| Summary: | 碩士 === 國立臺灣大學 === 園藝暨景觀學系 === 101 === Lisianthus [Eustoma grandiflorum (Raf.) Shinn.] is an important cut flower crop in Taiwan for exportation to Japan. Modeling the effects of daily light integral and temperature on leaf initiation, flower initiation, and flower development of Eustoma is presently limited. Japanese growers define early- and late-flowering cultivars based on leaf number below the flower and days to flowering by growing plants at 15-20oC. However, it is required to determine whether this definition could be directly adapted to the growing conditions in Taiwan.
Plug seedlings of Eustoma ‘Claris Pink’, ‘Rin’, and ‘Ceremony Blue Flash’ were planted in phytotrons with mean temperatures of 14.0, 17.6, 22.6, 27.7, and 32.7oC in summer under 12.5-13.5 h natural daylengths. All plants bolted at 3 weeks after treatments. Optimum temperature for leaf initiation was 22.6oC for the three cultivars. Base temperature for leaf initiation was estimated to be 2.8-3.6oC, and thermal time of 26.3-31.3oCd was required for each leaf initiation. Leaf number below the flower and time from planting to flower initiation, flower bud visibility, and flowering decreased with increasing temperature from 14.0 to 32.7oC. Late-flowering ‘Ceremony Blue Flash’ had more leaf number below the flower and longer time to floral development than ‘Claris Pink’ and ‘Rin’. Base temperature for flower initiation was estimated as 5.2-6.5oC and thermal times required from planting to flower initiation were 353.1, 424.9, and 518.0oCd for ‘Claris Pink’, ‘Rin’, and ‘Ceremony Blue Flash’, respectively. Internode increased and stem diameter, leaf thickness, flower diameter, and shoot dry weight decreased with increasing temperature.
Optimum temperature for leaf initiation was estimated as 22.5oC for ‘Ceremony Blue Flash’ planted in autumn under 11-12 h natural daylengths. Base temperature for leaf initiation was 4.8oC and 45.5oCd was required for each leaf initiation. Leaf number below the flower, time from planting to flower initiation, flower bud visibility, and flowering increased with decreasing temperature from 32.5 to 14.0oC. Thermal time from planting to flower initiation was 1199.2oCd. Plug seedlings of the three Eustoma cultivars were planted in a pad and fan house with 0%, 65%, and 75% shading level. Leaf initiation rate was fastest in plants grown without shading, and decreased with increasing shading level. Leaf number below the first visible flower bud, time from planting to flower initiation and flower bud visibility increased with more shading. Delayed flowering or flower blasting was observed in plants grown under 65% and 75% shading. Plants grown under 65% and 75% shading were longer than those without shading. Shading did not affect internode of ‘Claris Pink’ and ‘Rin’, whereas internode of ‘Ceremony Blue Flash’ increased with increasing shading level.
Seedlings of the three cultivars were planted at 23/18oC in an artificial lighting room with 12 h photoperiod under 4.4, 8.8, 13.2, and 17.6 mol‧m-2‧d-1 daily light integral (DLI). Plants grown under 17.6 mol‧m-2‧d-1 had the highest leaf initiation rate. Leaf number below the flower decreased with increasing DLI. Late-flowering ‘Ceremony Blue Flash’ had more leaf number below the flower than ‘Claris Pink’ and ‘Rin’. Cultivar difference in leaf number below the flower was more obvious in plants under low DLI (4.4-8.8 mol‧m-2‧d-1) conditions. Time from planting to flower initiation, flower bud visibility, and flowering decreased with increasing DLI. Plant height and internode were higher and leaf was thinner in plants grown under 4.4 mol‧m-2‧d-1.
Seedlings of the three cultivars were planted under 9 h daylength (ND), 9 h ND + 5 h high-intensity discharge (HID) supplement lighting (ND with HID), 9h ND + 5 h incandescent light (I) bulb for day extension (DE) (ND + I DE), 9 h ND + 5 h HID for DE (ND + HID DE), and 9 h ND + 5 h I for night interruption (NI) (ND + I NI) in a pad and fan house. Fewer leaf number below the flower and shorter time from planting to flower bud visibility and flowering were recorded in plants grown under long day conditions. Earlier flower initiation and wider stem diameter were found in those grown under higher DLI. Plants were shorter and leaves were thicker when grown under ND + HID DE. ND + I NI and ND + I DE treatments resulted in longer internode and more flower buds. Branch number did not differ between these lighting treatments. Flower diameter and petal number were higher in plants grown under ND + HID DE.
Seedlings of the three cultivars were planted in an artificial room at 20.5 and 25.5 oC in combination with four daily light integrals of 4.4, 8.8, 13.2, and 17.6 mol‧m-2‧d-1. Modeling the effects of temperature and daily light integral were established for predicting leaf number below the flower, days from planting to flower bud visibility and flowering. The models were validated with sowing the seeds every two weeks and seedlings grown in a plastic greenhouse under 11.0-13.5 h daylengths in Taiwan.
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