Volume 10, No. 2, 1986

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(pp. 81-100)
Cell Membranes and Seed Leachate Conductivity in Relation to the Quality of Seed for Sowing
Alison A. Powell1
The leakage of solutes, including electrolytes, from seeds into water can be detected by measurement of the electrical conductivity of seed leachates. The level of leakage is influenced by the stage of seed maturation at time of harvest, the degree of seed ageing and the incidence of imbibition damage. The influence of these factors on leakage is discussed with particular emphasis on the role of deteriorated and damaged membranes in determining solute loss. The application of conductivity measurements to the  prediction of the germination and vigour of seed lots is discussed.
Additional index words: seed maturation, ageing, imbibition damage.
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(pp. 101-110)
A Critical Analysis of Maguire's Germination Rate Index
R. F. Brown and D. G. Mayer1
The concept and use of Maguire's (1962) index of germination rate (G.R.) was examined from both a practical and theoretic perspective and found to be unsatisfactory. Anomalies arose in that similar germination patterns gave rise to different values of G.R., and, conversely, each value of G.R. covered a wide range of germinations.

The method did not conform to any accepted measure of germination rate and was found to be very sensitive to early germinating seeds but insensitive to later ones. In published literature, G.R. was nearly always very closely correlated with total germination. Thus, G.R. seems to be redundant and its use should be discouraged in favour of citing total percent germination which has the dual advantage of being unambiguous and possessed of clear biological meaning.
Additional Index Words: Germination rate, seedling vigour, vigour rating
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(pp. 111-120)
Endogenous Inhibitors in Corn Seed Genotypes: Inhibition of Root Growth on Roll Towel Germination Tests
A. G. Taylor and E. M. Chirco1
Poorly developed root growth of White Lightning, a heterozygous sugary enhancer (se) sweet corn, has been observed in roll towel germination tests. A large percentage of seedlings would be considered abnormal due to this poor root growth. Soaking seeds for 8 hours in water and/or placing fewer seeds per roll towel improved root growth and percent normal seedlings.

Leachate from White Lightning was assayed on lettuce seed germination and growth. Lettuce root growth decreased linearly with a logarithmic increase in leachate concentration while percent radicle emergence was not affected. Autoclaving the leachate further reduced lettuce root growth which indicated that the inhibitor was not heat labile and not microbial in nature. Leachate of White Lightning decreased root growth of other corn genotypes. White Lightning seed quality was reduced by mechanical injury, accelerated aging or freezing. As seed quality decreased, electrical conductivity increased and percent germination decreased and lettuce root growth was reduced.
Additional index words: Zea mays, toxins, allelopathy, White Lightning, leachate, conductivity.
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(pp. 121-128)
Effect of Defoliating Corn Inbreds on Seed Quality1
B. L. Vasilas and R. D. Seif2
Two field experiments were conducted at the University of Illinois Agronomy and Plant Pathology South Farm to determine the effects of defoliating corn (Zea mays L.) inbreds on seed quality as determined by warm germination and cold germination tests.

In the first experiment, defoliation treatments of 0, 50, and 100% were applied by hand to inbredlines FRMo17rhm and FR27rhm at the 7-leaf, 14-leaf, anthesis, late milk, and soft dough stages in 1982 and the 7-leaf, 14-leaf, anthesis, milk, and dent stages in 1983. In the second experiment, defoliation treatments of 0,50, and 100% were applied to six inbreds (Fr27rhm, FRMo17rhm, FR632, MS71, FR25, and FR16) at the 14-leaf stage.
The effect on seed quality was influenced by the level of defoliation, growth stage when the defoliation treatments were applied, genotype, and environmental conditions. Partial defoliation never affected warm germination and in only a few cases affected cold germination. Reductions in germination scores in response to complete defoliation were associated with reductions in kernel size. The inbred most sensitive to defoliation, FRMo17rhm, was also the inbred which produced the fewest total leaves.
Additional index words: Zea mays L., warm germination, cold germination.
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(pp. 129-136)
A Basic Computer Program for Compiling Personal Bibliographies1
D. A. Davidson, E. E. Roos, and P. C. Stanwood2
USDA-ARS, National Seed Storage Laboratory
Fort Collins, Colorado 80523
A computer-based information retrieval system for personal bibliographies is described. The system consists of two interactive computer programs, written in Microsoft BASICA for the IBM-PC-XT3 personal computer, that enable the user to enter and edit (LIT), search (SEARCH), and print in a convenient format, bibliographic files. The linkage of this system to a mainframe computer to accommodate large bibliographic files is also discussed.
Additional Index Words: Bibliography database, information retrieval, microcomputer, literature search, references.
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Major Seed Problems in Forestry Symposium
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(pp. 137-138)
Biotechnology in Future Forest Regeneration
S. L. Krugman

(pp. 138-139)
Pathological Problems in Forest Seeds
R. L. Anderson

(pp. 140-141)
Preservation of Recalcitrant Seeds
P. C. Stanwood

(pp. 142-150)
Evaluation of Tree Seeds by Electrical Conductivity of Their Leachate
F. T. Bonner and J. A. Vozzo1
Tests with the ASA-610 and ASAC-1000 Automatic Seed Analyzers indicate that these instruments can provide valid estimates of pine seed quality based on electrical conductivity of seed leachate. Conductivity data can be used to predict laboratory germination of loblolly pine to within 6.5 percent and slash pine to within 7.2 percent. Significant correlation of conductivity measurements with nursery emergence was also demonstrated. Limited data indicated that the method should also be satisfactory with other pine species.
Additional index words: Pinus taeda, P. elliottii, seed quality, rapid tests.

(pp 151-171)
Special Prechilling Techniques for Tree Seeds
D. G. W. Edwards1
The procedure known as prechilling, or stratification, to break dormancy in tree seeds is discussed in terms of its effects on germination capacity and germination rate.

Treatment prolongation and poor control of prechilling temperature have been blamed for premature germination before the seeds can be sown, rendering the seeds useless to the nursery grower, Over the last decade, several independent researchers have demonstrated that by changing and controlling seed moisture content during refrigeration, premature germination can be delayed or eliminated and, in some species, germination capacity can he considerably increased, The main effect is on speed of germination, believed to be llrought about by germination synchronization, Plant growers should find the new procedures advantageous since they permit prcchilled seeds to be stored for varying periods, thereby providing flexibility in the initiation of the prechilling treatment as well as the safe storability of treated seeds when sowing is delayed. Practical-scale methods of application have yet to be developed.
Additional index words: stratification, premature germination, seed moisture content, germination synchronization, cold storage.