Search Results
Abstract
Germination of Myrica pennsylvanicum was increased by exogenous application of kinetin to scarified, cold-stratified seeds. Gibberellic acid (GA3) at 500 and 900 ppm decreased time required for stratification and increased total percentage germination. GA3 was more effective than kinetin for increasing germination.
Abstract
After 48 days rooting percentages and quality were highest for cuttings from Hibiscus rosa-sinensis plants grown under a reduced light intensity (65% natural light) regardless of (2-chloroethyl)phosphonic acid (ethephon) sprays at 100-5,000 ppm or indolebutyric acid (IBA) treatment to cuttings (0.8%). Ethephon and IBA treatments only affected cuttings from plants grown in 100% natural light, but rooting was not superior to that of cuttings from plants grown under reduced light. After 62 days, there were no treatment differences.
Abstract
An examination of dormancy in seeds of Eastern Redbud, Cercis canadensis L., showed that dormancy is controlled by permeability of the testa. Scarification by H2SO4 or mechanical abrasion permitted rapid and complete germination of dormant seed. Stratification was necessary only if seed were not scarified. Nonscarified seeds showed almost no water uptake during 55 days at 5°C, while scarified seeds had a steep imbibitional gradient. Germination was not stimulated by adding oxygen. No growth inhibitors were detected in dormant seed, and no promoters were found in chilled seeds.
Abstract
Both physical and metabolic events were found important in the dormancy-regulating mechanism of seed of Elaeagnus umbellata Thunb. Covering structures offered mechanical resistance to germination, but they did not restrict the flow of water to the embryo. Oxygen concentrations from 60 to 100% increased germination, indicating that the endocarp and seed coat may restrict gaseous exchange by the dormant embryo. Restricted gaseous exchange may compliment a germination-inhibiting substance found in dormant seed. Gibberellic acid decreased the stratification period, but kinetin and potassium nitrate were ineffective.
Abstract
Root knot caused by the southern root-knot nematode (Meloidogyne incognita (Kofoid & White) Chitwood) is a serious disease of sweet potato (Ipomoea batatas (L.) Lam.) in most production areas of the U. S. and especially in the southern states (3). Considerable variation in pathogenicity of this obligate parasite on sweet potato was reported by Giamalva et al. (1) in 1963. In 1973, Martin and Birchfield (2) reported the discovery of a race of M. incognita that was highly virulent and reproduced abundantly on a sweet potato line, L4-73, that had been established as resistant to root-knot nematode populations commonly found in Louisiana. This strain of M. incognita, herein designated the “resistance breaking” (RB) race, was provided through the courtesy of Dr. W. J. Martin of the Department of Plant Pathology, Louisiana State Univ., Baton Rouge. These findings have caused considerable concern about the future of breeding for root knot resistance in sweet potato, since the existence of RB races makes the work much more difficult and complicated. A breeding line of sweet potato (W-51) was developed at the U. S. Vegetable Laboratory, in cooperation with Clemson University, that is resistant to both the common and the RB race of root-knot nematodes (M. incognita). It also carries resistance to fusarium wilt (Fusarium oxysporum f. sp. batatas (Wr.) Snyd. & Hans.) and the sweet potato flea beetle (Chaetocnema confinis Crotch.). W-51 is being released for use as a root knot resistant parent in sweet potato breeding programs.
Carolina Bunch is a sweetpotato cultivar that combines high yield, excellent flavor and appearance with multiple pathogen and pest resistances. It is ideal for home or market gardens, because of its short vine and bunch habit that allow for production of high yields in a limited space. The roots are fusiform with uniform shape and a smooth, bright, light copper skin and dark orange flesh. When baked, the roots have a smooth texture and are sweet, moist and have excellent flavor and appearance. This sweetpotato can be grown virtually without pesticides. It has very high levels of resistances to southern root knot and other species of nematodes, Fusarium wilt, feathery mottle virus, sclerotial blight in plant beds, and Streptomyces soil rot. It has good resistance to many soil insects including several species of wireworm, Diabrotica, Systena, and flea beetles. In the southern US, it yields better than `Jewel' in a growing season of 110-120 days. Foundation roots are available in limited quantities from South Carolina Foundation Seed Association, Inc, 1162 Cherry Hill Rd, Clemson SC 29634-0393.