Search Results

You are looking at 1 - 10 of 720 items for :

  • dark���light cycles x
  • Refine by Access: All x
Clear All
Free access

Nguyen Phuc Huy, Vu Quoc Luan, Le Kim Cuong, Nguyen Ba Nam, Hoang Thanh Tung, Vu Thi Hien, Dung Tien Le, Kee Yoeup Paek, and Duong Tan Nhut

-elongated ex vitro explants as the source under dark–light cycles for plant regeneration through internode tissue cultures. The results of this study provide a new approach to micropropagation of P. callosum for commercial propagation. Materials and Methods

Open access

G. D. Blanpied

Abstract

Two studies were carried out to determine if the relatively constant length of seasons (LOS) for ‘Delicious’ apples (Malus domestica Borkh.) was controlled by the number of light-dark cycles (days). Potted, bearing trees received 19-hour light-dark (19 L-D) cycles and 24-hour light-dark (24 L-D) cycles in growth chambers during July and August. At the end of treatment period, 19 L-D trees received 15 more light-dark cycles than 24 L-D trees. In the second study, orchard trees were illuminated with 2200–4400 lux for 75 min beginning at midnight during July and August. Measurements of skin chlorophyll, flesh firmness, titratable acidity, total soluble solids content, and ethylene evolution of harvested fruits as well as internal C2H4 concentrations in attached fruit indicated that maturation and ripening of ‘Delicious’ apples were not affected by these treatments.

Free access

Zejin Zhang, Dongxian He, Genhua Niu, and Rongfu Gao

a 12-h photoperiod (24-h light–dark cycle). CO 2 concentration was controlled at 500 ± 50 μmol·mol −1 and PPF at canopy level was maintained at 160 μmol·m −2 ·s −1 , provided by fluorescent lamps. Effects of drought and rewatering on net CO 2

Free access

Desmond G. Mortley, Douglas R. Hileman, Conrad K. Bonsi, Walter A. Hill, and Carlton E. Morris

PPF for 18 h daily, and the temperature lowered from 28/22 °C light/dark to a constant 20 °C. Plants remained under these conditions for 14 d, after which the original PPF and temperature cycles were restored. Nutrient solution. A modified half

Free access

Eduardo J. Chica and L. Gene Albrigo

collected at 0800 and 1500 hr . Data were analyzed using a repeated measurements model with four tree replicates. ANOVA was used to compare CsFT transcript abundance before and after the cold front. Influence of light/dark cycles on transcript abundance

Full access

Toshio Shibuya, Junki Komuro, Norio Hirai, Yoshiko Sakamoto, Ryosuke Endo, and Yoshiaki Kitaya

in a growth chamber maintained at 28 °C and a relative humidity of 50% at a photosynthetic photon flux ( PPF ) of 300 μmol·m −2 ·s −1 provided by FLs (FHF32EX-N-H; Panasonic, Kadoma, Japan) in a 12/12-h light/dark cycle. After the cotyledons had

Free access

Susan M. Hawkins and Carol D. Robacker

little bluestem by culturing mature caryopses under dark conditions, so that light was excluded from the cultures, on Linsmaier and Skoog (LS) medium with kinetin and 2,4-D ( Li et al., 2009 ). Shoots were regenerated by transferring the calli to medium

Open access

Isaac Biran and Anton M. Kofranek

Abstract

Net photosynthesis, as measured by dry matter changes, was reduced following the dark periods when foliage plants were grown in extended, alternate dark-light cycles. Longer dark periods resulted in greater reduction; however, recovery was observed if the light duration was increased. No visual quality reduction was observed in Tradescantia fluminensis Veil and Asparagus setaceus Jessop which was grown under 14 days light: 14 days dark cycles for 84 days. Similarly, the quality of mature leaves and stems of Philodendron scandens Subsp. oxycardium (Schott) Bunt grown under 24 days dark: 24 days light cycles for 96 days was not impaired; however, new shoots and leaves were abnormal. Dry matter partitioning of Philodendron was affected by light conditions and growth activity. In plants with no active growth, the dry weight of leaves, stems, and roots was increased under adequate light condition and decreased under darkness. Stems were stronger sinks than leaves. In all treatments, when new shoots started their active growth, they became the main carbohydrate sinks with a concomitant reduction of weight of the mature organs. Reduction in percent dry matter following the lowering of the light intensity was observed. Determining and measuring the critical percent dry matter at which plant injury occurs are suggested as practical methods to evaluate the plant’s condition and how it may respond during and after the marketing period.

Open access

Seung Moon Roh and Harold F. Wilkins

Abstract

Flowering was accelerated by incandescent light day extensions of 3 minutes of light and 27 minutes of dark or longer light cycles and by 15 minutes of light and 15 minutes of dark cycles when BCJ-ruby incandescent light was given to young shoots from non-vernalized bulbs. If bulbs were vernalized for 3 weeks, cool white fluorescent light accelerated flowering as a day extension. As a night interruption, incandescent, fluorescent or BCJ-ruby incandescent cyclic light treatments accelerated flowering of shoots from vernalized or non-vernalized bulbs.

Day extensions of cyclic fluorescent or BCJ-ruby light treatments of 6 minutes on and 24 off or 3 minutes on and 27 off did not mediate a phytochrome controlled flowering response and along with the fact that there was no photoreversibility between day extensions of incandescent, fluorescent or BCJ-ruby incandescent light, indicate a high energy reaction involvement in the flowering of the lily.

As a night interruption treatment, a phytochrome mediated flowering response was observed with 3 minutes of light on and 27 off or 6 minutes on and 24 off cyclics of fluorescent or BCJ-ruby incandescent light treatments. However, as the light period increased to 15 minutes on and 15 off or under a continuous light cycle, there were no differences in the flowering response between fluorescent or BCJ-ruby incandescent. As night interruptions there was a reversibility response by R — FR, but not by FR — R. This indicated the simultaneous operation of the phytochrome and the high energy reaction.