Search Results

You are looking at 1 - 3 of 3 items for

  • Author or Editor: J. Biermann x
Clear All Modify Search

Abstract

Freezing injury of highbush blueberry flower buds (Vaccinium corymbosum L. cv. Rancocas and an experimental hybrid) were investigated after natural freezing and by differential thermal analysis (DTA). Terminal buds were less hardy than median and basal buds on the same twig. Apical, less mature florets were also less hardy than median or basal, more mature florets within each bud. DTA analysis of intact flower buds showed that a rate independent free water exotherm was followed by numerous rate dependent floret exotherms. Floret lethality was associated only with the rate dependent low temperature exotherms. Buds were held over water-glycerol solutions in desiccators so that they came into equilibrium with a relative humidity of 100%, 98% or 96% at 4°C. Artificially hydrated buds were hardy to –10° and artificially dehydrated buds were 15°C hardier. A mean survival temperature of the florets (MSTF) from DTA analysis, derived at slow cooling rates related closely to lowest survival temperature (LST66) from artificial freezing hardiness tests. In mid-winter, under environmental conditions of low temperature and low relative humidity, flower buds of a hardy hybrid lost all DTA exotherms and were hardy to at least –40°. Tissue dehydration and accompanying loss of floret low-temperature exotherms was associated with extreme cold tolerance of blueberry flower buds with the hardy experimental hybrid.

Open Access

Abstract

Inoculation of the various potting media with the mycorrhizal fungus Glomus fasciculatum (Thaxter) Gerd. & Trappe resulted in root colonization of geranium (Pelargonium × hortorum L.H. Bailey) by the endophyte that persisted after transplanting. By flowering time, mycorrhizal transplants grown at 11 or 43 ppm P were more uniform in growth than nonmycorrhizal transplants grown at the same nutrient regimes, had greater leaf areas and leaf weights, had increased root and shoot weights, and had lower foliar Mn concentrations. Mycorrhizae were sufficiently well-established on most seedlings at a minimum of 2 weeks after emergence to persist and continue to develop after transplanting. Pretransplant inoculation with G. fasciculatum increased subsequent geranium growth over that of nonmycorrhizal controls when both were transplanted into soil heavily infested with mycorrhizal fungus inoculum, even though size of mycorrhizal and nonmycorrhizal plants did not differ at the time of transplanting. Posttransplant inoculation with G. fasciculatum did not affect the growth of plants which were already mycorrhizal at transplant, but increased the growth of previously nonmycorrhizal transplants. Pretransplant inoculation in soil, peat, or vermiculite resulted in larger plants than posttransplant inoculation in these media.

Open Access

Growth and flowering of chrysanthemum, poinsettia, fuchsia, hydrangea, and geranium grown on rotating shelves were compared with that of plants grown in full ambient sunlight on a stationary greenhouse bench. Ambient insolation reaching plants on the rotating shelves was ca. 55% of that on the stationary greenhouse bench on a sunny day and ca. 60% of full insolation on a cloudy day. Plants grown on the rotating shelves required two to six days longer to flower and were smaller in height, weight, and number of flowers compared to plants under full light. The lasting of chrysanthemum leaves and petals was lessened by growth on rotating shelves compared to plants grown in full light while there was no effect on the lasting of poinsettia bracts or of hydrangea leaves and sepals under simulated home conditions.

Free access