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uniformity. Breeding new grape cultivars with improved traits, such as early ripening and naturally large berry size, is one way to offset increasing production costs and broaden market access. Although most cultivated table, raisin, and wine grapes are the
The effects of pollination treatments on fruit set and five berry characteristics [mass, diameter, number of apparently viable seeds (well-developed, plump with dark seed coat), total seed number (includes apparently viable and partially developed seeds), and harvest date] were examined on three highbush blueberry cultivars. Pollination treatments included unpollinated, open pollinated, emasculated, and three hand pollinations that used pollen from the same flower, from the same cultivar, or from a different cultivar. Berries matured earliest and were smallest with the most apparently viable seeds in `Northland', `Patriot' had the greatest fruit set and smallest seed number, and `Bluecrop' matured the latest. Fruit set was greater, berry size larger, seed number smaller, and maturation later in 1990 than 1991. For all three cultivars, berries were generally smallest, latest maturing, and had the fewest seeds when pollination was prevented and were largest with the most seeds and earliest maturing in open visitation. Emasculation resulted in berries similar to those from unpollinated flowers. For berry characteristics, cross-pollination was of benefit for `Patriot' and possibly `Northland' but not `Bluecrop'. Thus, commercial highbush blueberry planting designs must be based on the pollination requirements of the particular cultivar. `Northland' berries almost always had seeds, while `Patriot' showed high levels and `Bluecrop' low levels of parthenocarpy.
Diploid plants in Vaccinium section Cyanococcus, including plants of V. darrowi Camp, V. atrococcum. Heller (diploid V. corymbosum L.), a V. atrococcum × V. darrowi F1 hybrid, and a V. atrococcum × V. elliottii Chapmn. F1 hybrid, were hand pollinated in a greenhouse with pollen from diploid V. arboreum Marsh. (Section Batodendron). The resulting seeds were germinated and the seedlings were transplanted to a high-density field nursery. Forty of these F1 intersectional hybrids were selected after 2 1/2 years and transplanted to a 1.5 × 4-m spacing. Most of these plants were vigorous and flowered heavily in subsequent years, but only a small percentage of the flowers produced fruit. In 1990, however, >4000 berries were harvested from the 35 surviving plants. Open-pollinated seed from a much smaller number of berries was planted in Dec. 1987; these seeds produced ≈200 seedlings, some of which had moderate to high fruit set in a field nursery in 1989. Six of these seedlings, which were selected for high vigor, high fruit set, and characteristics intermediate between section Cyanococcus and section Batodendron, had fruit set ranging from 19.4% to 92.7% when pollinated with pollen from tetraploid V. corymbosum cultivars. One of the six seedlings was highly self-fruitful, and some intercrosses among the six seedlings produced much viable seed. Large-scale introgression of V. arboreum genes into tetraploid highbush cultivars likely will be possible by the methods used in this study.
Performance characteristics for eighteen strawberry cultivars (Fragaria ×ananassa), nine from California and nine from other North American sources, were evaluated in annual hill culture, with and without preplant soil fumigation (2 methyl bromide : 1 chloropicrin, 392 kg·ha-1). Plants grown in nonfumigated soil yielded 57% and 46% of the fruit produced by plants on adjacent fumigated soil for cultivars from California and other North American origins, respectively. Plants in nonfumigated soils also developed fruit with lower berry weight (94% and 95% of fumigated trials) and smaller spring plant diameter (83% and 76%) for California and other sources, respectively. Trait values for exotic cultivars ranged from 39% to 80% of those for California cultivars, and the variance component due to germplasm sources explained 41% to 81% of the phenotypic variance of random effects in the experiment. Conversely, significant germplasm source × fumigation interactions were not detected for any of the growth or performance traits evaluated, and the proportion of variance attributable to these interactions was at most 2% of that due to germplasm source. These results demonstrate that strawberry growth and productivity for California and other North American germplasm sources are increased similarly by fumigation. Despite differing selection history, germplasm developed outside of California contains no obvious genetic diversity useful for developing cultivars specifically adapted to the sublethal effects of organisms in nonfumigated soils.
equimolar amounts as glucose and fructose, particularly in wine grape cultivars ( Coombe, 1992 ; Kliewer, 1967 ; Matthews and Shackel, 2005 ). Concomitant with sugar accumulation, berry volume and softness increase, whereas malic acid declines, and in red
Fruit size, number of receptacle cells, and mean cell size were determined throughout development of secondary fruit of three day-neutral strawberry (Fragaria ×ananassa Duch.) cultivars grown in a greenhouse. Cells were counted after enzymatic separation of receptacle tissue, and mean cell volume was estimated from cell count and receptacle tissue volume. Size of mature fruit was small (3.8 g) in `Tillikum', medium (11.5 g) in `Tristar', and large (15.6 g) in `Selva'. Fruit size was correlated with the number of achenes per berry. Mature fruit of `Tillikum' had a lower fruit fresh weight per achene and lower achene population density (achenes per square centimeter) than the larger-fruited cultivars. The average number of cells per mature fruit was 0.72 × 106, 1.96 × 106, and 2.94 × 106 for `Tillikum', `Tristar', and `Selva', respectively. The relative difference among cultivars in the number of receptacle cells was established by the time of anthesis. In all cultivars, cell division was exponential for 10 days following anthesis and ceased by the 15th day. Mean cell volume increased slowly during active cell division, but rose rapidly and linearly for 10 days after cell division halted. Mean cell volume of all cultivars increased > 12-fold after anthesis and was ≈ 6 × 106 μm3 in mature fruit. The genotypic variation in the size of mature fruit was not the result of large differences in either duration of cell division after anthesis or mean cell volume, but rather was primarily due to differences in the number of receptacle cells established by anthesis.
Plant growth regulators (PGRs) [antigibberellins (mepiquat chloride, uniconazole, ancymidol, daminozide, chlormequat, ethephon, methazole), cytokinins (BAP, kinetin, BTP, 2iP), and ABA] were evaluated at various concentrations and timings for promotion of seed trace development and germination of four stenospermic grape cultivars (Vitis spp.): `Venus', `Mars', `Reliance', and `Saturn'. Data include seed trace number per berry, percent of seed traces with endosperm (sinkers), sinker fresh weight, and percent seed trace germination. Several PGRs effectively increased seed number and percent sinkers over control treatments. PGRs had little effect on seed fresh weight and percent germination. PGRs promoted greater increases in percent sinkers than seed number on all cultivars. The number of viable seeds per sample (seed number × percent sinkers) was increased over controls by up to 802% on `Reliance', 239% on `Saturn', 154% on `Mars', and 153% on `Venus'. A moderate percentage of viable seeds from treatments and controls of `Mars', `Venus', and `Saturn' germinated and established normal seedlings. The very small seed traces of `Reliance' did not germinate from either controls or treatments. The results indicate that PGRs can stimulate seed trace formation in some stenospermic cultivars and therefore may be useful tools in grape breeding programs. Chemical names used: abscisic acid (+/-)cis-trans isomer (ABA); a-cyclopropyl-a-(4-methoxy-phenyl)-5-pyrimidinemethanol (ancymidol); 6-benzylaminopurine (BAP); 6-benzylamino-9-(2 tetra-hydropropanyl)-9H-purine (BTP); (2-chloroethyl) trimethyl-ammonium chloride (chlormequat); succinic acid 2,2 dimethyl-hydrazide (daminozide); (2-chloroethyl) phosphonic acid (ethephon); 6-(dimethyl-allylamino) purine (2iP); 6-furfurylaminopurine (kinetin); N,N-dimethyl-piperidinium chloride (mepiquat chloride); [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] (methazole); E-1-(4-chlorophenyl)-4,4-di-methyl-2-(1,2,4-triazol-1-yl)-1-pentan-3-ol (uniconazole).
cultivars, HyRed and Crimson Queen, whereas yields of ‘Stevens’ and ‘HyRed’ were similar ( Table 3 ). ‘Searles’ yielded the least fruit, which was consistent with growers’ experience. Upright density and berry number were the same across all cultivars
are older female cultivars with small, black berries, making them difficult to distinguish phenotypically. Both ‘San Jacinto’ and ‘La Salle’ are reported to be seedlings of ‘Scuppernong’ ( McLeRoy and Renfro, 2008 ), but their marker profile rules out
-phase microextraction gas chromatography–mass spectrometry in five rabbiteye blueberry cultivars at four maturities. For any given compound, there were often small measurements and few with much larger measurements, resulting in a mean distribution that was not