Horticultural Seed Pathology - An Introduction
Martin M. Kulik1 and Phillip C. Stanwood2
Seed pathology, the area of plant pathology that deals with seedborne pathogenic microorganisms and viruses and the diseases that they cause, is one of the oldest areas of the parent science. However, it is only recently that its importance in agriculture has been fully appreciated. In this paper, several seedborne pathogens that cause important diseases of major horticultural crops with detection and control are discussed.
Additional index words: Seedborne diseases, fungi, bacteria, viruses, nematodes, detection, control.
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Storage of Seed of Mojave Desert Shrubs1
Burgess L. Kay, Charles C. Pergler, and Walter L. Graves2
Increased use of the California deserts has resulted in plant and soil degradation which can best be minimized by revegetation with shrubs. However, due to the erratic seed production of desert plants, seed may not be available for collection from the wild when needed. Therefore, native seed banks are necessary to assure availability. In this study seed from 22 species of Mojave desert shrubs were placed in four storage environments.
Additional index words: Shrub seed storage, desert shrub seed.
The Development of a Systems Approach to Training Seed Analysts
Steven B. Glassman1
A systems approach is described for developing and implementing training programs, The approach directs attention to the training needs of the laboratory and the individual. The system ensures that the design and implementation phases in the program are flexible, and adjust to experience through feedback mechanisms. This approach is being used by Agriculture Canada to redesign training programs for its analysts.
Additional index words: System, training requirements, job analysis, training design, training implementation, feedback.
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Automated Seedling Length Measurement for Germination/Vigor Estimation Using a CASAS (Computerized Automated Seed Analysis System)1
R. D. Keys, R. G. Margnpuram and G. A. Reusche2
An automated seedling length measurement analysis has been developed for use with a CASAS (Computerized Automated Seed Analysis System), in which a seed germination test sample is scored for both germination and vigor (as indicated by seedling or seedling part length ). The methodology of the analysis is applicable to most major crop seeds.
Additional index words: Seed-analyzer, seed vigor, seed computer, seed quality.
Evaluating Seed Leachate Measurements Relative to Imbibition Time and Solute Volume
J. A. Vozzo1
Leachate conductivity of sand, shortleaf, slash, Scotch, loblolly, and Virginia pine (Pinus clausa, P. echinuta, P. elliottii, P. sylvestris, P. taeda, and P. virginiana) seeds was measured using different imbibitions and rinse times. Conductivity levels, as measured in μA, were greatest for Virginia and Scotch pine seeds imbibed for 48-hours and for sand pine seeds imbibed for 24-hours.
The movement of solvent which affects solute concentration and its net movement through the seed coat are discussed. This discussion includes speculation on selective membrane permeability.
Additional index words: seed testing, leachate, sand pine, shortleaf pine, slash pine, Scotch pine, loblolly pine and Virginia pine.
Moisture Stress and Soybean Seed Quality
R. W. Yaklich1
The effect on seed yield and quality of 2-week periods of moisture treatment during seed development and maturation were investigated. Seeds of soybean [Glycine max (L.) Merr.] cv. Elf were sown 3.5 cm deep at a rate of 9 seeds/m of row in rows 0.17 m apart in 1980. Plots three m2 were formed when plants had 3 nodes on the main stem. Moisture treatments began when plants bore a flower at the node immediately below the uppermost node having a completely unrolled leaf. Plot treatments were of 2 weeks duration and consisted of 2.5 cm of irrigation per week or covering with a portable plastic house to withhold moisture.
The growing season of 1980 was the hottest on record because of the number of days that the temperature attained or exceeded 32.2oC. Seed quality was good as measured by sandbench emergence and field emergence, but the accelerated aging test showed that seed from plots where moisture was withheld during pod fill were low in vigor. The last two treatment periods occurred during pod fill and the plots covered by plastic houses had significantly less yield than the corresponding irrigated plots. The covered plots at the end of pod fill were the only plots with a significantly smaller seed size. The basal seed most frequently aborted. It was concluded that reduced moisture during seed development reduced yield by reducing seed number and size.
Additional index words: Glycine max, vigor, accelerated aging.
Cell Wall Composition and Enzymatic Degradation of Atriplex gardneri (Moq) Dietr. Seed Bracteole1
P. W. Burton, W. F. Campbell, A. S. Bittner, and A. J . Johnson2
Chemical clarification of composition of the bracteole restraint on Atriplex gardneri ( Moq) Dietr. seed germination, and development of a pre-treatment to enhance germination were the objectives of this study. Following acid hydrolysis of bracteole cell walls, analyses revealed 17% lignin, 33% glucose, 29% xylose, 7% arabinose, 1% galactose and less than 1% mannose. Delignified and lignified cell walls were incubated with cellulase supplemented with B-D-glucosidase, crude-hemicellulase and polygalacturonase separately and in combination. Sequential treatment of lignified cell walls by cellulase followed by polygalacturonase induced 14% degradation. All other treatments produced less than 10% degradation.
Additional index words: Lignin, glucose, xylose, arabinose, galactose, mannose, cellulose, impermeable seed coats.
Soaking and Other Seed Pretreatment Effects on Germination and Emergence of Sugarbeets at High Temperature1
J. M. Nelson2, A. Jenkins3, and G. C. Sharples2
Sugarbeet (Beta vulgaris L.) seeds soaked in 50 times their weight of water for 1/2 to 8 days and air dried had faster rates of germination than washed or control seeds in laboratory tests at 38°C. Water temperatures of 15 or 25°C were superior to temperatures of 5 and 35°C during soaking treatment.
Additional index words: Beta vulgaris L., fusicoccin, gibberellic acid, kinetin, salinity.