Ten tomato cultigens were crossed with L. peruvianum accessions PI 126443 and PI 129152. Fruit (536 total) were harvested between 15 and 65 days after anthesis (DAA). Culturable embryos were obtained from 13% of the fruit. There were 140 embryos plated, from which 36 plants were obtained (7% of fruit, 26% of embryos plated). 'Campbell 28', Fla. 7217, and Fla. 7182 were the most efficient tomato lines for producing F1 plants, there was no difference between the L. peruvianum accessions. No embryos were obtained beyond 57 DAA. No trend in embryo viability was detected between 15 and 56 DAA. Of 248 backcross fruit, 94 embryos were plated (38% of fruit) and 15 plants were obtained (6% of fruit, 16% of embryos plated). Female parents with the best percentage of plants per fruit crossed were Fla. 7217, Fla. 7215, and 'Campbell 28' with 15, 8, and 7%, respectively. No plants were obtained from 45 crosses on Fla. 7182.
C. Scott, R.K. Nishimoto and C.S. Tang
Cyperus kyllingia and Cyperus brevifolius are problematic turfgrass weeds in Hawaii. Both are closely related weed species with similar morphology and growth characteristics. C. kyllingia appears to be a more successful weed with regards to interference than C. brevifolius. Greenhouse experiments were conducted to compare the levels of interference exerted by C. kyllingia and C. brevifolius upon Cynodon dactylon turfgrass. C. kyllingia reduced the growth of C. dactylon by about 50 %, while C. brevifolius did not significantly reduce C. dactylon growth. These results correspond with the chemical profiles of C. kyllingia and C. brevifolius. Analysis has shown that C. kyllingia contains two sesquiterpenes which have been identified as potentially allelopathic components of Cyperus rotundus. C. brevifolius contains waxes and the two sesquiterpenes found in C. kyllingia are absent. This suggests that allelopathy may be the mechanism responsible for the different levels of interference exhibited by C. kyllingia and C. brevifolius, and these species may provide an important model for the study of allelopathy.
Richard C. Funt, M. Scott Biggs and Mark C. Schmittgen
Physiological disorders of apples, such as cork spot and bitter pit, are a result of low soil calcium, low or excessive soil moisture, large fruit size, and environmental conditions. We report on the effect of microirrigation treatments on apple fruit when irrigation is applied as water alone or water plus a calcium (Ca)/boron (B) solution with applications applied over the tree canopy or under the tree canopy. Apples were harvested from trees in their 4th to 7th leaf and the number of fruit and size of fruit varied from year to year. In most years, there were no significant differences among treatments for fruit Ca. Fruit B was significantly higher in treatments where B was applied through the irrigation. Fruit N/Ca levels were lower when the fruit size was smaller, which was due to a higher number of fruit per tree. Year to year variations in fruit Ca levels also were likely to temperature, humidity, rainfall, fruit size, and shoot growth.
R.N. Trigiano, M.C. Scott and G. Caetano-Anollés
Four chrysanthemum (Dendranthema grandiflora) spontaneous and radiation-induced sports from the cultivar `Charm' and phenotypically differing only in flower color were individually characterized using arbitrary signatures from amplification profiles (ASAP). ASAP analysis is based on a two-step arbitrary primer amplification procedure that produces “fingerprints of fingerprints.” In the first step, `Charm', `Dark Charm', `Dark Bronze Charm', `Salmon Charm', and `Coral Charm' were fingerprinted by DNA amplification fingerprinting (DAF) with standard octamer arbitrary primers. Diluted products from three monomorphic fingerprints for each cultivar were subsequently reamplified using four minihairpin decamer primers. Each of the 12 ASAP profiles revealed about 30% polymorphic loci and some were used to uniquely identify cultivars and estimate genetic relationships. The ASAP technique permits identification of previously genetically indistinguishable plant material and should facilitate marker assisted breeding and protection of ownership rights.
Willard T. Witte, Scott Schlarbaum, Roger Sauve and Phillip C. Flanagan
Efforts have been underway since 1988 to establish a nursery research station in McMinnville, TN. Approximately 80 acres of farm property has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining funding via the Capacity Building Grants Program to initiate a plant evaluation and introduction program at the new station. Initial trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, and Ulmus. Herbaceous genera are Echinacea, Hemerocallis, and Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Complementary grant proposals have been recently submitted. Design, funding and support of all Tennessee introduction and evaluation programs will be discussed.
Willard T. Witte, Scott Schlarbaum, Roger Sauve and Phillip C. Flanagan
Since 1988, efforts have been underway to establish a nursery research station in McMinnville, Warren County, Tennessee. Approximately 80 acres of farm property adjacent to the Collins scenic river has been conveyed to Tennessee State University (TSU) for this purpose. Scientists at TSU, Tennessee Technological University, University of Tennessee, and USDA's National Arboretum and Shade Tree Laboratory have cooperated in obtaining grant funds via the Capacity Building Grants Program to initiate a plant evaluation and introduction program. Replicated trials of woody genera include Acer, Castanea, Cornus, Lagerstroemia, Quercus, Syringa, Ulmus. Herbaceous genera are Echinacea, Hemerocallis, Hosta. Plantings will be made over a three year period as infrastructure at the new station develops. Additional grant proposals have been recently submitted.
S.J. Scott, M. Stevens and R.C. Gergerich
Three methods to inoculate Lycopersicon esculentum 'VF Pink' seedlings with tomato spotted wilt virus (TSWV) were compared. Treatments were 1) two inoculations by hand (rubbing leaves with a sterile cotton swab), 2) a single inoculation using a paint sprayer at 3.56 × 105 N· m-2, and 3) two spray inoculations. All three methods were effective (>95% infection) under moderate temperatures in the spring, but hand inoculation was not effective under hot conditions in the summer. In another experiment, spray inoculation was used to compare effects of light intensity and the leaf inoculated on susceptibility of L.. hirsutum PI 127826, L. pimpinellifoliom LA 1580 and `VF Pink' to TSWV isolate 85-9. All three genotypes were susceptible under full sun and 60% shade cloth in the greenhouse. Inoculation of youngest leaves produced the highest virus titer. Background optical density for noninoculated plants differed between lower and upper leaves in the ELISA assay.
S.J. Scott, M. Stevens and R.C. Gergerich
Seedlings of eight accessions of L. hirsutum and susceptible L. esculentum `VF Pink' controls were spray inoculated twice in the greenhouse with tomato spotted wilt virus (TSWV) Arkansas 85-9. Plants lacking symptoms were reinoculated, then evaluated for TSWV by enzyme-linked immunosorbent assay (ELISA). Controls were consistently infected; sixty noninfected L. hirsutum were propagated by cuttings and inoculated with TSWV isolates T2 (lettuce), G-87 (gloxinia), 87-34 (tomato) and a mixture of the four isolates. All selections became infected in at least one test, but systemic infection was often delayed. Additional wild Lycopersicon species and numbers of accessions evaluated for resistance to TSWV include L. cheesmanii (9), L. chmielewskii (17), L. hirsutum (24), L. hirsutum f. glabratum (17), L. parviflorum (4) and L. pennellii (44). No new sources of strong resistance have been identified yet. Evaluation of additional species and accessions is continuing.
Scott N. White, Nathan S. Boyd and Rene C. Van Acker
Experiments were established to evaluate the suitability of growing degree-day (GDD, T base = 0 °C) models for predicting emergence, tip dieback, and flowering of lowbush blueberry ramets in Nova Scotia, Canada. Data for model development were collected from quadrats established in several non-bearing and bearing blueberry fields throughout the dominant blueberry production areas in northern and central Nova Scotia. Blueberry ramets emerged between 222 and 265 GDD (6 May to 14 May) and reached 90% emergence between 619 and 917 GDD (7 June to 5 July). Emergence continued to slowly increase until late summer or early fall. Tip dieback began between 598 and 792 GDD (14 June to 21 June) and duration of this phase depended on whether late-emerging ramets developed to tip dieback. A four-parameter Weibull and a three-parameter Gompertz equation adequately explained cumulative blueberry ramet emergence and cumulative ramets at tip dieback as functions of GDD in the non-bearing year, respectively. The four-parameter Weibull function also explained the relationship between cumulative flowering ramets and GDD in the bearing year. Flowering ramets were first observed between 376 and 409 GDD (19 May to 30 May) in the bearing year. Model predictions for initiation of emergence, tip dieback, and flowering were 243, 692, and 389 GDD, respectively. Models were validated with independent data sets collected throughout northern and central Nova Scotia. The relationship between the percentage of open flowers on individual ramets and GDD in the bearing year was well described by a Gaussian model at two sites with a predicted peak number of open flowers between 552 and 565 GDD.
Scott B. Lukas, Joseph DeFrank and Orville C. Baldos
In Hawaii, Waltheria indica (uhaloa) has been identified for expanded usage as a roadside groundcover in lowland dry ecosystems. Seed dormancy through lack of germination of viable seeds was identified in uhaloa. The presence of physical dormancy in uhaloa seeds was determined and dormancy relief methods were evaluated including hand scarification, dry heat temperature exposure, hot water exposure, and mechanical abrasion in an electric drum scarifier. As a compliment to dormancy relief, long-term storage parameters were evaluated for scarified and nonscarified seeds. The elucidation of physical dormancy was determined through hand scarification, resulting in 96% germination compared with 8% of nonscarified seeds, but is not practical on a large-scale basis. The greatest practical dormancy relief was achieved with a mechanical electric drum scarifier lined with 80-grit sandpaper for a duration of 15 or 30 seconds producing 95% and 99% germination, respectively. Seeds immersed in boiling water for 3 and 5 seconds resulted in 58.6% and 57.7% germination, respectively. Dormancy relief through dry heat exposure was inferior to other relief methods, producing 39% germination at 75 °C for 60 minutes. Nonscarified seeds exhibited minimal loss of viability during 10 months of storage at 5 °C at 12% and 50% relative humidity (RH), but a significant decline in viability of scarified seeds was detected.