The interaction among temperature, photoperiod, and irradiance on survival of Chamaecereus silvestrii (yellow sport) flat-grafted onto Hylocereus trigonus Haw. rootstock was studied in an effort to understand the basis for elevated scion necrosis during winter. Plants were placed in glasshouses maintained at 12, 16, 20, or 24 °C under either daylight (moles per day), 66% daylight or daylight + 100 μmol·s−1·m−2 irradiance levels. Plants were grown with an 8-hour (short day) or 8-hour + 4-hour night interruption (long day) photoperiod. Cactus scion necrosis increased under short days and a growing temperature of 12 °C and was nearly eliminated by long-day conditions and a growing temperature of 16 °C. Irradiance did not affect scion necrosis. Plant quality rating was highest when plants were grown under long-day conditions at 16 °C.
Jasmonates are a class of plant hormones involved in plant defense and stress responses. For example, jasmonate-induced defense responses in Lycopersicon esculentum include increases in activity of proteinase inhibitors, polyphenol oxidases, and peroxidases. As part of our efforts to reduce or control greenhouse pest infestations, we hypothesized that methyl jasmonate (MeJA) could induce these biochemical changes in common greenhouse crops. We studied Impatiens wallerana `Super Elfin Pink', L. esculentum `Big Boy', Petunia ×hybrida `Bravo Lavendar', Viola ×wittrockiana `Imperial Beaconsfield', Coleus ×hybridus `Wizard Jade', Nicotiana alata `Saratoga Lime', Pelargonium ×hortorum `Pinto Pink', and Tagetes erecta `Antigua Primrose'. Polyphenol oxidase and peroxidase activity was studied in the first four species, and proteinase inhibitors were studied in all eight. We sprayed plants with 0, 5 × 10-6, or 10-4 molar MeJA and made measurements after 24 hours. We detected a small increase in polyphenol oxidase activity of plants treated with 10-4 molar MeJA; 5 × 10-6 molar had no effect, and L. esculentum had the highest polyphenol oxidase activity. Peroxidase activity was not affected by MeJA. I. wallerana had the highest peroxidase activity, L. esculentum and V. ×wittrockiana had the lowest. 5 × 10-6 molar MeJA increased proteinase inhibitor activity in most species, and 10-4 molar increased activity in every species except P. ×hortorum.
Our objectives in this study were to identify the flowering response of Kalanchoe spp. to photoperiodic treatments and characterize flowering and vegetative characteristics of flowering plants. Twenty vegetatively propagated Kalanchoe spp. were grown under one of four photoperiodic treatments: 1) short days (SD; 8-h photoperiod) for 16 weeks; 2) night interruption lighting (NI; 2000 to 0200 hr) for 16 weeks; 3) SD for 8 weeks then transferred to NI for 8 weeks; or 4) NI for 8 weeks then transferred to SD for 8 weeks. Kalanchoe beauvardii, K. behariensis, K. fedtschenkoi, K. longiflora, K. marmorata, K. marnieriana, K. streptantha, K. tomentosa, and K. vigueridoi did not flower under any treatment. Kalanchoe laetivirens and K. rosei had minimal flowering when exposed to NI followed by SD, whereas K. pumila had minimal flowering when exposed to SD followed by NI. Kalanchoe glaucescens, K. laciniata, K. manginii, K. nyikae, K. rotundifolia, K. uniflora, and K. velutina flowered when exposed to SD for 8 or 16 weeks, and node number below the inflorescence and days to first open flower for these species increased when NI preceded SD. Kalanchoe millotii flowered under a 16-week SD treatment only. No plants flowered when grown under only NI. We classified K. glaucescens, K. laciniata, K. manginii, K. millotii, K. nyikae, K. rotundifolia, K. uniflora, and K. velutina as obligate SD plants. Flower diameter, total flower number, total color index, shoot length, branch number, and leaf length and width varied among species. Based on these ornamental characteristics, we identified K. glaucescens, K. laciniata, K. manginii, K. nyikae, K. uniflora, and K. velutina as potential ornamental flowering potted plants.
Five cuttings from different node positions on stock plants were taken from each of 3 Clematis cultivars (Jackmani, Contesse de Bouchard, and Gypsy Queen) and Clematis purpurea plena elegans. Actively growing plants with 5 nodes were acquired. Node number increased from 1 at the base of the plant to 5 at the tip of the plant. Cuttings were treated with or without 0.1% IBA (indole-3-butyric acid) and placed in 1 of 5 different media: 100% washed sand (WS), 50% washed sand and 50% sphagnum peat (WP), 50% sphagnum peat and 50% perlite (SP), 100%) perlite (PT), or 50% sphagnum peat plus 25% perlite plus 25% vermiculite (PV). Rooting date, primary and secondary root number, and root dry weight were collected after 8 weeks. `Gypsy Queen' showed the earliest rooting with the greatest root development. Jackmani showed the worst rooting. Media WS and PT showed the best rooting whereas WP and SP showed the worst. Cuttings taken from the first 3 nodes rooted the best. As node position increased root number and dry weight decreased and time to root increased. Application of IBA had no significant effect on time to root or degree of rooting.
A phone survey was conducted to assess the total impact of the floriculture industry on the Minnesota economy. Data were collected from wholesale growers, garden center retailers, chain stores, and florists. Information was gathered on `hard good' sales associated with greenhouse produced plants as well as plant sales. In addition, data on labor and salaries associated with the production, distribution, and retailing of plants and goods associated with the floriculture industry was collected. This data will be provided to local flower growers organizations to enable these groups to actively lobby for their concerns within the state.
Lypcopersicum esculentum cv `Money Maker' seeds were germinated at constant 20C. Three days after germination seedlings were randomly divided into 3 groups and placed into 3 growth chambers maintained at 23/17, 20/20, or 17/23C (day/night temperature) (DT/NT). Irradiance and photoperiod were maintained at 250 μmol s-1 m-2 and 12 hrs, respectively. At the 2 leaf stage, plants in each chamber were divided into 3 groups of 3 plants each to receive a growth regulator treatment. Growth regulator treatments consisted of spray applications of either ancymidol (52ppm), GA3 (12ppm), or water applied every 3 days for 21 days. Measurements were taken on internode length and chlorophyll content after 21 days. Internode length increased as the difference (DIF) between DT and NT increased (DT-NT). Exogenous applications of GA3 overcame inhibition of stem elongation resulting from a -DIF environment. Application of ancymidol did not significantly decrease stem elongation in a -DIF environment. Temperature regime had a significant impact on chlorophyll content per mg dry weight. In contrast, growth regulator applications had a significant impact on chlorophyll content cm-2. There was no significant impact of either temperature regime or growth regulator treatment on the chlorophyll a/b ratio.
The interaction between day/night temperature (DT/NT) and irradiance during the photoperiod prior to the inductive night on Pharbitis nil (L.) cv. Violet flower induction was studied. Plants exposed to 12 or 18 °C NT did not flower regardless of DT. When NT was 24 or 30 °C, percent flowering plants increased progressively as DT increased from 12 to 30 °C. Percent flowering plants and total flower bud number per plant was greatest when seedlings were induced with a 24 or 30 °C DT/30 °C NT regime. DT/NT did not affect the node number to first flower. Irradiance did not affect flowering. Temperature effects on P. nil flowering could be described as a function of average daily temperature, where flowering increased as temperature rose from 22 to 30 °C.
Rose plants (cvs `Royalty' and `Lovely Girl') in an established canopy were cut back to node 1, 3, 5, 7, 9, 11, or 13 from the base of the stem at harvest. Harvest was defined as the reflexing of the outermost petal. Most rose stems were composed of 13 nodes, therefore, pruning to the 13th node involved removing the flower only. Three leaf removal techniques were evaluated: 1) no leaf removal, 2) removing the node leaf only, or 3) removing all leaves on the stem. Total break number increased as the node position which stems were cut back to increased. For instance, break number increased on `Lovely Girl' from 1.8 to 2.6 breaks as node position increased from 1 to 13. The number of lateral breaks which developed into marketable flowers also increased as the node position which stems were cut back to increased. `Lovely Girl' flower number increased from 0 to 2.6 flowers per stem as node position increased from 1 to 13. Leaf removal reduced the number of marketable flowering shoots. For instance, flowering shoots decreased from 2.6 to 1.4 per stem on stems cut at the 13th node following removal of all leaves on that stem. `Royalty' had more lateral breaks than `Lovely Girl' but also had more non-flowering lateral breaks following pruning. Commercial implications of this research will be discussed.
Interaction between simulated shipping and rooting temperature and harvest year was studied on Lilium longiflorum. Bulb dormancy and maturity appear to be separate phenomenon and are affected by temperature differently. Shoot emergence (an indicator of release from dormancy) was hastened by 10 °C shipping and 10 to 20 °C rooting temperatures in both years. Flower induction was affected differently by simulated shipping and rooting temperatures during 1992 and 1993, indicating that bulb maturity differed between the 2 years. Final leaf and flower number decreased because of shipping or rooting temperature, but only when bulbs were mature and received cool temperatures (<16 °C) before a 6-week vernalization treatment. Immature bulbs (at harvest) are unresponsive to vernalizing shipping and rooting temperatures. Prevernalization handling temperature and vernalization treatment length should vary with year based on degree of bulb maturity to achieve consistency in final morphology. Internode length is associated more with the time elongation is suppressed after dormancy is broken than with flower induction (where internode length increases as the length of time elongation is suppressed after breaking of dormancy increases).