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Neil O. Anderson

Seed-propagated lilies have the potential to revolutionize Easter lily production, eliminating clonal disease transmission, costly production and shipping. Five F1 interspecific hybrids, Lilium × formolongo (L. longiflorum × L. formosanum), were evaluated to establish an initial forcing schedule. The hybrids included `Raizan Herald', `Augusta F1', `Raizan No. 1', `Raizan No. 2', and `Raizan No. 3'. Two hundred seeds/hybrid were sown in early July in plug trays. Ten weeks after sowing, seedlings were transplanted into 3-inch pots. At the 20-week stage, the seedlings were repotted into 6-inch standard pots for the final production phase. All hybrids had low germination rates (<20%). Hybrids were grown under two photoperiod treatments (short, long days) at 21 °C with n = 10 reps/hybrid/treatment. Plants were evaluated for no. days to visible bud, leaf unfolding rate, final plant height, leaf number, bud count, flowering dates, and the no. of shoots/bulb. Ten weeks after sowing, hybrids had one to four leaves/plant. At 20 weeks, the leaf number had increased to as many as 40. Despite the lack of a cold treatment, most hybrids initiated flower buds. Visible bud date occurred as early as 20 weeks after sowing. Photoperiod had no effect on leaf number, stem height, and flower bud initiation. Plant height exceeded 15 inches by week 16 in most hybrids, indicating the need for plant growth regulator applications. The next steps in product development for seed-propagated Easter lilies will be outlined.

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Philip A. Loretan, Fred A. Avicki, Desmond G. Mortley, and Wiletha Horton

A cooling system using the principles of heat transfer was designed to provide a temperature difference of 6C between root and shoot zones and to study the effect of this difference on growth, yield, and phenology of `TI-155' sweetpotato [Ipomoea batatas (L.) Lam.] grown using the nutrient film technique in a greenhouse. Treatments were temperature control (20C) and variable temperature (26C) in a randomized complete-block design with two replications. A modified half Hoagland's nutrient solution with a 1 N: 2.4 K ratio was used and was changed every 2 weeks. Nutrient solution pH was maintained between 5.5 and 6, and electrical conductivity, salinity, and solution temperature were monitored at regular intervals. Storage root fresh and dry weights (except for fibrous root dry weight) and foliage fresh and dry weights were not significantly influenced by root zone temperature. Leaf expansion rate and vine length were lower for root zone temperature control plants; stomatal conductance, transpiration, and leaf unfolding rates were similar for both treatments.

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Yaping Si and Royal D. Heins

Sweet pepper (Capsicum annuum `Resistant Giant no. 4') seedlings were grown for 6 weeks in 128-cell plug trays under 16 day/night temperature (DT/NT) regimes from 14 to 26 °C. Seedling stem length, internode length, stem diameter, leaf area, internode and leaf count, plant volume, shoot dry weight (DW), seedling index, and leaf unfolding rate (LUR) were primarily functions of average daily temperature (ADT); i.e., DT and NT had similar effects on each growth or development parameter. Compared to ADT, the difference (DIF, where DIF = DT - NT) between DT and NT had a smaller but still statistically significant effect on stem and internode length, leaf area, plant volume, stem diameter, and seedling index. DIF had no effect on internode and leaf count, shoot DW, and LUR. The root: shoot ratio and leaf reflectance were affected by DT and DIF. Positive DIF (DT higher than NT) caused darker-green leaf color than negative DIF. The node at which the first flower initiated was related to NT. The number of nodes to the first flower on pepper plugs grown at 26 C NT was 1.2 fewer than those of plants grown at 14 °C NT.

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Desmond G. Mortley, P.A. Loretan, C.K. Bonsi, and W.A. Hill

Growth chamber studies were conducted to evaluate the effect of four diurnal temperatures (24/18C, 26/20C, 28/22C, and 30/24C) on yield, leaf expansion and unfolding, and vine length of sweetpotatoes [Ipomoea batatas (L.) Lam]. Four vine cuttings (15 cm in length) of `TI-155' and `Georgia Jet' were grown for 120 days using a modified half-Hoagland nutrient solution with a 1:2.4 N:K ratio. Irradiance at canopy level averaged 600 μmol·m–2·s–1 at an 18/6 photoperiod, and RH of 70%. Storage root number/plant for both cultivars decreased with increased temperature. Storage root fresh and dry weights for both cultivars increased with temperatures up to 28/22C and declined at 30/24C. Foliage fresh and dry weights were not influenced by temperature for either cultivar. Leaf expansion rate and vine length were highest at 26/20C and lowest at 24/18C for both cultivars. Leaf unfolding rate was not affected by temperature foe either cultivar, but was more influenced by time of measurements.

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James E. Faust and Joanne Logan

. Similarly, cutting quality increased with increasing DLI. For example, cutting dry mass and stem caliper increased as DLI increased up to 15 mol·m −2 ·d −1 . Chong et al. (2014) also showed that the leaf unfolding rate of the shoots in the poinsettia stock

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Yun Kong, Katherine Schiestel, David Llewellyn, and Youbin Zheng

resources rather than light. However, intercropping snow peas with tomatoes did not affect the stem extension rate or leaf unfolding rate of tomato plants before fruit harvesting compared with no intercropping treatment ( Fig. 3 ). This indicates that

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Ryan M. Warner

unfolding rates and an increase in the number of nodes formed below the first flower. Mattson and Erwin (2003) previously noted that increasing temperature from 12 to 24 °C decreased petunia ‘Avalanche Pink’, ‘Dreams Rose’, and ‘Wave Purple’ node number

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Hans-Peter Kläring and Angela Schmidt

) demonstrated that for cucumber, increasing the difference between day and night temperature (DIF) increased stem elongation and leaf area while leaf unfolding rate was unaffected. A negative DIF had the opposite effect. Some energy-saving approaches suggest

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Kellie J. Walters and Christopher J. Currey

. J. Plant Sci. 72 307 316 Karlsson, M.G. Heins, R.D. Gerberick, J.O. Hackmann, M.E. 1991 Temperature driven leaf unfolding rate in Hibiscus rosa-sinensis Scientia Hort. 45 323 331 Lopez, R.G. Runkle, E.S. 2004 The effect of temperature on leaf and

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Wook Oh, In Hye Cheon, Ki Sun Kim, and Erik S. Runkle

99 110 Karlsson, M.G. Werner, J.W. 2001a Temperature affects leaf unfolding rate and flowering of cyclamen HortScience 36 292 294 Karlsson, M.G. Werner, J.W. 2001b Temperature after flower initiation affects morphology and flowering of cyclamen