Abbreviation: PMT, photomultiplier tubes. 1 Associate Professor of Seed Science and Technology. 2 Agricultural Engineer, U.S. Dept. of Agriculture, Agricultural Research Service, National Forge Seed Production Research Center, Corvallis, OR 97331. 3
A.G. Taylor, D.B. Churchill, S.S. Lee, D.M. Bilsland, and T.M. Cooper
Most farmers in Sub-Saharan Africa plant local cultivars introduced generations ago. Various national and international organizations and development projects introduce annually hundreds of improved germplasms to a country, and test these under farmer conditions for adaptability and acceptability. Although some local varieties perform well under traditional farming practices, many disease and insect pest resistant improved varieties out-yield local cultivars even under low-input production conditions of Africa. Regrettably, the seed production and distribution system in most of these countries are poorly developed; thus the promising varieties remain unavailable to the majority of farmers. To overcome this problem, the University of Arkansas-led Rwanda Farming Systems Research Project (FSRP) personnel trained farmer-cooperators in the production of good quality bean (Phaselous sp.) seeds. This, and the development of a farmer to farmer seed distribution system that led to quick diffusion of improved bean varieties in the project area will be discussed.
Kanti M. Rawal and Keith Redenbaugh
Polygalacturonase (PG) is the principal enzyme responsible for the softening of tomato during ripening. Transformation of tomatoes with antisense PG (asPG) results in significant delay in softening so that fruits with color and flavor can be harvested and shipped from the fields to distant markets. Safety evaluations of the genetically engineered tomato varieties were conducted from two perspectives: a) agricultural, and b) human food. Data were submitted to the appropriate agencies to obtain approvals for commercial production and to seek advisory opinion for the safety of food for human consumption. Calgene Fresh Inc. was created to develop human resources, physical facilities and logistic capabilities for year round supply of high quality branded produce. Vertical integration from seed production to direct consumer marketing is necessary to optimize the business endeavor.
Bruce M. Pollock
The book, Agricultural Biotechnology: Issues and Choices Information for decision Makers, from USDA and Land Grant Colleges discusses risk evaluation for the use of legislators concerned with public policy. However, that discussion is entirely theoretical. The 1970 epidemic of Southern Corn Leaf Blight caused by the pleiotropic gene for Cytoplasmic Male Sterility provides material to use in real-world risk evaluation for biotechnology. Approximately 1×1012 corn seeds are planted annually in the US. Assuming a mutation rate of 1×10-6, then 1×106 mutations can be expected annually. The poster will evaluate the importance of this number using assumptions based on fold-increase during seed production. Unfortunately, it is not possible to evaluate the risk of incorporating another pleiotropic gene into commercial crops because insufficient data are available on the frequency of pleiotropy.
David A. Dierig, Anson E. Thompson, and Earl R. Johnson
Genetic markers have not yet been described for Lesquerella fendleri (Gray) Wats. a potential new industrial oilseed crop. Seeds of this species are also utilized as a primary component in some desert wildflower seed mixes. Allozyme variation was analyzed for aconitase (ACO), phosphoglucomutase (PGM), and phosphoglucose isomerase (PGI). Four codominant loci, useful as markers, were clearly resolved. In an open-pollinated population, an outcrossing rate and pollen gene frequency was obtained from 20 random families, using these loci. This initial estimate indicated that seed production primarily resulted from outcrossing. Male sterility was discovered in six bulk populations derived from single plant selections. The frequency of this trait, which could affect the outcrossing rate, was found to occur in 15 percent of the plants. Additional populations will be analyzed for validation.
Kenneth W. Mudge and Chin-Chang Chu
In vitro asymbiotic seed germination, subculture, and outplanting of orchids is presented as a laboratory exercise suitable for students of plant propagation or tissue culture. Dendrobium antennatum (Lindley), Phalaenopsis (Blume) white hybrid, or both, are used in this exercise because they flower predictably in the greenhouse, are reliable for seed production, and germinate and grow rapidly in vitro. The exercises can be used to instruct students in the skills involved in orchid seed sterilization, sowing, and culture, as well as instruct students in the unique features of orchid reproductive biology and symbiosis. A schedule is suggested for stock plant flower pollination, capsule harvest, seed sowing, and seedling subculture so that the necessary plant material is available for students to sow, subculture, and outplant seedlings during a single laboratory session.
Michael N. Dana and Ricky D. Kemery
Interest in direct-seeding establishment of wildflowers as a component of landscape planting has continued to increase. Seed may be very expensive. Information is needed on the quality of seed available to consumers and the landscape industry. The goal of this work was to assess the level and consistency of seed quality available from the wildflower seed production/marketing industry. Eleven species of native prairie forb wildflowers and eight species of “garden” wildflowers from seven companies were purchased in 1992 and 1993 and subjected to germination testing. Germination procedures were those of AOSA where available, or generalized from the literature when no guidelines existed. Results showed significant variation among wildflower species, among companies supplying the same species, and over the two seed years tested in the study. These data reinforce the need for seed quality testing and reporting as a part of the sales of wildflower seed.
A.A. Abdul-Baki, H.H. Bryan, G.M. Zinati, W. Klassen, M. Codallo, and N. Heckert
Prolific flowering is essential for economic seed production in sunn hemp (Crotalaria juncea L.). Since flowers appear as racimes on the distal portions of secondary branches and since the branching is restricted by a strong apical dominance, lifting the apical dominance by cutting the tops of plants should induce more branches and more flowers per plant. We evaluated this concept in a field experiment conducted in 1999 at the Tropical Research and Education Center, Univ. of Florida, Homestead, by cutting main stems of 100-day-old plants in a dense stand (113,000 plants/ha) at 30, 60, and 90 cm above the soil surface. Cutting at all heights induced more branching and flowering than the control. The highest positive response was in plants in which the main stem was cut at 90 cm above soil surface.
Scott Reid, Judy Harrington, and Harrison Hughes
Inland saltgrass, Distichlis spicata var. stricta (Torr.) Beetle, is a native western U.S. grass that has potential in turf situations. Elite clones with outstanding potential have been selected. Poor seed production appears to be the main limiting factor for its use as turf in saline conditions. In order to better understand seed set, 40 genotypes were examined for chromosome number and morphology. Chromosome numbers of root tip metaphase spreads varied with the most common being 2n = 38. However, chromosome numbers of 39, 40, 42, and 74 were also observed. Meiotic examination of anthers revealed 19 bivalents for those with 38 chromosomes while those with 42 had 20 bivalents with 2 unpaired chromosomes. The unpaired chromosomes lagged at anaphase. Crosses among genotypes of different chromosome number have resulted in good seed set. Harvested seed are germinable and plants from these crosses are being grown for further studies.
Erik J. Sacks and Dina A. St. Clair
The influence of cryogenic pollen storage on fruit set and seed production in tomato (Lycopersicon esculentum Mill.) was investigated. Flowers pollinated with pollen samples stored for 5 weeks at –80C, with or without 20 h precooling at 4C, had similar fruit set and number of viable seed per fruit as those pollinated with fresh pollen. Pollen samples, which were repeatedly cooled (–80C) and warmed (to 22 to 24C) for up to six cycles, continuously maintained the same viability as the fresh pollen. When cryogenically stored pollen of L. esculentum 2-837, LA359, LA3198, and LA3199 were used to pollinate LA359, the number of viable seed formed per fruit differed significantly. Results of this study suggest that pollen cryopreservation can be used successfully for tomato breeding and germplasm storage.