Takashi Fudano

Typically, hydrangea (Hydrangea spp.) plants produce flowers from early to mid-summer. However, their basal shoots often continue to produce flowers from late summer to autumn, and we call this unseasonal flowering. The flowering frequencies and flowering period durations of basal shoots were studied using 23 hydrangea cultivars and lines in 2017, 2018, and 2019. The flowering frequencies of basal shoots were relatively high in ‘Christmas’, ‘Endless Summer’, ‘Ezo’, ‘Rosea’, and ‘Sumida-no-hanabi’ in each year of the study. The flowering period durations of basal shoots ranged from one to six months among the cultivars and lines studied. Basal shoots of ‘Endless Summer’ and ‘Rosea’ continuously flowered during each year of the study period. The basal shoots of ‘Hatsushimo’, ‘Jyogasaki’, ‘Maihime’, ‘Masja’, ‘Ms. Hepburn’, ‘Uzu’, and No. 5 never flowered after August in any of the study years. Using ‘Masja’ and ‘Rosea’, axillary buds expected to develop into basal shoots were studied for flower bud initiation in November 2018. Flower bud initiation was observed in 8.9% and 77.4% of axillary buds of ‘Masja’ and ‘Rosea’, respectively. The number of nodes produced before flower bud initiation in the buds ranged from 10 to 12 and 8 to 13 in ‘Masja’ and ‘Rosea’, respectively. The numbers of nodes corresponded to those of the basal shoots that flowered up to August 2019 in both cultivars. The number of nodes produced by basal shoots of ‘Rosea’ that flowered after August 2019 ranged from 14 to 19, which was higher than those observed for the axillary buds expected to develop into basal shoots in November 2018. In conclusion, the flowering period duration of hydrangea basal shoots differs among cultivars. The floral initiations on the apical buds of the basal shoots after the previous autumn largely contribute to unseasonal flowering occurrences after August in hydrangea.

Hydrangea (Hydrangea spp.) flower buds usually differentiate from the end of summer through autumn, but some cultivars can also produce flower buds in spring. In the present study, we selected cultivars with high potential for such unseasonable flower bud production in Japan by evaluating the flower bud production on pinch-treatment-induced axillary shoots. We also examined the pinching time and the difference between the two shoot types: previously formed shoots that developed from buds formed in the previous autumn and basal shoots that formed in the current spring. We found that ‘Christmas’, ‘Endless Summer’, and ‘Rosea’ had the highest frequencies of unseasonable flower bud production on the axillary shoots of previously formed shoots (90.0%, 80.0%, and 90.0%, respectively) and basal shoots (90.0% for all three cultivars). When the buds were pinched in mid-April, the axillary shoots that formed on both shoot types flowered from early July to mid-August, which was approximately 1 month later than for seasonably produced flower buds in the same cultivars. In 2011, 98.0%, 90.5%, and 84.0% of the axillary shoots that developed on previously formed shoots flowered in ‘Christmas’, ‘Endless Summer’, and ‘Rosea’, respectively, while in 2012, 63.2%, 54.9%, and 75.3% flowered, respectively. Similar values were seen for the basal shoots, with the exception of ‘Christmas’ in 2011 and ‘Endless Summer’ in 2012, which both had lower flowering rates than previously formed shoots. In ‘Rosea’, flower bud differentiation started just after the pinch treatment, and the frequency of flower bud production decreased when the pinch treatment was conducted after late April. Thus, ‘Christmas’, ‘Endless Summer’, and ‘Rosea’ were considered to have high potential for unseasonable flowering following pinch treatment in early spring. However, unseasonable flower bud production may often be suppressed in pinched basal shoots.

To identify ways to improve the winter production of 'Kyo-temari' parthenocarpic tomatoes without the use of heating, we compared the effect (October 2011 to March 2012) of covering a poly tunnel with a newly developed polyvinyl alcohol and polyethylene (PVA) film instead of with a conventional film, i.e., polyvinyl chloride (PVC). Light transmittance at wavelengths of 2,500–25,000 nm was lower in the PVA than in the PVC film, so it retained a higher level of heat. The daily minimum temperatures in both tunnels were 0.5–2.8°C higher than in a non-covered tunnel during the same period, and the time during which the temperature remained below 5°C was shorter in the PVA-covered tunnel. The relative humidity and daily maximum temperature in this tunnel were lower than in the PVC-covered tunnel. The number of fruits was higher in the PVA-covered tunnel. Furthermore, the proportion of small ones was larger, and their Brix was significantly higher. Thus, covering tunnels with this newly developed film can increase the number and quality of 'Kyo-temari' tomato fruits grown in winter using a non-heated production system.<br>

The flowering traits of 'Emmer' and 'Pyramidale', two ancestral wheat varieties that are now used to make two types of beer brewed in partnership with Kyoto University scientists, were investigated in detail. These varieties are classified as T. turgidum L. ssp. dicoccon and ssp. turanicum, respectively, and little information is available about their agronomic characteristics. Through evaluation of the internal factors determining their flowering time (photoperiodic response, vernalization requirement and narrow-sense earliness), we revealed that the two varieties are spring-habit and photoperiod-sensitive. While the narrow-sense earliness of 'Emmer' is less intense than that of 'Pyramidale', the photoperiodic response of 'Emmer' is more intense than that of 'Pyramidale'. Based on a genetic analysis using the F₂ population of the two varieties, we concluded that 'Pyramidale' harbors a photoperiod-insensitive allele in the Ppd-A1 locus, the same allele reported by Wilhelm et al. (2009). This photoperiod-insensitive allele is expected to be a useful genetic resource in the breeding of tetraploid and hexaploid wheat.

The number of buds per inflorescence fluctuates irregularly in the sweet pea (Lathyrus odoratus L.) winter-flowering variety 'Early Pink'. The number of buds per inflorescence and the fluctuation of the number of buds per inflorescence differ remarkably among plants. The number of buds per inflorescence, diameter of flower stalks, dry matter of cut flowers, and diameter of internodes increased, and short cyclic fluctuations if] the number of buds per inflorescence were suppressed as the frequency of removing immature inflorescences increased. Using a moving average, the fluctuation Of the number of buds per inflorescence was found to be a combination of two periodic fluctuations in 26 of 36 plants. The 2-3, 4-6. 8-12, and more than 115 node periodic fluctuations were found in 10, 15, 11. and 16 plants, respectively. From these results, the factors that cause the number of buds per inflorescence to fluctuate are discussed.

Fusarium 'F959', a pathogenic sensitive strain to taro, was inoculated on 'Celebes'. The inoculated corms were kept in the dark at 25℃ for 15 days. Paraffin sections were made from the inoculated corms and observed cytologically under a light microscope. In control specimens, about 1mm transparent cell layers and meristematic cell layers (normal periderm) were formed under the wound surface. The cells of all transparent layers were significantly lignified . When Fusarium was inoculated to the wound, the transparent cell layers expanded to 2-5 mm and were not lignified. It was considered that periderm formation was not normally performed by Fusarium. Further, it was investigated whether delaying the time of inoculation after wounding would influence the response of corm to the pathogen. When the interval between wounding and inoculation was 12 hours or more, there was no expansion of transparent cell layers observed. It was considered that normal periderm formation was facilitated by some kind of defense responses occurring in the tissue of the taro.

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.<br>

The possibility of producing cut flowers used exclusively for flower arrangement (i.e., bouquet, home flower display and flower basket) was studied in Gypsophila paniculata L.<br> 1. Effects of planting density on the yield by cul flower size (floret number and shoot length for bouquet were ≧1000 and ≧60 cm, those for home flower display were ≧300 and ≧40 cm and those for flower basket were ≧50 and ≧15 cm, respectively) were investigated. The number of cut flowers for home flower display use doubled at 3-fold density compared with that of standard density (i.e., 4.4 plant/m²). The yield of cut flowers for flower basket use increased to 2.3 times the standard when planted at 4-fold standard density.<br> 2. Five cultivars were tested to determine how inflorescence architecture, that is branching habit, internode length and the number of florets per unit dichasium affected the yield at 4-fold standard density. The yield of cut flowers for bouquet or home flower display in 'Bristol fairly' was higher than that of any other cultivars and that for flower basket use in 'New face' and 'Bristol fairy' was higher than that of any other cultivar.<br>

Photosynthetic rate and partitioning of photosynthate in sweet pea (Lathyrus odoratus L.) 'Early Lavender' whose leaves were administered ^<13>C during the flowering period were investigated. 1. The apical portion was a strong sink for ^<13>C-photosynthates under 100% and 50% full sunlight. Partitioning of photosynthates to the apical portion increased significantly when the young flower buds were removed from the inflorescences on the first and second nodes above the inflorescences which had two open flowers. 2. The photosynthetic rate was the highest in the leaflet on the same node as the inflorescence which had two open flowers. The photosynthetic rate of the leaflet was decreased by removing the young flower buds of the inflorescence. The photosynthates from the treated leaves were translocated preferentially to the inflorescence on the same node. 3. The photosynthetic rate was kept high even in leaves on lower nodes. More photosynthates were partitioned to the apical portion of a shoot from lower leaves than those from the upper ones.