The vase life of cut ornamental flowers, including dahlias, is important breeding target in determining their quality and consumers’ preference. Therefore, we initiated a research breeding program in 2014 to improve the vase life of dahlias. We chose 22 commercial cultivars as initial breeding materials, and repeatedly crossed and selected promising offspring with long vase life for two generations, from 2014 to 2016. Three lines, 505-13, 629-18 and 606-46, were judged to be the most suitable as new cultivars with long vase life. We registered these cultivars with Japan’s Ministry of Agriculture, Forestry and Fisheries and released them as ‘Eternity Torch’, ‘Eternity Romance’ and ‘Eternity Rouge’. These three new dahlia cultivars had genetically determined long vase lives of 6.3 to 12.0 days (1.4 to 2.2 times the vase life of a standard cultivar, ‘Kamakura’) in distilled water, 9.0 to 13.4 days (1.1 to 2.0 times the vase life of ‘Kamakura’) in GLA (10 g·L^-1 glucose, 0.5 ml·L^-1 kathon CG, and 50 mg·L^-1 aluminum sulfate) under 23 °C, 12-h photoperiod, and 70% RH conditions in 2018 and 2019. Cut flowers cultivated at five locations nationwide with different cultivation seasons in 2019 also showed similar long vase life, clearly indicating that the long vase life of our three cultivars were not due to the environment but the characteristics of cultivars.

‘Italian ryegrass Chukanbohon Nou 3 Go’ (hereinafter called ‘Nou 3 Go’), a diploid and early parental Italian ryegrass (Lolium multiflorum) cultivar with low nitrate-nitrogen concentration, was registered in 2011. The cultivar was developed by phenotypic recurrent selection of nitrate-nitrogen concentration in the seedlings and adult plants for five cycles. The plants showed more than 30 % reduction in nitrate-nitrogen concentration compared with that of ‘Yushun’. Heading date of the plants was similar to that of ‘Hataaoba’, and dry-matter yield of the plants was similar to that of ‘Hataaoba’ and ‘Yushun’. The F1 progenies from crosses of ‘Nou 3 Go’ with existing cultivars contained nitrate-nitrogen concentrations intermediate between those of the parents. This shows that the trait of low nitrate-nitrogen concentration in ‘Nou 3 Go’ is easily attached to an existing cultivar and line. ‘Nou 3 Go’showed lower nitrate-nitrogen and higher amino acid-nitrogen translocation in the xylem from the roots to the shoots compared with that of the parental generation, despite that the amount of nitrate-nitrogen uptake by the roots was not affected. Nitrate-nitrogen concentration in ‘Nou 3 Go’ in detached shoots was also lower than that of the parental generation. The low nitrate-nitrogen concentration of ‘Nou 3 Go’ reflects decreased root-to-shoot transport of nitrate-nitrogen and reduced capability for nitrate-nitrogen accumulation in the shoots.

Growth disorders of horticultural crops caused by clopyralid residues in manure compost derived from imported livestock feeds have been reported. In this study, symptoms of clopyralid injury in several ornamental plants were observed, and the degree of their susceptibility was evaluated by using test media containing 0 – 25 µg·kg ^-1 -DW of clopyralid. Clopyralid-induced injuries were observed in members of the Asteraceae family, such as chrysanthemum (Chrysanthemum × morifolium), marigold (Tagetes patula), cosmos (Cosmos bipinnatus), aster (Callistephus chinensis), sunflower (Helianthus annuus), and zinnia (Zinnia elegans), and Fabaceae family (crimson clover [Trifolium incarnatum]). Symptoms were observed within 2 weeks of sowing or planting on the test media. The common symptoms were inward rolling of the margins of new developing apical leaves, cessation of or abnormally shaped stem apex and flower buds, and reduction in stem length and fresh weight of the above-ground parts. In sunflower, an abnormal hypocotyl elongation was observed. The degree of these symptoms was dependent on clopyralid concentration. No clopyralid induced injuries were observed in plants belonging to the Violaceae (Pansy [Viola × wittrockiana]) and Gentianaceae (eustoma [Eustoma grandiflorum]).

The combined effect of sodium dodecyl sulfate (SDS) and additives was evaluated. Cherry tomatoes were washed with 2 % SDS and 3 % citric acid (CA), allyl isothiocyanate (AIT), levulinic acid (LA) or phytic acid (PA) for 30 min. The combined treatment of SDS and LA showed a synergetic bactericidal effect on the aerobic microflora and coliform, and the population of aerobic microflora and coliform was decreased by 2.6 log CFU/g and 3.1 log CFU/g, respectively. Similarly, the population of inoculated E. coli O157:H7 was reduced by the combined treatment of SDS and LA, and the population decreased from 5.8 log CFU/g to 2.6 log CFU/g. On the other hand, no synergetic effect on the population of aerobic microflora, coliform or E. coli O157:H7 was observed for the combination of SDS and other additives (CA, AIT and PA). In contrast to bacteria, the combination of SDS and each additive (CA, AIT, LA and PA) did not reduce the mold population (Rhizopus stolonifer and Cladosporium sphaerospermum) inoculated on cherry tomatoes, and washing decreased the mold population by < 1.7 log CFU/g. The skin color of the cherry tomatoes was not affected by the washing treatments with SDS combined with additives, and no significant differences were detected in the L*, a* and b* values among the treatment conditions. Rhizopus and Cladosporium are important spoilage fungi in tomatoes (Chua et al. 2021, Mehyar et al. 2011), and if the growth of mold can be inhibited during storage, the shelf life is expected to be significantly extended.