Kiyoshi Ohkawa

Effects of air temperature and time on rosette formation in seedlings of Eustoma grandiflorum (Raf.) Shinn

Abstract Seedlings of Eustoma grandiflorum (Raf.) Shinn. were induced by temperatures above 25°C to grow as rosettes. The season had an additional unknown effect, especially on plants grown in the intermediate temperature range. Exposing germinating seedlings to high temperatures for as little as 3 days reduced stem elongation, and treatment for more than 14 days completely inhibited elongation even when plants were subsequently grown at lower temperatures.

Influence of temperature prior to seed ripening and at germination on rosette formation and bolting of Eustoma grandiflorum

Abstract Rosette formation and subsequent bolting of Eustoma grandiflorum are influenced by temperature conditions prior to seed ripening and after germination has commenced. Rosette formation was decreased if parent plants were matured at 23 18° C (day/night) temperature and was increased at 33 28° C . Further low temperature seed treatment of hydrated seeds at 3°C or 10°C for 5 weeks decreased rosette formation and enhanced subsequent seedling bolting. Different cultivars responded differently to the various seed temperature treatments. Cultivars which formed rosettes easily, showed less of a response to low temperature after harvest. However, if seeds were ripened under a cooler environment, then germinated at low temperatures and seedlings grown in a cool environment, rosette formation of seedlings in E. grandiflorum was essentially eliminated.

Effects of benzyladenine on bud break of roses

Abstract The uppermost axillary buds of some cut-rose cultivars fail to grow following flower harvest, especially in the winter season. In Japan, of the 60 cultivars grown under cover for cut-rose production, cultivar ‘Blue Moon’ syn.Mainzer Fastnacht shows strong dormancy after harvest. The practice of bending the petiole of the uppermost leaf was not effective in breaking dormancy in ‘Blue Moon’. Smearing BA lanoline paste (0.25%) on to the cut surface 0.5 cm above the axillary bud completely broke bud dormancy and hastened growth. Four applications of BA, from early October to March, increased saleable flowers by 78% over the untreated control.

Cutting-grafts as a means to propagate greenhouse roses

Abstract A propagation method for rose nursery plants was studied by using a 2-node scion tongue-grafted on to an unrooted stock cutting. Uniform and disease-free nursery plants could be produced efficiently in a short period all the year round. Under greenhouse production trials, such cutting-grafts of ‘Sonia’ on R. multiflora ‘K-1’, R. indica ‘Major’, R. ‘Manetti’ and R. wichuraiana produced flowers of the same number and quality as when budded on to R. multiflora seedling root stock.

Effects of storage temperature and duration on flower bud development, emergence and flowering of Zephyra elegans D. Don

Abstract The dormancy of Zephyra elegans corms was broken by storage at 25 °C or 30 °C for 22 weeks. However, following storage at 30 °C, flowering was delayed and the proportion of corms which flowered was less than with storage at 25 °C. With successional plantings it was possible to bring Zephyra into flower from February to June. However, days to emergence and flowering were longer and the proportion of corms producing flowers less for corms planted in February to April (stored for 9–11 months) than for corms planted between October and January (stored for 5–8 months). When shoots were approximately 8 mm, all corms had initiated flower buds. When shoots were about 20 cm, anther and ovule formation began and flowering occurred in March when the flower stem was about 50 cm. After storage at 25 °C to break dormancy, subsequent preplanting treatment of corms for 2 weeks at 15–25 °C under moist conditions resulted in rapid shoot elongation, rooting and flower bud development. The earliest flower bud development occurred with the 15 °C preplanting treatment.

Effects of gibberellins and benzylandenine on dormancy and flowering of Lilium speciosum

Abstract GA 4 + 7 (1000 mg/l), alone or in combination with BA (100 mg/l), was found to induce shoot emergence and flowering in dormant bulbs of L. speciosum , while GA 3 , alone or in combination with BA, had no effect. BA had a significant influence on increasing flower numbers, particularly when combined with GA 4 + 7 .