Two new seedless grape cultivars were released in 1999 from the grape breeding program at the Univ. of Arkansas. `Jupiter' is the fifth release from the program. `Jupiter' is blue-fruited, has large berries, non-slipskin texture, and a mild muscat flavor. Yields of `Jupiter' were very good in replicated trials, and hardiness is also adequate for production in all areas of the South. `Jupiter' ripens 5 days later than `Venus', but earlier than `Mars' or `Reliance'. `Neptune' is the sixth release and first white-fruited cultivar from the program. It has medium-sized berries, large clusters, non-slipskin texture, and a mild, fruity flavor. Yields of `Neptune' were moderate in replicated trials. `Neptune' ripens 17 days later than `Venus' and 3 days earlier than `Mars'. Both cultivars were developed and evaluated with a commercial cultural system including routine fungicide applications, and fungicides will be required to reliably produce these cultivars. Neither of these cultivars has been tested in a Pierce's Disease region of the United States, and it is not anticipated that either will have resistance to this disease.
J.R. Clark and J.N. Moore
Timothy F. Bourne and J.N. Moore
Twelve seedling blackberry (Rubus spp.) populations were tested over 2 years for cold hardiness of stem and bud tissues. Seedling populations resulted from a partial diallele of crosses made among nine parents representative of three categories of cold hardiness. Viability testing of xylem, phloem, and bud tissues was conducted following exposure to a temperature lethal to 50% of tested tissue. Significant population effects (P < 0.05) occurred for xylem and bud cold hardiness in 1988 and for xylem, phloem, and bud cold hardiness in 1989. Results were similar for the 2 years, although there was a greater discrimination between populations for xylem and phloem cold hardiness in the 2nd year. Seedling populations having `Darrow' as a parent showed less tissue damage than the other eight populations. The populations having `Brison' as one parent showed consistently poor hardiness with the exception of one resulting from a cross of `Brison' × `Darrow'. This population showed consistently good hardiness, indicating that dominance effects may play a role in cold hardiness of blackberries.
John R Clark and J.N. Moore
Blue Ridge, Cape Fear, Georgiagem, and O Neal southern highbush blueberry cultivars were grown for 5 years on a fine sandy loam soil in a comparison of plants either mulched with uncomposted pine sawdust and woodchips or nonmulched. Other cultural practices were identical and all plants received the same amount of trickle irrigation. A significant mulch × cultivar interaction for yield and mulch × plant age interactions for yield, individual berry weight, and plant volume were found. Cape Fear was the highest-yielding mulched cultivar, followed by Blueridge, Georgiagem, and O Neal. Mulched plants had higher yields and produced larger plants. Average individual berry weight was greater for mulched plants in the first year of harvest, but not different among treatments in other years. The data reveal that these southern highbush cultivars performed similar to northern highbush (Vaccinicum corymbosum L.) in their need for mulching for adequate production on upland soils.
Bruce P. Bordelon and J.N. Moore
Various plant growth regulators were used to stimulate endosperm and embryo development in four stenospermic grape cultivars. Five antigibberellins were applied to clusters at 1000 and 100 ppm two weeks prior to bloom. Two cytokinins were applied at 1000, 500, and 250 ppm 20 days after bloom. Combinations of the treatments were also made. Data collected included: 1) cluster weight, 2) berry weight, 3) number of `sinker' and `floater' seed traces, 4) `sinker' weight and 5) percent germination. Significant differences were found among treatments for some of the variables. Differences also occurred among cultivars. Percent germination was greater for cultivars with large seed traces. The technique appears to have promise as an alternative to ovule culture/embryo rescue for intercrossing stenospermic grapes.
Bruce P. Bordelon and J.N. Moore
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).
Jose Lopez-Medina, B.J. Murphy, and J.N. Moore
Isozyme staining and SDS-PAGE of soluble proteins were performed using leaf homogenates from 6- to 8-month-old field-grown seedlings resulting from the cross of either `Heritage' or `Nova' raspberry with ARK-577 diploid blackberry, the latter used as the pollen-donor parent. Four enzyme systems were tested: ADH, PGM, MDH, and PGI. Of these, ADH and PGM did not show any activity; MDH was monomorphic in both raspberry and blackberry parents, with activity at the same migration distance. PGI was polymorphic in the two raspberry cultivars, showing three dimeric bands, but monomorphic in blackberry; the allele for PGI in blackberry being common to that allele coding for the most cathodal band in raspberry. This phenomenon, in addition to poor resolution of bands (due, perhaps to low enzyme activity) and evidence of accidental self-pollination in our populations, prevented us from positively identifying the hybrid offspring using isozymes. By SDS-PAGE of soluble proteins, two bands were detected that seemed to be unique to ARK-577 blackberry and were also expressed in some of the offspring, suggesting a hybrid origin of these seedlings. Morphological comparisons indicated that those seedlings possessing the two unique bands highly resemble the blackberry male parent, greatly supporting their hybrid origin. Unless additional analysis shows otherwise, SDS-PAGE can be used to identify Raspberry–Blackberry hybrids during their vegetative stage of development, and might prove applicable to other interspecific hybrids of Rubus.
Sylvia J. Brooks, James N. Moore, and J. Brad Murphy
Fruit of four clingstone peach [Prunus persica (L.) Batsch.] seedling populations, 54 advanced selections, and the cultivars Allgold and Goldilocks were analyzed for sugar content, soluble solids concentration (SSC), and acidity. Sucrose, glucose, fructose, and sorbitol were identified and quantified by high pressure liquid chromatography (HPLC) analysis. Variation was found for all the sugars between the seedling populations. Comparison of the means for the advanced selections with `Goldilocks' indicates that progress has already been made toward selection for a sweeter peach. Glucose, fructose, sorbitol, SSC, and acidity (citric) differed significantly for two harvest years, while sucrose and total sugar concentrations showed no significant yearly variation. A fruit maturity study revealed no significant changes in SSC, percentages of glucose, fructose, and total sugar during ripening on the tree. Acidity and percent sorbitol decreased, while the sugar: acid ratio and percent sucrose increased with increasing maturity. Broad-sense heritability of SSC, acidity, and sugar: acid ratio bad values >0.72, while values for individual sugars and total sugars were much lower. Transgressive segregation for each sugar was found in seedling populations.
Timothy F. Bourne, J.N. Moore, and Milon F. George
Four interspecific grape hybrids (Vitis spp.) developed in Arkansas were evaluated for primary bud hardiness by differential thermal analysis. Buds from two locations were analyzed over 2 years for acclimation, midwinter hardiness, and deacclimation. In addition, effects of two training systems on cold hardiness of buds were evaluated in one location. The buds of the two genotypes with the greatest component of V. vinifera in their ancestry acclimated more slowly than did the other genotypes. Ultimate midwinter bud hardiness was greater in the genotypes possessing less V. vinifera than other parentage. No effect on cold hardiness due to training system was noted. No natural winter freeze damage was observed on any of the genotypes in the period of observation.
Victorine Alleyne, James N. Moore, and J. Brad Murphy
The color and chemical composition of three strawberry (Fragaria ×ananassa Duchesne) cultivars, `Arking', `Cardinal', and Earliglow' and one advanced selection, A-7383, were examined at four maturity stages in a 2-year study. Cultivar- and maturity-related differences were observed in CIELAB color space coordinates, L*, a*, b*, anthocyanin concentration, percent soluble solids; pH, titratable acidity, sugar/acid ratio, and total solids, insoluble solids, fructose, and sucrose content. No cultivar effect was detected for glucose concentration. `Arking' and `Cardinal' had the most intense red color and were similar in L*, a*, b* values, titratable acidity, and the concentration of anthocyanin, soluble solids, total solids, and fructose. They differed significantly in pH, sugar/acid ratio, and insoluble solids. A-7383 and `Earliglow' exhibited differences in all measured characteristics except total solids. A-7383 fruits contained the lowest anthocyanin concentration and were the darkest and least red of the genotypes.
J.N. Moore, John R. Clark, and Justin R. Morris
The impending release of a new blackberry cultivar and a new grape cultivar by the University of Arkansas Agricultural Experiment station will be discussed. The blackberry, tested as A-1536, is an erect, thornless type ripening two weeks before 'Navaho'. It produces very firm, highly flavored fruit similar to 'Navaho'. The grape, tested as A-1335, is a blue-seeded juice grape with good adaptation to areas with high summer temperatures where 'Concord' does not ripen evenly. Fresh fruit and processed juice quality has been rated equal to or better than 'Concord' juice for quality attributes.