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- Author or Editor: C.J. Simon x
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A method is described for separating large and small pollen effectively from a heterogeneous mixture. This method potentially is applicable to separation of pollen grains of different ploidy levels, since “unreduced” 2n pollen is larger than normal pollen (n); it might then be used to increase the efficiency of a breeding program employing sexual polyploidization and to diminish crossing inefficiencies in interploid crosses.
Maintenance of genetic resources within the National Plant Germplasm System includes preserving the genetic constituency of accessions as close to the original sample as possible. Genetic changes that can arise during seed regeneration include both an overall loss of genetic diversity within heterogenous accessions and changes in the gene frequencies within accessions. Two germplasm collections are being examined with molecular methods at the Western Regional Plant Introduction Station (WRPIS) for evidence of such genetic change. In the case of pea, gross observation of seed and plant characters indicate that vigorous plant culling during a comprehensive Pea Seedbourne Mosaic Virus eradication program a decade ago resulted in the overall loss of genetic diversity in some heterogenous accessions. Isozyme data has corroborated these observations. Molecular markers are beginning to be used, both to quantify possible genetic changes in accessions as a result of the eradication process, and to document success in reintroducing diversity by repeating the eradication process with additional seed from archival seedlots. In the case of ryegrass, the practice of bulking the seed harvested from regeneration plots may bias the seedlot toward genotypes that are more fruitful. Isozyme analysis after two regeneration cycles showed that balanced sampling (equal seed no./plant) maintained allele frequencies close to the original seed sample. A bulk harvest sample and a sample with an equal number of spikes harvested from each plant showed some significant change in allele frequency, but no significant changes were seen in the allelic richness of accessions, or in the level of an accession's overall heterozygosity. A regeneration sample with an equal number of seed/plant will therefore best preserve gene frequencies within accessions, but loss of an accessions overall diversity will not diminish as a result of less than ideal sampling methods in ryegrass.
Methyl cinnamate and citral, compounds used in large quantities by perfume and flavoring industries, are the major constituents of essential oils found in certain basil varieties. The composition and quantity of oil, sequestered in as many as 16 different types of glandular structures, however, has been shown to change over time with plant development. In this study, we used scanning electron microscopy to characterize glands associated with leaves and flower parts of 3 lines of Ocimum basilicum, 2 with a high percentage of metyl cinnamate and one with high citral (as rel. percent of total oil). Density and distribution of oil producing glands were visualized with a tissue printing method on adaxial and abaxial leaf surfaces of young, mature, and post-mature leaves. Scanning electron micrographs revealed the morphology of six types of glandular structures. Density of oil-producing glands decreased with leaf expansion. The tissue printing method allowed for rapid visualization of oil-containing glands. The density of resulting prints will be easily quantified with computer image analysis.
Postharvest longevity of some cut flowers is shortened by exposure to ethylene gas. Adverse effects of ethylene may be prevented by treatment with 1-methylcyclopropene (1-MCP) gas. Responses of 14 different native Australian cut flowers to 1-MCP and ethylene applied at concentrations of 10 nL·L-1 and 10 μL·L-1, respectively, were examined. Each gas was applied alone for 12 hours at 20 °C and they were also applied in series. Vase lives of Ceratopetalum gummiferum, Chamelaucium uncinatum, Grevillea `Kay Williams' and `Misty Pink', Leptospermum petersonii, Telopea `Shady Lady', and Verticordia nitens were reduced by ethylene treatment. Treatment with 1-MCP generally protected these cut flowers against subsequent exposure to ethylene. The 1-MCP treatment usually did not extend their vase lives in the absence of exogenous ethylene.
Abstract
The open pollinated carrot (Daucus carota L.) ‘Beta III’ was released and widely distributed in 1986, primarily for its value as a garden cultivar and for an improved source of carotenes for providing vitamin A. It is a promising population for breeders to extract inbred lines for improved hybrids.
Abstract
Hybrid carrots (Daucus carota L.) are gaining a larger share of the market once devoted exclusively to open-pollinated cultivars. The carrot inbred Florida 524 has been used extensively as the male parent in experimental hybrids tested in Florida, California, Wisconsin, Texas, and Arizona. These trials have revealed that Florida 524 has good combining ability for fresh market characteristics. Florida 524 is being released jointly by the University of Florida and the U.S. Department of Agriculture.
Abstract
Flavor is an important factor in establishing consumer preference of carrots. Although harsh, strong flavor frequently occurs in available cultivars, the dominance of mild flavor in hybrids from harsh and mild parents suggests that carrot flavor can be improved rapidly when mild-flavored inbreds are available (1). Carrot inbred B2566 has been selected as a source of improved flavor and was used as a male parent in experimental hybrids tested in California, Florida, and Wisconsin. B2566 has demonstrated good combining ability for important fresh market characteristics of color, shape, and seed productivity along with desirable mild, sweet flavor and succulent texture. Because of these qualities, B2566 is being released jointly by the USDA, the Univ. of Florida, and the Univ. of California.
Like everything for the past 2 centuries, agriculture has depended increasingly on fossil fuel energy. Pressures to shift to renewable energy and changes in the fossil fuel industry are set to massively alter the energy landscape over the next 30 years. Two near-certainties are increased overall prices and/or decreased stability of energy supplies. The impacts of these upheavals on specialty crop production and consumption are unknowable in detail but the grand lines of what will likely change can be foreseen. This foresight can guide the research, extension, and teaching needed to successfully navigate a future very unlike the recent past. Major variables that will influence outcomes include energy use in fertilizer manufacture, in farm operations, and in haulage to centers of consumption. Taking six increasingly popular fruit and vegetable crops and the top two horticultural production states as examples, here we use simple proxies for the energy requirements (in gigajoules per ton of produce) of fertilizer, farm operations, and truck transport from Florida or California to New York to compare the relative sizes of these requirements. Trucking from California is the largest energy requirement in all cases, and three times larger than from Florida. As these energy requirements themselves are all fairly fixed, but in future will likely rise in price and/or be subject to interruptions and shortages, this pilot study points to two commonsense inferences: First, that fruit and vegetable production and consumption are set to reposition to more local/regional and seasonal patterns due to increasing expenses associated with fuel, and second, that coast-to-coast produce shipment by truck will become increasingly expensive and difficult.
Abstract
Carotenes from vegetables and fruits are vitamin A precursors that contribute about half of the vitamin A in the U.S. diet (3) and two-thirds of the world diet (5). Carrots typically contain 65 to 90 ppm carotenes (1) and are estimated to be the major source of carotene for U.S. consumers (3). Few pro-vitamin A sources surpass the carotene content of typical carrots, although red palm oil can contain >825 ppm carotenes (2). Genetic selection for higher carotene levels in carrots could increase the dietary consumption of carotene and consequently vitamin A. A high carotene mass carrot population was developed for use in breeding, genetic, and biochemical studies of carrot (Fig. 1).