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David Ruiz, Manuel Rubio, Pedro Martínez-Gómez, Jesús López-Alcolea, Federico Dicenta, Encarna Ortega, María Dolores Nortes, Antonio Molina, Antonio Molina Jr., and Jose Egea

‘Cebasred’ and ‘Primorosa’ are very early-season ripening apricot cultivars ( Prunus armeniaca L.) which join high productivity, high fruit quality and attractiveness, with resistance to Plum pox virus (PPV), a valuable characteristic due to the

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Stephen M. Southwick and Kitren Glozer

Many commercially grown stone fruit including apricots (Prunus armeniaca L.), peaches and nectarines [P. persica (L.) Batsch], plums (P. salicina Lindl., P. domestica L.), prunes (P. domestica L.), and pluots (P. salicina × P. armeniaca) have a tendency to produce high numbers of flowers. These flowers often set and produce more fruit than trees can adequately size to meet market standards. When excessive fruit set occurs, removal of fruit by hand thinning is necessary in most Prunus L. species to ensure that remaining fruit attain marketable size and reduce biennial bearing. Over the years there have been numerous attempts to find chemical or physical techniques that would help to reduce the costs associated with and improve efficiencies of hand thinning, however, alternate strategies to hand thinning have not been widely adopted for stone fruit production. In the past 10 years, several chemical treatments have shown promise for reducing hand thinning needs in stone fruit. Management of flowering by chemically reducing the number of flowers has been particularly promising on stone fruit in the Sacramento and San Joaquin Valleys of California. Gibberellins (GAs) applied during May through July, have reduced flowering in the following season in many stone fruit cultivars without affecting percentage of flowers producing fruit. As a result, fruit numbers are reduced, the need for hand thinning is reduced and in some cases eliminated, and better quality fruit are produced. There are risks associated with reducing flower number before climatic conditions during bloom or final fruit set are known. However, given the changes in labor costs and market demands, the benefits may outweigh the risks. This paper reviews relevant literature on thinning of stone fruit by gibberellins, and summarizes research reports of fruit thinning with GAs conducted between 1987 and the present in California. The term thin or chemically thin with regard to the action of GA on floral buds is used in this paper, consistent with the literature, although the authors recognize that the action of GA is primarily to inhibit the initiation of floral apices, rather than reduce the number of preformed flowers. At relatively high concentrations, GA may also kill floral buds. Chemical names used: gibberellic acid, potassium gibberellate.

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M.A. Moreno, M.C. Tabuenca, and R. Cambra

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Dangyang Ke and Adel A. Kader

Fruits of `Bing' cherry (Prunus avium L.), `Red Jim' nectarine (Prunuspersica L.), `Angeleno' plum (Prunus salicina, L.), `Yellow Newtown' and `Granny Smith' apples (Malus domestica Borkh.), and `20th Century' pear (Pyrus serotina L.) were treated with 0.25% or 0.02% O2 (balance N2) at 0, 5, or 10C to study the effects of these insecticidal low-O2 atmospheres on their postharvest physiology and quality attributes. Development of alcoholic off-flavor was associated with ethanol accumulation, which was the most common and important detrimental effect that limited fruit tolerance to low O2. Relatively higher storage temperature (T), higher respiration rate (R), and greater resistance to gas diffusion (r) enhanced while relatively higher O2 concentration (C) and higher soluble solids concentration (SSC) reduced off-flavor development. Using a SAS computer program to do multiple regression analysis with T, C, R, r, and SSC as variables, models were developed for prediction of fruit tolerance to insecticidal low-O, atmospheres. Comparison of fruit tolerances and published information on the times required to completely kill specific insects by O2 levels at or below 1% suggests that low-O2 atmospheres have a good potential for use as postharvest quarantine treatments for some fruits.

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John P. Edstrom, Joseph H. Connell, Warren C. Micke, and James T. Yeager

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W.R. Okie, G.L. Reighard, T.G. Beckman, A.P. Nyczepir, C.C. Reilly, E.I. Zehr, W.C. Newall Jr., and D.W. Cain

Long-term field trials of a wide range of peach [Prunus persica (L.) Batsch] germplasm on two peach tree short-life (PTSL) sites revealed marked differences in survival among lines. Generally, cuttings and seedlings of a given line performed similarly, as did ungrafted seedlings and their counterparts grafted to a commercial cultivar. No apparent relationship existed between a line's chilling requirement and survival. B594520-9 survived best in Georgia and South Carolina, providing significantly greater longevity than Lovell, the standard rootstock for use on PTSL sites. B594520-9 is derived from root-knot-nematode-resistant parentage, and progeny of surviving seedlings have demonstrated root-knot resistance similar to Nemaguard seedlings.

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J.A. Plummer and D.T. Bell

Australian everlasting daisies (Asteraceae, Tribe Inulae) have considerable potential as bedding plants, but little is known about their germination requirements. Florets have a papery corolla, which imparts considerable longevity of the floral display even under dry conditions. The influence of temperature, light and gibberellic acid (GA3) was determined for several species with spectacular floral displays. Germination in petri dishes was optimum over the range of 10 to 20C, with little or no germination at extreme temperatures. Light stimulated germination in most species with little or no germination occurring under dark conditions. In the dark, GA3 stimulated germination to similar levels observed in light-treated seeds. In most species, germination in the dark was optimum over the GA3 concentration range 1 to 100 mg·liter–1, and 500 mg·liter–1 was often inhibitory.

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Chad E. Finn and John R. Clark

- to late bloom; self-incompatible, known pollinizers are Sweetcot, Portici, Early Blush; appears resistant to Dideron and Marcus Plum pox virus isolates. BO 81604334 (Boreale ® ). A self-compatible, skin-cracking tolerant apricot. Origin