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Open access

M. H. Dickson and M. A. Boettger

Abstract

Lines and cultivars resistant to mechanical damage with white and colored seeds germinated 60–80% compared to under 20% for several major cultivars. Seed damage resistance was associated with transverse cotyledon cracking (TVC) resistance, r = .649, seed coat shattering (SH) resistance, r = .488, and seed coat weight, r = .373. The SH test indicates whether the seed coat is tightly or loosely adhered to the cotyledons. If % seed coat as a proportion of seed weight exceeded 10% and TVC and SH were under 10%, then damage resistance was almost always good. Weakness in any one character resulted in damage susceptibility. Damage resistant lines produced more vigorous seedlings than susceptible lines following seed maltreatment. Damage resistance was correlated, r = .722, with seedling vigor following seed impaction.

Open access

T. A. Nell, P. M. Marsh, and D. J. Cantliffe

Abstract

No differences were observed in water uptake, respiration rate and seed coat morphology of ‘New Era Bright Red’ and ‘New Era Dark Red’ geranium. Water uptake in some seeds was rapid in the first 12 hours following initiation of imbibition. Radicle emergence and germination occurred 3 days after swelling and respiratory activity began as soon as seeds imbibed water. Nonswollen seeds did not germinate. Seed coat surfaces appeared wax-like in both cultivars and no relationship between occlusion of the hilum fissure and germination was observed. Dipping seed in concentrated H2SO4 or hot water, or removing a portion of the seed, increased germination rate and germination to nearly 100%. Results suggest the seed coat in geraniums can be impervious to water uptake.

Open access

Daniel H. Diaz and George C. Martin

Abstract

An inhibitor was present in both seed coat and embryo of a high and a low chilling cv. of unstratified peach seeds and its concn decreased as stratification proceeded, Embryonic tissue retained more of the inhibitor than the seed coat. As the concn of inhibitor decreased, seed germination increased. The inhibitor was tentatively identified as abscisic acid (ABA) by chromatography. A bound inhibitor was also present in the seed parts of both cvs., and its concn increased in the embryo as stratification proceeded. More ABA and bound inhibitor were present in the high-chilling cv. than in the low-chilling counterpart, indicating that they may be related as factors which cause a cv. to require long periods of chilling. Application of ABA reduced germination percentage on stratified seeds without seed coats. Application of gibberellic acid (GA) and N-benzyladenine (BA) combined had a synergistic effect in promoting germination of dormant seeds.

Free access

Tina Wilson, Robert Geneve, and Brent Rowell

One possible influence film-coating may have on seeds is modifying water uptake and electrolyte leaking during imibibition. Film-coating is a seed treatment that can improve sweet corn germination, especially under cold soil conditions. Two shrunken-2 sweet corn varieties (`Even Sweeter' and `Sugar Bowl') were treated with a polymer film-coating and evaluated for water uptake patterns during imibibition. `Even Sweeter' is a low-vigor sweet corn, while `Sugar Bowl' is a high-vigor variety. Standard germination tests were performed according to AOSA rules and suggest film-coated seeds germinated at a slower rate than untreated seeds. After 4 days of imibibition, `Sugar Bowl' film-coated seeds had 5% germination, while untreated seeds had ≈20% germination. However, after 7 days, film-coated seeds had 94% germination with untreated seeds at 80% germination. Results were similar for `Even Sweeter'. Bulk electrical conductivity readings were taken over 24 h to determine the amount of electrolyte leakage during imibibition. Low-vigor `Even Sweeter' had 92% higher overall leakage than high-vigor `Sugar Bowl'. Additional conductivity readings were taken for both seed lots every 2 h for 12 h. Film-treated seeds leaked 15% less than untreated seeds for `Sugar Bowl'. However, `Even Sweeter' film-coated seeds actually leaked 17% more than the untreated seeds. In both cases, 70% of electrolyte leakage occurred within the first 12 h of imibibition. An imibibition curve was established for the two seed lots comparing untreated and film-coated seeds. During the first 6 h of water uptake, film-treated seeds weighed ≈50% more than the untreated seeds for both `Even Sweeter' and `Sugar Bowl'. Pathways for water uptake as influenced by film-coating shrunken-2 seeds will also be presented.

Open access

Terry L. Gilbertson-Ferriss and H. F. Wilkins

Abstract

Seed germination of ‘Royal Mix’ freesia was most rapid and uniform at 15.5° or 18.5°C under clear polyethylene or at 13° or 21.5°C under black polyethylene. Soaking seeds in running water prior to germination or removal of the seed coat did not improve seed germination

Free access

John R. Duval and D. Scott NeSmith

Production of triploid watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai] transplants is hindered by poor, inconsistent emergence, and frequent seed coat adherence to cotyledons. Seed coat adherence leads to weakened and slow growing plants. High seed costs, coupled with stand establishment problems, discourages transplant producers from growing this crop. Improvement of triploid watermelon emergence will lessen financial risks to growers and transplant producers and will provide a more reliable production system. Mechanical scarification was evaluated as a means to overcome inconsistent emergence and seed coat adherence. Seeds of `Genesis' triploid watermelon were placed in a cylinder with 100 g of very coarse sand (1.0 to 2.0 mm diameter) and rotated at 60 rpm for 0, 6, 12, 24, and 48 hours in a series of experiments. Number of emerged seed was recorded daily, to obtain emergence dynamics. No significant differences were observed in seed coat adherence among treatments. The longest duration of scarification However, enhanced emergence as compared to the control in three of four experiments. These data support earlier suggestions that a thick or hard seed coat is a factor contributing to poor germination and emergence of triploid watermelons.

Open access

Eric E. Roos

Abstract

Coated and raw (uncoated) lettuce (Lactuca sativa L.) seed obtained from commercial sources were subjected to 6 storage conditions (ranging from 21° C, 90% relative humidity (RH) to 5°, 40% RH) for a period of 3 years. Four types of packaging material differing in moisture-barrier properties were used. Samples were removed periodically for moisture and germination tests. Under poor storage conditions, coated seed deteriorated more rapidly than the raw seed controls. Under favorable storage conditions, both coated and raw seed retained full viability for the 3 years.

Open access

E. J. Hogue and L. J. LaCroix

Abstract

For prompt germination the seed of Russian olive (Elaeagnus angustifolia L.) required 9 to 12 weeks of after-ripening at a temperature of 5° C. When fruit and endocarp were removed, 50–60% of the non-after-ripened seed germinated. Complete germination was obtained by removing the endocarp and the seed coats. The germination inhibition appeared to be related to non-leachable inhibitors in both of these structures, and their influence was almost entirely restricted to the radicle end of the embryo. Kinetin was very effective in breaking the dormancy linked to the seed coats but did not influence dormancy when the endocarp was present.

Open access

Janet C. Henderson and David L. Hensley

Abstract

Seeds of black locust (Robinia pseudoacacia L.), common honeylocust (Gleditsia triacanthos L.), and Kentucky coffeetree (Gymnocladus dioica L.) were coated with an adhesive plus hydrophilic gel, adhesive only, or neither (control), planted in sand in the greenhouse, and then irrigated at 3-, 6-, or 9-day intervals. Percent germination of black locust seeds irrigated at 3-day intervals was decreased significantly with exposure to hydrophilic gel. Gel-coated Kentucky coffeetree seeds irrigated at 6-day intervals also had a percent germination significantly lower than those treated with adhesive alone, but germination of untreated seeds was not different from adhesive- or gel-coated seeds. No other significant difference in germination percentage was observed. Seedling heights and dry weights were not affected by seed treatment; however, decreased moisture availability because of longer time periods between irrigations tended to delay emergence and reduced seedling vigor.

Free access

Haim Nerson

Production of watermelons for seed consumption is popular in many regions of the world. In the Mediterranean area, large white seeds are preferred. Six breeding lines were selected for investigating the nature of black spot, an undesirable feature reducing the commercial value of the seeds. Black spot is expressed as blackened areas of the seed coat, mostly near the margin in mild cases, but extending over much of the seed coat in severe cases. Sowing date had a significant effect on expression of black spot. Seeds that developed in early summer (June) had low frequency and severity of black spot expression, whereas seeds that developed later in the summer (July–August) had markedly increased expression. Large differences were also observed among the breeding lines. There was a significant negative correlation between severity of black spot and seed weight, suggesting that black spot is a stress-related phenomenon.