Search Results

You are looking at 61 - 70 of 3,685 items for :

  • light quality x
Clear All
Author:

Abstract

Trees of ‘Golden Delicious’ apple (Malus domestica Borkh.) were established in 1973 in the following orchard management systems: slender spindle (SS), trellis (TR), interstem hedgerow (IH), and pyramid hedgerow (PH). Spur quality and percent photosynthetic photon flux (PPF) transmission declined from the top to the bottom of the canopy of all systems. The three conical central leader type trees (SS, IH, PH) produced a quarter of their fruit on or close to the central leader, while the palmette-shaped TR produced 60% in the center sections along the wire trellis. There was no difference between vertical fruit distribution in trees in the more intensive systems (SS, TR), but the larger trees (IH, PH) produced twice as much fruit in the top half of the canopy as in the bottom half. Trees in the SS had a lower percentage of PPF transmission values within the canopy than trees in the TR systems. Trees in IH generally had higher PPF transmission values within the canopy than the larger PH trees. The number of leaves per spur and specific leaf weight of spur leaves generally followed the light distribution pattern, and trees in the TR and IH systems had higher-quality spurs than the SS and PH systems. The SS and TR systems appeared more responsive to the orientation of the sun, having higher light transmission values on the east side of the canopy in the morning and west side in the afternoon, than the IH or PH systems.

Open Access

Broccoli (Brassica oleracea L. Botrytis group `Green Duke') seeds were cultured photoautotrophically (without sugar) or photomixotrophically (with sugar) in vitro for 3 weeks at 23 °C and150 μmol·m-2·s-1 photosynthetic photon flux (PPF). In vitro seedlings were stored for 0, 4, 8, or 12 weeks at 5 °C in darkness or under 5 μmol·m-2·s-1 of white (400–800 nm), blue (400–500 nm), or red (600–700 nm) light. Photosynthetic ability and soluble sugar contents were determined after removal from storage. Photomixotrophic seedlings contained approximately five times more soluble sugars than did photoautotrophic seedlings. Dark storage reduced soluble sugars in both photoautotrophic and photomixotrophic plants, but photosynthetic ability was maintained for up to 8 weeks in the latter whereas it decreased in the former. Illumination in storage increased leaf soluble sgars in both photoautotrophic and photomixotrophic seedlings. Soluble sugars in stems decreased during storage regardless of illumination, but remained higher in illuminated seedlings. Red light was more effective in increasing or maintaining leaf and stem soluble sugars than was white or blue light. Regardless of media composition or illumination, storage for more tan 8 weeks resulted in dramatic losses in quality and recovery, as well as photosynthetic ability. Seedlings stored for 12 weeks comletely lost their photosynthetic ability regardless of media composition or illumination. The results suggest that carbohydrate, supplied in the media or through illumination, is essential for maintenance of photosynthetic ability during low-temperature storage for up to 4 or 8 weeks.

Free access

Experiments were conducted to evaluate storage temperature, storage irradiance and prestorage foliar sprays of gibberellin, cytokinin or both on postharvest quality of Oriental hybrid lilies (Lilium sp. `Stargazer'). Cold storage of puffy bud stage plants at 4, 7, or 10 °C in dark for 2 weeks induced leaf chlorosis within 4 days in a simulated consumer environment, and resulted in 60% leaf chlorosis and 40% leaf abscission by 20 days. Cold storage also reduced the duration to flower bud opening (days from the end of cold storage till the last flower bud opened), inflorescence and flower longevity, and increased flower bud abortion. Storage at 1 °C resulted in severe leaf injury and 100% bud abortion. Providing light up to 40 μmol·m-2·s-1 during cold storage at 4 °C significantly delayed leaf chlorosis and abscission and increased the duration of flower bud opening, inflorescence and flower longevity, and reduced bud abortion. Application of hormone sprays before cold storage affected leaf and flower quality. ProVide (100 mg·L-1 GA4+7) and Promalin (100 mg·L-1 each GA4+7 and benzyladenine (BA)) effectively prevented leaf chlorosis and abscission at 4 °C while ProGibb (100 mg·L-1 GA3) and ABG-3062 (100 mg·L-1 BA) did not. Accel (10 mg·L-1 GA4+7 and 100 mg·L-1 BA) showed intermediate effects on leaf chlorosis. Flower longevity was increased and bud abortion was prevented by all hormone formulations except ProGibb. The combination of light (40 μmol·m-2·s-1) and Promalin (100 mg·L-1 each GA4+7 and BA) completely prevented cold storage induced leaf chlorosis and abscission.

Free access

European Food Safety Authority (2008) and the mean data in the United States ( Sanchez et al., 2005 ). Fig. 2. Nitrate content according to quality spectra in two LED-light intensities (Low and High) of four lettuce varieties. T0, L18 T8 Roblan ® ; T1, L18

Free access

Abstract

Schefflera arboricola Hayata ex. Kanehira was grown under light levels of 240, 480, and 720 μΕ m-2s-1. Plant grade and width were greatest when plants were produced under low light level but plant height and stem caliper were least. Leaf chlorophyll content was significantly lower under the high production light level than at medium or low levels. After subjecting plants to 0, 3, 6, 9, or 12 days of dark storage and a subsequent 12-week period indoors, growth index, fresh weight, and chlorophyll content generally were less as dark-storage duration increased. Leaf drop was greater and plant grade was lower as the duration of dark storage increased regardless of production light levels. After 12 weeks indoors, plants produced under 240 μΕ m-2s-1 and held for a period up to 6 days of dark maintained better plant quality than plants produced under the higher light levels.

Open Access

Abstract

Trees of old-line ‘Atwood’ navel orange [Citrus sinensis (L.) Osbeck] on Rubidoux trifoliate orange [Poncirus trifoliata (L.) Raf.] rootstock were planted in 1970 at 6 different spacings in 5 replications to determine effects of tree spacing on fruit quality, tree growth, yield, air temperature, light penetration, and production costs. Growth rate was measured by trunk circumference and tree height. Trunk circumference increased as spacing increased. Closely spaced trees were 0.7 m higher than widely spaced trees after 9 years. Fruit quality analyses showed no differences until the trees began to crowd. Fruit colored faster in 1980 on the widely spaced trees than on closely spaced trees. Fruit from trees spaced 5.5 × 5.5 m reached legal maturity (8:1, solids:acid ratio) 12 days ahead of fruit from trees spaced 2.7 × 4.6 m.

Open Access
Authors: and

Euphorbia pulcherrima `Glory' were grown under natural photoperiods from 5 Oct. to 20 Dec. in specially constructed growth chambers equipped with clear double-walled polycarbonate panels filled with liquids that served as spectral filters. The filters were a blue dye that increased far-red/red FR/R) light, a CuSO4 solution that decreased FR/R, and H2O (control) which did not alter FR/R from natural light. The FR/R values were 1.01, 0.86, and 0.34 for blue dye, H2O (natural), and CuSO4, respectively. FR and R were measured at 725-730 and 655-660nm, respectively.

Plants grown under the CuSO4 filter were 32% shorter, with shorter internodes (48%), greater leaf chlorophyll (25%), and more lateral branches (17%) than controls. Plants grown under blue dye filters did not differ from controls. All plants developed normal bracts and flowers.

Free access

Abstract

Flowering performance of crossandra, a potted flowering plant rising in popularity, is not always satisfactory under low interior light levels. However, research has not been conducted to determine the response of this species to low light levels and lighting duration. The response of plants to light conditions is variable. Aphelandra plants were taller but had suppressed flowering under low light (5).

Open Access
Author:

Abstract

Croton (Codiaeum variegatum Blume cv. Craigii) cuttings, enclosed in polyethylene bags, were placed in light (20 μmol·s−1·m−2) or darkness at 15°, 20°, or 30°C for 5, 10 or 15 days (simulated shipping) and then placed in a mist bed to root for 4 weeks. Final leaf loss in most of the treatments was <7%. Cuttings in simulated shipping for 15 days at 30° in darkness and light had 31% and 56% final leaf drop, respectively. These cuttings also produced fewer roots than controls. Root length increased with increased shipping duration and shipping temperature from 15° to 20°, without further increase at 30°. Regardless of temperature and duration in simulated shipping, cuttings shipped in darkness had roots 2.5 to 5 cm longer than those shipped in the light.

Open Access