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The effects of red light and far-red light on the main shoot elongation and flowering of long-day plant stock [Matthiola incana (L.) R. Br.] were compared. During the day, plants were covered with the films which convert light quality of sunlight into different red/far-red photon flux ratio, whereas at night the plants were irradiated with compact self-ballasted fluorescent lamps of red or far-red light. Plants exposed to high red/far-red photon flux ratio during the day and red light at night, flowered late and developed short internodes, whereas the opposite occurred on plants grown under low red/far-red photon flux film during the day and irradiated with far-red light at night, i.e., flowering was advanced and internodes were elongated. The same findings were obtained regardless of planting date. However, the contrast between the two lighting conditions was especially apparent between autumn-sown, winter-cultivated plants, and summer-sown, autumn-cultivated plants because temperatures are colder during the winter flowering period. In this experiment, spring-sown, summer-grown plants had shorter internodes and more leaves ; anthesis was advanced compared with plants sown at other times of the year. This finding will contribute to the efficient production of long-day flowering plant because advancing flowering by far-red light improves the utilization of the horticultural facilities by hastening crop turnover and reducing heating costs in winter.

Stock (Matthiola incana R. Br. cv. Asanami) was examined for ontogenic changes in leaf area, leaf weight, total nitrogen, nitrate nitrogen and phosphorus in individual leaves at successive growth stages. The final leaf number was 51 and the maximum leaf area at the 15a20th positions was different from the maximum leaf dry weight at the 33a36th positions. The dry weights of the lower leaves decreased little with aging although nitrogen and phosphorus were translocated from the lower leaves to the upper leaves on other parts up to the 30th position. The total nitrogen remained almost constant at 4.5 to 5.0% in actively developing leaves, but it decreased with age. The phosphorus concentration was higher in young leaves than in the older ones until the day before anthesis, when it decreased about above the 25th position to less than 0.35%. The translocated quotients (%) of both elements decreased with increasing leaf position from the 8th to 30th position. Nitrate nitrogen concentration in leaves above the 5th position decreased with increased node height ; the peak translocated quotient occurred at the 18th position. From these changes in dry weight, N and P contents in individual leaves during growth, we classified the leaves into three groups, lower leaves (1sta7th position), middle leaves (8tha30th position), and upper leaves (above 31th position). Lower leaves which developed slowly had higher translocated quotients of N or P. Middle leaves were finishing their development and N and P were retranslocated without any decrease in leaf dry matter contents ; flower buds became visible. Upper leaves continued to develop ; no export of N or P was apparent.

Effects of gibberellin A4 (GA4) and three GA biosynthesis inhibitors, uniconazole (UCZ), prohexadione-calcium (PCa), and trinexapac-ethyl (TNE) on growth and flowering of Matthiola incana (L.) R. Br. were investigated. In an early flowering 'Sourei', UCZ inhibited stem elongation and flowering. GA4, PCa and TNE promoted flowering at 20°/15°C and 25°/20°C (day/night) under 12-hr photoperiod as compared to the control. However, only PCa and TNE induced flowering of a late flowering 'Banrei' at 20°/15°C. Flowering was not induced in any treatment at 25°/20°C and 30°/25°C but stem elongation of both cultivars was promoted by GA4 and PCa at all temperatures. Under green house conditions in the winter, PCa promoted flowering of 'Banrei'. Although GA4 and PCa promoted stem elongation, they did not induce flowering in the summer. These results indicate that biosynthesis of GA4 and its deactivation are important factors that control stem elongation and flowering.

The effects of diurnal fluctuations between day and night temperature (DIF) during the early seedling stage of Matthiola incana (stock), Antirrhinum mains (snapdragon), Viola × wittrokiana (pansy) and Impatiens walleriana (Impatiens), were investigated to test whether they persisted.Under positive DIF, seedling height, internode length, and the 1st leaf petiole length were longer than in plants grown under negative DIF. Although positive DIF tended to favor leaf elongation and leaf unfolding rate, in that the leaves during the rapid extension (13 days after treatment started) were always longer than those grown under negative DIF, no significant difference was observed in the final measurement.The elongation response to DIF alteration during the rapid elongation was reflected in plant height, internode length, and leaf petiole length in all plant species. After DIF was altered, a significant difference on the final length was observed between the corresponding treatments (i. e. between positive DIF and alteration from positive to negative DIF, and between negative DIF and alteration from negative to positive DIF treatment). The response to DIF alteration from negative to positive was greater than that from positive to negative. The elongation after DIF alteration was greater in seedlings which were smaller at the time of DIF alteration than in the larger seedlings; the former were under the negative DIF until the alteration while the latter were under the positive DIF. This result could be summarized that the DIF during early nursery stage had a small effect on the growth after the treatment. We concluded that DIF could be applied in seedling production.

The effects of shading and fertilizing pre-treatments of mother stock (Matthiola incana R. Br.) plants and NH4+ : NO3- ratio in the medium on in vitro micropropagation through leaf and hypocotyl explants were investigated.1. In leaf explant culture, (1) shoot formation was enhanced when 'Ginshio' explants were taken from the mother plants grown under 75% shading and 1/2 strength Ootsuka liquid fertilizer. In 'Yukimatsuri' shoot formation was inhibited by shading mother plants grown in 1/2 and 1/4 strengths of Ootsuka fertilizer. (2) Reducing NH4+ : NO3- ratio in the medium promoted shoot formation in both cultivars.2. In hypocotyl explant culture, (1) shading mother plants for two weeks after sowing resulted in less shoot formation in both cultivars. (2) Addition of NH4+ to the medium, by which the ratios of NH4+ : NO3- were adjusted to 1 : 10 and 1 : 2 in 'Littlejem Yellow' and 'Yukimatsuri' respectively, enhanced shoot formation and increased the number of shoots per explant. The highest rate of shoot formation was 85% in both cultivars.3. Most shoots regenerated from leaf and hypocotyl explants appeared vitrified. Vitrified leaves, unlike normal ones, (1) had higher moisture content; (2) were larger; and (3) had poorly developed vascular bundles and palisade tissues. The stomata of vitrified leaves were frequently located above and below the epidermal cell layer and distributed irregularly.