Search Results

You are looking at 1 - 10 of 20 items for

  • Author or Editor: H. P. Rasmussen x
Clear All Modify Search
Authors: and

Abstract

Benzyladenine (BA), 6-(benzylamino)-9-(2-tetrahydropyranyl)-9H-purine (PBA), and (2-chloroethyl)phosphonic acid (ethephon) at 100-1500 mg/liter induced adventitious buds in anthurium (Anthurium andraeanum L.). Maximum adventitious shoot formation was produced with BA at 1000 mg/liter (3.6) followed by PBA 1500 mg/liter (2.2) and ethephon at 1000 mg/liter (1.8). Control plants exhibited no adventitious shoot formation.

Open Access

Abstract

Difficulty is frequently experienced in displaying associations of quantitative characters such as flower weight and vaselife with qualitative characters such as flower shape, petal attitude, color, and leaf damage in cut roses (Rosa hybrida L.) A scatter diagram technique which accommodates 2 quantitative and up to 12 qualitative characters applied to experiments on rose cultivars and floral preservatives revealed qualitative associations with increased vaselife and flower fresh weight in response to the use of various preservative solutions.

Open Access

Abstract

Cold irrigation water during mid-winter significantly reduced greenhouse soil temperatures, reduced rose and chrysanthemum relative turgidities, tended to partially or completely close stomates and decreased plant heights and fresh weights. Rose and chrysanthemum leaf relative turgidities were found to decrease from 86% and 79% before irrigation with 35°F water to 54% and 43% one hour after watering. Scanning electron micrographs of rose and chrysanthemum leaves were used to compare stomates during a 5 hour period after irrigation with 35°F and 65°F water. Photographs showed 35°F water caused stomates to close, produced a pronounced flaccidity of guard cells and caused considerable distortion of leaf epidermal cells within 1 to 2½ hours after its application. Chrysanthemum plant heights and fresh weights at flowering decreased significantly as irrigation water temperatures declined. No treatment differences in numbers of rose flowers were found, but stem lengths and fresh weights were reduced significantly.

Open Access

Abstract

Excellent, though limited, use has been made of electron optical equipment in the field of horticulture. The increasing availability and the refinements in such instruments as the electron microprobe X-ray analyzer, the scanning electron microscope and the transmission electron microscope have made them invaluable tools for the horticultural scientist. In an effort to extend the use of such equipment this paper discusses the operation, present and potential applications, sample preparation techniques and problems, and a glimpse of the future of electron optical equipment in horticulture.

Open Access

Abstract

Fresh, unfixed meristems of rose (Rosa hybrida L.) were viewed in the scanning electron microscope to determine the morphological differences and organogenesis of flowering and blind shoots. Gluteraldehyde fixed, ethanol dehydrated and critical point dried tissue was severely desiccated with individual cell walls becoming concave. Fresh tissue remained turgid for at least 10 min in the microscope. Visible signs of flower initiation were evidenced by the presence of sepal primordia followed by differentiation of petals, anthers and stigma. No evidence of flower initiation was observed in the blind shoot.

Open Access

Abstract

‘Tropicana’ rose plants (Rosa hybrida L.) were exposed to increasing periods of high intensity light (640 W/m2) beginning immediately after flower removal, in the fall and winter of 1975 and spring and summer of 1976. Flowers were also removed from ‘Forever Yours’ and ‘Cara Mia’ plants in the summer of 1976 and shoot length, stem diameter and bud diameter were evaluated as morphological indicators of blind shoot development. Plants were transferred to a growth chamber (300 W/m2) following the high intensity lighting treatment. Plants grown in the growth chamber without supplemental lighting had the highest percentage of blind shoots. Maximum blindness occurred during the winter months regardless of lighting treatments. Blind shoot production decreased with increased duration of supplemental lighting. Shoot length proved to be an effective indicator of blind shoots as early as 10 days following lateral bud initiation on all cultivars. The value of bud diameter and stem diameter as indicators of blindness was dependent on cultivars.

Open Access

Abstract

Intact shoot apex development of the carnation was studied with a scanning electron microscope using fresh tissue. Reproductive meristems were more resistant to desiccation from the hard vacuum and electron beam than vegetative meristems. Vegetative meristems, however, can be studied if the work is done quickly.

Structural changes which occurred in the developing carnation shoot showed that leaf primordia are initiated in a circular whorl. Floral initiation was easily determined by the appearance of a flattened apex and a pentagonal whorl of sepal primordia. Subsequent centripetal initiation of flower parts was easily recognized and identified.

Open Access

Abstract

The rate of absorption of distilled water by individual ‘Forever Yours’ cut roses was measured in continuous light (720 ft-c) and total darkness. Maximum water uptake in light (1.5 to 3.5 ml/hour) was found 24 to 48 hour (hr) after harvest followed by a gradual decline, while the lower (0.18 to 0.47 ml/hour) uptake in the dark persisted during the 120 hour study. Alternating 12 hour light and dark periods for 120 hours in a second study showed absorption rates change rapidly from light to dark or dark to light exposure. Statistical correlations were made among cut rose morphological parts and the rate of water uptake. Leaf area was found to be the factor most closely associated with water uptake in both light and dark. Anatomical studies revealed overall tissue degradation in rose stems kept in distilled water 5 days.

Open Access

Abstract

Calcium, K and Mg content of interclonal juniper grafts were determined using electron microprobe x-ray analysis of tissue in the immediate vicinity of the graft union. Considering xylen concn as a measure of mobile elements, Ca accumulated in the rootstock while K and Mg moved readily through the graft union. In phloem tissue, distribution was generally equal between rootstock and scion for all elements; Mg being slightly greater in the stock. In cortical cells, Ca accumulated in the scion. Microprobe data indicated a decreasing order of rootstock accumulation to be Ca, K, and Mg.

Open Access

Abstract

Comparative studies of clonal anatomy revealed visible differences in medullary ray cell diam in juniper cultivars with different chromosome numbers. Histological studies, made at 10-day intervals for 60 days after grafting showed no differences in developmental sequence but only differences in rate at which each stage occurred. Callus tissue form ation began 10 - 20 days after grafting; first in ‘Fountain’ and last in ‘Pfitzeriana Kallay’. Isodiametric cells from uninjured cambia appeared by the 20th day except with ‘Pfitzeriana Kallay’ scions. By an alternating series of radial and tangential divisions, these cells overwalled the injured graft surfaces, but was less pronounced in closely fitted grafts. Overwalling cells did not occur in ‘Pfitzeriana Kallay’ until 30 days after grafting. By 40 - 50 days, overwalling cells began, by radial divisions to produce organized cells which filled voids between graft partners and crushed intervening callus. Mixing of newly formed cells between stock and scion cambia occurred 50 - 60 days after grafting. These cells assumed the spindle-shape of typical tracheids and were oriented into a “cambial bridge.” New, normally oriented xylem subsequently formed from this new cambial tissue. In typical grafts, most new tissue arose from the understock prior to the 50th day after grafting. At 60 days, contribution from stock and scion were equivalent. Adjacent walls of mixed graft tissue were found to be unmodified and appeared as paired structures each with a middle lamella and secondary wall thickenings. Abnormally large numbers of pits were observed at the graft union.

Open Access