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New Guinea Impatiens have become a major spring crop for many commercial greenhouses. Along with increased sales has come a proliferation of new varieties from which commercial growers must choose. To help provide growers with information to make these selections the ornamental horticulture extension program at Penn State has tested landscape performance of New Guinea Impatiens in the sun and the shade each year since 1994. Cuttings are obtained from commercial producers and six plants of each variety are planted in landscape beds in the full sun and six plants are planted in landscape beds under a shade structure. Plants are evaluated on flowering, foliage and overall appearance every 2 weeks throughout the summer. Commercial growers can evaluate varieties on their own during the trial field day and results are made available in an annual report and are posted on the internet. A survey of participants in the 1995 field day indicated that 98% of those responding used the printed report to make or change their variety selections. Supplementing the printed report with the internet for distribution of results allows broad dissemination of detailed information including photographs and graphics that could not be easily distributed in hard copy form. In the future trial results posted on the internet could be used to supplement point of sale materials, providing growers and retailers with a powerful new marketing tool.
Several models of apple tree carbon balance have been developed, including a simplified model by our lab. Tree photosynthesis and total dry matter production is the best characterized except for root growth and root respiration. Once dry matter is produced and partitioned to the different organs (another key problem for modeling), the effects of carbon availability to the fruits on their growth and abscission needs to be modeled. Our approach is based on an observed relationship between increased abscission with decreased fruit growth rate of populations of fruit. From several empirical studies of fruit growth and abscission during chemical thinning or imposed stress early in the season, a relationship was found between % abscission and classes of fruit growth rates. It appears to be best if the fruit growth rate is expressed as a percent of the growth rate of the fastest growing group of fruits in each study. Thus in the model the fruit growth allowed by the available carbon each day is compared to a pre-determined maximum growth rate for the cultivar. The percent-of-maximum growth rate then determines how much abscission will occur. Then the growth rate of the remaining fruit is calculated. Additional parameters of the model allowed for a multiple-day buffer of carbon availability, an imposed fruit number reduction (i.e. equivalent to hand thinning), and temperature effects. Although there are more improvements planned, the initial tests have been promising with the simulations showing realistic patterns of fruit abscission and fruit growth.
A tissue culture screen for ethylene tolerance using 1-aminocyclo-propane-1-carboxylic acid (ACC) was optimized for a snapdragon (Antirrhinum majus) inbred line, OAK564. Two experiments were conducted using various concentrations of ACC (ranging from 0 to 100 μM). Presence of 5 μM ACC in the tissue culture medium elucidated biological activity in snapdragon seeds. This screen was used to determine relative sensitivity to ethylene in 48 hybrid lines. Different levels of sensitivity to ethylene were observed among the various hybrid lines. Moreover, 40,000 mutagenized seeds from three M2 populations, derived from different levels of EMS (0.5%, 0.75%, and 1.0%) treatments, were screened for ethylene sensitivity. A total of 231 putative mutants were recovered spanning eight distinct phenotypes based on the `triple response' assay. Of these putative mutants, 16 mutants were selected for further analysis, including at least one and up to three lines from each of the eight phenotypic classes. Plants were established in the greenhouse, and allowed to grow to maturity to collect selfed seeds. These seeds were once again screened with 5 μM ACC to determine the level of ethylene sensitivity present within each of the eight phenotypic classes. Responses in the M3 populations varied from complete ethylene tolerance to ethylene sensitivity. Implications of these results on the recovery of ethylene tolerant mutants will be discussed.
Current and future plans for reductions in federal and state funding suggest that government supported programs must find ways to reduce costs while maintaining or expanding programs. The current model of extension, with an agent for each commodity in every county is not likely to survive. Furthermore, the days when university-based specialists could afford to make house calls also are probably limited. Yet, the need for extension support in the floriculture industry is as great as ever. Increased chemical costs and regulatory pressure are restricting grower options and making it increasingly important that information dissemination and technology transfer occur in timely and appropriate ways. To try to meet the needs of the floriculture industry in Pennsylvania, we have begun a program to help develop independent greenhouse crop management associations to work with milti-county and university-based extension specialists to improve program delivery to the member greenhouses. The first of these associations has been established in the Capital Region in central Pennsylvania and is providing IPM scouting and crop management services to member greenhouses. Development of associations and linkages with and the role of extension are discussed.
DCPTA is a synthetically produced tertiary amine bioregulator with potential for increasing crop productivity at high light intensities. DCPTA reduces the number of days from planting to maturity in various potted ornamental crops, including `Fortune' daffodil (Narcissus L.), `Sonora' tulip (Tulipa L.), and `Jan Bos' hyacinth (Hyacinthus orientalis L.). Our objective was to examine how light intensity and DCPTA application influence growth and flowering of amaryllis (Hippeastrum hybridum Hort.). Flowering size bulbs of a micropropagated amaryllis clone were treated with 30 μm or no DCPTA and grown in full sun or 63% shade for 1 year. Number of scapes produced, flowers per scape, change in bulb fresh weight, number of bulblets produced, and bulblet weight were recorded and analyzed. There were no significant differences in days to first flowering or in number of flowers produced per scape among the treatments. DCPTA application at the recommended rate significantly reduced number of emergent inflorescences and the bulb biomass increase of hybrid amaryllis. Additionally, the interaction between light level and DCPTA appeared weak for amaryllis, and was only slightly significant relative to bulblet production. Chemical name used: 2-(3,4-dichlorophenoxy)triethylamine (DCPTA).
An amaryllis breeding program using diploid species not represented in commercial tetraploid cultivars has been underway since 1988. Objectives are to develop evergreen cultivars with attractive foliage and fragrant flowers of novel form and coloration. Five crosses with Hippeastrum papilio as a parent were evaluated at first flowering in the spring of 1990. The F-1's showed significant variation, suggestive of high heterozygosity within the parental genomes. Several natural tetraploids were identified among the progeny. Superior selections were made, and sib- or intercrosses accomplished. We estimate that a minimum of 50% genes from H. papilio will need to be maintained to guarantee evergreen foliage in the progeny. Superior F-1's have also been crossed with fragrant, trumpet-flowered primary hybrids, and new primary F-1's are being generated with H. papilio and these species or their hybrids, as well as with H. reticulatum var. striatifolium. A percentage of these germinated seedlings have been treated with colchicine to induce polyploidy. The best F-1 selections are also being micropropagated, and induction of polyploidy will be attempted in a percentage of the subcultures.
Water management is often the key to successful vegetable culture. Various mulching/tillage systems are often utilized in tomato production, depending upon the available resources of a particular grower, to achieve better water use efficiency. A study was conducted to compare six different mulching/tillage systems to observe the influence of these systems on soil water retention as well as on `Fabulous' tomato (Lycopersicon esculentum Mill.) production. Winter ryegrass and wheat were the cover crops utilized and were mowed with the following six treatments then applied: 1) Conventional tillage (CT), 2) black plastic over conventional tillage (BP), 3) no-till with cover crop sprayed with Glyphosate prior to transplanting (NT-GLY), 4) strip-till with cover crop sprayed with Glyphosate prior to transplanting (ST-GLY), 5) no-till in which cover crop was mowed periodically during the growing season (NT), and 6) strip-till with cover crop mowed periodically during the growing season (ST). This test was conducted under severe drought conditions (45.4 mm of rain from 1 July to 30 Sept. 1999) with plants receiving no supplemental water via irrigation at any time throughout the study. Soil moisture was measured periodically throughout the growing season at a depth of 20 cm; soil and mulch surface temperatures were taken at similar timings as soil moisture. Soil moisture levels during the growing season indicated different patterns of water depletion when comparing the six treatments. There was no significant difference between the winter rye and wheat with respect to water depletion or tomato yields. Lower early tomato yields under NT, ST, NT-GLY, and ST-GLY indicate that cooler soil conditions, while aiding in the retention of soil moisture, delay early tomato production when compared to the warmer soil conditions found under CT and BP. Results also indicate that late season harvests under NT and ST systems produce predominantly cull fruits with a high incidence of blossom-end rot. The NT-GLY and ST-GLY systems tended to produce comparatively lower levels of cull fruit and blossom-end rot in late season harvests than any of the other six treatments.
Miracle fruit (Synsepalum dulcificum) is the botanical source of miraculin, a natural, noncaloric sweetener. Miracle fruit plants have a bush-like architecture and produce multiple flushes of attractive red berries each year. The berries consist of a large seed, opaque pulp, and brilliant red peel. The pulp of the fruit contains a glycoprotein, miraculin, that binds to the tongue’s sweet receptors and induces a conformational change in response to acidic stimuli. Thus, a strong sweet sensation is imparted in the absence of sugars. The miracle fruit plant is becoming increasingly popular because of its taste-modifying properties, but the species lacks many of the breeding tools common to other crops. We report miracle fruit pulp transcriptomes from ‘Sangria’, ‘Vermilion’, ‘Flame’, and ‘Cherry’ morphotypes. A consensus transcriptome included 91,856 transcripts. Reads mapping to the miraculin gene had the highest representation in individual miracle fruit pulp transcriptomes. Other abundant transcripts primarily included Gene Ontology categories representing cellular components, nucleus and nucleic acid binding, and protein modification. The transcriptomes were used to design real-time quantitative reverse-transcription polymerase chain reaction (qRT-PCR) primers for actin, elongation factor 1α, and the miraculin gene. Analysis by qRT-PCR indicated that miracle fruit pulp and peel tissues had the highest abundance of miraculin transcripts, although other tissues such as leaf, root, and flower also had detectable levels of the target sequence. Overall, these results will support discovery research for miracle fruit and the eventual breeding of this species.
During the initial season of implementation, four tomato production systems differing in soil management, pest control practices, and level of inputs, such as labor, materials, and management intensity were evaluated. These systems were CON, a low input (no mulch, no trellising, overhead irrigation, preplant fertilization, scheduled pest control), conventional agrichemical system; BLD, a high input [straw mulch, trellising, trickle irrigation, compost fertility amendment, integrated pest management (IPM)], ecologically-oriented system that emphasized the building up of soil organic matter levels and used no agrichemicals to supply fertility or for pest control; BLD+, a system similar to BLD, except that agrichemical pesticides were used; and ICM, a high input system (black polyethylene mulch, trellising, trickle irrigation, fertigation, IPM pest control) that used agrichemicals to supply fertility and for pest control. Soil characteristics and fertility levels in the BLD and BLD+ systems were modified with extensive amendments of spent mushroom compost and well-rotted cattle manure. Levels of agrichemical NPK calculated to meet current crop needs were supplied to the CON and ICM systems, with 75% of fertility in the ICM system supplied through the trickle irrigation lines (fertigation). The BLD system had a greater soil water holding capacity and sharply reduced irrigation requirements. During a wet period, fruit cracking and evidence of water-mold root rot were significantly higher in the ICM system than the BLD and CON systems. Defoliation by Alternaria solani was greatest in the BLD system and least in the ICM system. The BLD and ICM systems resulted in a 1 week earlier peak yield compared to the CON system. The yield of No. 1 fruit was 55% to 60% greater in the BLD+ system than the other three systems, which were comparable in yield. Net return was highest in the BLD+ system, although the benefit/cost ratio was greatest in the CON system. This multidisciplinary study has identified important differences in the performance of diverse production systems during the unique transitional season.