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  • Author or Editor: Mike A. Nagao x
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Abstract

Field-grown ginger (Zingiber officinale Roscoe cv. Chinese) were treated with 3 weekly foliar sprays of GA3 at 0, 1.44, and 2.88 mM; ethephon at 0, 3.46, and 6.92 mM; or daminozide at 0, 3.13, and 6.26 mM to evaluate their effects on flowering, shoot emergence, and rhizome yield. GA3 inhibited flowering and shoot emergence, while ethephon and daminozide had no effect on flowering but promoted shoot emergence. Rhizome yields were increased with daminozide and decreased with GA3 and ethephon. Chemical names used: gibberellic acid (GA3); (2-chloroethyl)phosphonic acid (ethephon); butanedioic acid mono(2,2-dimethylhydrazide) (daminozide).

Open Access

Abstract

Poor germination in Carica papaya L. was partly due to the absence of embryos in about 20% of the seeds. Final germination and the rate of seedling emergence were improved by seed separation with 1.097 g·em−3 sucrose solution and soaking with 1.0 M potassium nitrate (KNO3) or 600 ppm gibberellic acid (GA3). Final germination was 87.8% for the KNO3 treatment and 80.5% for GA3. Seedlings from KNO3 treatments were normal, whereas GA3 caused excessive elongation of stems.

Open Access

Abstract

In Kona, Hawaii, coffee is dormant from December to February. Water is critical for spring vegetative growth (1), on which next year's flowers are produced. Water stress has reduced extension growth, node number, and leaf area of coffee (5), and irrigation has increased internode extension and node production (3). The objective of this study was to determine the effect of amount and frequency of irrigation on vegetative growth of coffee.

Open Access

Flowering of Macadamia integrifolia trees was monitored following application of 220 mg/liter gibberellic acid (GA3) at various times preceding the onset of the flowering season. In untreated trees, flowering extended over a 4-5 month period. When GA3 was applied at 2, 3 and 4 months before the onset of anthesis, raceme production during the entire flowering season was inhibited. A slight reduction in raceme production was observed when GA3 was applied at 1 month preceding anthesis. This application coincided with appearance of the earliest infloresceuces. GA3 application after the onset of anthesis did not alter the flowering pattern of trees during the remaining 4 months of the flowering season. Results suggest that GA3 inhibits flower initiation, but has no effect on raceme emergence after flower bud differentiation has occurred. The relationship between flower initiation and raceme emergence will be discussed.

Free access

Uniconazole (0.2 g a.i. per cm trunk diameter) was applied as a soil drench to 2-year-old potted macadamia (Macadamia integrifolia Maiden & Betche) trees, and reapplied yearly for 4 additional years. Uniconazole significantly reduced tree height and trunk diameter 1 year after initial treatment, and suppressed shoot extension for the duration of the study. It significantly increased flowering the second year after initial treatment, the first year that both the control and treated trees flowered. Subsequently, no differences in flowering were observed until the fifth year, when flowering was significantly less in treated trees, probably due to reduced shoot and trunk growth and tip dieback. Chemical name used: E-1-(p-chlorophenyl)-4,-4-dimethyl-2-(1,2,4-triazole-1-penten-3-ol) (uniconazole).

Free access

Flowering of Macadamia integrifolia trees was monitored following application of 220 mg/liter gibberellic acid (GA3) at various times preceding the onset of the flowering season. In untreated trees, flowering extended over a 4-5 month period. When GA3 was applied at 2, 3 and 4 months before the onset of anthesis, raceme production during the entire flowering season was inhibited. A slight reduction in raceme production was observed when GA3 was applied at 1 month preceding anthesis. This application coincided with appearance of the earliest infloresceuces. GA3 application after the onset of anthesis did not alter the flowering pattern of trees during the remaining 4 months of the flowering season. Results suggest that GA3 inhibits flower initiation, but has no effect on raceme emergence after flower bud differentiation has occurred. The relationship between flower initiation and raceme emergence will be discussed.

Free access

Uniconazole at 0.20 g-ram of a.i./cm of trunk diameter was applied as a drench to potted 2 year-old M. integrifolia cv. Kau trees in July 1990, and reapplied in August 1991, August 1992 and August 1993. Observations between December 1991 to December 1993 showed that elongation of newly emerging vegetative flushes was inhibitedwithin 6 months after the initial treatment. Shoots had a compact appearance, and the overall height of the trees was shorter than in untreated trees. By December 1993, diameters of the treated trees were also signficantly smaller than the controls. Uniconazole increased the number of racemes, number of racemes with mature fruit set and fruit production in young trees during the 1992 and 1993 seasons. The effect was more pronounced in 1992 compared to 1993. Results from this study show that young macadamia trees can be brought into heavier bearing at an early age with uniconazole treatments.

Free access

The objective of this study was to develop models to predict the occurrence of the flowering peak of macadamia nut (Macadamia integrifolia). At Hilo and Kona, weather and `Ikaika' flowering data were collected. The best model that described the time from the starting date of the flowering season to the highest flowering peak was days = 249.15 + 0.12 (total growing degree days) - 5.81 (maximum temperature) - 6.26 (minimum temperature). The model predicted the highest peak 4 days before it occurred at Hilo and 4 days after it occurred at Kona. Two statistical models, one for each location, were developed to predict the time from the starting date of the flowering season to the first peak. At Hilo, the best model was days = 118.61 - 0.11 (total growing degree days) + 0.000168 (total solar radiation). The model predicted the first peak 1 day before it occurred in the field. The best model at Kona was days = (-156.34) + 12.67 (minimum temperature) + 0.01 (total growing degree days). The model predicted the first peak on the day it occurred in the field. These models may aid growers in predicting the flowering peak so that bees can be brought into orchards at the proper time to increase cross-pollination.

Free access

Chinese rose beetle (CRB) (Adoretus sinicus Burmeister) preferential feeding based on leaf carbohydrate content was determined using `Hawaiian Wonder' snap bean (Phaseohs vulgaris L.) plants exposed to 0% ,40%, or 80% shade for 2 days. Plants exposed to 0% shade before CRBs fed had 8.5% leaf area consumed compared with 2.8% and 3.6% for 40% and 80% shade, respectively. Leaves exposed to 0% shade had a higher carbohydrate content than leaves exposed to 40% and 80% shade. Darkening the apical and subtending leaf with aluminum foil for 1 day before CRBs fed shifted CRB feeding from heavy feeding on the apical leaf and light feeding on the subtending leaves to a reversed feeding pattern-light feeding on the apical leaf and heavy feeding on the subtending leaves. Three snap bean cultivars grown under similar environmental conditions were compared to `Hawaiian Wonder' using a unifoliate split-leaf technique. Cultivars with a high endogenous carbohydrate content in their leaves had a higher percentage of leaf area consumed by CRBs than cultivars with low endogenous carbohydrates. This report suggests that high endogenous carbohydrate content in leaves stimulates CRB feeding.

Free access

Unsynchronized flowering and fruit ripening of coffee prohibits mechanical harvesting and results in high labor costs. Coffee (C.arabica c. Guatemalan) trees were sprayed at the beginning of the 1988 and 1989 flowering season with solutions of benzyladenine (BA), gibberellic acid GA3 (GA), and Promalin (PR) or were pruned in 1988 to determine effects on synchronizing flowering and ripening. Growth regulators affected the time to flowering and harvesting compared to the control, however, treatment effects were dependent on the time of growth regulator application. Application of PR and GA at 100 mg/l in Jan 1988 shortened the average days to flowering by 16 and 13 days, and the average days to harvest by 15 days compared to the control. Pruning of three apical nodes of primary lateral branches in Feb 1988 caused delays in flowering, reduced flower and fruit number per tree, and caused branch dieback.

Free access