Search Results

You are looking at 41 - 50 of 3,687 items for :

  • light quality x
Clear All

Abstract

A 2 × 4 × 4 factorial experiment was conducted to test the effect of combinations of soluble fertilizer (20N–8.8P–16.6K) and controlled-release fertilizer (14N–6.2P–11.6K, Osmocote) on flowering, growth, and quality of Hibiscus rosa-sinensis L. grown under two light levels, 840 μmol·s-1·m-2 (full sun) and 420 μmol·s-1·m-2 (50% shade). Plants grown in full sun flowered earlier and had a larger number of buds and flowers than those in partial shade; how ever, flower diameter was greater with 50% shade. Plants grown in 50% shade were larger and had a darker green color and higher plant quality than those grown in full sun. Light level determined the effect of soluble fertilizer on number of buds, flowers, plant size, leaf area, fresh weight, foliar color, and plant quality. The effect of controlled-release fertilizer (CRF) on flower diameter, leaf area, and foliar color was influenced by light level. Soluble fertilizer and CRF interacted on total buds, flowers, plant size, foliar color, and plant quality. The optimum conditions for growth of high-quality hibiscus plants was found to be 50% shade and a fertilizer combination of 200 ppm N/12 g CRF per 18-cm pot.

Open Access

Abstract

Alstroemeria L. ‘Regina’ plants grown at 22°C did not flower, regardless of photoperiod treatments. If grown at 13°, plants flowered sooner under long photoperiod treatments than under natural days (ND). Incandescent (Inc) or red light treatments applied as a night interruption (NI) promoted earlier flowering than NI-far-red, ND, or short days (SD). Number of flowering shoots was unaffected by light quality. Plants grown under SD treatments produced the fewest flowering shoots. Flower production was related to early commencement and subsequent duration of the flowering span, as all plants ceased flowering on similar dates. When plants were rotated every 20, 30, or 40 days between SD and NI-Inc light treatments, the days to flower were delayed compared to plants grown continuously (nonrotated) under NI-Inc. Nevertheless, plants which were rotated between the various SD and NI-Inc light treatments flowered sooner than plants under continuous SD. Days to flower were reduced when plants were transferred monthly (December to June) from SD to either ND, 20 hr Inc, or 10 or 20 hr of high-intensity discharge (HID) lights. Flowering was hastened by 20 hr of HID lighting when compared to Inc during the months when the natural photoperiod was less than 12 hr, but had no influence when the 20-HID light treatment commenced after the natural photoperiod was greater than 12 hr. Maintaining plants under SD past January delayed the start of flowering, regardless of subsequent light treatments.

Open Access

The growth and development of Achillea ×millefolium L. `Red Velvet', Gaura lindheimeri Engelm. & Gray `Siskiyou Pink' and Lavandula angustifolia Mill. `Hidcote Blue' were evaluated under average daily light integrals (DLIs) of 5 to 20 mol·m-2·d-1. Plants were grown in a 22 ± 2 °C glass greenhouse with a 16-h photoperiod under four light environments: 50% shading of ambient light plus PPF of 100 μmol·m-2·s-1 (L1); ambient light plus PPF of 20 μmol·m-2·s-1 (L2); ambient light plus PPF of 100 μmol·m-2·s-1 (L3); and ambient light plus PPF of 150 μmol·m-2·s-1 (L4). Between 5 to 20 mol·m-2·d-1, DLI did not limit flowering and had little effect on timing in these studies. Hence, the minimum DLI required for flowering of Achillea, Gaura and Lavandula must be <5 mol·m-2·d-1, the lowest light level tested. However, all species exhibited prostrate growth with weakened stems when grown at a DLI of about 10 mol·m-2·d-1. Visual quality and shoot dry mass of Achillea, Gaura and Lavandula linearly increased as DLI increased from 5 to 20 mol·m-2·d-1 and there was no evidence that these responses to light were beginning to decline. While 10 mol·m-2·d-1 has been suggested as an adequate DLI, these results suggest that 15 to 20 mol·m-2·d-1 should be considered a minimum for production of these herbaceous perennials when grown at about 22 °C.

Free access

Experiments were conducted to correlate the response of chrysanthemum [Dendrathema ×grandiflorum (Ramat.) Kitamura] plants to light environment based on various quantitative light quality parameters by growing plants under 6% or 40% CuSO4 and water spectral filters. Using a narrow band width (R = 655-665 and FR = 725-735 nm) or a broad band width (R = 600-700 and FR = 700-800 nm) for R: FR ratio calculation, 6% CuSO4 filter transmitted light with a higher R: FR ratio than 40% CuSO4 or water filters. Light transmitted through 40% CuSO4 and water filters had similar narrow band R: FR ratios (≈1.2), but the broad band R: FR ratio (2.0) of 40% CuSO4 filter was higher than that of water filters. The estimated phytochrome photoequilibrium (ϕ) value varied considerably with the photochemical properties of phytochrome used for estimations. Final height and internode length of plants grown in 6% or 40% CuSO4 chambers was ≈30% less than of plants in corresponding control chambers. Leaf and stem dry weights were reduced by light transmitted through CuSO4 filters. The results suggest that broad band R: FR ratio correlated more closely to above plant responses than the narrow band R: FR ratio. Blue (B): R and B: FR ratios (not absolute amount of blue wavelengths) correlated well with plant response, suggesting that involvement of blue light should not be ignored in expressing plant response to light transmitted through CuSO4 filters. At present, the presentation of complete spectral data would be the most useful in explaining plant response to light environment.

Free access

There is significant interest in using non-chemical methods to control seedling height in vegetable transplant production. One method being evaluated is the use of greenhouse films that filter signifcant amounts of far-red light from ambient light, resulting in shorter tranplants. This study was undertaken to evaluate fruit yield and quality of field-grown tomatoes produced from seedlings grown under light-filtering plastics. Tomato seedlings were grown under clear polyethylene tents or light-filtering laminate tents in a polyethylene-covered Quonset greenhouse in northern Ohio. Standard 288 deep plug trays, filled with MetroMix 360, were used. Seedlings were placed under the tents at the cotyledon stage and transplanted 28 days later. Once in the field, they were grown as staked plants under open conditions using locally accepted horticultural practices. Differences in seedling height were detected within a few days after being placed under the tents. Compared to those grown under clear polyethylene tents, seedlings grown under the light-filtering plastic increased in height more slowly and were shorter at transplanting. At harvest, within each of the three cultivars tested, no significant differences in fruit number, yield, or mean fruit size were found between treatments. It is inferred that this non-chemical method for reducing vegetable transplant height may be a viable production option in the future.

Free access

Abstract

Plant width and bract color were greater after the production period for ‘Annette Hegg Dark Red’ and ‘Gutbier V-14 Glory’ poinsettia (Euphorbia pulcherrima Willd. ex Klotzsch) when fertilized with Osmocote 14N-6.1P-11.6K than Osmocote 18N-2.6P-10K. Plant height, width, bract color, foliar color, and plant quality increased as fertilizer rates increased from 3 to 9 g/pot. Plants fertilized with 14N-6.1P-11.6K had the least bract loss, greater fresh weight, and the best plant quality after the 30-day postharvest period. Poinsettias fertilized with the lowest rate of 3 g/pot and held for the shortest storage duration had the least leaf, bract, and cyathium loss and highest fresh weight and plant quality. Plants illuminated with the incandescent (INC) light source had the lowest leaf loss and highest fresh weight when compared to cool-white fluorescent (CWF).

Open Access

Abstract

Regardless of season, location, harvest date, or size, ‘Wolcott’ blueberry fruits sorted with transmitted light according to their anthocyanin (ACY) contents were reasonably well separated for quality as expressed by pH, titratable acid (AC), soluble solids (SS) and the SS/AC ratio. Quality of fruits of the same ACY class differed according to cultivar (‘Wolcott’, ‘Berkeley’, and ‘Jersey’). AC content of the fruit decreased slightly during the season regardless of ACY class or cultivar. This consistent reduction in AC as the season progressed was accompanied by increases in the SS/AC ratios and development of decay. Location of harvest (farm to farm) influences SS somewhat. A long harvest interval produced a small but consistent effect on all quality parameters.

Open Access

The anthocyanin in `Sensation Red Bartlett' pear skin was characterized and quantified, and the effect of light quality on fruit color development was evaluated. Anthocyanin concentration was related to fruit chromaticity values. Pigments were analyzed using high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). One of two spots detected in the TLC chromatogram did not change color with molybdate sprays, indicating the possible presence of peonidin. HPLC analysis confirmed the presence of a major and a minor pigment, which co-eluted with cyanidin 3-galactoside and peonidin 3-galactoside. Monomeric anthocyanins in the pear skin extract were 6.83 mg/100 g of fruit peel. To study light quality, gelatin filters allowing passage of different wavelengths of-light were attached over the exposed side of `Sensation Red Bartlett' pears 1 month before harvest. Chromaticity was recorded before the filters were attached and after their removal at harvest using the Commission Internationale del'Eclairage (L*, a*, and b*) color space coordinates. Following color measurements, anthocyanin was extracted from individual skin disks. Skin beneath all filters yielded less hue than the control. Wavelengths that transmit above 600 nm had the largest effect on chroma, a*, and b* values. Fruit wrapped in aluminum foil to obscure all light had the highest luminosity. Wavelengths from 400 to 500 nm gave darker, less chromatic, and redder pear fruit. All treatments yielded higher anthocyanin content than the control. There was a tendency toward increased anthocyanin content with longer wavelengths. The simple linear regression of the log anthocyanin content on L* value and (a*/b*) provided an R 2 = 0.41.

Free access

Abstract

Nutrient solutions containing concentrations of 200, 300, 400, and 500 ppm N were applied to Rosa hybrida cv. Caliente grown under either 18 hours of high pressure sodium light of 110µEm-2s-1 quantum flux density or ambient light. Supplemental light increased yield and decreased foliar N and time to flower compared with ambient light. The lowest N level (200 ppm) produced the highest yield under ambient light, but 300 ppm N was optimum under supplemental light High N concentrations reduced stem grade under ambient light. Stem length, stem diameter, fresh weight, keeping quality, days to flower, and foliar nitrogen were not significantly affected by nitrogen treatment.

Open Access

Influence of photosynthetically active radiation (PAR) microclimate in the canopy of four training systems [open-center with high trunk (OH); open-center with middle trunk (OM); open-center with low trunk (OL); and a traditional round canopy (RC)] on the growth, yield and fruit quality of apple were studied in the Beijing area. The results showed that: 1) the growth and yield potential were affected by canopy light microclimate. The average leaf chlorophyll content from OH, OM and OL systems was 12.3% to 18.1% greater than that from the RC system. Trees from OH, OM, and OL systems produced 84.2% to 89.7% of shoot forming flower clusters compared to only 47.3% to 50.9% of the RC shoots. Training system did not affect total yield of 8-year-old trees, but in 10-year-old trees the RC system had lower yields compared with open-center systems. 2) Fruit quality was also affected by canopy light microclimate. The average anthocyanin content in the skin of fruit from OH, OM, and OL systems was 35.9% to 46.1% higher than that from the RC system, but chlorophyll content from the OL system was higher than in the open-center systems. Meanwhile, the contents of TSS and esters in apple flesh from the open-center systems were significantly higher than that from the RC system. 3) When the relative value of PAR in canopy exceeded 33.8%, the growth index of trees (chlorophyll: return-bloom ratio) exceeded 66.6% and the fruit quality index (TSS × anthocyanin) exceeded 94.7%. When PAR was less than 20.6%, the growth index was under 37.2% and the fruit quality index was under 67.5%. PAR value was significantly correlated with the growth and fruit quality index in the four training systems, and the total canopy volume of higher PAR(exceeding 33.8%, relative value) from OH, OM, and OL systems was 37.1% to 45.0% greater than that from the RC system.

Free access