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  • Author or Editor: M. M. Nelson x
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Abstract

Hastened fruit maturation following MH application to apricot trees was found to be associated with MH-induced seed abortion. The time and degree to which premature abscission of seedless fruits occurred was related to time of resumption of shoot growth and to crop load. Fruits in which the seeds aborted early in the season grew like those containing seeds when competition between their growth and vegetative growth was reduced to a minimum.

Open Access

Abstract

Alternate bearing in the pistachio, in contrast to other tree fruit species, is caused by abscission of abundant inflorescence buds during the heavy crop year. Bud abscission was found to increase as the number of nuts per branch increased. Branch girdling between the developing nuts on 1-year-old wood and the inflorescence buds on current wood reduced bud abscission to practically the same extent as that resulting from removing the young nuts from the branches. Application of para-chlorophenoxyacetic acid delayed but did not alter the degree of bud abscission. The greater the crop load in 1970, the shorter the shoot growth in length in 1971.

Open Access

Abstract

In contrast to other fruit tree species that produce flower buds in limited quantity at the same time a heavy crop is being produced, the pistachio (Pistacia vera L.) produces abundant inflorescence buds which, for the most part, abscise during the summer. Thus, alternate bearing in the pistachio is effected by a unique mechanism. Evidence is presented which suggests that the abscission of the inflorescence buds is the result of assimilate depletion when a heavy crop is produced.

Open Access

Abstract

A resurgence of interest has been focused on the search for a chemical which would evolve ethylene after foliar application and thus induce plant growth responses. One such compound, 2-chloroethylphosphonic acid (Ethrel), has been under study as a peach thinner at the University of California orchards at Davis. It has been assumed that the peach thinning induced by Ethrel was caused by the ethylene gas which is released after application. As an adjunct to the work with Ethrel, we were interested in the thinning action of ethylene gas and the resultant gross effects on the treated tree parts.

Open Access

Abstract

3-CPA when applied to peach moves slowly, accumulating in the margins and veins of leaves, and the epidermal and sub-epidermal layers in the fruit and the micropylar end of the ovule. Equal degrees of fruit thinning resulted when fruit or leaves alone were treated with 3-CPA. Treating both leaves and fruit resulted in an additive thinning effect. Uniform spray coverage is emphasized to obtain uniform thinning results.

Open Access
Authors: and

We examined an in vitro culture method for propagating unconditioned, field-grown broccoli (Brassica oleracea L. Botrytis group) from peduncle explants by testing 20 cultivars in fall and spring. Propagation was affected significantly by genotype (cultivar) and season. The percentage of explants regenerating shoots was significantly higher for cultivars grown in spring (17% to 100%) than in fall (0% to 66%). Shoot regeneration from explants of plants within a cultivar also varied significantly (0% to 100%). Additionally, the number of propagules produced per explant was influenced by cultivar and was highly correlated with the percentage of explants regenerating shoots. This method for propagating field-grown broccoli lines is useful, but its applicability can be limited by genetic and environmental factors.

Free access

Abstract

Fig fruits treated with 2-chloroethylphosphonic acid (Ethrel) during Period I (initial rapid growth) ceased growth and abscissed. Treatment during Period II (slow growth) stimulated growth and maturation, but quality equal to that of later maturing control fruits was not attained unless the fruits were treated late in Period II. Although Ethrel-treated fruits matured from two to more than three weeks earlier than control fruits, their ultimate average diameter, fresh and dry weights were not significantly different from the control.

Open Access

Abstract

As with most other drupe fruits, curves representing growth in length and diameter of seeded pistachio nuts reveal 3 distinct periods, 2 cycles of rapid growth separated by 1 of slow growth. Growth curves of seedless pistachios, however, are similar to those of almond (a dry drupe) in which a rapid growth phase is followed by one of inconsequential growth. Embryo development in the pistachio is delayed longer than in other drupes; it is not evident macroscopically until about 30 days after completion of the initial period of pericarp growth. Seedlessness, the symptoms of which are not manifest until after most pericarp growth has occurred, frequently appears to be associated with necrosis of the apical portion of the funiculus supporting the seed, and consequent seed abortion.

Open Access

Abstract

Foliar sprays of 2-chloroethylphosphonic acid (ethephon) at petal fall or when the ovules had grown to 4 or 9 mm resulted in an acceptable level of thinning on ‘Johnson’ and ‘Halford’ peach. Thinning of ‘Fay Elberta’ with ethephon occurred at the 5- to 9-mm ovule length. Foliar sprays of 1,1,5,5-tetramethyl-3-dimethylaminodithiobiuret (ER-3952) effectively thinned ‘Johnson’ and ‘Halford’ at the 4- to 9-mm ovule length but gave poor results with ‘Fay Elberta’.

Open Access

Abstract

The rate and total germination of cucumber (Cucumis sativus L.) seeds incubated at 12°C was markedly increased by acetone infusion with fusicoccin (FC). Gibberellic acid (GA4/7) was less effective than FC but more effective than GA3 or (2-chloroethyl)phosphoric acid (ethe-phon) in promoting rapid germination. Infusion of GA4/7 alone or in combination with kinetin and/or ethephon into muskmelon (Cucumis melo L.) seeds increased total germination at 16°C The growth regulators were generally not effective in promoting low temperature germination of watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai) seeds.

Open Access