Abstract
A 24 or 48 hour soak in gibberellins (GA) did not influence the total germination of open-pollinated rabbiteye blueberry seeds (Vaccinium ashei Reade, cv. Tifblue). GA4+7 at 100-500 ppm stimulated early germination of seeds from the 2nd to 4th week after sowing, with the maximum effect occurring after 3 weeks. The 48-hour, GA4+7, 100 ppm treatment stimulated germination from the 2nd to 5th week after sowing. Stimulation of earlier germination by GA4+7 hastened seedling transplanting by 2 to 4 weeks. Germination of mature seeds (large, filled) was significantly higher than immature (medium-size, filled) or imperfectly (partially-filled) developed seeds. GA4+7 did not increase germination of immature or imperfectly developed seeds.
Abstract
Embryo growth of the pecan (Carya illinoensis (Wang.) K. Koch) is mechanically restricted by the shell. This effect can rapidly be overcome by germinating the seeds between 30 and 35°C.
Abstract
Seed of pepper (Capsicum annuum L. cv. Early Calwonder) receiving a sodium hypochlorite treatment germinated faster and showed more rapid early growth than seed treated with water alone or with sodium hypochlorite followed by an acid rinse.
Seeds of Aquilegia chrysantha Gray were germinated under a variety of temperature regimes. Germination was nearly 90% under a day/night cycle of 25/20C, but was reduced to ≤ 40% under constant 25C or a 25/10C day/night cycle. With days between 25 and 29C (night = 20C), germination percentage dropped gradually to ≈ 60% with increasing temperature. With days >29C, germination declined dramatically such that no germination occurred at 31C. Neither kinetin (4.6 to 46 μm) nor ethephon (6.9 to 207 μm) was able to reverse the inhibitory effects of 33C days. Our results indicate that germination of A. chrysantha seed is sensitive to temperature and that germination ≈ 75% can be obtained under a 25 to 27C day/20C night regime. Chemical names used: 2-chloroethylphosphonic acid (ethephon); 6-furfurylaminopurine (kinetin).
Presowing treatments and temperature regimes were tested to improve germination of Alstroemeria hybrids 3 to 12 months following harvest. In addition, seeds from 20 intraspecific F1 hybrids of five selections were also tested 3 to 7 or 8 to 12 weeks following harvest. Seeds were pretreated by chipping the seedcoat above the embryo, general abrasion of the entire seedcoat, or soaking 12 hours in distilled water, GA, (0.029, 0.29, 2.9 mm), or KNO3 (0.5 and 1.0 m). Pretreatments were evaluated under three environmental regimes: 8 weeks at a constant 18-25C (warm), 4 weeks at 18-25C followed by 4 weeks at 7C (warm-cold), or 4 weeks at 7C followed by 4 weeks at 18-25C (cold-warm). There was an interaction between pretreatment and environmental regime for percent germination. Germination percentages for the water soak and GA, at 0.29 or 2.9 mm were significantly higher than for the other pretreatments, but were not significantly different from one another. The warm-cold environment yielded higher germination percentages than the other environments. The time to germination was longest for the cold-warm regime. This response depended on the genotype and the age of the seed. Chemical name used: gibberellic acid (GA3).
To determine optimum germination temperatures and effective dormancy-breaking procedures, field-grown (1983-85) seeds of `Bandera' Rocky Mountain penstemon (Penstemon strictus Benth), `Cedar' Palmer penstemon (Penstemon palmeri Gray), and firecracker penstemon (Penstemon eatonii Gray) were subjected to various cold stratification and incubation temperature treatments. Increased germination following an 8-week stratification occurred in seed lots containing dormant seeds, but a 2-week stratification generally failed to break dormancy. Older (1983) seeds of `Bandera' and `Cedar' penstemon germinated to full viability without stratification. All species showed a marked decrease in germination percentage above 20C; 15C consistently produced maximum germination after 4 weeks. At 15C, mean times to 90% of total germination were 11, 22, and 29 days for `Bandera', `Cedar', and firecracker penstemon, respectively. Transfer of seeds failing to germinate at warm temperatures (25 and 30C) to 15C and applying 720 μm gibberellic acid (GA3) solution was effective in breaking primary dormancy of firecracker penstemon and secondary dormancy of `Bandera' penstemon. Our findings suggest that incubation below 20C, combined with 8 weeks of stratification or the use of after-ripened seed, may improve seed propagation efforts for these species.
Abstract
In the tomato (Lycopersicon esculentum Mill.) the ability of PI 341988 to germinate at 10°C is controlled by a recessive gene, tentatively symbolized Itg.
Abstract
Seeds of tomato (Lycopersicon esculentum Mill.) and pepper (Capsicum annuum L.) were either germinated before planting, primed (immersed in an aerated solution of potassium phosphate and ammonium phosphate for 72 hours (tomato) or 120 hours (pepper) and dried), or left untreated (raw) and then planted with gel in loamy sand and sandy soils. There was little difference in response from the tomato seed treatments. In pepper, germinated seeds emerged much earlier and established heavier plants. Differences in emergence due to seed treatments generally were greater in loamy sand than in sandy soil.
Abstract
The endocarp of ‘Manzanillo’ olive (Olea europaea L.) seeds was subjected to several treatments in order to determine its effect on germination of the olive seed. The endocarp inhibited germination in stratified as well as unstratified olive seeds. Removing the endocarp resulted in high percentages of germination, but only when it was completely removed or when the radicle end was removed. The endocarp did not inhibit germination by preventing imbibition, since water uptake occurred in the seed through the untreated endocarp and through the clipped cotyledon end. The endocarp also did not contain water soluble inhibitors that prevent germination. Rather, the endocarp seemed to inhibit germination through mechanical resistance. High percentages of germination can occur only when the structure of the endocarp is altered, reducing its resistance to embryo expansion.