Supplemental Irradiance Control of Petunia Seedling Growth at Specific Stages of Development.

Graper, David; Healy, Will; Lang, D. S.

doi:10.17660/actahortic.1990.272.22

Cited by 4 publications

(7 citation statements)

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“…Pramuk and Runkle (2005b) reported that flowering of Celosia, Impatiens, Saliva, Tagetes, and Viola occurred 10, 12, 11, 4, and 12 d earlier, respectively, as mean DLI during the seedling stage increased from 4.1 to 14.2 molÁm -2 Ád -1 . Petunia provided with HPS SL at 83 mmolÁm -2 Ás -1 at longer and/or later periods during the seedling stage of 0 to 20 d after germination flowered earlier (Graper et al, 1990). However, the effect of high DLI on flowering was smaller in Season II of this study and insignificant in spring because of higher ambient irradiance.…”

Section: Discussioncontrasting

confidence: 52%

“…Therefore, there was very little leaf area to receive the SL during the first third period and hence, it was generally not effective. Graper et al (1990) reported that the critical period for the irradiation of petunia seedlings was 10 to 15 or 10 to 20 d after germination, and HPS SL at 83 mmolÁm -2 Ás -1 before first leaf expansion was often 30% less effective. The last third period of petunia in our study was %12 to 21 d after germination because germination occurred at 5 to 7 d after seeding.…”

Section: Discussionmentioning

confidence: 99%

“…The effect of supplemental HPS lighting for seedlings is affected by ambient light conditions. Graper et al (1990) reported that the efficacy of SL decreased as ambient DLI increased from January to April. In this study, the mean DLI provided to the seedlings of Season II was much higher than that of Season I (Table 1; Fig.…”

Section: Discussionmentioning

confidence: 99%

“…When the ambient DLI is low, the only way to increase the DLI is to provide SL. However, SL during the entire production period is usually not commercially feasible because significant investments in lighting equipment and operation are required (Graper et al, 1990).…”

mentioning

confidence: 99%

“…One of the most cost-effective uses of SL is during the production of young plants, when plants are grown at a high density (Graper et al, 1990). Increasing DLI during propagation can increase transplant quality and hasten subsequent flowering in several herbaceous ornamentals.…”

mentioning

confidence: 99%

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Timing and Duration of Supplemental Lighting during the Seedling Stage Influence Quality and Flowering in Petunia and Pansy

Oh¹,

Runkle²,

Warner³

2010

horts

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Increasing the photosynthetic daily light integral (DLI) during the seedling stage promotes seedling growth and flowering in many bedding plants. Our objective was to determine the impact of increased DLI for different periods during the seedling stage on young plant quality and subsequent growth and development. Seeds of petunia (Petunia ×hybrida Vilm.-Andr. ‘Madness Red’) and pansy (Viola ×wittrockiana Gams. ‘Delta Premium Yellow’) were sown into 288-cell plug trays and placed under a 16-h photoperiod provided by sunlight plus 90 μmol·m−2·s−1 [supplemental lighting (SL)] or 3 μmol·m−2·s−1 [photoperiodic lighting (PL)] from high-pressure sodium lamps when the ambient greenhouse photosynthetic photon flux was less than 400 μmol·m−2·s−1 from 0600 to 2200 hr. Plants were grown at 20 °C under PL or SL for the entire seedling stage or were exposed to SL for one-third or two-thirds of the seedling stage. Seedlings were then transplanted into 10-cm pots and grown until flowering with SL at 20 °C. Shoot dry mass of transplants increased linearly with increasing DLI provided to seedlings in petunia (y = −4.75 + 1.86x, R2 = 0.76) and pansy (y = −3.94 + 3.47x, R2 = 0.78) in which y = dry mass (g) and x = DLI (mol·m−2·d−1). SL during the last two-thirds or the entire plug stage increased shoot dry mass and the number of leaves in both species compared with SL during the earlier stage or PL. SL during the last two-thirds or the entire plug stage accelerated flowering, but plants had a lower shoot dry mass and flower bud number at first flowering compared with that in SL during the first third or two-thirds or that in PL. Therefore, SL generally had greater effects on transplant quality and subsequent flowering when provided later in the plug stage than if provided earlier in production.

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Section: Discussioncontrasting

confidence: 52%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Timing and Duration of Supplemental Lighting during the Seedling Stage Influence Quality and Flowering in Petunia and Pansy

Oh¹,

Runkle²,

Warner³

2010

horts

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Longer Photoperiods with the Same Daily Light Integral Improve Growth of Rudbeckia Seedlings in a Greenhouse

Elkins¹,

Iersel²

2020

horts

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Supplemental light can increase growth and accelerate production of greenhouse crops, but it can be expensive if not provided in a way that promotes efficient use of the light. Dimmable light-emitting diode (LED) fixtures have the potential to reduce lighting costs because the output can be precisely controlled to meet crop needs. Because light is used more efficiently to drive photosynthesis at lower photosynthetic photon flux densities (PPFDs), we hypothesized that providing Rudbeckia fulgida var. sullivantii ‘Goldsturm’ seedlings with the same daily light integral (DLI), spread out over a longer photoperiod and at lower PPFDs, should improve growth. A DLI of 12 mol·m−2·d−1 was provided in a greenhouse over 12, 15, 18, or 21-hour photoperiods from a combination of sunlight and supplemental light from LEDs, using adaptive lighting control. Plants grown without supplemental light had an ≈12-hour photoperiod and received an average DLI of 5 mol·m−2·d−1, ≈58% less light than the four lighting treatments. Lengthening the photoperiod from 12 to 21 hours increased shoot dry mass (30%), root dry mass (24%), plant height (14%), leaf area (16%), and chlorophyll content index (48%), and decreased specific leaf area (26%). There was no significant effect of photoperiod on root mass fraction or compactness. Growth parameters of plants without supplemental light were 26% to 90% smaller compared with those in the 12-hour photoperiod treatment. Treatment effects on canopy size, seen as early as 2 weeks into the study, were correlated with final shoot dry mass. Longer photoperiods did not induce a shade-avoidance response, based on specific leaf area and compactness data. The 24% increase in root dry mass for the plants in the 21-hour photoperiod suggests that cropping cycles can be shortened by 1 to 2 weeks compared with the 12-hour photoperiod. This could result in more crop turns per year and increased profits. In addition, fewer lights would be needed for adequate growth, reducing the capital cost of the lighting system.

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High Pressure Sodium Irradiation and Infrared Radiation Accelerate Petunia Seedling Growth

Graper¹,

Healy²

1991

jashs

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The increase in photosynthetic photon flux (PPF) and plant temperature associated with supplemental high pressure sodium (HPS) irradiation were investigated during Petunia × hybrids Villm. `Red Flash' seedling development. Seedlings were treated for 14 days following emergence or 5 days after the first true leaf had expanded to 1 mm. Treatments consisted of continuous infrared (IR) radiation (Ambient + IR), ambient conditions with spill-over radiation from adjacent treatments (Ambient - IR), root zone heating to 19.5C (RZ Heat), continuous HPS irradiation at 167 μmol·s-1.m-2 PPF (HPS + IR) or continuous HPS irradiation at 167 μmol-1·m-2 PPF filtered through a water bath to remove IR (HPS - IR). Linear regression of natural log-transformed fresh weights indicated that increasing ambient PPF 53% and elevating plant temperature 4.3C (HPS + IR) increased seedling relative growth rate (RGR) by 45% compared with the control (Ambient - IR). Elevating plant temperature with + IR by 4.8C without supplementing PPF (Ambient + IR) increased RGR by 31% but failed to increase fresh weight (FW) above controls and resulted in etiolated plants that were unsuitable for transplanting. Once plants were removed from supplemental treatment and returned to ambient conditions, RGR for all treatments was similar. The increased FW promoted by IR and HPS treatments was maintained for up to 7 days after treatment. Therefore, the increased seedling growth responses observed with HPS treatment were due primarily to an increase in RGR during HPS treatment that is not sustained beyond treatment.

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Supplemental Irradiance Control of Petunia Seedling Growth at Specific Stages of Development.

Cited by 4 publications

References 0 publications

Timing and Duration of Supplemental Lighting during the Seedling Stage Influence Quality and Flowering in Petunia and Pansy

Timing and Duration of Supplemental Lighting during the Seedling Stage Influence Quality and Flowering in Petunia and Pansy

Longer Photoperiods with the Same Daily Light Integral Improve Growth of Rudbeckia Seedlings in a Greenhouse

High Pressure Sodium Irradiation and Infrared Radiation Accelerate Petunia Seedling Growth

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