The degree of resistance of the highly resistant Japanese bunching onion (Allium fistulosum L.) line ‘D8s’ against stone leek leafminer (Liriomyza chinensis (Kato)) biotype A to L. chinensis biotype B was evaluated by laboratory and field experiments. In the laboratory experiment, population growth rate, feeding preference, and oviposition preference of biotypes A and B of L. chinensis were investigated. The population growth rates of biotypes A and B on a highly resistant ‘D8s’ line against L. chinensis were significantly lower than on the susceptible variety ‘Chouetsu’. However, the effect of population density control of biotype B on ‘D8s’ was significantly lower than that of biotype A. The period required until next-generation adults emerged on ‘D8s’ was longer than those on susceptible varieties for both biotypes. Feeding and oviposition preferences were examined using ‘D8s’ and other susceptible varieties. The numbers of feeding punctures and eggs laid by biotypes A and B on ‘D8s’ were lower than those on the other varieties. Next, we investigated the field resistance of ‘D8s’ against larvae from July to October 2022. In the experimental field, biotype A adults were not detected but biotype B adults were present. The degree of damage by L. chinensis larvae on ‘D8s’ was significantly lower than on the other control varieties. These results indicate that ‘D8s’ is a breeding material with resistance against L. chinensis biotypes A and B.

Garden stock (Matthiola incana (L.) R.Br.) is a major floricultural plant in the winter season. In this study, dry seeds of Matthiola incana were irradiated with carbon (C) and iron (Fe) ion beams to investigate the effective element species and absorbed doses. The survival rate of the M₁ generation tended to decrease with increasing absorbed dose, and the absorbed dose-survival rate curve showed a shoulder at absorbed doses of 100 Gy in C-irradiation and 10 Gy in Fe-irradiation. Some shoot and flower morphogenetic mutants were obtained in the M₂ progenies. The shoot mutants contained dwarf, multibranch, and enlarged floral axis individuals, while the flower mutants had darker petal colors, narrowed petals, and an increased number of petals. The mutation rate increased with elevating absorbed dose and showed a negative correlation with the survival rate. Based on these results, it was suggested that absorbed doses of 100 Gy in C and 10 Gy in Fe, which are the shoulders of the absorbed dose-survival rate curve, are effective indicators for generating Matthiola incana mutants. The mutated flower phenotype was stably inherited, but the shoot mutant inheritance varied. These results demonstrate that ion beam irradiation of Matthiola incana dry seeds can produce mutants.

Lutein, known for its health benefits, is abundant in spinach (Spinacia oleracea); however, factors influencing its concentration remain unclear in spinach for processing. Therefore, in this study, the relationships between the variation in lutein concentrations with the season and developmental stages, and agronomic parameters, such as weather conditions, growth traits, and chlorophyll a fluorescence OJIP transients (OJIP transients), were investigated. Spinach was cultivated until flowering in autumn and winter sowing. Seasonal variation in the lutein concentration was categorized into increasing and decreasing phases. The concentration increased at low temperatures and decreased at the optimal growth temperature, indicating a negative correlation with atmospheric temperature. During the increasing phases, OJIP transient levels (Fv/Fo) decreased due to chilling stress–induced growth inhibition. During the decreasing phases, prolonged chilling stress over 2 months led to reductions in OJIP transient levels, such as the performance index and Fv/Fm. Notably, initiation of the decreasing phase coincided with the flower stalk elongation period. This suggests a direct effect of atmospheric temperature on the lutein concentration in spinach, with flower stalk elongation potentially contributing to lower concentrations. Furthermore, OJIP transients emerged as potential indicators for monitoring the lutein concentration in spinach for processing.

Climate change is expected to delay flower bud differentiation of strawberry nursery plants under natural conditions caused by high temperatures in autumn, which may destabilize early yields in forced cropping. In order to stabilize early yields, we investigated a simple method of flower induction: 3-day low-temperature storage (3D-LTS) treatment, using labor-saving tray plants and a vacant fruit pre-cooling refrigerator. First, we examined the quality of the tray plants to be used and found that large plants with three or four leaves at the time of runner cuttings showed accelerated flowering, whereas small plants with one or two leaves showed the same flowering date as the large tray plants under natural conditions, and flowering was not delayed. The effect of the start dates of 3D-LTS treatment on flower bud differentiation was examined, and the results suggested that the best time to start the treatment to promote flower bud differentiation varied among cultivars, and that it may be approximately 1 week before the time of flower bud differentiation under natural conditions at the cultivation site of each cultivar. The results suggest that 3D-LTS treatment for tray plants may be a low-cost and simple method to promote flower induction that avoids delays in flowering in the case of early planting.

Seedless grape cultivation requires a lot of cultivation management in a short period of time, which is a factor that hinders scale expansion, but a similar problem has been pointed out with ‘Shine Muscat’, where the cultivation area is rapidly increasing. Therefore, a more labor-saving technique is required. We considered early Gibberellin acid (GA₃) treatment, which has been put into practical use for ‘Sunny Rouge’, and conducted GA₃ treatment of ‘Shine Muscat’ at the early 7 to 8 leaf spreading stage, and elongation of the flower cluster decreased the berry density. In addition, by applying early GA₃ treatment and thinning the flower cluster when it reached a length equal to or longer than the beginning of flowering, it is possible to reduce the labor time necessary for berry thinning without increasing that for flower thinning, compared with GA₃ treatment at full bloom and thinning the flower cluster at the beginning of flowering. Regarding fruit quality, early GA₃ treatment was suggested to improve the sugar content and taste, and it was considered that there would be no major effect on the ease of eating the fruit with the skin, but there was concern that the grade would decline due to a deterioration in grape bunch shape.

This study aimed to investigate the effects of irradiation from light-emitting diodes (LEDs) on the growth of cut carnations using the standard-type variety ‘Moon Light’ and spray-type variety ‘Cherry Tessino’ in a warm-climate region of Japan. Carnations in this region are cultivated under heated conditions during the winter. The effects of irradiating carnations with white light (peak wavelengths of 450 and 628 nm) or red light (peak wavelengths of 625 nm) using LED-based continuous lighting or 16 h of extended daylight were examined by assessing the number of days from pinching to flowering, the number of flowers harvested, and flower quality. This study spanned from the first pinching in July to the end of cultivation in May. White or red light irradiation using LEDs reduced the number of nodes at flowering, shortened the number of days to reach flowering on lateral branches that undergo flower bud differentiation during the short-day period, and increased the total number of flowers harvested, although the effects varied depending on the variety and time of year. The effect on cut flower quality was also observed at both wavelengths, hardening the stems of cut flowers from the onset of flowering to December. A comparison of the effects of wavelength, showed that white and red light increased the total number of flowers to the same extent. Continuous lighting increased the number of cut flowers beyond the 16 h period. The findings of this study indicate that white light irradiation with two wavelength peaks is as adaptable as red light irradiation for cut flower carnation cultivation in a warm climate cropping system. Incorporating LEDs in actual cultivation requires consideration of night time operations in the facility when choosing a light source.

The melting texture of ‘La France’ pear develops only after the fruit has been pre-chilled at 1°C for several weeks after harvest. This melting texture has not been sufficiently evaluated based on physical properties, such as elasticity or penetration hardness. We investigated the melting texture characteristics of ‘La Prance’ pear by three physical methods: non-destructive vibration, visco-elastic, and conventional compression methods. Sinusoidal vibration signals from 100 to 2000 Hz were applied to the fruit. Then, the second resonant frequency (f₂) was obtained to calculate the fruit elastic index (E₂). Six visco-elastic indices: bulk elasticity (K), bulk viscosity (ζ), shear elasticity (μ), shear viscosity (η), Poisson’s ratio (σ), and apparent Young’s modulus (E_app) as well as strain were obtained by a damped vibration method. Another apparent Young’s modulus (E_comp) was also obtained by a conventional compression method. E_comp was significantly correlated with E₂ but not E_app. After the above physical measurements, the pear flesh was scored by an organoleptic test for texture and melting evaluation. Texture and melting scores were analyzed by four multiple regression methods (variable reduction, variable increase, stepwise, and forced input). The melting scores could be explained with two viscosity indices (ζ and η), suggesting that the viscosity is closely involved in the melting texture.

The relationships between stem pitting (SP) and flowering, yield, and fruit quality that influence citrus tristeza virus (CTV) infection were investigated in Hyuganatsu (Citrus tamurana hort. ex Tanaka), a key item for citrus cultivation in the Shizuoka Prefecture Izu region. SP tended to increase over the investigated period. Positive correlations were observed between SP and the number of flowers and soluble solid content. On the other hand, negative correlations were observed between SP and the harvested fruit number, yield, and fruit weight. Following these results, the number of flowers in Hyuganatsu rose with an increase in SP occurrences, but yields decreased due to increased physiological fruit drop and smaller a fruit size. Of the five CTV genotypes tested, Hyuganatsu trees infected with T3 genotypes showed an increase in SP occurrences. These observations indicate that T3 infection affects the yield reduction of Hyuganatsu. A negative correlation was observed between SP occurrences and yield, and so SP occurrences can be used as a diagnostic indicator of yield reduction in Hyuganatsu.