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- Author or Editor: William J. Carpenter x
Caladium hortulanum Birdsey cv. Candidum seed failed to germinate without light; maximum germination required daily, incandescent light of ≤4 hours. Lengthening daily lighting periods progressively reduced the days to 50% relative germination (T50) from 20 to 8, and days between 10% and 90% relative germination (T90 – T10) from 16 to 5. T50 and T90 – T10 were shortest (≈ 8 days) at 25 and 30C, while total or absolute germination percentage (G) was highest at ≈ 90%. G was 94% for seeds harvested immediately, but 75% or 38% for seeds that remained in fruits for 3 or 12 weeks after fruit abscission from the spadix. Total absolute germination was reduced from 95% to 87% when seed moisture contents declined to <14%. Seed storage for 7 days at from 10 to – 80 C-caused no reduction in G. Seeds were stored 6 months at 15C and 22%, 33%, or 52% RH without change in G, but storage at 5 or 25C and 11%, 75%, or 95% RH significantly reduced germination.
Priming permits seeds to slowly imbibe water at regulated rates and to begin the initial stages of germination. Hypertonic polyethylene glycol (PEG) 8000 solutions of 1.0 and 1.2 MPa at 15C improved seed germination of dusty miller (Senecio cineraria DC.). At 0.8 MPa, germination was promoted during priming. No differences in rates, span, or total germination were found among seeds primed for 1, 2, or 3 weeks with or without aeration during priming. Germination percentages of primed and nonprimed seeds were similar at 10, 15, 20, and 25C, but 42% to 81% higher for primed seed at 30 or 35C. Priming reduced days to 50% of total germination (T50) 23% to 61%, and germination spans in days 30% to 67%. Primed seeds germinated most rapidly and uniformly at 20 and 25C. No change in total germination, T50, or germination span resulted when moisture contents of primed seeds were lowered to 7.8% or seeds were held at –80C for 7 days. Primed seed performance was unchanged after storage at 5C and 52% RH for 16 weeks.
Abstract
Butia fruit coloration at removal from the infructescence indicates the ability of the seeds to germinate. Seeds from yellow-green fruits had significantly lower germination percentages than seeds from bright to dark yellow fruits. Soaking cleaned seeds in deionized water or aqueous GA3 solutions at 1000 ppm for 24 hr following mechanical or acid scarification failed to promote germination. Butia seeds required 90 to 150 days after-ripening at 5° to 25°C before sowing. After-ripened seed sown at 40° and held there for 2 to 3 weeks and at 30° thereafter had 70% to 80% germination and superior vigor. Constant 40° temperature during germination reduced seedling growth. After-ripening and germination at 40° substantially increased total germination and reduced germination time. Time required for germination declined as after-ripening increased from 30 to 150 days.
Abstract
Soaking palm seed in water for 1 to 21 days prior to planting reduces the number of days required for germination (3). Loomis (1) found soaking seeds of Acrocomia scierocarpa and Astrocaryum mexicanum palms for 2 to 3 weeks following hot water scarification at 100°C for 3 min hastened seed germination. Rees (3) reported soaking Copernicia cerifera (Mart.) seeds in water for 7 days at 38° to 42° also accelerated germination after planting. Presoaking Alexandra palm [Archontophoenix alexandrite (F.J. Muell.) H. Wendl & Drude] seed in water for 24 to 72 hr at 25° was reported by Nagao and Sakai (2) to stimulate germination. The purpose of this study was to determine the effect of temperature during a 7-day preplanting period on imbibed and nonimbibed seed and to compare seed soaking in water with moist peatmoss on germination percentages and numbers of days required to achieve 50% final germination.
Abstract
Temperature ranges for seed germination were determined for palm species Acoelorraphe wrightii (Griseb. & H. Wendl.) H. Wendle ex. Becc., Coccothrinax argentata (Jacq) L. H. Bailey, Sabal etonia Swingle ex Nash, and Thrinax morrisii H. Wendl. Total germination was highest with fewest days to 50% of final germination at 35°C Temperatures 5° to 10° above or below 35° frequently caused delayed, irregular, and reduced total germination. Temperatures exceeding 10° from 35° generally were inadequate for germination.
Abstract
Expanded foam sprays of (2-chloroethyl)phosphonic acid (ethephon), 6-(benzylamino)-9-(2-tetrahydropyran-yl)-9H-purine (PBA), and 6-benzylamino purine (BA) at 1000 and 2000 ppm applied at plant cutback increased the total number of flowering stems per plant and the number of stems from axillary buds within 30 cm of the bud union, compared with conventional sprays of the same chemicals and concentration. Sprays of plant growth regulators were most effective when applied at cutback, with less benefit from treatments 3 weeks before cutback or 1 or 3 weeks after cutback. No chemical or method of application effectively promoted shoot development from the bud union.
Abstract
Salvia (Salvia spendens, F. Sellow ex Roem & Schult.) seeds imbibed in distilled water at 6C for 6 days germinated earlier and with fewer days to 50% of total germination (T50) than non-imbibed seeds. Drying imbibed seeds for 1 to 5 days at 5C and 45% RH before sowing signficiantly reduced seed viability. Priming seeds in a hypertonic osmotic solution of aerated polyethylene glycol 8000 (PEG) at —0.8 MPa for 10 days at 15C improved germination of the three cultivars tested. In laboratory and plant growth chamber trials, seeds primed with PEG 8000 and nonprimed seeds had similar total germination at 20 and 25C, but primed seeds had significantly higher germination at 10, 15, and 30C. At 35C, PEG-primed seeds had 44% to 65% germination, while nonprimed seeds failed to germinate. Alternating 10 and 20C or 20 and 30C diurnally at 12-hr cycles did not increase total germination regardless of seed treatment. Seeds primed with PEG had lower T50 than nonprimed seeds at 10, 15, 20, 25, and 30C, with the largest difference at the most unfavorable temperatures for germination. Primed seeds stored at 5C for 1 to 16 weeks reduced total germination and the potential capacity for rapid germination.
Abstract
Photosynthetic lighting of spray pompon chrysanthemums from August to March plantings for 15 or 20 days during the vegetative period were taller at the start of short-day treatment with larger stem diameter than plants photoperiodically lighted and at flowering the plants had significant increases in plant height, fresh weight, and flower number. The largest benefits developed in October to January plantings. The usual fall and winter decline in plant quality of 9- and 10-week response group chrysanthemum cultivars at northern U.S. latitudes was prevented by 20 days of photosynthetic lighting.
Verbena (Verbena × hybrida Voss) seed germination varied with the water content of the substrate. Total germination percentages (G) were highest when substrates were 75% to 100% saturated and progressively declined with increased free distilled water (FDW) on the blotter paper substrate. Natural differences in G among cultivars at favorable substrate moisture levels increased when free water was present. Removing the seed hilums did not increase G of `Romance Scarlet' on a substrate with FDW, but significantly increased the G of `Showtime Blaze' and `Red A'. Au inverse relationship was found between seed moisture contents and G at high substrate moisture levels. `Romance Scarlet', `Showtime Blaze', and `Red A' had 64%, 73%, and 84% seed moisture contents and G of 72%, 18%, and l0%, respectively. The period of sensitivity to excessive water during germination was day 2 for `Red A' and days 2 and 3 for `Showtime Blaze'. The G of `Romance Scarlet' seed was not reduced when placed on a substrate containing FDW for 1 day. Removal of seed hilums from `Red A' significantly increased G during day 2 for seeds on a substrate containing FDW.
The germination of verbena (Verbena × hybrids) seed was found to be sensitive to high substrate moisture content. Cultivars varied in sensitivity to excessive substrate moisture content, with `Romance Scarlet' having higher total germination (G) in the presence of free water than `Showtime Blaze' or seedling `Red A'. Hilum cavity measurements of dry seeds showed larger hilum apertures with reduced depths for seeds of `Romance Scarlet' than for the others. Seed imbibition resulted in a rapid and extensive thickening of the hilum wall. The extent of hilum aperture closure varied among cultivars and the quantity of water present. Free water reduced hilum apertures 45% for `Romance Scarlet', 60% for `Showtime Blaze', and 86% for `Red A'. Seeds of `Romance Scarlet' and `Showtime Blaze' failed to germinate with lanolin covering the hilum, while seeds coated with lanolin, except for the hilum, had 67% to 78% G of nontreated seeds. This difference indicates that essential oxygen for the embryo was obtained through the hilum and micropyle of the seeds. Total germination varied with substrate moisture content, with seeds placed horizontally on 2%, 1%, or 0.5% agar having 80%, 75%, and 65% germination, respectively, for `Romance Scarlet' and 59%, 41%, and “24%, respectively, for `Showtime Blaze'.