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Abstract

Cut flower yield of four greenhouse rose cultivars was primarily influenced by solar radiation, while atmospheric CO2, air temperature, and soil nutrient levels were of lesser importance. Cultivars responded differently to atmospheric CO2 level and soil fertilization method. Roses fertilized with 20-20-20 in solution produced equivalent or greater flower yields than roses fertilized with 10-10-10 in dry form. Roses grown in CO2 enriched atmospheres did not require additional soil fertilization.

Regression coefficients and yield prediction equations were determined using nine environmental parameters. Monthly yield predictions were generally reliable, but cropping cycles and cultural practices decreased accuracy.

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

Four greenhouse rose cultivars were grown under 9, 12, and 16-hr daylengths from September to May during 1969-70 and 1970-71. Flower production was generally increased significantly under the 16-hr daylength, particularly during January and February. At this day length, rose stems flowered again more quickly, but with the same number of nodes present as in the other treatments. The internode between the 2 uppermost 5-leaflet leaves was significantly longer on plants grown at 16 and 12 hr than the 9-hr daylengths. Flower fresh and dry wt increased as the daylengths increased from 9 to 16 hr and the percentages of blind stems were found to decrease. Rose leaf and flower petal size were unchanged by the daylength.

Open Access

The effect of node position of axillary buds of greenhouse-grown Hybrid tea rose cultivars `Carefree' and `Adelaide Hoodless' on shoot induction and proliferation was investigated. Explants were cultured on a Murashige and Skoog (MS) medium containing 2 mg/l 6-benzyladenine (BA) and 0.1 mg/l α-napthaleneacetic acid (NAA). Axillary buds collected closest to the shoot apex gave rise to the highest shoot proliferation; whereas, those collected from the second, third, and fourth nodes yielded longer shoots and higher leaf number/explant. The influence of varying levels of BA concentrations in the culture medium was also investigated. It was observed that high BA concentrations, 1-3 mg/l, stimulated shoot proliferation. The effect of carbohydrate source, fructose versus surcose, on shoot induction was also investigated. A high shoot number/explant was observed on media containing fructose; however, longer shoots (>1 cm) were observed on media containing surcose as a source of carbon.

Free access

Premature flower bud abscission imposes a serious limitation on longevity of potted Hibiscus in interiorscape situations, Ethylene is known to be one causative factor. Past research has suggested that carbohydrate depletion of buds may also be involved,

A series of experiments was conducted to examine the relationship between carbohydrate levels and ethylene sensitivity of flower buds under low irradiance levels. Two cultivars were used: `Pink Versicolor', which is very susceptible to bud abscission, and the more resistant `Vista', In the first experiment, plants were harvested twice weekly after placement in interiorscape rooms (8.5 μmol m-2 s-1 for 12 hrs per day; 26.5°C day/night) until all buds had abscissed. At each harvest, buds from four size groups were collected for analysis. In the second experiment, source/sink strength of buds was manipulated by selective daily removal of certain sized buds. Remaining buds were collected just prior to abscission for analysis. In two additional experiments, `Pink Versicolor' plants were treated with either silver thiosulfate or ethephon prior to placement in interiorscape rooms. Plants were harvested twice weekly and buds collected. For all experiments, bud dry wt, total soluble sugars and starch content were determined.

Free access

Roses in nursery and landscape settings are frequently damaged by black spot, whose causal agent is the fungus Diplocarpon rosae F.A. Wolf. Potassium silicate was assessed as a media-applied treatment for decreasing the severity and incidence of black spot infection. Roses were treated with 0, 50, 100, or 150 mg·L-1 silicon as potassium silicate incorporated into irrigation water on either a weekly or daily schedule. Five weeks after treatments were initiated, plants were inoculated with D. rosae. Roses began to show visual symptoms of infection §4 days later. Roses that had 150 mg·L-1 silicon applied on a daily schedule had significantly more silicon present in their leaves than other treatments as measured by scanning electron microscopy and energy-dispersive x-ray analysis. In addition, roses that had 100 and 150 mg·L-1 silicon applied on a daily schedule had fewer black spot lesions per leaf and fewer infected leaves than any of the other treatments by the end of the experiment 7 weeks later. Although roses treated with higher levels of silicon on a daily basis fared better than roses in the other treatments, all of the roses were heavily infected with D. rosae by the end of the study. The results reported here indicate that using potassium silicate in irrigation water may be a useful component of a disease management system.

Free access

Sustainable horticultural production will increasingly have to rely on economically feasible and environmentally sound solutions to problems associated with high levels of bicarbonate (HCO - 3) and associated high pH in irrigation water. The ability of arbuscular mycorrhizal fungi (AMF; GlomusZAC-19) to enhance plant tolerance to HCO3 - was tested on the growth, physiology and nutrient uptake of Rosamultiflora Thunb. ex J. Murr. cv. Burr (rose). Arbuscular mycorrhizal colonized and noninoculated (non-AMF) plants were treated with 0, 2.5, 5, and 10 mm HCO - 3. Increasing HCO - 3 concentration and associated high pH and electrical conductivity (EC) reduced plant growth, leaf elemental uptake and acid phosphatase activity (ACP), while increasing alkaline phosphatase activity (ALP). Inoculation with AMF enhanced plant tolerance to HCO - 3 as indicated by greater plant growth, leaf elemental uptake (N, P, K, Ca, Fe, Zn, Al, Bo), leaf chlorophyll content, higher mycorrhizal inoculation effect (MIE), lower root iron reductase activity, and generally lower wall-bound ACP (at 2.5 mm HCO3 -), and higher soluble ALP (at 10 mm HCO3 -). While AMF colonization (arbuscules, vesicles, and hyphae formation) was reduced by increasing HCO - 3 concentration, colonization still occurred at high HCO - 3. At 2.5 mm HCO3 -, AMF plant growth was comparable to plants at 0 mm HCO3 -, further indicating the beneficial effect of AMF for alleviation of HCO3 - stress.

Free access

Premature flower bud abscission imposes a serious limitation on longevity of potted Hibiscus in interiorscape situations, Ethylene is known to be one causative factor. Past research has suggested that carbohydrate depletion of buds may also be involved,

A series of experiments was conducted to examine the relationship between carbohydrate levels and ethylene sensitivity of flower buds under low irradiance levels. Two cultivars were used: `Pink Versicolor', which is very susceptible to bud abscission, and the more resistant `Vista', In the first experiment, plants were harvested twice weekly after placement in interiorscape rooms (8.5 μmol m-2 s-1 for 12 hrs per day; 26.5°C day/night) until all buds had abscissed. At each harvest, buds from four size groups were collected for analysis. In the second experiment, source/sink strength of buds was manipulated by selective daily removal of certain sized buds. Remaining buds were collected just prior to abscission for analysis. In two additional experiments, `Pink Versicolor' plants were treated with either silver thiosulfate or ethephon prior to placement in interiorscape rooms. Plants were harvested twice weekly and buds collected. For all experiments, bud dry wt, total soluble sugars and starch content were determined.

Free access

) Intl. J. Agr. Sci. 85 931 935 Hatamian, M. Salehi, H. 2017 Physiological characteristics of two rose cultivars ( Rosa hybrida L.) under different levels of shading in greenhouse conditions J. Ornamental Plants 7 147 155 Healy, W.E. Heins, R.D. Wilkins

Free access