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during long-term cold storage. ‘RubyS’ showed strong resistance to the most serious apple pests and diseases as does ‘Alpsotome’ cultivar and is self-thinning as well. Overall, the results indicated that tree characteristics and fruit quality of ‘RubyS

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cooling (Kool-Cel ® Aluminum PDR system, 10.2 cm cellulose pad; Acme Engineering & Manufacturing Corp., Mukogee, OK). Transplant preparation. The heirloom tomato cultivar Cherokee Purple was self-grafted as the control (C) and scion on ‘Beaufort’ (B; De

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Approximately twenty native almond species have been described. Representative germplasm from seven of these are present in UC collections and have been used in crossing. Three specific breeding lines utilizing these species are described. One (1980 series) involved increasing yield potential through selection of high blossom density following gene introgression from Prunus fenzliana. A second involved incorporation of self-fertility, late bloom, smaller tree size, early maturity, high blossom density, and desirable nut characters from Prunus webbii into commercial breeding lines. A self-fertile selection resembling `Nonpareil' has been obtained from this material. The third line involves transmission of a unique thin, netted-surfaced, hard-shell phenotype from Prunus argentea.

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`Redhaven' peach trees [Prunus persica (L.) Batsch.] on their own roots or budded to seven rootstock [`Bailey', `Siberian C', `Lovell', `Halford' (seedlings), GF 655.2, GF 677 (`Amandier'), or `Damas' (GF 1869) (clonal)] were evaluated for rootstock influence on flower bud hardiness, live pistils at bloom, thinning requirements, marketable yield, and production efficiency after exposure to temperatures lower than – 23C in 1987 and to - 26C in 1988. In 1987, flower bud hardiness was as great on `Siberian C' as on own-rooted `Redhaven' and greater than on the other rootstock. Fewer live pistils were observed during bloom on GF 677 than on `Siberian C', `Lovell', `Damas', or self-rooted trees in 1987. In 1988, flower bud hardiness was greater on `Siberian C' and `Bailey' than on GF 677. At bloom, `Lovell' and `Siberian C' rootstock carried more flowers with live pistils than `Damas'.`Siberian C' and `Lovell' required significantly greater fruit thinning than all other rootstock and self-rooted trees. GF 677 produced a larger marketable crop than GF 655.2 or `Damas'. In addition, `Bailey', `Lovell', and self-rooted trees produced a significantly larger crop than `Damas'. No significant rootstock effect on production efficiency was detected in either year. Tree vigor during the growing season preceding each freeze did not significantly influence flower bud survival or productivity.

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Under California conditions `Granny Smith' apple does not “self-thin” sufficiently to promote good return bloom nor to provide fruit size desired for the fresh market. Preliminary studies conducted during 1985-87 indicated that 1-naphthyl N-methylcarbamate (carbaryl), 1-naphthaleneacetic Acid (NAA), and 1-naphthaleneacetamide (NAD) could be useful for thinning `Granny Smith'. Detailed studies conducted in 1988 and 89 using dilute handgun applications demonstrated that all 3 materials provided reasonable thinning as shown by fruit set counts. NAA and NAD tended to slow fruit growth as compared to carbaryl. Carbaryl tended to uniformly thin clusters while NAA and NAD were more likely to remove all the fruit from some clusters and few fruit from others, especially in 1988. Compared to the control, all materials applied in 1988 improved return bloom in 1989 with carbaryl having a slightly greater effect than NAA and NAD. As a result of these studies carbaryl at 1.7 to 2.2 kg (active ingredient) per ha as a dilute application is being suggested for grower trials in California.

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Under California conditions `Granny Smith' apple does not “self-thin” sufficiently to promote good return bloom nor to provide fruit size desired for the fresh market. Preliminary studies conducted during 1985-87 indicated that 1-naphthyl N-methylcarbamate (carbaryl), 1-naphthaleneacetic Acid (NAA), and 1-naphthaleneacetamide (NAD) could be useful for thinning `Granny Smith'. Detailed studies conducted in 1988 and 89 using dilute handgun applications demonstrated that all 3 materials provided reasonable thinning as shown by fruit set counts. NAA and NAD tended to slow fruit growth as compared to carbaryl. Carbaryl tended to uniformly thin clusters while NAA and NAD were more likely to remove all the fruit from some clusters and few fruit from others, especially in 1988. Compared to the control, all materials applied in 1988 improved return bloom in 1989 with carbaryl having a slightly greater effect than NAA and NAD. As a result of these studies carbaryl at 1.7 to 2.2 kg (active ingredient) per ha as a dilute application is being suggested for grower trials in California.

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Scaevola sericea is a plant native to Guam. The normal flower has petals that are usually white with slight, thin, magenta bands. The seeds for these plants were collected from a parent plant with dark magenta flowers growing in the wild. Plans are to self the parent plant to observe the variation in the seedling population. Four selections of S. serica were made and are being propagated for public release. Three of these selections have white petals with broad magenta bands or spots on the flower petals, in contrast to the usual white flower. One selection has a floral fragrance.

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Abstract

The ability of plants to slough off organs by an active separation of cells seems to be distinctive to the higher plants. It is an adaptation which permits self-pruning of aged leaves, ripe fruits, or unset flowers and the lessening of the number of stem apices. The interest in abscission as an active physiological process is heightened by the fact that it is becoming increasingly important as agricultural technology requires increasing mechanization – witness the pressing need for regulation of defoliation, fruit thinning, and fruit abscission for mechanical harvesting. The body of literature on abscission has become very large (12), and it would seem to be useful to ask ourselves to define the morphological events involved in abscission, the principal regulatory agents involved, and the main cellular processes in abscission development.

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It is well established that peach ( Prunus persica L. Batsch) requires some form of thinning early in the growing season to produce a crop of marketable size fruit ( Byers et al., 2003 ; Havis, 1962 ; Tukey and Einset, 1938 ). Early studies by

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Carbohydrates fulfill several roles in plants; as building stones, as a source of energy, and also, as recently demonstrated, as modulators of gene expression. Primary, photosynthetic production of carbohydrates (as well as their release from tree reserves) is linked with the carbohydrate-consuming processes through complex feedback and feedforward regulatory loops. With horticultural productivity as the goal, maximum resources must be diverted toward reproductive processes. Persistence of viable vegetative structures must be secured, however, to enable the function of tree systems and ensure the tree's potential for future years. Thus, in the carbohydrate resource allocation of fruit trees, a delicate balance must be maintained between the vegetative and reproductive needs. Flowering, fruit set, and fruit enlargement have been identified as three distinct, critical stages within the annual course of yield formation in citrus. While each of these stages has its own, salient developmental features, all require considerable amounts of energy and their occurrence is dependent, at least to some extent, on the availability of carbohydrates. Whereas flower bud differentiation may require only a threshold level of carbohydrates, floral development and anthesis consume large amounts of carbohydrates due to the very large number of flowers per tree and their high rates of respiration. Fruit set is more closely linked to carbohydrate levels. Fruitlet abscission acts as a self-thinning, feedback mechanism to adjust the tree's fruit population to the carbohydrate supply. This mechanism does not operate properly in certain mandarin cultivars, resulting in alternate bearing. The acquisition of fruit size appears to be most directly correlated with the availability of photosynthate. Elimination of alternative sinks by extreme thinning and girdling brings about tremendous increases in fruit size. The fruit's vascular system also expands in response to the increase in photosynthate availability. A dynamic model has been constructed to provide a quantitative analysis of citrus trees' carbon balance during the annual productivity cycle.

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