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  • Author or Editor: P. L. Carpenter x
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Abstract

Seedlings of Lolium multiflorum Lam., Lespedeza stipulacea Maxim., and Buteloua curtipendula (Michx.) Torr. were grown for 48 hours in darkness at constant temperatures of 22°, 27°, 32°, or 37°C either in distilled water or polyethylene glycol 20,000 (PEG) solutions with osmotic potentials of −3.2, −7.7, and −9.8 bars. Redicle growth rate decreased as concentrations of polyethylene glycol increased. Radicle growth was reduced at 32° and negligible at 37° for L. multiflorum. All levels of PEG-induced osmotic stress reduced radicle growth at 22° and 32°, while at 27° only higher levels reduced growth of L. multiflorum. PEG-induced osmotic stress reduced radicle growth of B. curtipendula significantly at all temperatures except 37°, where the lowest level of PEG had an insignificant effect on radicle growth. With L. stipulacea, low levels of PEG-induced osmotic stress did not have a significant effect on radicle growth, but an osmotic stress of −9 bars reduced growth at all temperatures.

Open Access

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.

Open Access

Abstract

Seeds of Andropogon gerardii Vitman., Panicum virgatum L., Sporobolus heterolepis (A. Gray) A. Gray., Bouteloua gracilis (Willd. ex H.B.K.) Lag ex. Griffiths, Lotus corniculatus L. ‘Empire’, Bromus inermis Leyss., Trifolium hybridum L., Medicago sativa L. Subsp. Sativa ‘Vernal’, and Poa pratensis L. ‘Park’ were pregerminated and grown for 48 hours at 5°C increments between 12° and 37° and at 47°. No radicle growth occurred at 47° for any species. Maximum growth occurred at 27° for B. inermis and 32° for P. virgatum and A. gerardii. For other species, maximum growth occurred over a range of temperatures from 22° to 32°. P. pratensis and B. inermis, C-3 grasses, had no growth but B. gracilis, P. virgatum, and A. gerardii, C-4 grasses, had significant radicle growth at 37°C.

Open Access

Abstract

Seedlings of Lolium multiflorum Lam., Lespedeza stipulacea Maxim., and Bouteloua curtipendula (Michx.) Torr. were grown at 5°C increments between 12° and 37°, 47°, and at alternating temperature regimes of 17°/10°, 25°/18°, 30°/24°, 37°/30°, or 43°/36°. Radicle growth for all species was inhibited at 12° or 17°, and under all alternating temperature cycles. Maximum growth for Lo. multiflorum occurred at 22°, and at 32° for Le. stipulacea and B. curtipendula. No species grew at 47°.

Open Access

Abstract

Elaeagnus umbellata (Thunb.) plants were planted in acid soil amended with CaCO3 equivalents of 0.0, 6.6, 13.2, 19.7, 26.4, 52.7, and 102.0 MT/ha of Ca(OH)2 and grown in the greenhouse for 21 months. The pH of the amended soil declined with time. Acetylene reduction rates increased with increasing Ca(OH)2 additions up to 26.4 MT/ha CaCO3 equivalent. The lowest dry matter accumulation in root, stem, leaf and nodule tissue occurred at the lowest pH (3.2) with surviving plants. Dry matter accumulations of leaves, roots and nodules were not statistically different at higher pH values.

Open Access

Abstract

Calcium adsorption on the root exchange sites of 4 vegetables as determined by the isotopic exchange method (Ca40–Ca45) was a function of its concentration in the external solution surrounding the roots. As the Ca concentration was increased over the range 0.2 me–8.0 me Ca/1, there was an increase in the Ca adsorbed on roots of sweet corn, cv. ‘Gold Rush’, garden bean cv. ‘Topcrop’, lettuce cv. ‘Bibb’ and cabbage. The Ca adsorption curve of all 4 vegetables showed a plateau between concentrations of 1 and 2 me Ca/1. Root CEC values obtained at Ca concentrations corresponding to this plateau compare closely with values reported by other methods, and are more representative of established CEC values than those reported where the Ca concentration in the external solution was 0.5 me Ca/1.

Open Access

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.

Open Access

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.

Open Access

Abstract

C2H2-reduction activity of excised root nodules of 9 woody species was studied to determine the N2- fixation capabilities at various temperatures. Nodules of nonlegumes [Alnus glutinosa (L.) Gaertn., A. rugosa (Du Roi) Spreng., Comptonia peregrina (L.) Coult., Elaeagnus angustifolia L., E. commutata Bernh., E. umbellata Thunb., and Shepherdia argentea Nutt.] had maximum C2H2-reduction rates near 30°C. Nodules of the nonlegume Hippophae rhamnoides L. and the legume Robinia pseudoacacia L. showed maximum activity at 20° and showed no significant change at 30°. The C2H2reduction activity of all species except E. angustifolia declined at 40°. High temperature injury (40°) was irreversible. Activity was very slight at temperatures near 0°. Arrhenius plots of the data indicate the reduction rate is biphasic with the change in activation energy occurring from 11° to 20° depending on species.

Open Access

Abstract

Field studies conducted for 2 years showed that glyphosate [N-(phosphonomethyl) glycine] or mixtures of glyphosate and preemergence herbicides applied as preplant and directed postplant sprays were effective in providing season-long weed control in commercial nurseries. Oryzalin [3,5-dinitro-N 4,N 4-dipropylsulfanilamide] at 2.2 or 4.5 kg ai/ha, and mixtures of simazine [2-chloro-4,6-bis(ethylamino)-s-triazine] at 1.1 kg ai/ha with diphenamid [N,N dimethyl-2,-2-diphenylacetamide] at 6.7 kg ai/ha, napropamide [2-(α-naphthoxyl)-N,N-diethylpropionamide] at 2.2 kg ai/ha, alachlor [2-chloro-2’,6’-diethyl-N-(methoxymethyl) acetanilide] at 2.2 kg ai/ha or oryzalin at 4.5 kg ai/ha were effective treatments when used after preplant application of glyphosate (2.2 kg ai/ha) or when combined with glyphosate (2.2 kg ai/ha). None of the herbicide treatments reduced growth of red maple (Acer rubrum L.), Norway maple (A. platanoides L.), or creeping juniper (Juniperus horizontalis Moench). Japanese spurge (Packysandra terminalis Sieb. and Zucc.) survival was reduced by treatments containing oryzalin.

Open Access