Self-compatible cultivars of Japanese apricot (Prunus mume Sieb. et Zucc.) have a horticultural advantage over self-incompatible ones because no cross-pollinizer tree is required. Self-incompatibility is gametophytic, as in other Prunus species. Self-compatible cultivars of Japanese apricot have a comon S-RNase (S^f-RNase) gene that can be used as a molecular marker for self-compatibility. In this study, we developed a PCR primer set, Ken2 and PM-R, from intron sequences of S^f-RNase gene, which can be used to specifically amplify the S^f-RNase gene fragment. Practical applications of the primer set for breeding programs for self-compatible Japanese apricot cultivars are discussed.

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Shoot tips excised from in vitro grown Chinese leek “Nakamidori” were successfully cryopreserved by vitrification. After 2 weeks cold-hardening, the excised shoot tips (1mm × 1.5mm) were precultured on Murashige and Skoog medium with 0.3M sucrose for 1 day at 5°C. The shoot tips were then osmoprotected with loading solution (LS) for 20 min at 25°C, dehydrated with plant vitrification solution 2 (PVS2) for 40 min at 25°C and immersed into liquid nitrogen (LN). The survival rate of cryoperserved shoot tips was about 80%. Shoot tips were also successfully cryopreserved by the encapsulation-vitrification method. The cold-hardened, precultured shoot tips were encapsulated with alginate-gel and simultaneously osmoprotected by LS solution for 90 min at 25°C. Then they were dehydrated with PVS2 for 120 min at 25°C and immersed in LN. The survival rate after cryopreservation amounted to about 80%. The optimal exposure time by PVS2 varied among specimens, especially depending upon whether meristem domes were covered with young leaves and the base of a leaf sheath. For the vitrification-based method, an appropriate unit of specimen for cryopreservation and an appropriate dehydration time using PVS2 were essential factors in achieving high survival rate.

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Relationship between weight of seeds and ploidy level of the seed-derived plantlets obtained from reciprocal crosses between diploid ‘Banpeiyu’ pummelo and two tetraploid varieties were examined to efficiently select triploid progenies for further breeding of the pummelo. Percentages of fully developed seeds obtained from the cross of ‘Banpeiyu’ pummelo with 4X Yuzu or 4X Natsudaidai were decreased by 48.0% and 8.4% as compared with the control, respectively. Seedlings obtained from these two crosses included triploids, tetraploids and hexaploid. ‘Banpeiyu’ pummelo as seed parent yielded a high percentage of triploids (88.0%) when crossed with 4X Yuzu, but low percentage (30.2%) when crossed with 4X Natsudaidai. In both crosses, the average weight of triploid seeds was significantly lighter than that of tetraploid seeds. Furthermore, all seedlings derived from undeveloped seeds were triploids.
Percentages of fully developed seeds obtained from 4X Yuzu or 4X Natsudaidai × ‘Banpeiyu’ pummelo were not different from those of seeds from open pollinated fruits, but weights of these seeds were extremely decreased compared to seeds from open pollinated fruits. Approximately 50% of in vitro cultured seedlings obtained from both crosses were triploid, while the others were tetraploids, which might be derived from nucellar embryos of seed parents. There was no difference in the average weights of seeds between have seeds yielding triploid seedlings and those yielding tetraploids that might have originated from nucellar tissue.

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Japanese chestnut is a traditional nut in Japan. Though almost all the produce from Japanese chestnut trees grown in China are shipped to Japan for processing, their characterization has not been reported. In this paper, we report the origin and discrimination of varieties in China using randomly amplified polymorphic DNA (RAPD) analysis. All varieties examined in this report could be discriminated by 162 kinds of RAPD markers raised from 8 primers. Four varieties introduced to China from Japan seemed to be seedlings of the same varieties being cultivated in Japan. One of the varieties introduced from Japan, ‘Moriwase’ had a low similarity to ‘Moriwase’ in Japan. This finding suggests that ‘Moriwase’ in China was misinterpreted during the process by which had been introduced from Japan, or propagated via seedling. Five varieties bred in China were classified in the same group as the old varieties in Japan.

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Eighty-five lotus cultivars including interspecific hybrids, Nelumbo nucifera and N. pentapetala (Walter) originated from China (50), Japan (32), India (2) and America (1) were evaluated by inter-simple sequence repeat (ISSR) analysis. Reproducible polymorphic bands were amplified by 5 (UBC811, 818, 840, 855, 857) among 100 ISSR primers tested. Compared with Asian cultivars, on American cultivars showed specific polymorphic bands that were detected in hybrid cultivars. Among Asian lotuses, there also were polymorphic bands specific to wild red lotuses orginating from China and primitive lotuses from Japan. A fingerprinting map of 85 lotus cultivars was Constructed using 20 polymorphic bands. The results of ISSR can be successively used for identification of lotus cultivars.

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To classify and estimate the wild evergreen azalea populations in the Kirishima Moutains, principal component analysis and cluster analysis were applied using morphological characteristics and compared with chloroplast DNA polymorphisms.
1. Wild azalea populations were divided into three clusters; Rhododendron kiusianum, R.keampferi and natural hybrids groups by cluster analysis. R.kiusianum and R.keampferi clusters were composed of individuals, which had chloroplast DNA patterns of each species and the natural hybrid cluster consisted of both DNA patterns.
2. On principal component analysis, the first principal component with a high contribution ratio expressed general morphologic characteristics of the wild azalea populations. This first principal component increased continuously from R.kiusianum at high altitude, natural hybrids, and to R.keampferi at the foot of mountain. The distribution of chloroplast DNA polymorphisms of azalea populations indicated correlation with this first principal component.

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Ophipogon jaburan Lodd is an important ground cover plant. We investigated its seed germination, methods of seed storage, and the effects of fertilizer on seedling growth. Seeds collected in late December remained green, while seeds collected in January were bule. Both seed types hardly germinated at 10 °C in an incubator, but showed germination percentages of 85 % or more at 20-30 °C. Therefore, seeds sown immediately after collecting did not emerge as seedlings until June outdoor. Intact seeds and depulped seeds retained their germinability for 1 month and 6 months, respectively, when stored at 4 °C with humidity of 80 % or more. When depulped seeds stored in moist sphagnum peat at 4 °C were sown in the beginning of June, near the suitable temperature for germination, seedlings emerged simultaneously in the middle of July. The starting of emergence was promoted and seedlings grew to sufficient commercial size within a year, when the seeds were sown in a heated greenhouse at 15 °C or more in February and the seedlings were subsequently transplanted in May after fertilizing with 50 mg or more nitrogen per individual.

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The differences between male and female plants in the growth of one-year-old asparagus (Asparagus officinalis L.), yield and quality of spear in forcing culture were investigated. Female plants had higher stalks and longer length to primary branch than male plants. One-year-old female plants produced a few or no fruits. There was no difference in the number of stalks between one-year-old male and female plants. One-year-old female plants grew more vigorously and produced larger stalks than males. The difference between one-year-old male and female plants in the number of spears was not significant. However, the size of individual spears of one-year-old female plants was larger than that of male plants. Thus, one-year-old female plants have a capacity for a higher spear yield than male plants in forcing culture. The spear top of female plants was tighter than that of male plants. Female plants developed less anthocyanin pigments in the scaly leaves of spear than male plants. These results suggested that female plants were more desirable than male plants in one-year-old asparagus forcing culture.

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To determine the adequate pruning time during the rest year of satsuma mandarin trees in a systemized-alternate bearing orchard, the sprouting ratio and growth in new shoots were compared among satsuma trees (cv:‘Haraguchi Wase’) pruned in mid-February, trees pruned in mid-March (bud-breaking time), and trees that were not pruned. Pruning was performed for the whole tree canopy, and most of the 1-year-old branches were cut, then new shoots sprouting and growth on 2,3-year-old branches were compared with those of non-pruned trees. As for sprouting of spring shoots, pruning strongly increased it, and trees pruned in March produced over seven times more shoots than those that had not been pruned. As for sprouting of summer shoots, the remarkable occurrence was observed only in the trees pruned in March. The average length and leaf color of the new shoots (spring and summer shoots) did not differ between pruned and non-pruned trees. These results suggested that the bud-breaking stage is the most appropriate time for pruning satsuma mandarin trees during the rest year in a systemized-alternate bearing orchard. On comparison of carbohydrate (glucose, sucrose, and starch) and nitrogen (total nitrogen and NO₃⁻) concentration in the bark of the 2 or 3 year-old branches, it was determined that pruning markedly decreased the starch concentration and slightly increased the soluble sugar concentration while the total nitrogen and NO₃⁻ concentrations increased before sprouting, depending on pruning time. These changes caused by pruning appeared to be a phase conversion to vegetative growth.

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Effects of air temperature and humidity in the greenhouse on the growth of the fall-cropped cucumber ‘Natsunokaori’ were investigated. In pinching and wire-training cultivation, air temperature of 30 °C and 60 % relative humidity promoted the development of fruit by suppressing growth of the 3rd and 4th lateral branches. Air temperature of 25 °C and 40 % relative humidity promoted the development of lateral branches by suppressing fruit growth. The total number of fruits were increased by air temperature of 25 °C and 40 % relative humidity. However, the percentage of marketable fruits was decreased during low temperature seasons.

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To stabilize the yield of fruit production in Vitis coignetiae Pulliat, which is a dioecious plant that requires pollination for fruiting, we investigated long-term pollen storage using organic solvents. The germination rate which was initially 50.6 %, was reduced to zero after 189 days of storage in low temperature (−20°C) and was also reduced to zero after 117 days of storage in acetone. However, the germination rate of pollen remained 22.8 % after one year of storage in diethyl ether. Artificial pollination of Vitis coignetiae Pulliat using pollen that had been stored for one year in diethyl ether achieved fruiting almost equal to that achieved using fresh pollen. Berry quality did not differ between fruits pollinated by stored pollen and those pollinated by fresh pollen. We conclude that long-term pollen storage over one year with diethyl ether may be a promising for stabilized fruit production in Vitis coignetiae Pulliat.

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To apply mulch for leaf and root crop cultivation with high planting density, we tried to use a paper mulch combined with seed tape, which allows simultaneous mulch installation and seed sowing. When growing Komatsuna (Brassica Campestris L.) and turnip using the trial paper mulch, a rate of germination exceeding 90 % was obtained. For radishes and carrots, the rate of germination exceeded 80 %. In Komatsuna culture, growth and yield were improved using this mulch rather compared to that using seed tape without mulch. Moreover, the labor hours for weeding were shorted to about 10 % using mulch culture compared to that without mulch culture.

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To determine the optimal period of raising seedlings depending on the size of rockwool cube, tomato seedlings were grown in three different size of rockwool cube, that is, large (length:width:height = 10:10:5 cm), tall (5:5:10 cm) and small (5:5:5 cm cube). Seedling growth was highest in large cube and lowest in tall cube at all timepoints. Optimal periods of raising seedlings were affected by rockwool-cube size. It was estimated that optimal periods of raising seedlings were 24 days in large and tall cubes, and less than 14 days in small. Root activities were not related to the optimal period. It was suggested that the ratio of root dry weight to the volume of rockwool cube was the dominant factor affecting the optimal period of raising seedlings.

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The effect of starting time of heating and night temperature during winter on the flowering of snapdragon (Antirrhinum majus. L.) cv. ‘Maryland Pink’ and ‘Light Pink Butterfly II’ which were seeded in October. The flowering was accelerated in ‘Maryland Pink’ by advancing the starting time of the heating at an identical night temperature. Cut flower quality of ‘Maryland Pink’ was best at a night temperature of 11 °C starting from the middle of November. Flowering was accelerated in ‘Light Pink Butterfly II’ by a night temperature of 16 °C starting from the middle of November. The flowering was accelerated on either cultivar by a higher night temperature setting. The plant height of ‘Maryland Pink’ and ‘Light Pink Butterfly II’ were higher when the plants were grown at low temperature.

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Effects of light break treatment every second or third night on the growth of certain leaf vegetables were evaluated. In experiment 1, spinach (Spinacia oleracea) was irradiated with 0.4~1.2 μmol·m⁻²·s⁻¹ (PPF) of light from an incandescent lamp for 51 minutes a mid-night every night (every night treatment), or for two hours at mid-night on Monday, Wednesday and Friday (interval treatment). In experiments 2, spinach and tsukena (Brassica campestris) received interval treatment with 1.0-1.5 μmol·m⁻²·s⁻¹ of light of incandescent lamp for two hours at mid-night. In experiment 3, spinach, lettuce (Lactuca sativa) and tsukena received interval treatment with 0.5-1.8 μmol· m⁻²·s⁻¹ of light from light emitting diodes (LEDs) for two hours at mid-night.
In experiment 1, under interval treatment, there was no bolting of spinach on the 26^th day of treatment. However, ratio of bolting plants was 22 % under every night treatment. In experiments 2 and 3, interval treatment with incandescent lamp or LED promoted spinach growth without bolting. In spinach, plant height, number of leaves and top dry weight were larger under interval light break treatment than under no light break. However, the growth of lettuce and tsukena were not promoted with light break treatment.

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The growth,head formation and leaf surface characteristics of bloomless cabbage cultivar ‘Yuryoku’ were investigated in comparison with a normally bloomed cabbage cultivar ‘Kinsyu’. Leaf surace of ‘Yuryoku’ seen through a scanning electron microscope was smooth. Compared with ‘Kinsyu’, the colors of outer leaf and head surface of ‘Yuryoku’ were as follows: The value of L* and a* were small and the b* value was large. The glossy rates (G_S75°) of outer leaf and head surface leaf of ‘Yuryoku’ were higher than those of ‘Kinsyu’. The touch-angles of water drop on outer leaf and head surface leaf of ‘Yuryoku’ were smaller than those of ‘Kinsyu’. There were no large differences between ‘Yuryoku’ and ‘Kinsyu’ except that the weight of ‘Yuryoku’ was a little lighter than ‘Kinsyu’. These results suggested that bloomless is the distinguishing characteristics of ‘Yuryoku’ and potentially useful to reduce the chemical application.

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The effects of two types of rootstock (Rosa odorata and Rosa multiflora), training method (high-rack and arching) and the presence or absence of permanent rootstock assimilation branches on the yield and cut flower quality in the rose ‘Asami Red (Rote Rose) ’ grown in rockwool in a plastic house were studied.
The high-rack training method produced a higher yield of cut flower stems compared with those grown by the arching training method. In both the high-rack and the arching training methods, the yield of cut flower stems of plants with permanent rootstock assimilation branches of Rosa odorata was higher than that of plants grown by cutting. However, on Rosa multiflora rootstocks, the yield of cut flower stems was reduced by permanent rootstock assimilation branches compared to that of plants without such branches. In both of the high-rack and the arching training methods, the cut flower stem length of plants with permanent rootstock assimilation branches of Rosa odorata was more increased than that of plants grown by cutting. However, on Rosa mutiflora rootstocks, the cut flower stem length of plants with permanent rootstock assimilation branches was shorter than that of plants without them.

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The effect of ethephon applications on growth and morphology in summer-to-autumn-flowering chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura = Chrysanthemum morfolium Ramat.) was studied for forced cut flower production under open culture. Flower bud differentiation of ‘Madobe’ and ‘Summer-yellow’ was strongly inhibited by 200-400 mg·liter⁻¹ ethephon applications when sprayed at 0-1,000 mg·liter⁻¹ ethephon concentrations. Leaf increasing terms of some cultivars were more elongated by 800-1,000 mg·liter⁻¹ ethephon applications than by 200 mg·liter⁻¹ and others were the same elongation when sprayed with 0-1,000 mg·liter⁻¹ ethephon concentrations. Cultivars with longer internodes showed more stem elongation using 200 mg·liter⁻¹ ethephon sprays than those with shorter internodes showed. Leaf numbers and stem lengths were not incleased and malformations occurred when they were sprayed with 200 and 1,000 mg·liter⁻¹ ethephon after bud differentiation in flower buds, flower and peduncle of those cultivars.
As a result, cultivars showing strongly inhibited flower bud differentiation and longer internodes after ethephon applications should be used for cut flower growing for flowering inhibition in summer-to-autumn-flowering chrysanthemums, ethephon sprays should be avoided after flower bud differentiation.

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Unbagged ‘Fuji’ apple fruits were fumigated with different concentraitions (38, 48 and 58 g·m⁻³) of methyl bromide (MB) for 2 hrs at 15 °C, then aerated for 1 hr. These fruits were then stored at 0 °C for 10 days followed by 15 °C for 7 days in a sealed styrofoam box. Carbon dioxide concentration in the box containing the fruits fumigated with MB increased during storage. In the fruits that had been fumigated with MB (20.1 g·m⁻³) and stored at 15 °C for 10 days in the sealed box without aeration, internal browning was observed in all fruits. These results indicated that aeration to reduce internal browning by MB fumigation was important. Carbon dioxide concentration in sealed box containing fruits fumigated with MB increased, but oxygen concentration slightly decreased. It was suggested that the organic acid could be utilized as a respiration substrate in fruits fumigated with MB. Titratable acidity in this fumigated fruits was remarkably lower than that of other fumigated fruits. Concentration of malic acid in these fumigated fruits decreased. These results showed that MB fumigation affected the organic acid metabolism in relation to respiration.

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