Search Results

You are looking at 1 - 10 of 14 items for

  • Author or Editor: William J. Martin x
  • Refine by Access: All x
Clear All Modify Search
Free access

William J. Martin and Dennis P. Stimart

Narrow-sense heritabilities and genetic correlations of ornamental quality traits of Antirrhinum majus (snapdragon) were evaluated with special reference to cut flower postharvest longevity (PHL). Inbreds P1 (16 days PHL) and P2 (3 days PHL) were hybridized to produce an F1 (P1 × P2) that was self-pollinated to produce an F2 population. The F2 were self-pollinated to produce F3 families and advanced through single-seed descent by self-pollination to the F5 generation. P1, P2, F1, F3, F4, and F5 were evaluated for ornamental quality traits. Quality traits were found to be quantitative and normally distributed. Narrow-sense heritability (h2) estimates were high and consistent across generations examined; PHL h2 ranged from 0.79 to 0.81 ± 0.06. Phenotypic and genotypic correlations revealed underlying physiological and pleiotropic interactions relevant to breeding programs aimed at simultaneous improvement of ornamental quality traits. PHL is inversely related to cut flower strength and days to flower, -0.44 ± 0.04 and -0.43 ± 0.44. Buds at discard is positively correlated to cut flower and plant diameter, cut flower weight and days to flower, 0.77 ± 0.05, 0.58 ± 0.06, 0.71 ± 0.06, and 0.77 ± 0.07, respectively. Gain from selection for quality traits of interest can be rapid.

Free access

William J. Martin and Dennis P. Stimart

On-plant floret longevity and cutflower postharvest longevity (PHL) of Antirrhinum majus L., snapdragon, were evaluated using inbreds P1 (16 day PHL) and P2 (6 day PHL), F1 (P1 × P2), F2 (F1 self-pollinated), F2 × F2 (among and within PHL categories: long, 17 to 25 days; middle, 9 days; and short, 2 to 3 days), and F3 families (F2 self-pollinated). F2 on-plant floret longevity and PHL correlated to later generation PHL. Prediction of progeny PHL from F2 × F2 matings appears feasible if genotypic value for PHL of F2 is known. Selection for PHL is best based on evaluation of multiple cutflowers per genotype. Significant additive and dominant genetic variance components contribute to PHL.

Free access

William J. Martin and Dennis P. Stimart

Stomatal density during plant development and inheritance of the trait were investigated with the goal of utilizing stomatal density as a correlated trait to cutflower postharvest longevity in Antirrhinum majus L. Inbred P1 (stomatal index = 0.2) was hybridized to inbred P2 (stomatal index = 0.3) to produce F1 (P1 × P2), which was backcrossed to each parent producing BCP1 (F1 × P1) and BCP2 (F1 × P2). P1, P2, F1, BCP1, and BCP2 were used to examine changes in stomatal density with plant development and early generation inheritance. An F2 (F1 self-pollinated), and F3, F4, and F5 families, derived by self-pollination and single seed descent, were used to obtain information on advanced generation inheritance. Stomatal density was stable over time and with development of leaves at individual nodes after seedlings reached two weeks of age. Therefore, stomatal density can be evaluated after two weeks of plant development from a leaf at any node. Stomatal density is quantitatively inherited with narrow sense heritabilities of h2 F2:F3 = 0.47 to 0.49, h2 F3:F4 = 0.37 ± 0.06 to 0.60 ± 0.07, and h2 F4:F5 = 0.47 ± 0.07 to 0.50 ± 0.07.

Full access

Dennis P. Stimart and William J. Martin

The time required to maintain plants on a standardized basis (effort) was investigated in 24 gardens of various plant composition over 5 years. Cluster analysis of data grouped gardens into five clusters based on magnitude and timing of effort. Plants grown in containers required up to 20 times more effort annually than plants grown in other gardens in ground beds. Gardens planted with annuals required about 80% less effort than container gardens but 75% more effort than other gardens evaluated. As the number of taxa in gardens decreased, effort decreased and was less variable throughout the year. Enumeration of effort in relation to garden composition should be used to project management cost for gardens.

Free access

William J. Martin and Dennis P. Stimart

Stomatal density is being investigated as a highly correlated trait to postharvest longevity (PHL) and subsequently may be used for selection in early generations of breeding germplasm. To this end, leaf imprints were created from Antirrhinum majus L. (snapdragon) P1, P2, F1, BC1 (F1×P1), BC2 (F1×P2), F2, and F3 plants and evaluated for stomatal densities. Cut flowers of P1, P2, F1, BC1 (F1×P1), BC2 (F1×P2), and F3 were harvested after the first five flowers opened and evaluated for PHL. Additionally, cut flowers from these lines were evaluated for leaf surface area. Populations for evaluation were grown in the greenhouse in winter and spring 1999-2000 in a randomized complete-block design according to standard forcing procedures. Twenty-five cut flowering stems of each genotype were held in the laboratory in deionized water under continuous fluorescent lighting at 22 °C for PHL assessment. The end of PHL was defined as 50% of the flowers drying, browning, or wilting. Data will be presented on the correlation between stomatal density and PHL.

Free access

William J. Martin and Dennis P. Stimart

Cut flowers of Antirrhinum majus L. (snapdragon) P1, P2, F1, F3, and F2 × F2 plants were harvested after the first five flowers were open and were evaluated for postharvest longevity to further evaluate genes conditioning postharvest longevity. F3 progeny evaluated were derived by selfing F2 selections of long keeping, mid-range, and short keeping types. F2 × F2 progeny evaluated were derived from crosses within and between postharvest longevity categories. Populations for evaluation were grown in the greenhouse in winter 1998-1999 in a randomized complete-block design according to standard forcing procedures. Thirty plants of each genotype were held in the laboratory in deionized water under continuous fluorescent lighting at 22 °C for postharvest assessment. The end of postharvest life was defined as 50% of the flowers drying, browning, or wilting. Data will be presented on postharvest longevity and allelic relationships within populations.

Free access

Jaime A. Weber, William J. Martin, and Dennis P. Stimart

Progeny of 158 F5 × F5 crosses of Antirrhinum majus (snapdragon) selected within and among cut flower postharvest longevity (PHL) categories (long = 12.6-16.8 days, middle = 9.3-12.1 days, and short = 4.8-8.9 days) were evaluated for PHL and quality traits. Results were compared with previous studies involving F2 × F2 progeny, and F3, F4, and F5 inbred lines. Heritability of PHL in F5 × F5 progeny (0.77 ± 0.11) agrees with that of inbred lines (0.79 to 0.81) but is higher than in F2 × F2 progeny (0.41). Therefore, selection for increased PHL should progress more rapidly and predictably through application of inbred lines rather than F2 individuals. Significant differences between F5 × F5 progeny PHL categories confirm PHL is heritable with a significant additive component. Heritabilities of quality traits in A. majus are high, suggesting selection for quality traits should progress without difficulty. Phenotypic and genotypic correlations of PHL with quality traits are not consistently significant across PHL studies in A. majus. Discrepancies between studies suggest most traits may not be correlated to PHL or are subject to strong environmental influence.

Free access

Jernej Jakse, William Martin, John McCallum, and Michael J. Havey

The commercial production of onion (Allium cepa L.) inbreds, hybrids, and open-pollinated (OP) cultivars would benefit from a robust set of molecular markers that confidently distinguish among elite germplasms. Large-scale DNA sequencing has revealed that single nucleotide polymorphisms (SNPs), short insertion-deletion (indel) events, and simple sequence repeats (SSRs) are relatively abundant classes of codominant DNA markers. We identified 398 SNPs, indels, and SSRs among 35 elite onion ulations and observed that all populations could be distinguished. Phylogenetic analyses of simple-matching and Jaccard's coefficients for SSRs produced essentially identical trees and relationships were consistent with known pedigrees and previous marker evaluations. The SSRs revealed that elite germplasms from specific companies or breeding programs were often closely related. In contrast, phylogenetic analyses of SNPs and indels did not reveal clear relationships among elite onion populations and there was no agreement among trees generated using SNPs and indels vs. SSRs. This discrepancy was likely due to SNPs and indels occurring among amplicons from duplicated regions (paralogs) of the onion genome. Nevertheless, these PCR-based markers will be useful in the quality control of inbred, hybrid, and OP onion seed lots.

Full access

J Austin Gimondo, Christopher J. Currey, Darren H. Jarboe, Martin Gross, and William R. Graves

Drawbacks of traditional synthetic fertilizer led us to explore a biologically based (bio-based) alternative. Our objective was to quantify the efficacy of wastewater-grown algae pellets and pastes harvested from rotating algal biofilm systems as fertilizers for three crops, ‘Honeycomb’ marigold (Tagetes patula L.), ‘Beefsteak’ tomato (Solanum lycopersicum L.), and ‘Ambrosia’ sweet corn (Zea mays L.). Factorial experiments were designed for each crop with fertilizer type (algae pellets, algae paste, a synthetic controlled-release fertilizer, or a commercially available bio-based fertilizer from wastewater treatment) and substrate (commercial or custom-made) as factors. Shoot growth, shoot nutrient concentration, and substrate pH and electrical conductivity (EC) were affected by fertilizer, substrate, or their interaction. Algae pellets and paste supplied nutrients to all three species effectively, increasing shoot size, dry weight, perceived health, and nutrient concentrations compared with unfertilized controls. Notwithstanding some variability among crops, performance of algal materials was similar to that of the synthetic fertilizer and better than that of the commercial bio-based fertilizer. As a bio-based fertilizer that supplies plants with recycled nutrients sequestered from wastewater, wastewater-grown algae can reduce the impacts of mineral nutrition management in container-crop production by partially supplanting synthetic fertilizer use.

Full access

William J. Lamont Jr., Martin R. McGann, Michael D. Orzolek, Nymbura Mbugua, Bruce Dye, and Dayton Reese

Plasticulture technology, especially high tunnels for extending the production period of a wide variety of horticultural crops, is an accepted production practice worldwide. In particular, high tunnels offer a production system that minimizes the effect of the environment on crop production and allows growers to continue to farm in densely populated areas. Only recently has the use of high tunnels in the U.S. been investigated and this research has been centered in the northeastern U.S. In 1999 the High Tunnel Research and Education Facility was established at Pennsylvania State University that resulted in the development of a unique high tunnel design. A detailed description of the new design and construction is presented in this report.