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Randall P. Niedz, Michael G. Bausher, and C. Jack Hearn

Fresh pollen from Citrus tachibana Macf. was oven-dried (37C), freeze-dried, or placed into anhydrous acetone, and stored at -20C over silica gel. Pollen freeze-dried or stored in anhydrous acetone did not germinate 24 hours after treatment; oven-dried pollen germinated in 1 hour and was comparable to fresh pollen. Pollen that was oven-dried for 12 hours and stored for 1 year was used to pollinate a monoembryonic hybrid of `Temple' (origin unknown) × `Orlando' (C. paradisi Macf. `Duncan' ×C. reticulata Blanco `Dancy'). Glutamate-oxaloacetate transaminase (GOT) isozyme profiles verified progeny hybridity.

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Timothy F. Wenslaff and Paul M. Lyrene

Two diploid yellowleaf Vaccinium elliottii Chapmn. clones were pollinated with pollen from the tetraploid southern highbush cultivar `Misty' (largely V. corymbosum L). These interspecific crosses, which normally yield few hybrids because of a triploid block, were made with and without the use of V. elliottii mentor pollen mixed with V. corymbosum pollen. Mentoring had no effect on the number of hybrids produced when V. elliottii `Silverhill' was the seed parent, but when V. elliottii `Oleno' was the seed parent, no hybrids were produced unless mentor pollen was utilized. The difference was postulated to be a greater ability to produce one-seeded berries in `Silverhill' than in `Oleno'.

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J.W. Grosser, J. Jiang, F.A.A. Mourao-Fo, E.S. Louzada, K. Baergen, J.L. Chandler, and F.G. Gmitter Jr.

Seedlessness is an important breeding objective of most citrus scion improvement programs, but production of quality seedless triploid citrus via interploid crosses has historically been limited by the low quality of available tetraploid parents. Production of tetraploid hybrid parents from elite diploid scion cultivars via protoplast fusion is now a practical strategy, and numerous hybrids can be produced on a timely basis from a wide range of parents. Such hybrids can be used as pollen parents in interploid crosses to generate improved seedless triploid fresh fruit cultivars. Herein we report the production of 15 such hybrids from 17 different parents, including sweet orange [Citrus sinensis (L.) Osbeck], mandarin/tangerine (C. reticulata Blanco), grapefruit (C. paradisi Macf.), pummelo [C. grandis (L.) Osbeck], tangor (C. reticulata × C. sinensis), and tangelo (C. reticulata × C. paradisi) germplasm. All hybrids were confirmed by cytological and RAPD analyses, and have been budded to selected rootstocks to expedite flowering.

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Liu Lian Sen, He Shan Wen, and Lin Mei Hong

Abstract results showed that many germplasms of P. Armeniaca. P. persica and a few germplasms of P. Salicina had immersed into those of P. mume. Some cultivars (strains) possessed species characteristics coming from 2 or 3 of the 3 species in a single plant. All of the plants tested were transition types of the related varieties such as var. bungo and so on. Some new characteristics of P. mume were found in a few strains. The resources were classified into highly, mediumly and lightly backcrossed types. The mean yield index and fruit weight of highly back-crossed type (HB) were significantly higher than those of the other 2 types. The setting rate of HB was higher and significantly higher than that of lightly and mediumly type, respectively. There were no significant differences in mean bitter index and flower index among them.

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J.R. Ballington

The genus Kalmia L. is endemic to North America. Kalmia latifolia is the best known species in the genus. It is a rounded evergreen shrub to small tree that ranges from northern Florida to New England. Flower color varies from white to pink, but at lower elevations in the southeastern U.S., pink flowers quickly fade to white. It is a diploid species with 2n = 2x = 24 chromosomes. Kalmia angustifolia var. caroliniana only occurs in the southeastern US. It is a thin upright evergreen shrub to 1.5 m tall. Flower color is either light pink or rosy purple, and the flower pigments appear to be heat stable. It is also diploid. Kalmia latifolia has not crossed readily with any other Kalmia species to date, but a small number of hybrids have been produced. The objective of the present study was to intercross K. angustifolia var. caroliniana with K. latifolia to attempt to develop color stable pink flowered Kalmia hybrids for warm climates. The crosses were made at Cary, N.C., from late April through mid May and included two clones of each species. Only one parental combination was successful and involved a rosy purple form of the former species. With this cross 15 mature seed capsules resulted from 38 pollinations. Numerous seedlings initially germinated, of which about 15% were albinos. Only 38 seedlings survived to transplanting. Thirty seedlings remain relatively vigorous 8 months after potting and are phenotypically intermediate between the parents. Their potential will depend on their ornamental characteristics once they reach maturity.

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W. Vance Baird, Agnes S. Estager, and John K. Wells

Using laser flow cytometry, nuclear DNA amounts were estimated for 12 Prunus species, representing three subgenera [Prunophora (Prunus), Amygdalus, and Cerasus (Lithocerasus)], two interspecific hybrids, four cultivars, and a synthetic polyploid series of peach consisting of haploids, diploids, triploids, and tetraploids (periclinal cytochimeras). Peach nuclear DNA content ranged from 0.30 pg for the haploid nuclei to 1.23 pg for the tetraploid nuclei. The diploid genome of peach is relatively small and was estimated to be 0.60±0.03 pg (or 5.8×108 nucleotide base pairs). The polyploid series represented the expected arithmetic progression, as genome size positively correlated with ploidy level (i.e., DNA content was proportional to chromosome number). The DNA content for the 12 diploid species and two interspecific diploid hybrids ranged from 0.57 to 0.79 pg. Genome size estimates were verified independently by Southern blot analysis, using restriction fragment length polymorphism clones as gene-copy equivalents. Thus, a relatively small and stable nuclear genome typifies the Prunus species investigated, consistent with their low, basic chromosome number (× = 8).

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Shujun Zhou, Xin Tan, Liqin Fang, Jia Jian, Ping Xu, and Guoliang Yuan

Modern lily cultivars originate from hybridization of Lilium of Liliaceae. The genus contains ≈80 wild species classified into seven sections: Lilium, Martagon, Pseudolirium, Archelirion, Sinomartagon, Leucolirion, and Oxypetala ( De Jong, 1974

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Antonio Figueira, Jules Janick, and Peter Goldsbrough

Journal Paper no. 13,164 of the Purdue Univ. Agricultural Experiment Station. We acknowledge the assistance of James Jones on the hybridization experiments and Gary Durack and staff from the Purdue Univ. Cytometry Laboratories. We thank CEPLAC