Fruit tree nutrition is one of the most important factors in terms of growth and productivity. Measurement of nutritional requirements is an important aspect of nutrient management because nutritional disorders reduce yield and fruit quality. This review explores how nutrient imbalances affect the yield and fruit quality of fruit trees, and presents methods for diagnosing fruit tree nutritional disorders in order to correct nutritional deficiencies. In orchards, differences between soil sampling sites and locations of fruit tree roots when the root system is deep and unevenly distributed make it difficult to obtain representative soil samples from which to measure the forms of nutrients available to the trees. The delayed response of fruit trees to fertilizer applications compared with annual crops makes it difficult to determine their nutritional status through soil analysis immediately after application. In addition to soil analysis, plant tissue analysis is used to determine nutritional status and fruit tree nutritional requirements. In particular, earlier analysis in the growing season could allow sufficient time to correct any deficiencies before harvest. A recent approach that relies on analysis of the ionome, which is defined as the entire mineral nutrient and trace element complement in an organism, through simultaneous quantitative measurement enables comprehensive evaluation of multi-element composition. This approach could be especially effective as major decreases in yield and fruit quality are often caused by the interaction of several elements. Until recently, studies of fruit tree nutritional disorders have focused on particular nutrients, not multiple elements. Therefore, the application of ionomic analysis is a promising approach to elucidate multi-element interactions for accurate diagnosis of nutritional disorders.

To develop equations to predict the titratable acidity of grape berries at harvest from air temperature, we analyzed several years of datasets on wine grapes grown in experimental vineyards in seven prefectures and of table grapes grown in 37 prefectures in Japan. Although the number of days from the full-flowering date to harvest date varied with the cultivar, the temperature throughout the period of 40 to 50 days before the harvest date was the most strongly correlated with the titratable acidity of all tested cultivars. The titratable acidity at the harvest date of the wine grape cultivars decreased as the mean temperature of the period increased as did that of the table grape cultivars, although the latter did not decrease much above 24°C. The titratable acidity of the wine grape cultivars showed good linear regression with the mean temperature from 60 to 99 DAF (days after full-flowering) in ‘Chardonnay’, from 65 to 109 DAF in ‘Monde Briller’, and from 35 to 84 DAF in ‘Colline Verte’. That of table grape cultivars grown in cold regions showed good quadratic regression with the mean temperature from 50 to 92 DAF in ‘Kyoho’, from 46 to 91 DAF in ‘Pione’, and from 52 to 93 DAF in ‘Suzuka’. The titratable acidity of table grape cultivars grown in warm regions was estimated to be about 0.5 g/100 mL. These regression equations can be used to select cultivars to plant and to identify suitable regions for each cultivar, as well as to estimate changes in acid concentration under global warming. We also determined the relationship between the rate of acid reduction of the wine grape cultivars and temperature from serial measurements of titratable acidity to allow growers to predict the change in titratable acidity.

We examined hexose- and sucrose-accumulating grapevines to elucidate genetic and transcriptional control of berry sugar composition in table grapes. Sugar composition was classified into two types: a hexose accumulator that accumulates fructose, glucose, and no or trace amounts of sucrose and a sucrose accumulator that accumulates fructose, glucose, and a large amount of sucrose. Segregation ratios among diploid seedling populations of S₁ and F₂ indicate that the trait of sucrose accumulation is controlled by a single major recessive gene. Transcriptional levels of sugar accumulation-related key genes were monitored during berry ripening using two hexose-accumulating cultivar/selections and one sucrose-accumulating cultivar. Gene expression of sucrose transporter and sucrose phosphate synthase coincided with a rapid increase in sugar accumulation after the onset of berry ripening; gene expressions of those enzymes and cell wall invertase were not significantly different between sucrose- and hexose-accumulators and gene expression of vacuolar acid invertase decreased after the onset of berry ripening in both sucrose- and hexose-accumulators. Gene expression of sucrose synthase (catalyzes the reaction of sucrose cleavage) in the hexose accumulators remained constant throughout berry development, whereas the expression in sucrose accumulators was significantly lower, with a concomitant sharp rise in sucrose accumulation. These results suggest that sucrose synthase may play a critical role in the sugar metabolism of sucrose-accumulating grape berries.

Polymethoxyflavones (PMFs) are naturally occurring O-methylated flavones predominantly accumulated in different citrus tissues that show numerous human-health promoting activities. O-methyltransferase (OMT) family members are involved in the biosynthesis of PMFs in plant species including citrus. Although the distribution of PMFs has been determined in citrus cultivars, the relation between the accumulation of PMFs and the related OMT gene expression in leaves and flavedos (exocarps) of citrus cultivars remains to be clarified. In this study, we investigated the accumulation of nobiletin and tangeretin in the leaves and flavedos of various citrus cultivars widely grown in Japan. As expected, the accumulation of nobiletin and tangeretin varied among the citrus cultivars and the two tissues, and nobiletin and tangeretin accumulated at higher levels in flavedos than in leaves. In particular, we clearly demonstrated that the nobiletin content showed a significant and positive correlation (r = 0.824, P = 0.00182) between leaves and flavedos. Based on these results, the concentration of PMFs in leaves could be utilized as an early selection marker for seedlings in the juvenile phase that are expected to accumulate a higher amount of PMFs in fruit, resulting in a shortening of the breeding period. We also identified two novel candidate genes, CreOMT1 and CreOMT4, putatively involved in PMF biosynthesis in citrus. Notably, the expression of CreOMT1 showed a significant correlation (r = 0.700, P = 0.0243) with the nobiletin content in the flavedos of 10 citrus cultivars. Our results provide valuable information for developing new citrus cultivars that could accumulate higher PMFs and insight into elucidating the PMF biosynthetic pathway in citrus in the future.

The ‘Siam Red Ruby’ (Citrus grandis) is a new lycopene-accumulating pumelo variety, which is grown only in the Pakpanang area of the Nakhon Si Thammarat province of Thailand. In this study, we harvested ‘Siam Red Ruby’ fruit at five ripening stages, and the changes in the accumulation of carotenoid and carotenogenic gene expression were investigated in the pulp. During the ripening process, the contents of phytoene, ζ-Carotene, lycopene, β-carotene, β-cryptoxanthin, and all-trans-violaxanthin increased gradually, while the contents of α-carotene and lutein decreased in the pulp of ‘Siam Red Ruby’. In the mature fruit of ‘Siam Red Ruby’, a high amount of lycopene was accumulated in the pulp, accounting for more than 93.26% of the total carotenoid content. The massive accumulation of lycopene led to an attractive red color of the ‘Siam Red Ruby’ pulp. In addition, gene expression results showed that the increases in the expression of upstream genes (CitPSY, CitPDS, CitZDS, CitZISO, and CitCRTISO), and decreases in the expression of genes downstream (CitLCYb1, CitLCYb2, CitLCYe, CitHYb, and CitHYe) was the main mechanism of lycopene accumulation in the pulp of ‘Siam Red Ruby’ pumelo.

Aster koraiensis, a plant indigenous to Korea, has recently attracted a great deal of attention as a potential functional food and pharmaceutical product due to its preventive and therapeutic efficacy against various diseases. Despite increasing demand, supply of A. koraiensis is limited to wild populations and small-scale wild plant growers. In an attempt to establish cultivation practices in open-field production platforms, this study investigated the effects of soil mulching, planting density, and fertilizer treatment on the above-ground dry matter yield of A. koraiensis for two years after transplantation. The maximum dry matter yield was obtained at 1,935 kg DW·ha⁻¹ and 3,803 kg DW·ha⁻¹ in the first and second years, respectively, under soil mulching and 15 × 15 cm planting density conditions. Soil mulching during the first year after transplanting significantly promoted plant growth, and increased yield, indicating its beneficial effects on the establishment and early growth of A. koraiensis plants. Fertilizer treatment increased yields up to 3.7-fold in the second year after transplantation. In addition, this study employed remote sensing technologies using a drone equipped with a multispectral sensor to evaluate the normalized difference vegetation index (NDVI) of experimental plots across different plant growth stages. The results revealed that NDVI values at 60 days after shoot emergence in the second year after transplantation produced the highest correlation with dry matter yield in a simple exponential regression model. Remote sensing technologies and the proposed regression model could be applied to optimize cultivation practices and enable precision agriculture for A. koraiensis crops.

It is commonly recognized that vegetables in their best season are delicious and have high nutritional value. We investigated the monthly and yearly variations in radical-scavenging (RS) activity, an indicator of antioxidant activity, ascorbic acid, and degrees Brix of Brassica rapa var. perviridis (komatsuna) cultivated in the Kanto region, Japan. RS activity was significantly higher in December, January, and February than in the other months in all tested years (2010–2015). For two varieties (summer and winter varieties) their RS activity was significantly higher in winter than in summer. The weight proportion of leaf blades and petioles at harvest was similar (leaf blade:petiole = 4:6) both in the summer and winter, indicating that the difference in the RS activity of komatsuna between the two seasons was not due to the weight ratio, but to the increase in the RS activity of leaf blades in the winter. There were no significant differences in the RS activity of komatsuna between summer (30 days) and winter (80 days) cultivation periods, greenhouse and open-field cultivations, and producers. Multiple years of field studies revealed that the antioxidant activity, ascorbic acid content, and degrees Brix of komatsuna in the Kanto region were higher in winter than in other seasons, and suggested that komatsuna with a similar quality level may be produced when grown in regions with similar weather conditions.

Parthenocarpy is a phenomenon that induces fruit set and development without pollination and fertilization. In tomato (Solanum lycopersicum L.) cultivation, parthenocarpy is considered to be an attractive trait, as it reduces the financial and labor costs involved in fruit set. Parthenocarpic genes pat-2 and pat-k are used as the source of parthenocarpic tomato cultivars in Japan. However, the effect of pat-2, pat-k, and their combined effect on vegetative and fruit traits are poorly understood, even though they are important for breeding parthenocarpic tomato cultivars. In this study, we introduced pat-2 and/or pat-k into a model tomato cultivar, ‘Micro-Tom’, to compare their effects on one genetic background, and then examined their vegetative and fruit traits. Lines carrying pat-2 showed greater leaf and stem size and stomatal conductance compared with the wild-type (WT), whereas there was no significant difference in vegetative traits between a line carrying only pat-k (pat-k) and WT. In addition, the content of total soluble solids (TSS) in pollinated fruits of pat-k and the lines carrying pat-2 was higher and lower than that of WT, respectively. Although it is possible that genes linked to pat-2 or pat-k caused these effects, these results suggest that pat-2 and pat-k have pleiotropic effects on these vegetative and/or fruit traits. Moreover, the rate of fruit set of unpollinated fruits in a line carrying pat-2 and pat-k (pat-2/pat-k) was significantly higher than that in pat-k, and unpollinated fruits of pat-2/pat-k were significantly heavier than those of pat-k and a line carrying only pat-2, suggesting that the effects of pat-2 and pat-k on parthenocarpy are additive. The results of this study can be used as fundamental information for the breeding of parthenocarpic tomato cultivars using pat-2 and pat-k.

Chinese cabbage (Brassica rapa L. var. pekinensis) is an economically and agriculturally significant leafy vegetable that is extensively cultivated throughout the world. Vernalization is exposure to prolonged cold that alters gene expression and accelerates a transition from the vegetative to reproductive phase. Premature bolting caused by exposure to cold inhibits head production and reduces the yield of Chinese cabbage, and developing a late bolting line is important for breeding. Therefore, it is critical to identify the genes showing differential expression patterns during cold treatment in Chinese cabbage. However, there are few studies on the transcriptome profiling of different durations of cold treatments in Chinese cabbage. Here, we analyzed the gene expression profiles in a Chinese cabbage inbred line, RJKB-T24, given different durations of cold treatments using RNA sequencing. Differentially expressed genes (DEGs) between non-vernalized and vernalized samples tended to be downregulated, and some genes involved in the flowering pathway (including BrFLC and BrMAF genes) were downregulated following cold treatment. Functional enrichment analysis indicated that some DEGs were involved in the stress response and hormone signaling pathways. For genes involved in the FRI-containing complex, a known activator of FLC in Arabidopsis thaliana, only BrFRL1 showed changes in expression. In contrast to A. thaliana, BrVIP and BrVRN genes showed different expression patterns between paralogs during cold treatment, suggesting that Chinese cabbage’s flowering pathway is somehow different and more complex than in A. thaliana. These outcomes provide significant insights into the genetic control of bolting and flowering that occur during the vernalization of Chinese cabbage.

By using a stable isotope method, partitioning of photosynthates was examined in a modified arching (MA) technique that achieved a high cut flower productivity to clarify how photosynthates produced by bent shoots are distributed within a plant at different developmental stages of harvest shoots. The translocation ratios from bent shoots at four days after harvest, eight days after harvest, for 10 cm-shoots, flower budding, and blooming were 44.0, 40.2, 51.0, 38.3, and 23.4%, respectively, and plants at the blooming stage had lower translocation ratios compared to those at the other developmental stages. The distribution of photosynthates produced by the bent shoot parts varied with the plant stage of the harvest shoots. The partitioning ratios of roots and crowns at four days, eight days, for 10 cm-shoots, flower budding, and blooming were 63.9, 53.5, 17.5, 26.6, and 81.0%, respectively. From these results, it was revealed that in the period from blooming to the next sprouting, roots and crowns were strong sinks. The partitioning ratios of mother stems were 36.2, 46.4, 7.2, 15.0, and 8.2%, respectively. We estimate that the mother stems are a strong sink right after harvest and absorb the photosynthates for the new sprouting. At the 10 cm-shoot and flower budding stages, photosynthates were partitioned to harvest shoots at 75.2% and 58.4%, respectively, indicating that they were distributed preferentially to vigorously growing harvest shoots. A total of 11.4% of the photosynthates were partitioned to harvest shoots at the blooming stage, suggesting that the photosynthates from the bent shoots were not involved directly in flower blooming. This study will contribute to improving the MA technique and cut rose production.

The Hirado azalea is a large flowering plant and Rhododendron scabrum, R. ripense, R. × mucronatum, and other related cultivars are considered to be its parents. In this study, we investigated the correlation of Hirado azalea cultivars with wild species and old cultivars by analyzing anthocyanidin composition patterns and the expression of anthocyanin biosynthesis genes. Hirado azalea cultivars were divided into four groups according to their pigment compositions. Hirado azalea cultivars with only cyanidin derivatives had red colored flowers similar to those of R. scabrum. Hirado azalea cultivars with both cyanidin and delphinidin derivatives as well as flavonol produced similar flower colors to those of R. ripense and R. macrosepalum. Hirado azalea cultivars with only flavonol had white colored flowers similar to those of R. mucronatum ‘Shiro-ryūkyū’. Hirado azalea cultivars with cyanidin derivatives and flavonol exhibited a wider range of flower colors compared to their parents. All samples expressed F3'H, DFR, and ANS genes, as determined by real-time quantitative RT-PCR. However, the F3'5'H gene was expressed only in samples containing delphinidin derivatives. Moreover, ‘Shiro-ryūkyū’ also expressed all four genes, as did cultivars with colored flowers, even though its flowers are white. These results suggested that the hybridization of Hirado azalea using R. scabrum as the base may produce a wide range of flower colors besides red owing to the presence of the F3'5'H gene from R. ripense, R. macrosepalum, and ‘Shiro-ryūkyū’.

In the present study, we evaluated the effects of intermittent low temperature storage (ILTS) following cold imbibition of Eustoma seeds as a low-cost method. The objective of this study was to investigate the effects of the total number of cold storage days and the lengths of ILTS cycles for seedlings on the subsequent growth and flowering of three cultivars with different susceptibilities to rosetting: ‘Nancy’, ‘Exe Lavender’, and ‘Bolero White’. Before sowing, the seeds were imbibed with water at 10°C under a dark condition for 35 days. A cycle of 6D/6D (6 days in a refrigerator kept at 10°C in the dark/6 days in a greenhouse kept at a high ambient temperature) was repeated 0, 1, 2, 3, 4, and 5 times to attain 0, 6, 12, 18, 24, and 30 days of cold storage (DCS), respectively. Using a cycle of 6D/6D at least one time (6 DCS) increased the bolting and flowering percentages and accelerated the bolting date by 6–10 days and the flowering date by 4–9 days in ‘Nancy’, a high-rosetting cultivar. The percentage of harvesting was above 80% only in seedlings subjected to 24 and 30 DCS in ILTS. In addition, under equal 30 DCS of ILTS, cycles of 3D/3D × 10 times, 6D/6D × 5 times, and 15D/15D × 2 times were investigated by exposing the seedlings to a high ambient temperature for 3, 6, and 15 days and then transferring them to a refrigerator (10°C) for 3, 6, and 15 days, respectively. ILTS cycles of 3D/3D and 6D/6D resulted in earlier bolting and flowering dates than cycles of 15D/15D. The cycle of 15D/15D resulted in a lower percentage of marketable harvesting and an increased number of nodes to the first flower. These results suggest that applying ILTS with a cycle of 6D/6D at least four times can be an efficient method to promote the bolting and flowering of Eustoma without applying air conditioning to the entire greenhouse.

2-Pyridinecarboxylic acid (2-PCA) acts as an inhibitor of ethylene biosynthesis in Arabidopsis thaliana by binding to the active site of 1-aminocyclopropane-1-carboxylate oxidase. In this study, we examined the action of 2-PCA in comparison with the action of 3-PCA, a recently discovered stimulator of flower opening, in cut flowers of the spray-type carnation cultivars, ‘Light Pink Barbara (LPB)’, ‘Carnet’, ‘Collin’, and ‘Zulia’. With ‘LPB’ flowers, 2-PCA at 0.5–5 mM did not prolong the vase life, whereas 3-PCA at 5 mM did so. With the other three cultivars, 3-PCA generally promoted flower opening of all the cultivars. On the other hand, the action of 2-PCA on flower opening and senescence varied with the carnation cultivar and time of harvest, resulting in a shortened, unchanged or lengthened vase life of the flowers. 2-PCA also caused severe bending of flower stems in all cultivars, which lowered the display value of the flowers. The present results showed that 2-PCA is not likely to be a useful flower care agent in carnation flowers.

Prunus × yedoensis Matsum. ‘Somei-yoshino’ is one of the most popular flowering cherry cultivars in Japan. However, because flowering cherries have strict self-incompatibility (SI), it is difficult to develop selfing families or inbred lines for breeding and genetic studies. SI in Prunus is achieved through arrest of self-pollen tube growth in the style by ribonuclease S-RNase. To determine a suitable way to overcome SI in Prunus, we examined the influence of hot water immersion on RNase activity in the style of ‘Somei-yoshino’. When the styles were immersed in 20°C, 30°C, and 40°C water baths, their RNase activity was not significantly different from that of untreated styles (P > 0.05); however, it significantly decreased in styles heated in 50°C water baths (P < 0.01). Furthermore, the RNase activity decreased with an increase in the incubation time (e.g., 1, 3, and 5 min). Additionally, heat treatment at 50°C promoted the growth of self-pollen tubes in the style. Some self-pollen tubes even reached the bottom of the style. The high temperature treatment with reduced RNase activity can overcome stylar SI in Prunus.

We found a variant in the carnation genome, the 1-aminocyclopropane-1-carboxylate synthase gene (DcACS1) that had only DcACS1b, suggesting it is a homozygote of the gene in the carnation cultivars ‘Skyline’ and ‘Scarlett Plus’. The ‘Mini-tiara’ carnation is obtained by an interspecific cross between carnation and wild pink, one of which, Dianthus knappii. D. knappii, had three ACS1 genes orthologous to DcACS1b; i.e., DkACS1b.1, DkACS1b.2, and DkACS1b.3. The composition of ACS1 homologs was analyzed in sub-cultivars of the ‘Mini-tiara’ carnation by PCR amplification of intron 1, intron 2, and 3'-UTR. Each sub-cultivar of the ‘Mini-tiara’ carnation had two ACS1 genes with various combinations. ‘Mini-tiara 0707’ had only DcACS1a, suggesting it is a DcACS1a/DcACS1a homozygote. ‘Mini-tiara Topaz’ had DcACS1a and DcACS1b, ‘Mini-tiara Ruby’ had DcACS1a and DkACS1b, and ‘Mini-tiara Lilac’ had DcACS1b and DkACS1b.2. These findings suggest that the ‘Mini-tiara’ carnation has two genes from a virtual group of at least five ACS1 gene homologs of carnation and D. knappii. The discovery of a DcACS1b homozygotic carnation and inheritance of ACS1 homologous genes in the ‘Mini-tiara’ carnation from carnation and D. knappii suggests the allelic nature of carnation DcACS1a and DcACS1b genes.

This research evaluated the attention capacity of 70 pupils in the sixth grade with the intervention of indoor air quality regulated by indoor plant placement in the classrooms of two elementary schools in Seoul, South Korea. Two sets of three-week measurements were conducted with an interval of 12 weeks from 27th June to 7th October, 2016. We divided subjects into two groups (Group I and II): subjects in Group I occupied classrooms without indoor plants and those in Group II occupied classrooms with indoor plants. The classrooms with indoor plants had indoor levels with constant air temperature (approximately 26°C), relative humidity (around 50%), and carbon dioxide (CO₂) (around 1100 mg·m⁻³). Additionally, 12-week placement of indoor plants reduced the indoor concentrations of airborne contaminants. After 12 weeks of the experiments, the subjects’ attention capacity improved as demonstrated by a standard questionnaire (Frankfurt Aufmerksamkeits-Invertar, FAIR). Indoor plant placement showed little difference in terms of efficiency (FAIR-E) and continuity (FAIR-C) scores, but exhibited a significant improvement for performance (FAIR-P) (increasing from 0.964 to 0.989) and quality (FAIR-Q) scores (increasing from 0.945 to 0.973). Based on multiple regression, the current study suggested that indoor plant placement was one of the most important factors to improve the attention capacity of pupils in classrooms.

We aimed to assess the effect of longkong peel extract (LPE)-silver particle-alginate coating on the postharvest decay and browning of longkong fruit during storage at 13°C and 90–95% relative humidity (RH). Longkong was coated with 0, 0.45 or 0.90 mg·L⁻¹ LPE in silver particle-alginate solution and then stored at 13°C and 90–95% RH for nine days. In the mixture consisting of the longkong peel extract and silver solution, the silver particle size was modified to yield fine particles. Electron micrography showed the presence of silver particle sizes ranging in size from approximately 71–625 nm. Fruit coated without LPE exhibited severe browning, weight loss and decay incidence during storage. Coating with 0.45 and 0.90 mg·L⁻¹ LPE significantly inhibited the increase in fruit browning by mainly reducing peroxidase (POD) and polyphenol oxidase (PPO) activities. LPE coating effectively reduced the longkong weight loss and decay incidence. No fruit treatment showed a significant titratable acidity change or increased soluble solids at the end of storage. These results indicate that coating with LPE is a promising approach to inhibit decay and browning and to maintain the quality of longkong during low-temperature storage.