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Open access

Lawford Baxter and Luther Waters Jr.

Abstract

A laboratory experiment was conducted to determine the effect of the hydrophilic polymer Waterlock B100 on the imbibition, respiration, and germination of seeds of the sweet corn (Zea mays L. var. saccharum) hybrid ‘Mevak’ at soil water matric potentials of -0.01, -0.40, -1.0, and - 1.5 MPa. Coated seeds had a higher final percentage of imbibition, higher rates of respiration, and germination at -0.01 and -0.40 MPa than uncoated seeds, but as the water potential decreased, the seed coating had a deleterious effect on the physiological processes leading to germination.

Free access

Jose P. Morales-Payan and Bielinski M. Santos

Experiments were conducted in the Dominican Republic to determine the effect of physical and chemical treatments on the germination of the ornamental palms Roystonea hispaniolana Bailey (Royal palm), Acrocomia quisqueyana Bailey (Corozo palm), Sabal umbraculifera Mart (Cana palm), Phoenix canariensis (Canary Islands date palm), Veitchia merrillii (Becc) Bailey (Manila palm), Chrysalidocarpus lutescens Wendl (Areca palm), and Caryota urens (Fishtail palm). Treatments were seed immersion in water or gibberellic acid 3 (GA3) solution for 72 hours, immersion in concentrated nitric acid for 5 minutes, or cracking of the seed coat. Rate and percentage of emergence 90 days after treatment were measured. The best results for Roystonea, Phoenix, Veitchia, Caryota, and Chrysalidocarpus were obtained soaking the seeds in water or a 200-ppm gibberellic acid solution. Nitric acid and seed coat cracking significantly reduced the germination percentage in all the species, except Acrocomia guisqueyana and Sabal umbraculifera. Seeds of Acrocomia did not germinate as a response to any of the treatments tested. Sabal seeds germinated only after coat cracking or nitric acid treatment.

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George L. Hosfield and Clifford W. Beninger

Seed coat color in dry bean (Phaseolus vulgaris L.) is determined by the presence or absence of tannins, flavonoids, and anthocyanins. Black beans contain three main anthocyanins that are responsible for their black seed coat color: delphinidin 3-O-glucoside, petunidin 3-O-glucoside, and malvidin 3-O-glucoside. Leaching of anthocyanins occurs in many black bean genotypes during thermal processing (i.e., blanching and cooking). Black beans that lose their dark color after processing are unacceptable to the industry. Since the marketability of black beans can be adversely affected by thermal processing, an experiment was conducted to ascertain whether pigment leaching was due to qualitative or quantitative changes in anthocyanins during processing. Four black bean genotypes that showed differential leaching of color were investigated. `Harblack' retains most of its black color after processing while `Raven' loses most of its color. `Black Magic' and `Black Jack' are intermediate between `Harblack' and `Raven' in processed color. Bean samples (119 ± 1.5 g) of the four genotypes were thermally processed in 100 x 75-mm tin cans in a pilot laboratory. Seed coats were removed from the cooked beans, freeze-dried, and placed in solutions of formic 10 acid: 65 water: 25 methanol to extract anthocyanins. The extracts were analyzed by HPLC. Although all genotypes retained some color, there were no detectable anthocyanins in seed coats of the cooked beans. In a second experiment, raw beans of each genotype were boiled in distilled water for 15 minutes. All four genotypes lost color during boiling, but `Harblack' retained most of its color and had a five-fold higher concentration of the three anthocyanins than did the other genotypes. `Harblack' may retain color better than other black beans because of physical characteristics of the seed coat.

Open access

G. E. Short, R. Loria, and M. L. Lacy

Abstract

‘Miragreen’ garden pea seeds from individual seed lots were sorted into bleached, partially-bleached, and non-bleached categories. Seeds were either soaked for 48 hours in aerated water at 22°C, coated with thiram fungicide, or received no treatment. Seeds were planted in Conover loam soil where damping-off and seedling rot were primarily caused by Pythium ultimum Trow and Fusarium solani (Mort.) Sacc f. sp. pisi (Jones) Snyd. & Hans. No differences in germination in vitro were found among bleached, partially bleached, and non-bleached seeds. However, seedling emergence in the field was greater from untreated non-bleached seeds (69%) than from untreated bleached seeds (30%); emergence from partially bleached seeds (58%) was intermediate. Regardless of degree of bleaching, all seedlings were a normal green color after emergence, and appeared equal in vigor. Pea yields from untreated bleached seeds were less than from untreated non-bleached seeds, apparently because pea-emergence damping off was so much greater with bleached than with non-bleached seeds. No yield differences occurred with fungicide-treated seeds. Soaking partially bleached seeds for 48 hours in aerated water at 22°C prior to planting in April was as effective in improving emergence in artificially infested soil as coating seeds with thiram. However, when seeds were planted in mid-June, the thiram treatment gave higher seedling emergence than the soaking treatment. In general, high yields were achieved by early planting of seeds and minimum root rot.

Free access

Marietta Loehrlein and Dennis T. Ray

Triploid watermelon seed does not germinate in cold, wet soils as well as diploids; germination is slower due to reduced embryo size and thicker seed coat; fissures on the seed coat provide safe harbour for fungal spores; and triploid fruit set is later than most diploid cultivars. Because of these problems producers often transplant rather than direct-seed seedless watermelons. Seed priming has been shown to improve germination in other crops and would be an attractive method allowing for direct seeding of seedless watermelons. Seed from open-pollinated 4n × 2n crosses were primed in solutions of H2O, polyethylene glycol 8000, KNO3, or left untreated. Treatment times were 1, 3, or 6 days, and treated seed were subsequently dried for either 1 or 7 d. Seed were scored for germination in the laboratory and emergence under field conditions. Germination was better using H2O than KNO3 and PEG but not always better than the untreated control. Treatment time of 1 day was superior to 3 or 6 days, but length of drying time was insignificant. In the field trial, treatments did not differ in emergence.

Open access

P. A. Bonamy and F. G. Dennis Jr.

Abstract

cis, trans-Abscisic acid (ABA) was identified by combined gas chromatography-mass spectrometry (GC-MS) in a partially purified methanol extract of mature seeds of peach (Prunus persica (L.) Batsch). No germination of intact seeds occurred during seed maturation. Germination of excised embryos increased with maturity, but ABA content of embryonic axes and other seed parts was not related to germination potential. Drying and storage of seeds increased both free and bound ABA in the embryonic axes, but did not significantly affect ABA content of other seed portions. Free and bound ABA decreased on imbibition except for free ABA in the seed coat and bound ABA in the embryonic axis, Levels of free and bound ABA paralleled one another, suggesting that although the former may be converted to the latter, bound ABA is not a major source of free ABA.

Open access

B. Dehgan and B. Schutzman

Abstract

Seeds of Zamia furfuracea Ait. (cardboard plant) were treated following removal of the sarcotesta (fleshy seed coat) with concentrated H2SO4 and 1000 ppm GA3 in a 4 × 4 factorial combination. The highest total germination of 82.2% in an average time of 74.5 days (germination value = 0.070) was achieved when seeds were exposed to H2SO4 for 15 minutes. Average number of days to germination was reduced to 37.7 when 30 minutes of H2SO4 treatment was followed by 24-hour GA3 soak without significantly affecting percent germination (germination value = 0.103). Interactions of H2SO4 and GA3 are explained by the effect of H2SO4 on sclerotesta (stony seed coat) thickness and the effect of GA3 on the accelerated development of an immature embryo.

Open access

S. L. Kitto and Jules Janick

Abstract

Synthetic seed coats were applied to asexual embryos of carrot (Daucus carota L.) by mixing equal volumes of embryo suspension and a 5% (w/v) solution of polyethylene oxide (Polyox WSR-N 750) and dispensing 0.2 ml drops of this mixture onto teflon sheets. Drops dried to form detachable wafers consisting of embryo suspension embedded in Polyox. Embryo survival after drying was determined by redissolving wafers in embryogenic medium and culturing the rehydrated embryo suspension on filter paper supports in petri dishes for 2-3 weeks. When dried to constant weight (6.5 hr) 3% of asexual embryos coated with 2.5% Polyox survived encapsulation, whereas survival of uncoated embryos was nil. Pretreating the embryogenic suspension with 10−6 m abscisic acid (ABA) during the 14 day embryo induction phase increased coated embryo survival to 40% of the initial number of embryos.

Free access

Richard L. Hassell and D.W. Kretchman

Germination inhibitors found in parsley (Pertroselium hortense) seed have serious effects on field establishment. Studies have been conducted on chemical and physical attributes in relation to cultivar, age of seed and location of the seed on the seed stalk. Results indicate that the inhibitor is highly soluble in H2O and can be removed with as little as a half-hour aqueous wash. Soaking 30 g (∼500 seeds/g) of seed in an aerated graduated cylinder containing 100 ml distilled H2O for 24 hours then applied to radish, lettuce, and parsley seeds revealed complete germination inhibition of these seeds. Decreasing the soaking time did not reduce the inhibitory effects of the solution. Location of the inhibitor within the seed was found to be specific to the seed coat. The amount of inhibitor present varied with the cultivar and seed lot within that cultivar. Size and age of the seed had little effect on the amount and strength of the inhibitor. Location of the developing seed on the seed stalk effected the amount of inhibitor present. Primary umbels contained the least amount of inhibitor when compared to the secondary and tertiary umbels.

Open access

R. B. Beverly

Abstract

Many researchers have discussed the need for precision planting in research plots and have designed new or have modified existing planters to fit their needs. Commercially available precision planters are very expensive and are best suited to planting small, round, or coated seeds, but are less adapted to large irregularly shaped seeds. Inexpensive planter mechanisms have been adapted for precision planting by various modifications (1, 4, 5). However, these planters were either hand-pushed, or failed to provide for wide seed spacing in the row.