Institute of Vegetable and Floriculture Science

In this study, we investigated the differences in efficient vibrational pollination related to flower characteristics among 10 commercially available Japanese tomato cultivars, focusing on their shapes, weights, and natural frequencies. Although the acceleration thresholds for pollen dispersion varied depending on the excitation frequency and tomato cultivar, they were significantly higher at 100 Hz compared to 15, 30, and 50 Hz. For cherry tomato cultivars, the acceleration thresholds were lower at 50 Hz, while for large and medium tomato cultivars, those were lower at 15–50 Hz than those at 100Hz. No correlation was found between the acceleration threshold for pollen dispersal and the amount of pollen per flower. The natural frequencies of the flowers were examined by applying vibrations ranging from 5 to 100 Hz to the flowers using a non-contact shaker and measuring the displacement with a high-speed camera. Although the natural frequencies varied among individual flowers, differences were also observed among different varieties. Furthermore, the optimal period for vibrational pollination of ‘Momotaro Hope’ was determined to be from 1 day before to 4 days after flowering, in terms of the acceleration threshold for pollen dispersion, which closely aligns the optimal period identified in previous studies.

The development of new cultivars exhibiting high levels of disease resistance and superior quality is critical for vegetable production. Recent advances in genomics and DNA sequencing technologies have facilitated the identification of sequence variants associated with specific phenotypes. This has enabled the development of novel and improved DNA markers for integration into marker-assisted selection (MAS). The application of MAS has significantly enhanced the efficiency of stacking loci responsible for disease resistance and quality characteristics. This paper provides an overview of recent research findings related to DNA markers and their applications in breeding in Japan, focusing primarily on vegetables from Brassicaceae, Solanaceae, Cucurbitaceae, and Allium, as well as strawberries.

Hydrosols, also referred to as hydrolates, are valuable yet underutilized byproducts of essential oil distillation. They consist of residual essential oil compounds combined with water-soluble phytochemicals, many of which exhibit notable biological activities. Research has demonstrated antimicrobial effects - including the inhibition of biofilm formation - as well as antioxidant properties that counteract oxidative stress. These biofunctional features make hydrosols attractive for diverse applications: in agriculture as biopesticides, in food preservation as natural additives and anti-browning agents, in pharmaceuticals as antimicrobial or antitumor agents, and in cosmetics as bioactive ingredients. The present study focuses on the chemical profile of hydrosols derived from four Artemisia species and evaluates their potential uses. Water distillation remains the dominant extraction method, accounting for around 93% of global essential oil production, typically performed via hydro-distillation or steam distillation. This process generates two phases: the essential oil and its aqueous counterpart, the hydrosol. Analytical results confirmed the presence of key compounds such as trans-pinocarveol, 1.8-cineole, and spathulenol, supporting their multifunctional properties. Overall, these findings highlight hydrosols as sustainable natural products with promising roles across multiple industries. From a circular economy perspective, valorizing such byproducts enhances resource efficiency and provides environmentally friendly alternatives to conventional synthetic additives.

ABSTRACT This study investigated the effects of sudden stress on African violet leaves to establish a method for comparing heat stress tolerance. A simplified approach to estimating the high-temperature sensitivity of African violet was developed by detecting leaf colour changes using a spectrophotometric colour-difference metre. First, we used a representative variety of ‘ionantha’ to determine optimal experimental conditions, selecting a treatment of at 55°C hot water for 10 min, followed by hue measurement after 1 h. Subsequently, three varieties with different temperature tolerances were analysed by measuring hue, physiological indices, ion leakage via electrical conductivity (EC). The most representative parameter of leaf colour change was ‘Δa’, which reflected a decrease in green colour due to chlorophyll degradation. The ‘Δa’ colour score correlated strongly with ion leakage, which was further supported by histological observations of leaf tissue. Using this method, we screened African violet varieties for heat stress tolerance. The resulting rankings and significance of each variety were consistent with those for ion leakage. These findings suggest that the spectrophotometric colour-difference metre provides an effective high-throughput screening method for assessing thermotolerance in African violet.

日本では主要な野菜の周年供給体制が確立され，加工・業務用需要が拡大している．安定供給の需要が高まる中，露地条件で栽培されるキャベツにおいて，生育モデルを用いた生育予測は生育状況の把握・予測に有用である．本研究では，結球開始期からの生育を扱った既存の生育モデルを改良し，定植以降の生育度合いを示す要素として投影面積をモデル要素に追加するとともに，収穫部位への乾物分配率の変化時期を用いて結球の開始期を予測可能な改良モデルを開発した．既存モデルが扱っていなかった春と秋の二作型を対象とし，気象変化を考慮すべき状態変数に対しては個別にパラメーター推定を行った．シミュレーションの結果，投影面積，葉球の乾物重・新鮮重をそれぞれRMSE=123.1（cm2），16.7（g），240.8（g），平均絶対誤差率（%）=39.2，14.9，8.1の誤差で予測した．特に葉球部新鮮重の予測誤差は許容範囲とされる10–20%程度に収まっており，実用上十分な精度を示した．また，収穫部位への乾物分配率や生育段階に応じた日射利用効率の設定により，結球開始時期や生育初期の詳細な予測が可能となった．

Although the scent of flowers generally changes during anthesis, this phenomenon has not been investigated in potted carnations. In this study, we examined the scent emissions of potted carnations using the fragrant Dianthus caryophyllus ‘HINAARARE.’ The plants were maintained under a 12-h light/dark cycle, and immediately after the flowers had opened, scent emissions were investigated at 2-day intervals for 15 days. The predominant scent components detected were isoeugenol, a type of phenylpropanoid/benzenoid, and the sesquiterpene β-caryophyllene. The unique sweet scent of this cultivar is believed to be attributable mainly to these two compounds, along with the fatty acid derivative1-octen-3-ol, which has a relatively low aroma threshold. The total scent emissions were characterized by an apparent diurnal rhythm, being lower during the light period and higher during the dark period. This rhythmicity was mainly associated with the emission of isoeugenol and β-caryophyllene, thereby suggesting that the strength of the scent in potted carnations, as perceived by humans, varies between day and night. In addition, we investigated the relationship between an increase in petal in-rolling, a typical symptom of flower senescence, and scent emission. However, no clear correlation was detected. To the best of our knowledge, this is the first study that has provided evidence of a diurnal rhythm in scent emissions from carnations.

同時期に同一圃場で栽培されたさまざまな遺伝的背景を持つアブラナ科野菜のコマツナ, タイサイ, ケール, キャベツ, ルタバガおよび葉ダイコン6作目, 計30品種・系統を使って, 可食部のNa, K, Ca, Mg, P, Fe, Zn, Cu, Mn, Mo, SrおよびBaを分析した. 作目ごとに供試した品種・系統は限られているが, 無機元素別に分析すると作目ごとにほとんどの元素でp < 0.05で有意な品種・系統間差が認められた. 無機元素含有量に特徴のある品種・系統も見られた. 作目間にも, Znではp < 0.05で, Na, K, Ca, Mg, Fe, Cu, Mn, Mo, SrおよびBaではp < 0.001で有意な差が認められ, 作目ごとの無機元素含有量には一定の傾向が見られた. 参考として分析した別圃場で栽培された芽キャベツとナバナを含めた場合, 今回供試したアブラナ科野菜では, 緑黄色野菜に分類されるコマツナ, タイサイ, ケール, 葉ダイコン, 芽キャベツおよびナバナで全般に無機元素含有量が高かった. 緑黄色野菜が無機元素摂取の点でも重要であることが改めて示された.

Vegetable plug seedlings have a short optimal transplanting period. Fertilizer restriction can extend this period, but the effect on later growth remains unclear. We investigated the effects of long-term storage of broccoli plug seedlings (Brassica oleracea L. var. italica) with fertilizer restriction on leaf number increase, leaf expansion, and the timing of flower bud differentiation in spring and autumn crops. In addition to conventional one-month seedlings (1 MS), we prepared 2- and 4-month seedlings (2 MS, 4 MS) and planted them all out on the same day. Seedling storage had no effect on the rate of leaf number increase or the timing of flower bud differentiation. These results suggest that the transition from vegetative to reproductive growth is not affected by seedling storage, and is instead determined by the leaf number increase after transplanting (regardless of storage period, the plants developed about 13 leaves after transplanting in autumn). However, longer storage suppressed the expansion of leaves that had appeared before transplanting, particularly during the first 20 days after transplanting, resulting in a lower relative expansion rate. This difference was more pronounced in the autumn crop, and was thought to be due to differences in temperature during the early stages after transplanting between spring and autumn crops. We found no significant relationship between seedling storage and head diameter or weight at harvest, but we found a positive correlation between leaf area during the growth period after transplanting (except for a certain period immediately after transplanting) and head weight, particularly during the flower bud differentiation stage. Therefore, seedlings stored for longer tend to exhibit suppressed leaf expansion. As a result, differences in leaf area after transplanting may mediate the effect of seedling storage on head weight.

Chrysanthemum (Chrysanthemum morifolium Ramat.) is a short-day plant, and flowering is stimulated when the photoperiod is shorter than a variety-specific threshold (critical day length). In Japan, summer-to-autumn-flowering cultivars (SA-cvs.) flower from July to September. Little research has been conducted to understand why SA-cvs. bloom earlier than autumn-flowering cultivars (A-cvs.). We conducted a comparative study of the relationship between the photoperiodic response of flowering and the gene expression of florigen FLOWERING LOCUS T-like 3 (FTL3) and antiflorigen anti-florigenic FT/TFL1 (AFT). SA-cvs. had a longer critical day length than A-cvs. However, in both groups, a decrease in AFT and increase in FTL3 were consistently observed below the critical day length when flowering was promoted. The opposite responses (less flowering, low FTL3, and high AFT) were observed for longer than the critical day lengths. This indicated that flowering in SA-cvs. was controlled by the regulation of AFT/FTL3 expression, similar to that in A-cvs. Next, we studied the mechanism that causes a variation in critical day lengths. In SA-cvs., the photosensitive phase, which occurs at night, occurs earlier than that in A-cvs. This indicates a variation in the endogenous time-keeping mechanism. This was supported by the fact that the circadian rhythmicity of leaf movement was weaker in SA-cvs. than that in A-cvs. Thus, variation in the endogenous time-keeping mechanism may cause a longer critical day length and earlier flowering time in SA-cvs.