A pollen-free strain was obtained in the F₂ generation by cross-breeding of Lilium × formolongi variety ‘Akita Kiyohime’ and Easter lily (Lilium longiflorum) variety. The gene for pollen-free is recessive inheritance. The incidence of pollen-free individuals in the F₂ generation is influenced by seed germination rate, bolting rate, and flowering rate of the strain, and fluctuates. The cultivated strain shows vigorous growth of Lilium × formolongi in addition to being completely pollen-free, and can produce cut flowers with smaller bulbs than the conventional Easter lily variety.

Since most of main commercial cultivars of Japanese pear (Pyrus pyrifolia Nakai) are self-incompatible, supply of pollen and artificial pollination is required. To promote pollen production efficiency, we investigated flower bud harvesting methods, training of trees and plant growth regulator treatments. Simultaneous harvest at 50% of full bloom was the most efficient. Among training systems, tree joint training, in which main stem of each tree were bent horizontally at 70 to 90 cm height, and tips were grafted into the adjacent tree, increased the number of flower buds compared to stand-alone non-bent trees, or horizontally bent non-grafted trees. The efficiency of hand harvest of flower buds was higher in joint trees than in stand-alone non-bent trees, or flat trellis trees. In ‘Shinko’ pear trees, the number of flower buds increased by the gibberellin biosynthesis inhibitors (daminozide and paclobutrazol), and the synthetic ethylene (ethephon) application in shoot growth period. In conclusion, simultaneous harvest at 50% of full bloom and tree joint training system were efficient, and daminozide, paclobtrazol and ethephon treatments were effective for promotion of flower buds of ‘Shinko’ pear trees.

Citrus greening disease (Huanglongbing, HLB) is a major citrus disease in tropical and subtropical regions of the world, and is transmitted mainly by the Asian citrus psyllid (ACP, Diaphorina citri Kuwayama). In Japan, the distributions of the disease and of ACP have expanded in the past 30 years, and the distributions may expand further with global warming. For efficient and accurate disease control, spatiotemporal estimation of ACP establishment is essential. Here we predicted current and future potential distributions of the ACP in Japan from geospatial data of its thermal and vegetative niches. We defined a thermal niche as an area where the ACP can survive cold winters, and a vegetative niche as an area where Murraya paniculata trees, a host plant of the ACP, grow vigorously. By overlaying meteorological and land-use grid square data at a spatial resolution of approximately 1 km in QGIS software, we identified thermally and vegetatively suitable areas for ACP establishment. Currently suitable areas lie in coastal regions in Kyushu and Shikoku, and parts of the Kii and Izu peninsulas. In the late 2040s, when the average minimum temperatures in Japan are predicted to increase by 2°C under the RCP8.5 scenario (worst-case climate change scenario of IPCC), suitable areas will be wide spread in the coastal regions of Kyushu, Shikoku, and Honshu.

The purpose of this study was to clarify the characteristics and potential preventative measures for yellow spots, a disorder that affects the pericarp of the new citrus cultivar, ‘Mizuki’. Yellow spots were found to be the primary disease affecting the pericarp in ‘Mizuki’ and exhibited different symptoms to sunburn. Yellow spots were first observed in mid–late July, and increased in frequency in mid–late August. New instances of yellow spots were observed as late as December. Observation of pericarp sections at the site of yellow spot occurrence revealed browning in some of the oil glands, which was absent in healthy sections. More than 80% of the pericarp sections exhibited one browning oil gland. There were fewer occurrences of yellow spots in the inner canopy than in the outer canopy. In the outer canopy, yellow spots more commonly occurred in fruits exposed to sunlight than to shade. Coating the fruit with black shade cloth suppressed the development of yellow spots. This approach was particularly effective when the coating was applied prior to late July, but ineffective when the coating was applied after late August. This study also showed that higher solar radiation resulted in increased yellow spot occurrence. This study therefore suggests that yellow spot occurrence in ‘Mizuki’ is affected by both the stage of fruit development and solar radiation conditions, and that yellow spot occurrence may be suppressed by controlling the amount of solar radiation received by the fruits.

We examined the effects of different forcing dates and hydrogen cyanamide combination treatments on dormancy breaking, vegetative growth, and reproductive growth in two low chilling requirement southern highbush blueberry cv. ‘Kestrel’ and ‘Star’ under inadequate chilling conditions. The pot grown 3-year-old plants were treated with 0.5% hydrogen cyanamide, or remained untreated before moving into an unheated high tunnel greenhouse on the date when the chill hour (CH.) was achieved. ‘Kestrel’ was forced on CH. 50, 100, and 150, and ‘Star’ was forced on CH. 50, 150, and 400. The hydrogen cyanamide treatments shortened the days to vegetative budbreak after treatment, and significantly promoted bud breaking and leafing compared with the controls despite the accumulated CH. It is suggested that chilling compensation by hydrogen cyanamide is effective even if the accumulated chill is limited for these low-chill varieties. Although flowering seemed to be unaffected by the treatments, the peak harvest was significantly advanced and the fruit development period was also shortened. These results were associated with the promotion of vegetative budburst, such as an early leaf out increased photosynthetic rate and canopy establishment during the early growing season, which contributed to the fruit growth. Our results suggested that forcing cultivation for low-chill blueberry under inadequate chilling conditions by hydrogen cyanamide is effective for compensating chill which leads to the early vegetative growth.