Abstract
Thirteen seed treatments were compared to determine the optimal method to produce asparagus (Asparagus officinalis L. cv. Viking) seeds suitable for axenic culture. Treated seeds were examined for microbial contamination by culture on an agar medium and for percent germination by incubation on moistened paper. All treatments that included benomyl in acetone (2.5%, w/v) with 20% household bleach (0.1% sodium hypochlorite) were superior to the other treatments in eliminating bacterial and fungal contaminants without decreasing seed germination. Ethanol (70%) and hydrogen peroxide also decreased contamination levels, but ethanol decreased germination significantly. No evidence of internal contamination was detected when aseptic seeds were germinated and cultured on agar medium. Chemical names used: methyl(1-[(butylamino)carbonyl]-1H-benzimidazol-2-yl] carbamate (benomyl).
A radish (Raphanus sativus L. cv. Scarlet turnip white tipped) seedling growth test was developed to examine promotive effects of 2-(3,4-dichlorophenoxy) triethylamine (DCPTA) on seedling vigor and plant development. Compared with controls, seed treatment using 30 μm DCPTA significantly (P = 0.05) enhanced the rates of root and hypocotyl elongation and seedling dry weight. Enhanced hypocotyl development by DCPTA showed a significant linear correlation (r = 0.83) with the increased taproot yield of mature plants grown from DCPTA-treated seeds. The harvestable taproot yield and harvest index of plants grown from seeds treated with 30 μm DCPTA were increased 109% and 38%, respectively, as compared with controls. Incubation of radish seeds in 30 μm DCPTA with actinomycin-D, alpha-amanitin, amisomycin, or cordycepin significantly reduced DCTPA-mediated seedling growth. These results indicate that nuclear gene expression and translation of mRNA on 80S ribosomes are required for the acceleration of seedling development by DCPTA.
Abstract
The effect of seed environment and stage of germination during vernalization on flower induction in globe artichoke was investigated. Soaking the seed in water for 48 hr at 70° F prior to vernalization at 35° to 45° for 15 days with adequate moisture and oxygen, resulted in a higher percentage of bolters. Air temperatures above 65° immediately after sowing the vernalized seed caused devernalization, while a week of 50° to 65° had no effect. Seed treatment with chloro-choline chloride inhibited vernalization. Gibberellic acid sprays substituted successfully for vernalization with a large percentage of plants. A minimum of 10 leaves were required for bud initiation with all effective vernalizing treatments. Through vernalization and by subsequently growing the plants at an optimum temperature and light environment, the normal biennial reproductive cycle of artichoke was reduced to 6.5 months.
. 2008. The soil type at the site was a Tetotum loam (fine-loamy, mixed, thermic Aquic Hapludults) that contained 3.3% organic matter and had a pH of 5.2. Plots were 4.8 m × 4.8 m and there were four seeding treatments: 1) 302 kg·ha −1 ‘Greenkeeper
Membrane damage associated with rapid influx of water during imbibition can play a role in the poor emergence and seedling vigor associated with sweet corn germination. Film-coating as a seed treatment has been used to improve germination and vigor in sweet corn and this improvement may not be associated with changes in imbibition rate. Two seed lots of shrunken-2 variety sweet corn, low-vigor `Even Sweeter' and high-vigor `Sugar Bowl', were treated with a hydrophilic polymer film-coating and evaluated for differences in emergence and water uptake. Both cultivars were grown at 19, 21, and 26 °C with no effect on emergence due to film-coating. Imbibition curves were established for untreated and hydrophilic film-coated seeds. Film-coated seeds showed an 18% increase in fresh weight compared to untreated seeds for both cultivars during a 6-h period. Bulk conductivity tests resulted in no significant mean difference between untreated and hydrophilic-treated seeds after 24 h. These seed lots have been treated with a hydrophobic polymer and are currently being evaluated for cold temperature emergence and imbibition rates. Water entry during imbibition will also be compared for untreated sugary (su) and shrunken-2 (sh2) seeds using the fluorescent compound trisodium salt, 8-hydroxypyrene-1, 3,6-trisulfonic acid (HPTS).
Commercial production of bunched broccoli on the Eastern Shore of Virginia has been limited because of shortened internodes resulting in thick, tough stalks. A field study was completed to examine the influence of plant type (transplants or direct seeded), plant population (5800 or 8700 plants/ha), and N application (112 kg/N with zero, one, or two sidedress applications of 40 kg·ha–1) on marketable yield, head diameter, and stem diameter of `Packman' broccoli. None of the measured characteristics improved significantly with sidedress N application. Marketable yield and average head weight were significantly correlated (P = 0.01) to the total number of heads harvested (r = 0.70 and r = –0.91, respectively). More heads were harvested for the high population, direct-seeded treatment and fewer for the low-population transplants. Average stem diameter of transplants was slightly greater than that of direct-seeded broccoli being significant (P = 0.05) in the second and third harvests. However, few stems were of commercially acceptable diameter regardless of treatment combination. Additional evaluation of cultural management strategies and cultivar selection is needed to successfully promote commercial production of bunched broccoli in this growing area.
The effectiveness of solid matrix priming (SMP) and seed brushing was further evaluated by using an thermo-gradient table (Seed Processing, Holland) set at 10 different temperatures from 12 to 30 °C. Intact or brushed seeds of gourd (Lagenaria siceraria) were primed with Micorocel E (Celite Corp.) at 25 °C for 3 days in the mixture of 10 seed: 1 Microcel E: 3 water, by weight, and the primed seeds were dried again for long-term storage. SMP treatment significantly increased earlier seed germination at all temperatures. However, the difference in seed germination rate between intact and SMP-treated seeds was most pronounced at somewhat lower temperatures of 18-22 °C. SMP-treated seed showed about 20% final germination rate at 12 °C, whereas intact seeds did not germinate at all. Seed brushing treatment itself did not influenced the germination rate. However, brushing treatment before SMP treatment significantly increased the SMP effect. Combined use of chemicals in solution further increased the early germination. Details of various seed treatment methods will be presented.
A study was conducted in southeastern Oklahoma to determine treatments or combinations of treatments that provided the best weed control and crop yield for watermelon. `Allsweet' watermelons were grown with different combinations of mechanical and chemical weed control. Treatments included naptalam, clomazone, naptalam + clomazone, bensulide, naptalam + bensulide, napropamide, trifluralin, dcpa, ethalfluralin, sethoxydim, paraquat, glyphosate, cultivation, cultivation + hoeing, cultivation + paraquat, cultivation + glyphosate, and one treatment with no weed control. Glyphosate and paraquat were applied as wipe-on when weeds were taller than watermelons. The five treatments with greatest yields were (in descending order) cultivation + hoeing, trifluralin, cultivation + paraquat, cultivation, and dcpa. The treatments with lowest yield were the control, paraquat, glyphosate, and naptalam. A visual rating (0–10, 0 is poor, 10 is ideal) was taken about 5 weeks after seeding. Treatments with a visual rating of 6 or more were trifluralin (9.4), cultivation + hoeing (9.3), napropamide (9.3), cultivation + glyphosate (7.5), cultivation + paraquat (6.8), dcpa (6.7), and cultivation (6.5). With the exception of the cultivation + hoeing, all plots were weedy at harvest time. Suppression of selected weeds by a herbicide usually allowed rapid growth of the remaining weeds.
The effects of the dry-back temperature on sh2 sweet corn seeds primed via solid matrix priming combined with sodium hypochlorite (SMPsh) were studied. Seeds of two sh2 sweet corn cultivars: Crisp N'Sweet 711 (CNS-711) and How Sweet It Is (HSII) were primed via SMPsh. After the treatment, the seeds were dried-back from 50-54% to 6-7% moisture content at 20, 30 or 40C and 25% RH. The rate of dehydration was significantly lower in CNS-711 compared to HSII at all dry-back temperatures. In both cultivars, seed respiration after 4, 16, and 32h of imbibition was greater in those dried at 30 and 40C compared to 20C or non-primed seed. Enzyme activity (glutamic acid decarboxylase activity) was decreased in HSII seeds dried at 20C. There were no differences among treatments in CNS-711. Leakage conductivity was significantly less when the seeds were dried-back at 30C or 40C compared to 20C or nonprimed seeds. Laboratory germination and seedling fresh weight were greater in seeds dried-back at 30C compared the others temperatures or non-primed seeds. The low rate of desiccation at 20C (30h and 8h in CNS-711 and HSII, respectively) may not suppress germination events after priming, thus damaging the embryo during dry-back. This work demonstrated the importance of dry-back temperature to the efficacy of SMPsh seed treatment in sh2 corn.
Rhamnus alnifolia and Rhamnus lanceolata are shrubs of modest size with lustrous foliage. We evaluated seed germination of both species and propagated R. alnifolia by using softwood cuttings collected in early June. For R. alnifolia, cold stratification for up to 90 d resulted in 48% germination and a germination value of 1.9, whereas only 7% germination occurred among seeds stratified for 120 d. Seeds of R. alnifolia did not germinate if they were untreated or if scarified and stratified. Rhamnus lanceolata required 120 d of stratification to germinate, but percentages were low (≤ 5). Survival of germinants of both species was 90 to 100% regardless of prior seed treatment. Seedlings grew uniformly and had a mean leaf count of 11 and a mean height of 20 cm after 102 d. Application of 3000 and 8000 mg/L indole-3-butyric acid (IBA) in talc led to 85% rooting of R. alnifolia, whereas rooting was ≤ 15% after use of solutions with those IBA concentrations. While 75% of untreated cuttings rooted, fewer roots formed without IBA. More roots developed in 100% vermiculite than in 1 vermiculite: 1 perlite (by volume), which also diminished the number and apparent health of leaves on cuttings during the rooting period. We conclude that talc-based IBA and vermiculite should be used to root softwood cuttings of R. alnifolia, and that both species can be propagated from stratified seeds. Rhamnus lanceolata is more recalcitrant than is R. alnifolia and merits further study to optimize germination success.