Volume 8, No. 1, 1983

Download Cover, Contents, Bylaws and Reports

(pp. 1-5)
Longevity of Cantaloupe Seed1
Louis N. Bass
ABSTRACT:
Seeds of 27 cantaloupe cultivars were stored 23½ years at 10, 21, and 32 C.  At 32 C seed of  only three cultivars showed any signs of life. Seeds of only two and three cultivars gave 0% germination after storage at 10 and 21 C, respectively. At 21 C seeds of two cultivars  germinated over 50% in 10 days. Seeds of numerous cultivars showed dormancy and germinated later. At 10 C seeds of four cultivars germinated better than 75%. Differences in seed longevity among cultivars were variable.
Additional index words: Cucumis melo, seed storage, viability, germination.
Download entire article

(pp. 6-14)
Germination Response of Loblolly Pine to Temperature Differentials on a Two-Way Thermogradient Plate
F. T. Bonner1
ABSTRACT:
A two-way thermogradient plate (TGP) was used to test temperature response of two lots of loblolly pine (Pinus taeda L. ), one dormant and the other nondormant. Both stratified and unstratified seeds were tested on 144 alternating or constant temperature regimes which ranged 14 to 33 C.

Alternating temperatures in the range of 18-21 C (night) and 28-32 C (day) gave the quickest germination for unstratified seeds, thus confirming the suitability of the current ISTA prescription of 20/30 C for this species. Stratification widened the range of temperature at which germination was satisfactory, especially on the cooler part of the TGP. The best constant temperatures were 25 to 28 C; stratification widened the range to 22 to 28 C for the nondormant lot, but did not change this range for the dormant lot. Seeds in constant temperatures benefited more from stratification than did seeds in  alternating temperatures.
Additional index words: Pinus taeda (L)., Stratification, Seed testing, Germination rate.
Download entire article

(pp. 15-24)
Proteolytic Activities in Germinating Seeds of Curcurbita moschata1
Reiner H. Kloth and Walter E. Splittstoesser2
ABSTRACT:
Enzymatic activity capable of cleaving the peptide bond of Nα-benzoyl-DL-arginine-p-nitroaniline (BAPAse activity) and Nα-benzoyl-DL-arginine-β-naphthalinide ( BANAse activity) was found in cotyledons of germinating seeds of Cucurbita moshata Poir. 'Waltham Butternut'. Removal of the embryonic axis did not influence the maximum level of enzyme activity.

BAPAse activity was separated into two fractions by Sephadex G-50 and DEAE chromatography. The BAPAses were inhibited by N-ethylmaleimide and iodoacetamide suggesting that the enzymes were sulfhydryl dependent while BANAse activity was not inhibited. The BAPAses were not inhibited by arginine, γ-aminobutyric acid, asparagine, glutamate or ornithine at a concentration 5-fold greater than the substrate. Neither BAPAses or BANAse were capable of cleaving peptide bonds found in the seed globulin, the water soluble, heat stable protein derived from the seed globulin or N-α-benzoyl-L-argininamide. These enzymes may degrade small arginine containing peptides derived from the original seed globulin,
Additional index words: arginine, BAPAse, BANAse, Nα-benzoyl-DL-arginine-P-nitroaniline, Nα-benzoyl-DL-arginine-α-naphthalamide, globulin.
Download entire article

(pp. 25-30)
Effects of Embryo Removal Upon Reserve Protein Degradation in Curcurbita moschata1
Walter E. Splittstoesser2
ABSTRACT:
Reserve protein degradation began the second day of germination in cotyledons of Cucurbita moschata Poir. 'Walthan Butternut', and was complete by the sixth day of germination. The original salt soluble, heat stable protein was converted into water soluble, heat stable protein and finally into free amino acids. Removal of the embryo tissue had no effect upon the degradation rate or pattern.

Cyclohexamide or polyethylene glycol prevented protein breakdown when applied to axisless cotyledons. Cyclohexamide severely reduced protein degradation when applied on the third day of germination. It was concluded that emybro tissue was not required for reserve protein degradation in this species; that enzymes required for protein degradation were synthesized during germination; and that cotyledon expansion was required for reserve protein degradation. It was suggested that the metabolic activity caused by cotyledon expansion may serve as an internal sink for the products of storage protein degradation, reducing their concentration to a noninhibitory level.
Additional index words: Cyclohexamide, cotyledon expansion, globulin.
Download entire article

(pp. 31-40)
Achieving Maximum Germination Potential in Germination Tests of Soybean1
Q. E. Schultz and P. D. Evenson
ABSTRACT:
Prehydration of soybean seed resulted in an average 3.6% increase in germination for 100 soybean lots. The prehydration treatment resulted in an increase in moisture ranging from 2.2% to 8.3% with a similar response to prehydration occurring at all moisture levels. The response to prehydration decreased as mechanical damage levels increased.

The initial moisture content of the seed had no effect on the response to prehydration. Water content increased in the seed at a linear rate of 0.2% per hour in the prehydration chamber under the conditions of this study. This contrasted sharply with imbibition of 4.5% per hour for non-prehydrated seed on Kimpak. The prehydration of soybean seed prior to germination may reduce or prevent imbibition injury.
Additional index words: Glycine max (L.) Merr., Prehydration, imbibition, imbibition injury.
Download entire article

(pp. 41-46)
The Effect of Growth Promoting Substances and Gels on the Emergence and Dry Weight of Tomato and Pepper1
M. D. Orzolek2
ABSTRACT:
Addition of ascorbic acid (250 ppm), phosphoric acid (250 ppm) and gibberellic acid (GA3, 200 ppm) to germinated seed-gel mixtures of tomato and pepper prior to planting affected the emergence and growth of the seedlings. Ascorbic plus gibberellic acid significantly increased the emergence rate, but not dry weight of pepper; while gibberellic acid in combination with either phosphoric or ascorbic acid significantly increased the emergence, but not dry weight of tomato.

Germination of tomato seeds significantly increased their emergence as indicated by ERI values compared to dry seeds; but no difference was observed with pepper seeds. There were differences in the performance of the gels. The starch polyacrylate polymer performed the poorest; while the aluminum silicate and hydroxyethyl cellulose performed equally well.
Additional index words: Ascorbic acid, phosphoric acid, gibberellic acid, pre-germination.
Download entire article

(pp. 47-54)
Pyrrolizidine Alkaloid Levels in Tall Fescue Seed as Influenced by Seed Age, Location, and Variety1
T. A. Jones, R. C. Buckner, and P. B. Burrus II2
ABSTRACT:
Tall fescue (Festuca arundinacea Schreb.) long has had a reputation as a poor-quality forage because of an assortment of toxicological problems experienced by animals grazing this species. Summer syndrome toxicity is associated with a seed-transmitted endophytic fungus (Epichloe typhina (Fr . ) Tul., Acremonium coenophialum Morgan-Jones and W. Gams) which, in turn, is associated with pyrrolizidine alkaloid accumulation, especially N-formyl and N-acetyl loline. The objectives of this study were 1) to assay the major seed-producing areas and varieties in the U. S. for loline alkaloids and 2) to investigate the effect of age of seed at planting on loline alkaloid levels of seed harvested from these stands.

Seed lots of the Kentucky varieties 'Kentucky 31' and 'Kenwell' contained much higher levels of loline alkaloids than the Oregon varieties 'Alta' and 'Fawn.' Certified 'Kenhy' seed produced from stands sown with recently harvested foundation seed high in loline alkaloid content tended to have much higher levels than seed produced by stands sown with seed stored 2 years or more. Differences between varieties and seed production areas are more likely due to cultural practices, length of seed storage, or historical factors than to strict genetic or location effects. The lower loline alkaloid levels resulting from establishment with 2-year-old seed is attributed to impersistence of the endophyte. Results suggest that other unknown factor(s) may contribute to a total loss of loline alkaloid accumulation capacity in seed only 3 months old.
Additional index words: Festuca arundinacea Schreb., N-formyl loline and N-acetyl loline alkaloids, Acremonium coenophialum Morgan-Jones and W. Gams, Epichloe typhina (Fr. ) Tul., Tall fescue endophyte, summer syndrome, Tall fescue toxicity.
Download entire article

(pp. 55-60)
Seed Vigor Testing - 19821
Dennis M. TeKrony2
ABSTRACT:
The status of seed vigor testing was determined by surveying seed testing laboratories in the Association of Official Seed Analysts (AOSA) and the Society of Commercial Seed Technologists ( SCST ) . The survey indicated that 61% of the 102 laboratories responding were testing for seed vigor, which was 10 percentage points higher than in 1976.

The vigor tests conducted by the largest percentage of all laboratories responding were; cold test (72% ), tetrazolium (66% ) and accelerated aging ( 65% ). Nearly two-thirds of the 61 laboratories conducting vigor tests were conducting three or more different tests in their laboratories. The tests which have shown the greatest increase since 1976 in laboratories testing for vigor were; accelerated-aging, conductivity and tetrazolium.Corn and soybeans were the crops tested most frequently for seed vigor in 85 and 74%, respectively, of the responding laboratories. The SCST laboratories tended to conduct more vigor tests per laboratory and a greater number of samples per test annually than the AOSA laboratories.
Download entire article