or irrigation when soil pressure potential at a 30-cm depth reached 40 or 60 kPa, respectively. When production began in 1986, trees were either irrigated until harvest (1-7 Aug.) or until October. Beginning in 1989, class A pan evaporation was used to schedule irrigation by replacing 60% of evaporation. Trees were irrigated from budbreak to harvest or October, from beginning of stage III fruit growth until harvest or October, or trees were not irrigated. The irrigation treatments were in factorial combination using sod middles, with annual ryegrass (Lolium multiforum Lam.) seeded under the trees or a sod-herbicide strip. The ryegrass was seeded in October, then killed at the onset of stage III fruit growth. Water application was reduced 32% to 57% when irrigation was discontinued after harvest compared to irrigation until October. Irrigation before stage III fruit growth did not affect fruit yield, size, or pruning weights compared to trees irrigated at the onset of stage III fruit growth. Trunk size was increased by irrigation; however, there were no differences in trunk size among irrigation treatments. Irrigation occasionally increased fruit size and yield compared to no irrigation. There were few differences in flower bud density, fruit set, yield, or fruit size among trees with reduced irrigation schedules compared to trees receiving irrigation from budbreak until October. Annual ryegrass decreased shoot growth in 1990 and flower bud density in 1991; however, fruit set was not affected. Annual ryegrass depleted excess soil moisture during the spring in some years, then conserved soil moisture after it was killed. Using sod with annual ryegrass under the trees may be a viable alternative to management with sodherbicide strips.

PEACH PISTIL RESPONSES TO MULTIPLE FALL ETHEPHON APPLICATIONS

Ethephon (100 mg·liter-1) was applied to mature peach trees [Prunus persica (L.) Batsch. cv Jerseydawn] on 1, 2, 3 or 4 dates beginning 15 Sept. 1990 at approximately 2 week intervals for a total of 12 treatments. Ethylene evolution from flower buds and flower bud phenology were monitored through bloom the following spring. Total flower bud density, live flower bud density, percentage live pistils, yield and number of fruit per tree were also measured. The response to multiple ethephon applications was greatly influenced by the timing of specific treatment combinations rather than by the total amount of ethephon applied over the course of the experiment. Ethylene evolution was elevated for about 2 weeks following application(s), however, no clear relationships between bud phenology or survival and ethylene evolution was observed. Several of the multiple ethephon applications significantly delayed bloom to the 75% pink stage, however, none of the treatments significantly influenced development to 75% balloon or fully open stages. Several of the multiple applications caused significant pistil mortality.

Crop load effects on fruit mineral nutrition, maturity, fruiting and tree growth of ‘Cox’s Orange Pippin’ apple

The effects of crop load on fruit quality and mineral content were studied on apple trees (Malus domestica L. Borkh. cv. Cox’s Orange Pippin) by comparing fruit from heavily cropping trees with those from trees with naturally light crops or those which had been flower thinned. In light and thinned treatments, flower bud density was less, and fruit set greater than in heavy treatments. The heavy cropping trees had a higher proportion of fruiting spurs with only one fruit. When spurs with fruit of similar size at the end of the season were compared, those from the heavy treatment had greater primary and bourse leaf areas than did those from the other treatments. Average fruit size at harvest was greatest for the thinned treatment despite it having fruit numbers per tree similar to those of the light treatment. By seven weeks after full bloom, fruit from heavily cropping trees had higher calcium and magnesium contents, and by the end of the season, also lower potassium contents, than fruit from either light ...

SOIL INJECTION OF BAS 111-06W REDUCES SHOOT GROWTH IN PEACH

The growth regulator BAS 111-06W was applied twice each spring for 3 years to 5-year-old 'Loring' trees. First year treatments were foliar sprays (1 or 2 g a.i.), trunk paints (2 or 4 g a.i.), and soil shank injections (2 or 4 g a.i.). Foliar treated trees developed severe leaf shotholing or bacteriosis. Shank treatments were the most effective in controlling shoot growth. Thus, second and third year treatments consisted only of the shank applications. Both the 2 and 4 g rates were equally effective in reducing shoot elongation 10-34% annually. Treated trees bloomed 1-2 days earlier and had shorter bloom periods than the controls. Flower bud density and flower number were greater on treated trees. Fruit yields were not affected. Treated trees required less summer and corrective winter pruning, but had more short shoots to thin out.

GA3 SPRAYS ALTER THE FATE OF LATERAL MERISTEMS OF `REDKIST' PEACH.

G A3 sprays were applied to 10 primary scaffold limb replications with a handgun at three concentrations (25, 50, 100 mg/l), from May to September 1989. Flower bud thinning with G A3 applied in the year prior to bloom was examined for its effect on the developmental fate of lateral meristems. Limbs treated in late May had, on average, 45% more flower buds survive near-critical winter temperatures than did controls. During the period of greatest sensitivity to Flower Bud Density (FBD) reduction, GA3 treated limbs had vegetative bud densities (VBD) higher than control (on average 45% greater at 100 mg/l). On 9 June 100 mg/l reduced FBD by 78% compared to control and increased VBD by 57%, while on 6 July the same concentration. reduced FBD by 94% but VBD was increased by only 32%. These results appear to support the hypothesis that GA3 induced FBD reduction has more than one mode of action.

EFFECTS OF GENOTYPE AND ENVIRONMENT ON FRUIT BUD DENSITY IN PEACH AND NECTARINE

In the Southeast spring frosts often kill all or part of the flowers on peach trees. Increased flower bud density is one mechanism that increases the likelihood of enough flowers surviving to produce a crop. Mean buds per node in-North Carolina varied in 1986 from 1.6 for `Harko' to 0.4 for `Topaz'. The effect of environment on bud density was unknown. Therefore, for 3 years we compared the bud density of 25 peach and nectarine cultivars grown in completely randomized designs (4 reps per location, 10 twigs per tree) in Georgia and North Carolina. Genotypie variability was greater than that due to location or year effects. Cultivars selected for high bud density in one location can be expected to have high densities at other locations.

INFLUENCE OF IRRIGATION TREATMENTS ON PEACH GROWTH AND YIELD

Irrigation schedules were evaluated on `Cresthaven' to determine if water could be conserved without reducing fruit size or yield. Tensiometers were used to schedule trickle irrigation in 1984-88. Treatments were no irrigation or irrigation when soil matric potential reached 40 or 60 KPa 30 cm deep. When production began in 1986, trees were either irrigated until Oct. or until after harvest (1-7 Aug.). In 1989, class A pan evaporation was used to schedule irrigation by replacing 100% evaporation. Trees were irrigated from bud break to harvest or Oct., beginning at stage III fruit growth to harvest or Oct., or not irrigated. The irrigation treatments were in factorial combination with an annual ryegrass ground cover or herbicidestrip. The ryegrass was seeded in Oct., then killed at the onset of stage III fruit growth. Water application was reduced 50% when irrigation was discontinued after harvest compared to irrigation until Oct. Non-irrigated trees had smaller trunks than irrigated trees; however, there were no differences in trunk size among irrigation treatments. Non-irrigated trees yielded less total fruit and fruit over 7-cm diameter than trees irrigated until Oct., but there were no significant differences in yield among irrigated trees. Flower bud density or fruit set was not affected by treatment. The orchard floor management did not affect tree growth or yield.

Planting Method and Irrigation Rate Influence Vegetative and Reproductive Growth of Peach Planted at High Density

Several planting treatments modified vegetative and reproductive growth of young, own-rooted peach (Prums persica) trees evaluated at two levels of irrigation in a high-density orchard (5000 trees/ha). Trees planted in auger holes, narrow herbicide strips, and in fabric-lined trenches, but not those from raised beds, were smaller than control trees set in holes dug with a shovel. After two growing seasons, trees planted in the fabric-lined trenches were smaller and had more flowers per node and greater flower bud densities than trees in other planting treatments. Yield efficiency was greatest for this treatment, although fruit size was small throughout the orchard. Irrigation rates did not affect fruit yield or size. The effects of irrigation rate on vegetative growth were small compared to differences among planting treatments.

Yield Components in ‘Montmorency’ and ‘Meteor’ Sour Cherry

Abstract Two sour cherry (Prunus cerasus L.) cultivars ‘Montmorency’ and ‘Meteor’ were evaluated over two seasons to determine the relative importance of different components of yield. A path coefficient analysis was performed to determine the direct and indirect effects of primary, secondary, and tertiary components on limb yield. Fruit number, fruit weight, the number of lateral buds and spurs, and fruit set were found to be the most important components affecting limb yield in both cultivars. However, the fruiting habits of the two cultivars were significantly different. ‘Montmorency’ produced 68% of its fruit on lateral buds on 1-year-old wood, while ‘Meteor’ had 70% of its fruit on 2-year-old spurs. When the data were standardized by dividing by limb cross-sectional area, ‘Meteor’ had a higher flower bud density (number of flowers/cm2) and yield efficiency (grams of fruits/cm2) than ‘Montmorency’. Although ‘Meteor’ had higher limb yields than ‘Montmorency’, the ‘Montmorency’ trees sampled had about four times more limbs than ‘Meteor’, and, therefore, higher tree yields.

The growth of clingstone peach trees(Prunus persicaL. Batsch) propagated from hardwood cuttings in relation to time of propagation and planting

SummaryHardwood cuttings of the peach cv Golden Queen were taken during the winter at fortnightly intervals. Root development was measured after the cuttings had been treated with a 10-s dip of 1000 ppm IBA dissolved in 50% ethvl alcohol and 6 weeks’ bottom heat at 23°C. The percentage of satisfactorily rooted cuttings was highest in July (85%). Cuttings planted directly into the nursery grew into larger plants than those that were first potted and hardened in the greenhouse. Trees became progressively smaller with later planting. Flower bud density per unit butt area appeared to be greatest on trees propagated in late July. There was no difference in flower bud numbers due to time of planting in the nursery.