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The transition from vegetative growth to reproductive growth is carefully controlled by a number of independent signal transduction systems, one of which interprets photoperiod. Photoperiodic control of flowering time has been well-described in Arabidopsis and rice, revealing the presence of a generally common network of regulatory proteins. Timely and appropriate progression to flowering is critical to profitable production of cultivated strawberry (Fragaria ×ananassa), a species that includes long-day, short-day, and day-neutral cultivars. In an effort to characterize the photoperiodic flowering control mechanism in strawberry, the Fragaria orthologs of the photoperiod pathway genes were cloned and sequenced. Strawberry versions of Constans, Constans-like, Leafy, Flowering Locus T, and Suppressor of Constans Overexpression 1 were identified by screening cDNA libraries and through degenerate PCR approaches. Expression of these transcripts in short-day and day-neutral cultivars was tested under long and short photoperiods. Functional complementation of Arabidopsis mutants was performed where appropriate, alleles were identified, genetic linkage was determined where possible, and relationships between the strawberry genes and homologs from other species were studied. These trials define the mechanistic elements of an agriculturally important pathway in this valuable crop, and lays the foundation for transgenic studies in strawberry to manipulate the floral transition.

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the adaptive phenology of a species ( Moyses et al., 2018 ). During common bean domestication and dissemination from its centers of domestication, selection for photoperiod insensitivity allowed common bean to spread to higher latitudes ( Gepts and

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, uniform, and high rates of seed germination and seedling development is crucial. Hence, the present study was undertaken to examine the effect of different photoperiod and medium treatments on the speed of seed germination and seedling development in S

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germination and early seedling growth responses of C. bungei to photoperiod, temperature, and seed size to determine seed propagation requirements, develop standard germination procedures, and provide conservation strategies for C. bungei . Materials and

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Programmed flower induction of Calathea crocata Morr. et Joris is possible under the controlled environmental conditions of a multilayer growing room. A photoperiod of 10 hours for 9 weeks, growth at 18C, and a photosynthetic photon flux density (PPFD) of 71 μmol·s-l·m-2 induced flowering in more than 95% of the plants and in 50% to 80% of the shoots. In the meantime, none of the plants under natural conditions was induced. Significantly more flowers were induced when PPFD during the short-day treatment was 71 rather than 56 μmol·s-1·m-2. Flowers became visible 14 to 16 weeks after the start of the inductive treatment. Moreover, raising the CO2 concentration to 900 ppm for 5 months increased the leaf area and dry weight by 40%, and resulted in darker leaf color, longer flower stalks, and significantly accelerated flowering (10 days).

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Most ornamental crops can be classified as long-day, short-day, or day-neutral plants based on their flowering responses to the photoperiod (or the skotoperiod). Chrysanthemum ( Chrysanthemum × morifolium ) is a common ornamental crop with an

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Abstract

Zinnia elegans Jacq. ‘Carved Ivory’, ‘Cherry Ruffles’, and ‘Rosy Future’ were grown under short days (SD) or long days (LD) to determine the effect of photoperiod on flower initiation and morphological development. Plants grown under LD (14, 16, 18, or 24 hours) were greater in height, leaf size, flower diameter, and node number and flowered later compared to plants grown under SD (8, 10, or 12 hours). The greatest increases in plant responses occurred between 12- and 14-hour treatments. Supplemental irradiation (day continuation, night break, and predawn lighting) resulted in LD responses but did not equally affect days to flowering, stem diameter, or node number. Height and ray petal number were greatest for all cultivars under day continuation and flower diameter was largest under day continuation and predawn lighting. More LD before SD resulted in increases in height, stem and flower diameter, node number, ray petal number, and days to flowering, indicating a cumulative effect of LD on morphological development. Results demonstrate that Z. elegans is a facultative SD plant for floral initiation and development and that photoperiodic responses vary between genotypes.

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day-neutral plant ( Thomas and Vince-Prue, 1997 ), although some studies indicate that photoperiod, light quality, and light intensity can modify the flowering and subsequent growth of this plant ( Erwin et al., 2004 ; Heo et al., 2003 ; Neuray, 1973

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Abstract

Using the 9th and 10th International Mungbean Nursery (IMN) data, quadratic response surface models were developed to predict days to flowering (DF) of mungbean [Vigna radiata (L.) Wilczek] genotypes grown at 11-hr and 30 min and 13-hr and 30-min preflowering mean photoperiod ( P ) and 22 to 30C mean diurnal temperature ( T ) regimes. Both linear and quadratic effects were significant on DF and on the rate of progress towards flowering (1/DF); however, only the linear effect was significant in days to maturity (DM). The effect of T was more pronounced than that of P on DF of reduced-photoperiod-sensitive (RPS) genotypes. The earliest DF (flowering tendency) was estimated at 34 days after planting at the optimum mean diurnal temperature ( T 0) of 28C and the optimum mean photoperiod ( P 0) of 12 hr. At the suboptimal temperature ( T < T 0), the estimates of the base temperature Tb and the thermal time θr were 10C and 555 degree-days, respectively. Thus, flowering dates of these RPS mungbean lines can be predicted, which in turn will assist in the selection of proper planting dates.

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Common bacterial blight, incited by Xanthomonas campestris pv. phaseoli (Smith) Dye (Xcp), is a serious disease of common beans (Phaseolus vulgaris L.). Three experiments were conducted twice in growth chambers at 26 ± 1C under short (10 hours light/14 hours dark) and long (16 hours light/8 hours dark) photoperiods to determine the influence of these photoperiods, flower bud removal, pod development, and pre- and post-inoculation photoperiods on the reaction of common beans to Xcp. In one test, `PC-50' (susceptible; S) flowered earlier and was more susceptible to Xcp under the short photoperiod than under the long photoperiod. BAC-6 (resistant; R) flowered at the same time under both photoperiods but developed rapid leaf chlorosis (RLC) (hypersensitive reaction) under long photoperiods. Flowering and disease reactions to Xcp by XAN-159 (R) were similar under both photoperiods. In a second test, daily removal of flower buds of `PC-50' decreased its susceptibility to Xcp under the short photoperiod. RLC of inoculated leaves of BAC-6 occurred during flowering and pod development under both photoperiods. XAN-159 expressed a high level of resistance to Xcp but showed RLC at later pod development stages. In a third test, the disease reaction of `PC-50' was affected by the particular photoperiod applied post-inoculation but was not influenced by the photoperiod applied before inoculation with Xcp. The implications of these results in breeding beans for resistance to Xcp are discussed.

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