The long-lasting flower (sepaloid corolla) traits, known as “misome-shō” and hose-in-hose flower (petaloid sepal) traits, that exist in Japanese azalea cultivars are homeotic mutations caused by transposable mutations of MADS-box B class genes AP3 (ap3／ap3) and PI (PI-H／PI). DNA markers have been developed to detect each gene mutation. In this study, the possible co-expression of long-lasting and hose-in-hose flower traits controlled by B class gene mutations was evaluated based on floral characteristics in crossed progenies that were selected by DNA markers. In crossed progenies involving the F₁ hybrid of long-lasting flower cultivars and hose-in-hose cultivars as breeding parents, although individuals with both the PI-H mutant allele and ap3／ap3 mutant allele were predicted to appear in long-lasting flowers with petaloid sepals, all showed long-lasting flowers with non-petaloid sepals. In some of these individuals, the sepals were the same color and the petals and their adaxial epidermal cells were larger than those of normal sepals and similar to those of petals. Individuals with the PI-H mutant allele showed female sterility. These results indicate that it is difficult to produce individuals that co-express long-lasting and hose-in-hose flower traits controlled by MADS-box B class genes.

Flowering habits of progenies from crosses between Rhododendron oldhamii and evergreen azalea species native to Japan were investigated to clarify the inheritance of a fall flowering trait from R. oldhamii. The flower bud appearance date of the parents was the earliest in R. oldhamii and latest in R. eriocarpum and R. yedoense var. yedoense. Regarding fall flowering, all flower buds bloomed within the year in R. oldhamii. Some of the flower buds bloomed in R. kiusianum and R. tosaense, but no flowering was observed in other species. Fall flowering among F₁ seedlings was observed in all cross combinations. In addition, the frequency of fall flowering seedlings tended to be higher in the cross using evergreen azalea species with earlier flower bud emergence as a pollen parent. When an F₁ seedling of R. oldhamii × R. kiusianum was crossed with another strain of R. kiusianum, the first flowering dates of progenies were distributed continuously from July to March. These results revealed that the non-dormancy of the flower buds of R. oldhamii is dominantly inherited, and that flowering within the year is influenced by the date of flower bud appearance.

The quality and morphologic traits of stem-type broccoli differ depending on the month, which is problematic. We investigated the effects of differences in the position of pinching on the yield, morphologic traits of lateral flower buds, and quality of the stem-type broccoli variety ‘Stick Señor’ to produce high-quality lateral flower buds throughout the harvest period. The yield of saleable products, number and weight of lateral flower buds, and stem diameter were higher when the apical flower bud was pinched; thus, we consider that pinching is important to increase the yield and quality of ‘Stick Señor’. The yield of salable products and number of lateral flower buds increased when up to three nodes were removed and decreased with heavier pinching, such as removing eight nodes. The number and weight of the leaves of lateral flower buds decreased when up to three nodes were removed and increased with heavier pinching. Most leaves of the lateral flower buds are removed during the shipping of stem-type broccoli. Thus, the morphologic traits of lateral flower buds when up to three nodes are removed are considered suitable for shipping. Therefore, pinching of up to three nodes is desired when cultivating the stem-type broccoli variety ‘Stick Señor’.

The early flowering cultivar ‘Petit Soleil’ and late flowering cultivar ‘Petit Blanc’ of small-flowered lilies bred in Yamaguchi Prefecture were cultivated in different bulb cultivation areas, and the effects of precooling treatment before storage at chilling temperature on shoot elongation and cut flower quality were assessed. Shoot length differences were noted in the bulb cultivation area. Regarding the shoot length after chilling treatment, in both cultivars, the longer the precooling treatment, the longer the shoots. For the early flowering cultivar, there was no significant correlation between the shoot length at planting and cut flower traits and commercialization rate, but for the late flowering cultivar, the longer the shoot length at planting, the higher the cut flower weight and commercialization rate. In the August-planted, October-shipped crop, both cultivars were able to produce cut flowers with a high commercialization rate by precooling the bulbs to elongate the shoots to 1.3 cm or more and storing them by long-term freezing.

We investigated the effects of the intentional alternate bearing method on fruit weight, shoot structure, leaf photosynthetic ability, and carbohydrate content of the leaf in loquat (Eriobotrya japonica (Thunb.) Lindl.) cultivar ‘Mogi’ from 2019 to 2022. The treated (intentional alternate bearing) trees were divided into fruit-producing (fruiting shoot) and non-fruit-producing (non-fruiting shoot) areas, and compared with non-treated (conventional bearing) trees. Fruit weight was heavier on the treated trees than non-treated trees in all years, and this influenced the fruiting quantity per tree in 2019. In contrast, the numbers of fruit clusters and total shoots per tree were higher than on non-treated trees in 2021. This suggests that the intentional alternate bearing method for loquat can increase the fruit weight compared with the conventional bearing method. The shoot diameter and number of leaves were influenced by the interaction between treatments and years, with different effects between the groups. Although the total yield for three years was almost the same between treated and non-treated trees, the yearly yield increased progressively in treated trees. It is considered that the increase in the number of shoots from adventitious buds, resulting in an increased number of fruit clusters in treated trees. Photosynthetic rates, stomatal conductance, and transpiration rates of fruiting shoot leaves in treated trees were higher than those of non-fruiting shoots and non-treated trees. The Sum of the starch and sugar contents was the highest in non-fruiting shoot leaves of non-treated trees and the lowest in fruiting shoot leaves of treated trees. These findings suggest that the photosynthetic ability of the fruit-producing area was related to the increase in fruit weight, and carbohydrate accumulation in non-fruit-producing areas was related to fruiting and fruit quality.

To achieve stable production of cherry tomatoes during the summer season in Japan, we investigated the effects of external fog cooling on cherry tomato growth and yield. As a result, external fog cooling consistently maintained a lower air temperature inside the greenhouse and an elevated relative humidity compared with the external environment. The rate of leaf and flower truss emergence also increased. We considered that the expansion of individual leaf areas would increase the amount of intercepted light. Furthermore, we thought that the average fruit weight would increase by suppressing high temperatures and excessive transpiration, and thus improve cherry tomato productivity. Although external fog cooling and pad-and-fan systems offer comparable benefits, we deemed the external fog cooling system more advantageous because of its lower installation cost and ease of retrofitting into existing greenhouse structures.

We analyzed the data obtained from experiments performed on the cool-type garlic cultivar ‘Fukuchi White’ from 2011 to 2021 in the Kamikita region of Aomori Prefecture, Japan using transparent multi-cultivation. Garlic growing periods were identified and classified based on the beginning and end of snow cover and developmental stages. In the early growth stage (between planting and beginning of snow cover), on November 20th, growth tended to be poor and the sprouting time was delayed; however, the effect on yield was small. Growth changes were investigated based on the scale differentiation stage (SDS) after the snow disappearance date (SDD). In the middle growth stage (between SDD and SDS) and early period of bulb enlargement [between SDS and flag leaf emergence stage (FLES)], the difference in aboveground growth (plant height, leaf sheath diameter, number of green leaves, and total weight) between high- and low-yield years was small. The difference in growth between high- and low-yield years was relatively high in the late period of bulb enlargement [between FLES and the harvest stage (HS)]. After FLES, the foliage weight peaked higher and later, and the decrease in foliage weight was smaller in high-yield than low-yield years. The proportion of foliage weight to total weight in high-yield years was large. Therefore, it is considered necessary to increase and maintain foliage up to HS to increase yield. SDS was early in high-yield years, bulb enlargement started late, and fresh bulb weight increased rapidly 50 days after SDS.

Effect of nitrogen fertilization on dry matter production of spinach for processing was investigated using four nitrogen fertilizer levels: 0, 15, 30, and 60 g・m^–2 (N0, N15, N30, and N60, respectively). Dry matter production was analyzed based on daily intercepted radiation (DIR) and radiation use efficiency (RUE). Dry matter production rose with increasing nitrogen fertilizer levels. In N0 treatment, the leaf area index (LAI) value was significantly smaller than in the other treatments before the fraction of intercepted radiation was saturated. Therefore, the DIR value for treatment N0 was smaller than for the other treatments; this resulted in significantly lower dry matter production. In N15 treatment, the difference in dry matter may have been caused by that in RUE because the integral value of DIR was not significantly different among N15, N30, and N60 treatments. In the present study, specific leaf nitrogen (SLN) was not significantly different among the treatments on most survey dates. RUE of spinach regarding both table use and processing harvest periods was not significantly different between N0 and N15 or N15 and N30 in 2020, and among all treatments in 2022. LAI significantly differed between treatments from the early stages of growth, whereas SLN was not significantly different on most survey dates. These results suggest that spinach reduces DIR and maintains RUE when nitrogen is deficient. It is crucial to maintain the nitrogen content to develop sufficient LAI before the fraction of radiation-intercepted saturates, and to maintain a high RUE after the fraction of radiation-intercepted saturates to obtain sufficient spinach yields for processing.

In this study, we performed whole-genome resequencing analysis and developed DNA markers to distinguish between the fig cultivar ‘Masui Dauphine’ and sport cultivar ‘Summer Red.’ WGS short-read data for both ‘Masui Dauphine’ and ‘Summer Red’ were aligned using the genome of Horaishi_ver.1 as a reference. The alignment data were then variant-called for mapping software, and Single Nucleotide Variants (SNVs) specific to ‘Summer Red’ were extracted. Finally, cross-filtering was performed to eliminate SNVs common to variant data from two mapping softwares: BWA-MEM and Bowtie 2. Before cross-filtering, there were 6,194 and 28,790 SNVs between ‘Masui Dauphine’ and ‘Summer Red’ detected by Bowtie 2 and BWA-MEM, respectively; after cross-filtering, there were 131. Among these 131 SNVs, two Cleaved Amplified Polymorphic Sequences (CAPS) markers, s752 and s61, were developed. Both of these CAPS markers were effective at distinguishing between the two varieties grown in Aichi Prefecture.

This study aimed to distinguish between thrips (Thysanoptera) injury and other similar injuries on the internal parts of fig (Ficus carica L.) fruits. The symptoms that have been regarded as typical of thrips injury are internal browning of the fruit, with an irregular, glossy yellow pattern on the drupelets from the style to ovary and wilting of the stylar tips. The detection rate of thrips increases as the area affected by these abnormalities expands and becomes more visible, supporting the conventional perception that these symptoms are caused by thrips. However, in the presence of minor injuries that are not easily observed as a disorder, thrips are often not detected. I classified the main minor injuries in many fig cultivars into four types according to symptoms: A, uniform yellowing of the styles or stylar tips; B, uniform yellowing of the entire drupelet (from style tip to ovary); C, browning of the styles without a glossy yellow pattern; and D, fusing and browning of the styles without a glossy yellow pattern. Blocking thrips by sealing the ostioles with glue did not change the rates of occurrence of type A, type C (in certain cultivars), or type D symptoms. These symptoms are therefore likely to be caused by something other than thrips.

“Shielding-mulch cultivation” (NARO-S. mulch) can induce drought stress, leading to the production of high-quality fruits. However, the effect of NARO-S. mulch in terraced fields remains unclear. Thus, we verified the effect of applying NARO-S. mulch to terraced fields for the stable production of satsuma mandarin (Citrus unshiu Marcow.). We also examined the effect of shielding and mulching the planting row and applying an S. sheet on one side of the upper slope, ‘one side-S. mulch’, which is a cost-effective method for terraced fields for the stable production of high-quality fruits. Consequently, the maximum water potential in the leaves (ψmax), an indicator of drought stress on trees, was lower in both NARO-S. mulch and one side-S. mulch than in conventional mulch cultivation. The fruit soluble solid content during fruit growth was more than 1° higher in both NARO-S. mulch and one side-S. mulch than in conventional mulch cultivation. The ripe fruits of NARO-S. mulch and one side-S. mulch had a higher soluble solid content, slightly higher acidity, and were slightly smaller with a strong reddish skin color than those produced through conventional mulch cultivation. These results suggest that NARO-S. mulch can improve fruit quality even in terraced fields. The improvement in fruit quality was also observed with one side-S. mulch, suggesting that it is as effective as NARO-S. mulch in terraced fields and cost-effective.