Search Results

You are looking at 1 - 8 of 8 items for :

  • Author or Editor: Will Healy x
  • HortScience x
Clear All Modify Search

One-year-old corms of Liatris spicata Willd. produced from seed and 2-year-old corms from division of previously forced corms were placed under 8 hours of natural daylight plus 0, 4, 6, or 8 hours of incandescent (5 μmol·s-l·m-2) day continuation to equal 8-, 12-, or 16-hour photoperiods. Plants were grown under these photoperiods during the first 35 days after shoot emergence (initial) and then were grown under a second photoperiod of 8, 12, 14, or 16 hours until harvest (final). The combination of initial and final photoperiod treatments resulted in a total of 16 photoperiod combinations. Two-year-old corms flowered 10 days earlier than l-year-old corms, but l-year-old corms produced twice as many vegetative shoots and 15% more flowering shoots than the 2-year-old corms. Long initial photoperiod (14 or 16 hours) treatments. (LD) reduced-the days to flower by 8 days and increased flower shoot elongation by 20 cm, compared with initial short days (8 or 12 hours, SD). However, initial LD treatments decreased the number of flowering shoots by 50%, compared to initial SD treatments. An initial SD followed by a final LD did not decrease the number of flowering shoots, yet promoted greater stem elongation (92 cm) than continuous LD (83 cm).

Free access
Authors: and

Non flowering Alstroemeria `Regina' plants were divided into aerial components: stems and apical and basal leaves or underground components: rhizome, storage roots, stele and fibrous roots. Samples were collected from distal and proximal ends of the rhizome to allow comparisons between structures of different ages. Ethanol soluble sugars were extracted and measured using HPLC. Starch was degraded to glucose using amyloglucosidase and measured.

There were no age differences in the starch, total soluble sugar (TSUGAR) or total soluble carbohydrates (TCHO) in the rhizome or aerial portions of the plant. There was a preferential partitioning of starch, sucrose, TSUGAR and TCHO to underground plant parts. The storage roots were the primary sink for the stored carbohydrates. Stems contained large concentration of glucose while fructose was found in storage roots and old stems. Sucrose was found primarily in old steles and storage roots. Starch was partitioned almost exclusively into the storage roots with no difference due to age of the storage root. Up to 42% of the TCHO in the old storage roots was composed of a carbohydrate which co-chromatogramed with melezitose using HPLC.

Free access
Authors: and

Petunia `Red Flash' seedlings were grown under HPS (175 μmol m-2 s-1) photoperiod treatments of 10, 12, 14 or 16 hr at 20C soil temperature in a shaded glasshouse where the maximum peak PPF was reduced to 150 μmolm-2s-1. Seedling were transplanted after they had unfolded a specific number of leaves and grown under natural days or placed under photoperiod treatments which consisted of an 8 hr natural day with incandescent day extension treatments of 1 to 6 hours.

A 16 hr HPS treatment decreased the days to transplant (DTT) by more than 4 days and reduced the days from transplant to flower (DTF) by more than 5 days. The total reduction in days from sowing to flower (DSTF) was at least 8 days. When compared to unlighted controls, the reduction in DSTF was 26 days. The longer the seedlings remained under the HPS treatments, the shorter the DTF and DSTF. Premature shifting of plants to natural days resulted in up to a 9 day delay in DSTF. At photoperiods greater than 13 hr, the number of nodes subtending the inflorescence becomes constant regardless of number of leaves at transplant.

Free access
Authors: and

Aeschynanthus `Koral' plants were grown in photoperiods of 8 to 14 hr (8 hr natural daylight plus 0-6 hr incandescent light of 3 μmolm-2s-1) beginning January, March, or June. The number of weeks to anthesis and number of leaves on shoots reaching anthesis were not affected by photoperiod, but differed when treatments began. Number of shoots reaching anthesis per plant was greatest in photoperiods of 13 hr for treatments beginning January or June. Time of year influenced flowering more than photoperiod, suggesting a temperature interaction. A. `Koral' plants were given photoperiods of 12 or 24 hr (daylight fluorescent lamps at 100 or 50 μmolm-2s-1 respectively) at temperatures of 18 or 24 C. After 8 weeks, 18 C plants had fewer nodes before the first flower bud than 24 C plants. Number of nodes to the first flower bud was decreased under the 24 hr treatments at 24 C, while no difference to photoperiod was observed at 18 C. Flowering of A. `Koral' appears to be promoted by 18 C temperature where the plant behaves as a day neutral plant. At 24 C, A. `Koral' responds as a long day plant.

Free access
Authors: and

Petunia `Red Flash' seedling were grown under HPS (175 μmolm-2 s-1) photoperiod treatments of 10, 12, 14 or 16 hr at 20C soil temperature in a shaded glasshouse where the maximum peak PPF was reduced to 150 μmolm-2s-1. Seedling dry weight and individual leaf area were determined daily. The photosynthetic rate was determined when seedlings reached the second true leaf stage.

The dry weight response to increasing photoperiod durations was cubic with a peak at 14 hr. Seedling dry weight increased slowly during days 5 through 10 then increased rapidly during the next 7 to 10 days. This increase coincided with the unfolding of leaves one through four. The total leaf area showed a cubic response to the photoperiod treatments. The leaf area increased slowly then began an exponential increase after day 10. The photosynthetic rate per gram dry weight was increased by the 10 hr photoperiod treatment when compared to the 16 hr treatment. The increased photosynthetic rate was not observed when the data was calculated on a fresh weight or leaf area basis.

Free access

Petunia × hybrida Villm. `Red Flash' plants were irradiated for either 10 or 20 mol day1 photosynthetic photon flux (PPF) in growth chambers using one of the following treatments: 175 μmol m-2 s-1 for 16 h, 350 μmol m-2 s-1 for 8 or 16 h or 350 μmol m-2 s-1 for 8 h plus 8 h incandescent day extension (5 μmol m-2 s-1 PPF). These four treatments were designed to examine the effects of increased peak and total daily integrated PPF as well as increased photosynthetic (Pn) period and photoperiod resulting from supplemental irradiance treatment of seedlings. Previous seedling petunia research indicated a greater response to supplemental lighting during expansion of the second true leaf. Therefore, seedlings were sampled for analysis at the two leaf stage and also later at the four leaf stage to examine effects at a later stage of growth.

Increasing total integrated PPF increased total carbohydrate production, seedling dry weight, rate of seedling growth, and acid invertase activity once the seedlings reached the two leaf stage. Increasing total PPF resulted in greater partitioning into ethanol soluble sugars rather than starch at the two leaf stage. Increasing the photoperiod only, with an incandescent day extension treatment, reduced total carbohydrate production at the two leaf stage.

Maximal oxygen evolution was observed when seedlings received 350 μmolm-2s-1 for 8 h when expressed on a leaf area or dry weight basis. The use of an 8 h day extension treatment to extend the photoperiod from 8 to 16 h resulted in the lowest rates of oxygen evolution on a leaf area basis.

Free access

Aeschynanthus `Koral' plants were grown in photoperiods of 8 to 14 hours (8 hours of natural daylight plus 0 to 6 hours of incandescent light of 3 μmol·m-2s-1) beginning January, March, or June. The number of weeks to anthesis and the number of leaves on flowering shoots were not affected by photoperiod but differed based on when treatments commenced. Flowering was inhibited, regardless of photoperiod, when the daily temperature differential was larger than 10C. To study the interaction of photoperiod and temperature, Aeschynanthus `Koral' plants were grown under photoperiods of 12 or 24 hours (daylight fluorescent lamps at 4.3 mol·m-2·day-1) at 18 or 24C. After 8 weeks, plants grown at 18C had fewer nodes before the first flower bud than plants grown at 24C. Aeschynanthus `Koral' was day-neutral at 18C, but responded as a long-day plant at 24C.

Free access
Authors: and

Abstract

Vase life of Alstroemeria hybrida ‘Regina’ was longest in inflorescences with secondary and tertiary florets. The presence of additional florets on a cyme decreased the vase life of the primary floret. Maximum flower opening and normal coloration occurred when the primary florets were harvested at the “rolled petal stage”. Cutting Alstroemeria stems above the blanched portion of the stem before placement in water increased water uptake and vase life. When secondary florets were present, leaf removal did not decrease vase life.

Open Access