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  • Author or Editor: A. H. Halevy x
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Abstract

The use of tissue culture techniques for the propagation of Strelitzia reginae Banks has invariably failed due to oxidative browning of the explants. The brown exudate which diffuses into the medium is detrimental to further development of the in vitro explant, which eventually becomes necrotic and dies. S. reginae competence to respond to in vitro culture is thus dependent on minimizing and slowing down the browning of the explant. Terminal and axillary buds treated with antioxidant solution by total submergence for 24 hours, and cultured on an agar medium with charcoal, or on paper bridges in liquid medium with dithiothreitol, were found to be capable of growth and further shoot proliferation.

Open Access
Authors: and

Abstract

The causes for petal blackening of ‘Baccara’ rose petals and the differences between normal (red) and black flowers were investigated. Black flowers are frequent in field grown plants and dark red ones in those grown in unheated greenhouses during the winter. Two anthocyanins were isolated and identified: cyanidin 3,5-diglucoside (cyanin) and pelargonidin 3,5-diglucoside. The 2 pigments were found in both red and black petals. The content of both anthocyanin pigments as well as that of tannins, was several times higher in black flowers than in normal flowers. High polyphenolase activity was found in black petals, while no activity could be detected in normal red flowers. The blackening phenomenon is attributed to an increase in anthocyanin content at low temperatures, and to the accumulation of oxidation products of polyphenols.

Open Access
Authors: and

Abstract

Flower opening failure was encountered in cut iris flowers (cvs. Wedgwood and Prof. Blaauw) stored at low temperature for 4 days, then held for an additional day at 22°C. The cause was found to be water stress in the flowers as a result of a stem blockage developing during storage and shipment. In flowers harvested with the basalplate of the bulb attached to the stem, the plug apparently develops up into the stem. This failure of flower opening was overcome by pre-shipment cutting of the base of flowers harvested without the basalplate and conditioning in warm water. Conditioning with a preservative solution improved coloration. A new method for water flow resistance measurement in stem sections is described.

Open Access
Authors: and

Abstract

By various pinching, pruning and grafting experiments and by growing explant buds in nutrient culture, it was demonstrated that buds of varying nodes on the main stem of pepper plants differ in their readiness to flower. The upper ones, in proximity to the 1st branch-off, regardless of whether the 1st flower has actually appeared or is only about to do so, are close to flowering; whereas, the lower ones, situated farther from the first flower, are late to flower. The lowest buds are also the most juvenile and root easily. The state of juvenility decreases gradually towards the apex.

Open Access
Authors: and

Abstract

The removal of cotyledons retarded the development and flowering of California Wonder pepper. The effective action of the cotyledons in plant development lasted for about 7 days, the time required for the first pair of leaves to reach cotyledonary size. Removal after 7 days did not affect further development. Removal of the first pair of true leaves did not retard flowering.

Open Access

Abstract

Natural daylengths in summer at 38°N latitude are partially inductive for Chrysanthemum morifolium, Ramat. cvs. Albatross and Escapade. This is indicated by the number of nodes to the terminal bud in natural daylength compared to a night break treatment. One week of short days (SD) is enough to fully satisfy induction of the terminal bud as expressed by the number of nodes to flower. Three to four weeks SD are ample for the development of high quality flowers equal to those grown under continuous SD; there was no significant delay in flowering.

Open Access

Abstract

Direct coating of flowers of carnation (Dianthus caryophyllus L. cv White Sim) with Ag ions by spraying or momentarily dipping flower heads with AgNO3 (50-100 ppm) extended cut flower longevity and counteracted the enhancing effect of ethephon on senescence. Treating stems and leaves similarly had little or no effect. Stem base treatment with 1000 ppm was much less effective than treating the flower directly. Maximum efficiency of the AgNO3 spray was obtained when a period of 2 hours elapsed between the AgNO3 treatment and exposure to ethephon. In spite of the great extension in longevity, silver spray has limited practical use since it causes petal spotting.

Open Access

Abstract

The flower yield of glasshouse roses is made up of 3 components: number of flowers appearing in the upper buds of the branches, number of flowering branches from the plant, and number of flowers appearing on ‘other’ parts of the plant. The number of flowers produced is the product of the number of buds sprouted times the percentage that flower. Flowering potential of the uppermost bud on a branch is greater and the rate of flower abortion (“blindness”) is less, than of buds produced lower on the branch Reduction in yield found during winter in cv. Baccara was mainly due to “blindness” of the uppermost bud. ‘Marimba’ was more productive than ‘Baccara’ due to a larger number of both flowers per branch and flowering branches per plant. The productivity of ‘Baccara’ when grafted on R. indica was greater than that of ungrafted plants because of the greater number of flowering branches produced on grafted plants.

Open Access

Abstract

The interaction of the gibberellins GA3 and GA4+7 with SADH on growth and sex expression was tested on andromonoecious muskmelon (Cucumis melo L. cv. Ananas PMR). SADH effectively reduced internode length and increased female tendency of plants. GA4+7 had an opposite effect on both growth and sex expression. GA3 was much less effective in both respects. The growth regulators were mutually antagonistic when plants were treated with both GA and SADH. The endogenous level of gibberellin decreased in SADH-treated plants 2 and 7 days after treatment. Gibberellin content reached the level of untreated plants 2 weeks after treatment, some time before the growth retarding effect of SADH treatment disappeared. These results indicate that the effect of its effect on the endogenous levels of gibberellin.

Open Access

Abstract

One year old ‘Baccara’ roses budded on Rosa chinensis cv. ‘Major’ were planted in large containers and irrigated for 90 days with water containing various salinity levels (ca. 0.4 to 7.8 EC × 103). Salinization was obtained by either chloride or nitrate salts. Irrigation with water containing chlorides was more detrimental than with water containing nitrates at the same level of salinity. Stem and leaf growth and water uptake decreased with increasing soil salinity. A slight decrease was noticed even at 2.0 mmhos/cm, containing chlorides, the damage increasing with time, indicating a cumulative effect of soil salinity even at low salinity level.

Open Access