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Gibberellic acid, a plant growth regulator commonly sprayed for seedless bunch grape cultivars, was used to spray on the seeded muscadine grape cultivars `Carlos', `Fry', `Higgins' and `Triumph'. GA3 at 100 to 300 ppm were sprayed on leaves and fruit clusters before and after anthesis. The flower/fruit clusters also were dipped into a much higher concentration (1000 ppm) in addition to the sprayed concentration of GA3. Berry weight significantly increased in all the sprayed vines, with a maximal increase up to 50%. Early and more uniform ripening was observed in the cultivar `Triumph'. More than 20% of seedless berries also were found on the GA3-sprayed `Triumph' vines. However, the latter two responses (early ripening and seedlessness) did not occur in other cultivars tested. Similar results also were obtained in the dipping treatments. The results indicated that the seeded muscadine grapes responded well to the GA3 treatments in general, but genotype variation is obvious.
Genetic relationships among 42 grape accession of at least 15 species were estimated and compared using RAPD and isozyme techniques. These accessions were either hybrids or wild collections of the Asiatic species, the American species, the European grape (V. vinifera), and muscadine grape (V. rotundifolia). A total of 196 RAPD fragments were generated from twenty 10-mer primers. The pairwise similarities among the accession ranged from 0.46 to 0.94. A dendrogram was generated based on the RAPD similarity coefficients. Species/accessions were basically grouped together in accordance with their geographic origins. The similarities and dendrogram resulted from the RAPD analysis were consistent with the ones generated from the isozyme data, and also consistent with the known taxonomic information. This result suggest that the RAPD method, like isozyme, is an useful tool for studying grape genetic relationship/diversity and origination.
A greenhouse pot study was conducted with a Wynnville sandy loam surface soil to determine the influence of application rates of poultry litter (PL) on growth and nutrient uptake of collard (Brassica oleracea, Acephata Group L., cv. Champion), and the residual effects of PL on growth and nutrient uptake of cabbage (Brassica oleracea, Capitata Group L., cv. Rio Verde). PL at 0, 13, 26, 53, and 106 g·kg–1 was incorporated into limed (pH 6.5) and nonlimed (pH 5.2) soil. Collard plants were grown for 52 days. The residual effects of PL were evaluated by growing three successive crops of cabbage without further application of PL (total 218 days). Collard plants were severely damaged or killed within 7 days after transplanting when the application rate of PL exceeded 26 g·kg–1 soil. Maximum dry matter yield of cabbage shifted from 26 to 106 g PL/kg soil during three successive crops. After four successive growth periods, 6% to 37% of N, 3% to 62% of Ca, 20% to 120% of K, 5% to 60% of Mg, and 3% to 25% of P added through PL was removed by plants. The decrease in water-extractable K accounted for the decrease in the soil salinity. Our results suggest that application rates of PL ≥ 53 g·kg–1 soil can result in elevated levels of salts and NH3 in soil, which can produce severe salt stress and seedling injury.
Ovary temperatures of upward and downward facing flowers of `Junegold' Peach (Prunus persica (L.) Batsch) were measured on 5 nights in March 1991 to determine whether differential survival of ovaries following frost was related to flower orientation. Flowering twigs were removed from mature trees and positioned horizontally ≈ 1.5 m above ground level prior to occurrence of low temperatures (0-5C). Thermocouples were inserted through the hypanthium to contact ovaries of 10 upward and 10 downward facing flowers, and temperature and meteorological data were logged every five minutes. Under clear, calm conditions, temperature of upward facing flowers averaged 0.33C lower than that of downward facing flowers during the coldest period of the night, with maximal differences of 0.77C. Under cloudy, calm conditions, temperature differences between upward and downward facing flowers were less frequently observed and lower in magnitude (0.08 - 0.15C). Under windy conditions (>2.5 m/s), no temperature difference between upward and downward facing flowers occurred, despite strongly negative net radiation. Based on known values of ovary cold tolerance, it is concluded that differences in survival of Up to 38% could occur due to flower orientation when air temperature reaches critical values.
International experiences enhance opportunities for future employment in that many companies, and particularly government agencies desire graduates that comprehend the global economy of our world. Traditional and emerging opportunities with ports of entry, Homeland Security, and international companies are increasing. There are seven primary avenues to an International Experience for Auburn Horticulture students. In recent months, some students have been deployed to military assignments. Through the IPPS we have been able to facilitate student exchange programs. Several graduate students have accompanied faculty on plant expeditions or in agricultural development or research efforts. However, these three types of opportunities are not long-term or sustainable. The E.T. and Vam York Endowment provides monetary support, often equal to air fare, to faculty and graduate students for short duration trips. A similar endowment created by Bill and Margaret Stallworth provides monetary awards for airfare and other incidentals to undergraduates on international internships six months or longer in duration. The Henry P. Orr Fund for Excellence commemorates out-of-the-classroom experiences championed by Orr for almost 40 years at Auburn. The purpose of the Orr Endowment is to provide short-term study tours of gardens of the world for students and faculty. In Summer 2005 we begin our first Horticulture Study Abroad Program operated on a cost recovery basis providing 13 semester hours of academic credit at a cost similar to taking the same course load on campus. Altogether, our current goal is to involve about 10% of our students annually in international opportunities.
Resistance to grape anthracnose [Elsinoë ampelina (de Bary) Shear] was evaluated in 13 known Vitis species and five taxonomically undescribed grapes native to China. One hundred and eight clones of Chinese Vitis species were tested under field conditions between 1990 and 1992. Berry infection did not occur in these species. Leaves displayed strong resistance to anthracnose, although intraspecific variations were observed. There was no relationship between anthracnose resistance and geographical origin of the species. Results from this study indicate that oriental grape species are useful for disease-resistance breeding.
The grape is an important horticultural crop that is grown worldwide. Breeding a new grape cultivar by conventional means normally will take several generations of backcross, at least 15 years. The efficiency and speed of selection can be accelerated if genetic markers are available for early screening. This project is designed to generate RAPD markers linked to viticulturally important traits, including seedlessness and pistillate genes. A F1 population with 64 progenies of V. vinifera was used for the RAPD analysis. Bulked Segregant Analysis (BSA) method was used for RAPD primer screening. Three-hundred primers were screened between the two pairs of pooled DNA samples, seeded and seedlessness, pistillate and perfect flowers. At least 10 primers produced one polymorphism each between the pools. Further analysis revealed that one of these RAPDs cosegregated tightly with the seedlessness trait, while the others either had loose linkage or no linkage to the traits. To make the RAPD marker useful for breeding selection, an attempt was made to convert it into SCAR marker. The results demonstrated that the RAPD marker may be useful for grape breeding and interpreting inheritance of a particular trait in grapes.
Knowing a tree crop’s seasonal growth and development as a function of heat accumulation can facilitate scheduling of irrigation, pesticide applications, and harvest. Our objective was to compare the goodness of fit of applied models and determine which provides the best description of pistachio nut growth as a function of thermal unit accumulation. Three fruit growth traits of pistachio—pericarp (hull) + endocarp (shell) size, endocarp thickening and hardening, and embryo (kernel) size—exhibited clear nonlinear dependence on heat accumulation. We tested three nonlinear models—Michaelis–Menten, three-parameter logistic, and Gompertz—fitted to fruit development data to create a tool to forecast pest susceptibility and harvest timing. Observation of development began at full bloom and ended at harvest. Data were collected from six pistachio cultivars in one experimental and eight commercial orchards over 3 years. Analyses of residual distribution, parameter standard errors, coefficient of determination (R 2) and the Akaike information criterion (AIC) all demonstrated the Gompertz function was the best model. Cultivars differed significantly in all the three parameters (Asym, b, and c) for all three traits with the Gompertz model, demonstrating the Gompertz model can adjust to incorporate cultivar differences. The growth curve of the three traits together provided integrated information on nut biomass accumulation that facilitates predicting the critical timing for multiple orchard management practices.
Agrobacterium rhizogenes transformation is a more rapid method of obtaining transgenic and edited rubber dandelion (Taraxacum kok-saghyz) plants than Agrobacterium tumefaciens. The hairy root rol genes are present alongside transgenes after transformation, and they change the morphology of rubber dandelion significantly. Although these rol genes are useful visual markers indicating successful transformation of rubber dandelion, they modify the phenotype induced by the target transgenes and are ultimately detrimental to agronomic traits. Fortunately, the rol genes can be removed by conventional plant breeding because they segregate in progeny separately from the targeted transgenes. However, it is preferable to have preliminary identification of promising effects induced by transgenes or gene edits before rol gene removal so that only the best plants are used for breeding. Therefore, the goal of this research was to characterize rol– and rol+ plant morphology so that, in the future, rol+ transgene+ plants can be easily distinguished from rol+ transgene– plants. This requires that rol gene–induced morphological changes and simply assayed physiological traits are first characterized thoroughly so that transgene changes may be observed. Taproot formation is reduced or eliminated in rubber dandelion by rol genes, and rol-induced hairy roots are identifiable easily because they grow shallowly in potting soil, so only partial unearthing is needed. Both leaf and flower numbers are increased by rol genes, but leaves and flowers are smaller than in rubber dandelion wild type with longer stalks. The rosette doming phenotype caused by the induction of a large number of leaf primordia is obvious in rooted plants as young as 1 month old. Photosynthetic rates are reduced significantly in rol+ plants, although growth is not. An accurate description of the morphology of rubber dandelion after A. rhizogenes transformation may allow for initial selection of promising transformed plants before confirmation with polymerase chain reaction, by phenotypic comparison of plants expressing transgenes and the rol gene, with those only expressing the rol gene.
Clear (CM), and black plastic (BM) mulches and bare (BS) soil plus VisPore (V) row cover (VCM, VBM, VBS), CM, BM, and BS in combination with drip irrigation and three planting dates January 3rd, February 16th, and March 16th, 1990, were used to evaluate the yield of `Georgia' collard greens. At the 1st planting date, both mulches and row cover treatments had significantly higher yield. At the 2nd and 3rd planting dates there were significant interactions between mulch and row cover. The interaction at the the 2nd planting date showed that yield was highest with VCM and VBS treatments and at the 3rd planting date CM, BM and VBS increased yield, respectively. The number of days to harvest decreased with each planting date and bolting was not observed for any planting date or treatment combination.