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  • Author or Editor: Mike A. Nagao x
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Abstract

The abscission of young Macadamia integrifolia Maiden & Betche fruit was investigated in vitro with explants consisting of a single fruit attached at the distal end of a segment of the peduncle. A 30% reduction in fruit removal force (FRF) of explants incubated in distilled water was evident within 48 hr after excision and was correlated with increased ethylene production. Pretreatment of explants with 5 and 10 mm ethephon accelerated FRF reduction. Pretreatment with increasing concentrations of silver nitrate (AgNO3) to 1.47 mm or AOA to 0.05 mm, inhibited the reduction in FRF. FRF reduction also was inhibited by 1000 μm NAA and 100 pM 2,4-D. GA3 and BA had no effect. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon); 1-naphthaleneacetic acid (NAA); (2,4-dichloro- phenoxy)acetic acid (2,4-D); gibberellic acid (GA3); N-(phenylmethyl)-H-purin-6-amine (BA); (aminooxy)acetic acid (AOA).

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

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

Two types of raphides and 2 types of raphid idioblasts were observed in Dieffenbachia maculata (Lodd.) G. Don cv. Rudolph Roehrs. Small raphides, about 25 μm long and 0.4 μm wide, with barbs and grooves were found in idioblast cells similar in shape to adjacent ground parenchyma cells. Larger raphides, about 120 μm long and 4 μm wide, with wide grooves were found in spindle shaped, obtuse ended idioblasts, about 165 μm long and 40 μm in diameter.

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

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

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

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

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

Flower induction of longan (Dimocarpus longan) with potassium chlorate has improved the availability of longan fruit, but potassium chlorate is potentially explosive and often difficult to purchase, transport, and store. Previous reports suggested that hypochlorite enhances natural longan flower induction. This study is the first to demonstrate that chlorite- and hypochlorite- (bleach) induced off-season longan flowering is similar to chlorate-treated trees. Hypochlorite induction of flowering with bleach was likely the result of chlorate in the bleach solution. Chlorate was present in the leachate from potted longan trees treated with bleach and was detected in bleach before soil application. The quantity of chlorate found in bleach induced flowering to the same or greater extent as equivalent quantities of potassium chlorate, suggesting chlorate is an a.i. responsible for longan flowering.

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