Volume 4, No. 2, 1979

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Download AOSA-SCST SEED PATHOLOGY SYMPOSIUM (pp. 53-102, free download)

(pp. 1-11)
An Assessment of the Standardization and Ability of the ASA-610 to Rapidly Predict Potential Soybean Germination1
Miller B. McDonald, Jr. and Dale 0. Wilson2
The ASA-610 is a new commercial instrument developed to rapidly predict seed germination. This study was designed to determine whether the ASA-610 could predict soybean germination and which test variables influence ASA-610 results.

A positive correlation (+ 0.96) existed between ASA -610 current (μA/seed) values and conductivity (μmhos/seed) results indicating that the instrument monitors seed leachate.  Standardization studies using salt solutions revealed that cell fluid level and solution temperature aItered ASA-610 determinations. Analyses of soybean seed evaluations  showed that soak temperature, seed size, and initial seed moisture content influenced instrument performance. The seed treatments captan, captan+ thiram, and Vitavax 200 failed to have an effect on ASA-610 results. In a test of fifty soybean seed lots, the ASA-610 accurately predicted the germination of seeds which were high (> 80%) or low (< 20 %) in germination but not of seeds which germinated between 60 and 80 %.
Additional index words: Glycine max(L.) Merr., seed moisture, imbibition, seed  deterioration, seed size.
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(pp. 12-17)
Variability in Tests of Peanut Seed Germination1
G.A. Sullivan and J.C. Wynne2
The variability among peanut (Arachis hypogaea L.) seed germination tests performed at three locations was determined. Relationships between laboratory germination tests and field emergence were also assessed using samples from 10 seed lots.

The mean seed germination percentage of the three laboratories was significantly different (p = 0.01) and ranged from 78.3 to 85.7 % . The varia­tion in germination percentage of subsamples from the same seed lot was also significantly different (p = 0.01) as measured by the three laboratories. The differences in germination percentage between samples from the same seed lot ranged from 2 to 16%.  This variation among samples within a seed lot in­ dictated that a single test of seed germination is not a reliable estimate of the quality of a seed lot.
Seedling emergence in the field averaged about 20 % less than the mean of the germination tests. Field emergence ranged from a low average of 43% to a high average of 71%.  Average field emergence and the mean of laboratory tests were significantly correlated (r = 0.88), indicating that the mean of several germination tests is an excellent indicator of relative seed quality of a peanut seed lot.
Additional index words: Seedling emergence, sampling variability, seed laboratories.
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(pp. 18-23)
Penicillium Contamination of Grass Seed Germination Tests1
D. C. McGee2
Unusually high amounts of Penicillium spp. contamination of grass seed germination tests occurred in the Iowa State University seed germination laboratory in the winter of 1978-79. The contamination was particularly severe on blotters moistened with potassium nitrate, resulting in reduced ger­mination of Poa pratensis L. seeds.

The building air supply proved to be the major source of Penicillium inoculum, contaminating blotters at the time of test preparation. Seeds, potassium nitrate solutions and blotters did not carry significant amounts of inoculum. Severe contamination also occurred when paper towels moistened with KNO3 were used as substrata, but no con­tamination occurred when KNO3 moistened Kimpak tissues were used.
Additional index words: seed pathology, Poa pratensis L., laboratory ger­mination tests, aerobiology, Penicillium cyclopium, Penicillium pur­purogenum.
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(pp. 24-34)
A New Basis for Characterizing Germination1
Robert K. Campbell and Frank C. Sorensen2
Procedures for characterizing seed lots (i.e., by mean and variation of days to germination, peak germination date, and other useful properties) are com­monly complicated because frequency of days to germination does not have a normal distribution. A procedure is presented for minimizing this problem.

Tests of a seed lot of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) subjected to differing stratification periods and germination temperatures in­dicated that it is the rates at which seed embryos develop toward germination rather than days to germination that have a normal distribution. Consequently, by transforming cumulative percentages of germination to probits (a means for converting a normal sigmoid curve to a straight line) and fitting a straight line to probits regressed on rates rather than on days-or by plotting percentages on probit-scaled graph paper- the resulting intercept and regres­sion coefficient can be used to easily calculate all the standard properties for characterizing a seed lot.
Additional index words: Douglas-fir, Pseudotsuga menziesii, stratification, germination rate, skewness.
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(pp. 35-41)
A Combined Semi-Selective Medium and Serology Test for teh Detection of Xanthomonas Blight Bacteria in Bean Seed1
E. Trujillo and A. W. Saettler2
A technique using a semi-selective medium and serological test (SSMS) was developed for the detection of internally-home Xanthomonas blight bacteria in bean seed. The semi-selective medium permitted the growth of Xanthomonas to high population levels in the presence of contaminating organisms while the serological test was highly specific for Xanthomonas bacteria. The new technique consistently detected greater levels of internal Xanthomonas contamination in bean seed lots than the seedling injection technique presently used by the Michigan Department of Agriculture.

Additional index words: pathological testing.
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(pp. 42-48)
Ratio Analysis: A Tolerance Evaluation Procedure for Two Component Turfgrass Seed Mixtures1
T. P. Riordan2
A ratio analysis is used to determine whether a two component mixture of turfgrass is within tolerance. The procedure is not affected by changes in other crop seed, weed seed, or inert matter percentages; but it does take into consideration whether these values are within tolerance. The "Tolerance Section" of the Rules for Testing Seeds is followed; and the procedure is efficient, simple, highly accurate and adaptable to programmable calculator usage.

Additional index words:
Ratio analysis, programmable calculator, turfgrass mixtures.
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(pp. 49-52)
Ratio Analysis Program for Tolerance Evaluation of Two Component Turfgrass Seed Mixtures1
T.P. Riordan, A.H. Bruneau, R.C. Shearman and E.J. Kinbacher2
A program using a programmable calculator and printer has been developed in conjunction with a ratio analysis procedure to speed tolerance evaluation of two component turfgrass mixtures.

Additional index words: Ratio analysis, turfgrass seed mixtures, program­ mable calculator and printer.
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