The effects of CPPU [forchlorfenuron, N-(2-chloro-4-pyridinyl)-N-phenylurea] on berry development of Vitis labrusca and V. labrusca × V. vinifera cultivars was evaluated under field conditions. A concentration response was initially established by spraying clusters of `Himrod' at a mean berry diameter of about 5 mm with 0, 5, 10, or 15 mg·L–1 CPPU. Berry enlargement was monitored (16, 30, 44, and 59 days after treatment) during development. Cluster mass, number of berries per cluster, berry mass and firmness, and °Brix were determined at harvest. Berry mass was dramatically increased (2.3 versus about 3.6 g/berry) at harvest by all concentrations of CPPU. Cluster mass and compactness were also increased and berry firmness was linearly related to CPPU concentration (r 2 = 0.997). There was no significant effect on number of berries per cluster (79 to 86). °Brix, rachis necrosis at harvest, and berry abscission after 30 days of refrigerated storage (1 °C) were significantly reduced. Effect of time of CPPU application (0, 5, and 10 mg·L–1) was established by treatment of clusters at mean berry diameters of about 4, 5, 7, and 9 mm. Response was indexed by following berry enlargement at 14, 28, 42, and 56 (maturity) days after treatment. Maximum berry size for both 5 and 10 mg·L–1 was obtained from applications at 4 to 7 mm berry diameter. Relative response of seedless and seeded cultivars was compared by application of CPPU at 0, 5, 10, or 15 mg·L–1 to clusters (4 to 6 mm berry diameter) of seedless `Vanessa' and `Lakemont' and seeded `Concord' and `Niagara'. Bioresponse was determined by a time course of berry enlargement and berry and cluster mass, number of berries per cluster, and rating cluster compactness at maturity. Except for `Lakemont' at the 5 mg·L–1 concentration, CPPU at all concentrations increased seedless berry diameter significantly from the first measurement at 14 through 56 days after application. Berry and cluster mass and cluster compactness were significantly increased in `Vanessa'. In contrast, the only effect of CPPU on the two seeded cultivars was an increase in berry size in `Concord' and an initial increase in berry size 14 days after application in `Niagara'.
Abstract
6-Benzylamino purine (BA) solutions at 100, 200 or 400 ppm, applied to self-pollinated flowers of the partly self-incompatible olive (Olea europaea, L. cv. Chalkidikis) at full bloom, increased the set of normal seeded fruits in young potted trees, in the greenhouse. In mature orchard trees, only concentrations at 400, 600 or 800 ppm were effective. Applications of BA to open-pollinated flowers failed to increase fruit-set. BA applied to unpollinated flowers did not induce the formation of normal fruits and did not increase the number or size of smaller parthenocarpic fruits. The use of 2-naphthoxyacetic acid (2-NOA) and potassiumgibberellate (KGA3), after self-pollination of the flowers, did not affect the set of normal seeded fruits.
Abstract
Pot roses (Rosa hyb. cvs. Pink and Orange Margo Koster and Red Garnette) were sprayed with naphthaleneacetic acid (NAA) or 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA) prior to simulated truck shipment which lasted 5 or 6 days to study the effect on flower bud and leaf abscision and on leaf senescence. “Shipment” under refrigerated conditions (1-3°C) prevented bud and leaf abscission. ‘Red Garnette’ and ‘Orange Margo Koster’ had little or no bud and leaf abscission even at a warm “shipping” temperature (20-22°C); however, ‘Pink Margo Koster’ was severely affected. Observations under “home conditions” for 10 days after this warm “shipping temperature” revealed that all 3 cultivars had severe leaf senescence. NAA spray (15 and 30 ppm) severely accelerated leaf abscission and senescence. NAA prevented bud drop, but the buds did not open. PBA (50 ppm) greatly reduced leaf abscission both during “shipment” and in “home conditions”. PBA also prevented bud drop and flowers subsequently opened normally.
Abstract
Applications of 6-benzylamino purine (BA) and gibberellin A4 + 7 (GA4 + 7) over a period of 3 years significantly increased primary and secondary branching and total shoot growth of 6 apple cultivars (Malus domestica Borkh.) from the first through the fourth growing seasons in the field. In spur-type ‘Delicious’ and ‘McIntosh’, BA + GA4 + 7 was more effective than deblossoming, pruning, or branch spreading in inducing lateral branching.
Photoperiod, irradiance, cool temperature (5 °C), and benzyladenine (BA) application effects on Echinopsis ‘Rose Quartz’ flowering were examined. Plants were placed in a 5 °C greenhouse under natural daylight (DL) for 0, 4, 8, or 12 weeks, then moved to a 22/18 °C (day/night temperature) greenhouse under short days (SD, 8-hour DL) plus 0, 25, 45, or 75 μmol·m−2·s−1 supplemental lighting (0800–1600 hr; 8-hour photoperiod), long days (LD) delivered with DL plus night-interruption lighting (NI) (2200–0200 hr), or DL plus 25, 45, or 75 μmol·m−2·s−1 supplemental lighting (0800–0200 hr) for 6 weeks. Plants were then grown under DL only. Percent flowering plants increased as irradiance increased from 0–25 to +75 μmol·m−2·s−1 on uncooled plants, from 0% to 100% as 5 °C exposure increased from 0 to 8 weeks under subsequent SD and from 25% to 100% as 5 °C exposure increased from 0 to 4 weeks under subsequent LD. As 5 °C exposure duration increased from 0 to 12 weeks (SD-grown) and from 0 to 8 weeks (LD-grown), flower number increased from 0 to 11 and from 5 to 21 flowers per plant across irradiance treatments, respectively. Total production time ranged from 123 to 147 days on plants cooled from 8 to 12 weeks (SD-grown) and from 52 to 94 days on plants cooled for 0–4 weeks to 119–153 days on plants cooled for 8–12 weeks (LD-grown). Flower life varied from 1 to 3 days. BA spray application (10–40 mg·L−1) once or twice after a 12-week 5 °C exposure reduced flower number. Flower development was not photoperiodic. High flower number (17–21 flowers/plant) and short production time (including cooling time, 120–122 days) occurred when plants were grown at 5 °C for 8 weeks, then grown under LD + 45–75 μmol·m−2·s−1 for 6 weeks (16 hours; 10.9–12.8 mol·m−2·d−1) at a 22/18 °C day/night temperature. Taken together, Echinopsis ‘Rose Quartz’ exhibited a facultative cool temperature and facultative LD requirement for flowering.
Abstract
In axillary meristems laid down just prior or subsequent to commencement of growth regulator applications, exogenous gibberellic acid (GA) alone promoted runner formation. Strongly-inhibited axillary buds with leaf primordia responded to GA + BA (benzyladenine) with runner formation in the June-bearer ‘Fortune’. Few of the inhibited buds of the everbearer ‘Geneva’ responded to GA or GA + BA. Following application of BA alone, inhibited buds of June-bearing cultivars formed lateral crowns (‘Fortune’) or runners (‘Earlidawn’). Runner formation following chilling of June-bearing ‘Fortune’ plants exposed to short days (SDs) occurred from meristems initiated after satisfaction of the cold requirement. Comparable buds on plants receiving no chilling during SDs remained inhibited, as did axillary meristems present during SDs. In contrast, runners formed by chilled, everbearing ‘Geneva’ plants originated from axillary meristems initiated prior to chilling but not from subsequent meristems. Chilling ‘Geneva’ plants during exposure to SDs removed the inhibition from existing axillary meristems and promoted runner formation. Runnering did not occur in activley growing ‘Geneva’ plants maintained under long days (LDs).
Significant occurrences of phenotypic variation have been noted in micropropagated Rhododendron. Studies were undertaken to determine what aspects of micropropagation lead to variation. Rhododendron `Molly Fordham' was used to evaluate growth parameters and the incidence of variation in plants that originated from 3 month and 54 month old cultures. Plants from 3-month-old cultures were significantly wider than plants from 54-month-old cultures. Rhododendron `Aglo', `Molly Fordham', and `Scintillation' were used to evaluate growth and the incidence of variation in plants grown from microcutting bases and rerooted microcutting tips (retips). Three-month-old retips were significantly taller and wider than bases of the same age, but possessed fewer branches. The influence of in vitro N6-[2-isopentenyl]adenine (2-iP) concentration on the growth and phenotype of regenerated plants of `Aglo', `Molly Fordham', and `Scintillation' was examined. Data taken 3 months post-acclimation indicate that growth and the incidence of variation in response to 2-iP concentration is cultivar dependent.
Abstract
Foliar sprays of 10 and 100 mg·liter-1 CPPU were applied at petal fall of the king blossom (PF) or 18 days later to mature ‘McIntosh’/M.7 apple trees. All CPPU sprays reduced crop load. Treatments at PF reduced the crop to near the desired level of about five to six fruit per cm of limb circumference. Fruit weight was increased 21% and 67%, respectively, by 10 and 100 mg·liter-1 applied at PF. Treatments at PF increased fruit size more than at PF + 18, and 100 mg·liter-1 was more effective than 10 mg·liter-1. At the higher rate and later timing, CPPU appeared to retard ripening. These fruit were firmer, red color development was reduced, and degradation of starch appeared to be delayed. Fruit length : diameter (L:D) ratio and seed number were reduced by treatment at PF + 18 days. Total growth was increased on limbs treated with CPPU at PF + 18 days. CPPU at 10 mg·liter-1 reduced flower bud formation, and at 100 mg·liter-1 it nearly eliminated return bloom when applied at either timing. Chemical name used: N-(2-chloro-4-pyridyI)-N’-phenylurea (CPPU).
A relationship between ovary size at anthesis and final fruit diameter of 12 tomato (Lycopersicon esculentum Mill.) cultivars with a range of fruit sizes, shapes, and maturation rates was determined. `Fireball', `Michigan/Ohio Hybrid', and `New Yorker' produced nonfasciated, spherical fruits of intermediate maturation rate and showed a significantly higher correlation between ovary diameter at anthesis and final fruit diameter than `Small Fry', `Roma VF', `Early Cascade', `Campbell 1327', or `Ponderosa'. A linear regression of final fruit diameter at maturity on ovary diameter at anthesis of the cultivars was highly significant (r2 = 0.92**; ÿ = 22.5X - 0.3). Continuous root application of 0.01 μm BA to seedlings of `Fireball' significantly delayed anthesis. A single foliar application of 0.37 mM NOA to `Fireball' plants at the appearance of the first inflorescence significantly increased ovary diameter on the first inflorescence, but decreased ovary diameter on the second inflorescence. Treatment with NOA altered final fruit shape but not final fruit diameter. Single foliar applications of 0.1 mM GA stimulated stem and peduncle elongation but did not affect fruit size. Chemical names used: ß-naphthoxyacetic acid (NOA), N6-benzylaminopurine (BA), gibberellic acid, (GA).
Apricot (Prunus armeniaca L. cv.'Helena') shoots grown on a proliferation medium containing 3% sucrose, 0.4 mg·L–1 benzyladenine (BA), and 0.04 mg·L–1 indolebutyric acid (IBA) and solidified with 0.6% agar were stored at three different temperatures in the dark for up to 24 weeks. All shoots remained viable for 24 weeks when stored at 3 °C, while at 14 °C the percentage of survival decreased quickly after 12 weeks of storage. At 7 °C, percentage of survival started to decline after 18 weeks of storage. Shoots stored at 3 °C had the highest regeneration rates and shoot lengths following transfer to standard proliferation conditions. This temperature also had a beneficial effect on shoot proliferation during the first 12 to 18 weeks of the experiment.