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  • Author or Editor: S. Lavee x
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Abstract

Peach leaf and flower buds showed different light requirements for opening. Leaf bud opening required light, the active range for the process was 600 - 690 m. Flower bud opening was relatively light independent. Green light or low light intensities slightly promoted it, while red and white light or high intensities caused some inhibition.

Open Access
Authors: and

Abstract

An in vitro laboratory model for the study of leaf abscission induced by (2-chloroethyl)phosphonic acid (ethephon) was developed. Feeding of ethephon through the base of excised shoots of ‘Manzanillo’ olive (Olea europaea L.) resulted in a time- and concentration-dependent sequential increase in ethylene evolution from, and abscission of the leaves along, these shoots. The extent of leaf abscission was correlated with the early rate of ethylene evolution from individual leaves. A minimum induction period of about 50 hr was needed to induce the first leaf abscission. An ethephon pulse of 500 mg/liter for 1 hr or 250 mg/liters for 2 hr was enough to induce about 90% leaf abscission.

Open Access
Authors: and

Abstract

Leaves, stems, inflorescences and fruits from excised ‘Manzanillo’ shoots of olive (Olea europaea L.) basally fed with (2-chloroethyl)phosphonic acid (ethephon) were used to study the relation between ethylene evolution and abscission. The abscission response of the various organs to ethephon was directly related to concentration and length of exposure to a given treatment concentration. After an ethephon pulse treatment, stem tissues evolved increased levels of ethylene for a longer period than leaves, whereas the effect on petioles was shorter than leaves. Leaf abscission occurred after ethylene evolution from them declined. Inflorescences did not abscise even though induced to evolve high levels of ethylene. The rate of leaf ethylene evolution and abscission was higher in reproductive shoots than in nonreproductive shoots and was influenced by the number of inflorescences present on the shoot. Leaves on shoots with a large number of inflorescences senesced more rapidly than those with fewer inflorescences in our in vitro system and developed a marked chlorosis after 24 hours. Ethylene evolution from fruits on ethephon-fed shoots was low and abscission was erratic. The abscission layer between fruit and stem developed at no specific site along the pedicel or peduncle. Probable reasons for the specific levels and duration of ethylene evolution from the various tissues after an ethephon pulse are discussed.

Open Access
Authors: and

Abstract

The acid methanol extract from the exocarp of l,2-l4C(2-chloroethyl)ohosphonic acid 14c-CEPA treated peach fruits contained 4 radioactive substances in addition to 14c-CEPA. In the petroleum ether extract 3 such substances were found. The total radioactivity of these substances, compared to the 14c-CEPA and its inherent contaminants recovered from the peach fruit exocarp, did not exceed 3%. Neither the petroleum ether nor acid methanol fractions contained a true metabolite of CEPA as a result of reactions involving living tissue. The nature of the radioactive fractions and their significance is discussed. Additional examinations were made on the stability of these fractions and their distribution in the fruit. Sugars were involved in the formation of one of the major radioactive fractions.

Open Access
Authors: and

Abstract

Penetration of ethephon into peach fruits was determined using l,2-14C(2-chloroethyl)-phosphonic acid (l4C-CEPA). Most of the activity accumulated in the fruit exocarp, with only minute amounts in the mesocarp. No notable lateral translocation was apparent. The results suggest that active degradation of the compound takes place in the young fruit while in the older peach fruits the rate of l4C-CEPA degradation takes place at a slower rate.

Open Access
Authors: and

Abstract

With controlled temperatures low temperature efficiency in releasing peach buds from dormancy follows an optimum curve in which 6°C is the optimum for average lateral leaf buds and 10°C is about half as efficient. “Weighted chilling hours” instead of “chilling hours” was proposed as a chilling measurement criterion. A high temp of 21°C, when alternated daily with low temp, nullified the low temp effect; a high of 18°C had no effect. Interrupting the chilling by 2 separate periods of 11 and 12 days at 20°C did not show any nullifying effect, but greatly enhanced lateral leaf bud break.

Open Access
Authors: and

Abstract

Kinetin was found to induce anthocyanin formation in green ‘Manzanillo’ olives and to promote softening slightly. A concn effect in promoting the pigment was found up to 50 ppm. The duration of kinetin treatment affected the amount of anthocyanin formed. The kinetin effect on anthocyanin formation appeared to be independent of that on softening.

Open Access
Authors: and

Abstract

In a study of the purity and stability of 1,2-14C(2-chloroethyl)phosphonic acid when used as a radioactive tracer, 3 out of 4 radioactive impurities detected were found in all standards tested. In addition, 7 other non-radioactive compounds were found in 1 of the 14C-CEPA standards. One contaminant was found to be in equilibrium with the 14C-CEPA. No contaminants were detected on GLC of the non-radioactive CEPA standard. 14C-CEPA was non-enzymatically bound to some constituents in extracts of peach fruits, cv. Halford, particularly to sugars.

Open Access
Authors: and

Abstract

Ethephon (2-chloroethyl phosphonic acid) and Alsol (2-chloroethyl-tris-(2-methoxy-ethoxy)-silane) are effective in reducing the fruit removal force (FRF) required for harvesting fruit of olive (Olea europaea L.). The lowest FRF value was achieved with Alsol within 2 to 3 days after treatment, but only after 7 to 8 days with ethephon. Raising the pH of the ethephon spraying solution to 7.0 increased ethylene evolution markedly and decreased both the FRF value and the time needed to achieve this reduced value.

Open Access

Abstract

Control of woolly breakdown in ‘Elberta’ peaches was obtained by removal of the fruit to ambient room temperature (23–25°C) for 48 hours after 2 and 4 weeks' storage at 0°C. A 6 weeks' storage life was thus obtained. Warming the fruit after cold storage intervals shorter than 2 weeks was less effective after longer storage periods; the disorder was often enhanced by removal to room temperature.

A hypothesis to explain the development of woolly breakdown on the basis of these and previous data is discussed. It is suggested that further prolongation of storage could be obtained by repeated exposures to room temperature.

Open Access