Plants of Rhododendron × catawbiense Michx. cvs. Chionoides, Roseum Elegans, and Nova Zembla were cut back on May 14, 1974 and terminal buds removed at 2-week intervals throughout the summer starting on June 14 and examined microscopically for floral initiation and development. First evidence of floral initiation was found in samples taken on July 15 for ‘Chionoides’ and August 1 for ‘Roseum Elegans’ and ‘Nova Zembla’. Floral development continued in the buds of all cultivars into October, at which time buds were well developed and at the rest stage. The number of breaks resulting from removal of terminal buds was the greatest on plants pinched on August 1 and August 15. The percentage of breaks forming flower buds decreased on plants pinched after August 1 and no flower buds were formed on plants pinched after August 15.
Leaf tissue carbohydrates of Ilex opaca cv. ‘Miss Helen’ extracted with alcohol and methylated with trimethylchlorosilane (TMCS) and hexamethyl-disilizane (HMDS) were assayed by gas chromatography. This empirical procedure involved a one-hour refluxing of 1 g of air dried plant tissue in 80% ethanol, followed by taking 2 ml of the alcoholic extract to dryness at 70°C. Upon dryness the material was taken up with 0.25 ml anhydrous pyridine, and methylated with 0.1 ml of TMCS and 0.1 ml of HMDS. After 30 min of reaction time a 2 µl portion of the mixture was assayed by gas chromatography. Five carbohydrates, D-fructose, D-galactose, alpha-D-glucose, beta-D-glucose and sucrose were identified. These carbohydrates extracted from the plant tissue were of a soluble nature. No apparent starch or cellulose hydrolysis was observed as a result of the extraction procedure. Reagent grade carbohydrates were observed to anomerize during the extraction procedure, however no indication of this phenomenon was noted with the plant tissue. Recovery was in the order of 90% with good associated reproducibility.
Foliar sprays of succinic acid-2,2 dtmethylhydrazide (SADH) at 2500 ppm and (2-chlorethyl)trimethylammonium chloride (chlormequat) at 1500 ppm increased no. and size of tuberous roots of dahlias under short-day conditions. Root wt were frequently tripled, both in cultivars which normally form tuberous roots readily, and those which generally form slender, poor-quality roots. Plants grown from roots of treated plants were of excellent size, color, and quality. Similar treatments under long-day conditions caused formation of tuberous roots where untreated cuttings produced only fibrous roots.
N, N-dimethyl-2, 2-diphenylacetamide (diphenamid) and α, α, α,- trifluoro-2, 6-dinitro-N, N-dipropyl-p-toluidine (trifluralin) caused no injury to transplanted petunias (Petunia hybrida Vilm.) or marigolds (Tagetes patula L.) when incorporated in a mulch. Satisfactory broadleaf and grass weed control as denoted by indicator crops was achieved with both of these herbicides. Dichlobenil, 2,6-dichlorobenzonitrile, caused severe injury to both petunia and marigold transplants when applied in the herbicide-mulch combination. Control of broadleaf and grass indicator weeds with dichlobenil was excellent at all rates. Dimethyl tetrachloro terephthalate (DCPA) resulted in no visible injury to the marigold or petunia transplants when used in the herbicide-mulch combination, but control of grass and broadleaf indicator weeds was poor. When diphenamid and dichlobenil at the same rates were incorporated on peat moss, licorice root, pine bark or sugar cane mulches, no differences were observed among the mulches in regard to their ability to control weed growth. On established nursery stock, 2-chloro-4, 6-bis (ethylamino)-s-triazine (simazine) plus DCPA, simazine plus diphenamid, and 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea (diuron), applied directly to the soil surface performed better than the herbicide-mulch combination at the lower rates. At higher rates, both the direct spray on the soil surface and the herbicide-mulch combination performed satisfactorily.
Soluble leaf carbohydrates, macronutrient elements and growth responses to 3 levels of light were studied on field grown plants of Ilex opaca Ait. cv. Miss Helen. Soluble D-fructose, α-D-glucose, B-D-glucose and sucrose reached a maximum concentration expressed as a percentage of the dry weight of leaf tissue during the winter sampling periods, followed by a decline as bud-expansion approached. The maximum concentration of soluble D-galactose was found in newly matured leaf tissue. Soluble D-fructose, α-D-glucose, B-D-glucose and sucrose levels were not effected by the shade environments. The level of D-galactose increased under the shaded environment as compared to full sun plants. P and K levels in the leaf tissue were at high concentrations in newly matured leaf tissues, while Ca and Mg were at low levels. Both K and Mg levels were observed to be higher in leaf tissue from plants grown under the 92% shade conditions compared to full sun plants. Stem diameter was significantly reduced under the 92% shade conditions, while leaf size of plants grown under both 50% and 92% shade was significantly increased. Flower production was significantly reduced in plants grown under the 92% shade conditions.
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