Among large-scale research projects for reconstruction of agriculture and fisheries of the area damaged by the Great East Japan Earthquake and Tsunami (2011), the results of field trials and research concerning field vegetables including cabbage and broccoli were reviewed. In Miyagi Prefecture, to reconstruct the agriculture of the Sendai Plain coastal area, a mechanized and labor-saving culture system of field vegetables, that can coexist with paddy rice production as the primary source, was chosen. In this article, from such a point of view, an integrated mechanical culture system of cabbage is introduced and discussed. In addition, in Fukushima Prefecture, the specific situation regarding the radioactive pollution soon after the disaster led to research trials on nursery production. For labor-saving in nurseries, broccoli plug seedlings were raised by a bottom watering system with application of NaCl solution to increase the drought-resistance of seedlings. In Iwate Prefecture, open-field cucumbers were cultured by a fertigation technique to maintain vigor and extend the harvest period.
The Great East Japan Earthquake heavily damaged horticultural production in the Tohoku Pacific Ocean coastal region of Japan. In this paper, we will describe the reconstruction support for strawberry production in Miyagi Prefecture that was damaged by the disaster. We have been involved in supporting horticultural reconstruction efforts in this region since the earthquake struck in 2011. In 2012, the Japanese Government began a research project to support reconstruction of the affected agricultural area (“A Scheme to Revitalize Agriculture and Fisheries in Disaster Area through Deploying Highly Advanced Technology”). The horticultural research station for the project, located in Yamamoto-town (Miyagi Prefecture), is a Venlo-type greenhouse 0.72 ha in area. Yamamoto-town and nearby Watari-town, together represent a major strawberry production region in Tohoku. Therefore, technical support to reconstruct the strawberry greenhouse facilities was a high priority of the research project. Since inception of the project, we have provided technical information to growers and the local extension service, and we have cooperated with them to solve technical problems. Due to the amount of salt accumulated in the soil after being flooded by the earthquake-related tsunami, we determined that an elevated growing-bed system was the best option to resume strawberry production. Therefore, we designed and proposed an elevated growing-bed system consisting of individual growing containers and a crown-temperature control system; this system should prevent the spread of soil-borne diseases from occurring frequently in connecting long beds. Separate containers also provide the drainage needed to keep the root zone (air and water contents) amenable for growing strawberries. The crown-temperature control system, established by the National Agriculture Research Organization (NARO), was added to increase yield and reduce fuel consumption. Large-scale, multi-span greenhouses were constructed by the local government (total 152 growers, 41 ha) and the first strawberry cultivation restarted in September 2013. In the research station greenhouse, we have continuously demonstrated or developed new technologies and provided information to the growers.
Agricultural lands in the Kesen area, which is located in the coastal area of Iwate Prefecture, were severely damaged by the Great East Japan Earthquake on March 11, 2011. Empirical research was undertaken to promote agricultural restoration and reconstruction. This project was conducted to realize low-cost protected horticulture utilizing local resources effectively. In this area, where forestry was popular, there was abundant unnecessarily thinned timber. Three types of low-cost greenhouses were developed, including a wooden frame house built using lumber derived from thinning. A stove to use thinned timber as a fuel was also developed. To establish protected horticulture at a low cost, greenhouses that could be constructed with accessible materials were developed along with a device for sterilizing nutrient solutions using charged plasma. An environmental control program was developed based on a “ubiquitous environment control system (UECS)” for small-scale facilities. Disease control using hot water for long-term cultivation was carried out. Strawberry and tomato production was conducted to demonstrate the use of these developed elements and resulted in yields significantly higher than those obtained for these crops before the disaster.
In blueberry culture, when sulfur and NH4+ and K fertilizers are applied to soils, radiocesium in the soils may be released into the soil solution, absorbed by roots, and then translocated to fruit. We reanalyzed data from our previous experiment to evaluate soil factors affecting the concentration and total amount of natural stable Cs in blueberry organs and its translocation to fruit. During a 2-year pot experiment, 4-year-old rabbiteye blueberries (Vaccinium virgatum Aiton ‘Onslow’) were grown in three soils (Andosol, Cambisol, and Fluvisol) with or without soil treatment (acidification, NH4+ and K fertilization, or combined acidification-fertilization treatment). We measured the concentrations of 13 elements (N, Na, Mg, Al, P, K, Ca, Mn, Fe, Cu, Zn, Rb, and Cs) in samples of the soil solution and the blueberry fruit, leaves, branches and stems, and roots, as well as the pH of the soil solution. Acidification, fertilization, and combined treatment increased the Cs concentration in the soil solution within each soil. On the other hand, the Cs concentration in the whole bush was not changed significantly by any soil treatment. The Cs concentration in fruit, leaves, and branches and stems was significantly negatively correlated with concentrations of Na, Mg, K, and Ca in the soil solution. Among the three soils, the concentrations of these basic cations were lowest in the soil solution of the Cambisol. The fruit Cs concentration in the Cambisol did not change significantly with any soil treatments. In contrast, in the Andosol and Fluvisol, the fruit Cs concentration was significantly decreased by both acidification and fertilization. The whole-bush Cs content did not differ significantly among the soil treatments, whereas the percentages of Cs in fruit and roots depended greatly on the soil treatment within each soil, although the distribution trends relative to the control were opposite for fruit and roots. Our results suggested that the soil treatments to increase the concentrations of soil basic cations could reduce the rate of transfer of Cs to fruit and thereby contribute to a reduction in the Cs concentration in fruit, but not the whole-bush Cs content.
The effects of the jasmonic acid derivative n-propyl dihydrojasmonate (PDJ) on ethylene signal transduction and endogenous jasmonic acid (JA) in apples infected with Botrytis cinerea (gray mold) were investigated. Apples were dipped into 400 μM PDJ solution and then inoculated with B. cinerea. The fruit were stored at 25°C and 95% relative humidity for 16 days after PDJ treatment. The inoculation without PDJ application (PDJ− Ino+) showed larger B. cinerea lesion diameters compared to the PDJ application with inoculation (PDJ+ Ino+) and the untreated controls. In contrast, the PDJ+ Ino+ group showed a higher ethylene production rate, higher 1-aminocyclo-propane-1-carboxylic acid (ACC) concentration, and greater expressions of ethylene-related genes [MdACS1 (ACC synthase), MdACO1 (ACC oxidase), MdETR1 (Ethylene receptor 1), MdERS1 (Ethylene response sensor 1), and MdCTR1 (Constitutive triple response 1)], and endogenous JA, MdAOS1 (Allene oxide synthase 1) gene. However, the abscisic acid concentrations were decreased in the PDJ+ Ino+ group. The results suggest that PDJ application induces ethylene production through ethylene-related genes and endogenous JA, resulting in B. cinerea infection inhibition.
The suitable soil pH for passion fruit growth has been well studied; however, the optimal soil pH for producing high-quality fruit has not been determined. In this study, the effects of soil acidity on fruit quality were determined. One-year-old passion fruit plants were grown in pots filled with soil adjusted to four pH levels (pH 3.5, 4.5, 5.5, and 6.5). The numbers of flowers and fruits were counted, and the external appearance and juice quality of the harvested fruits was evaluated. Vegetative growth, physiological responses, and leaf mineral contents were also measured. At pH 4.5 and 5.5, fruit were heavier and larger, with a better peel color than the fruit at pH 3.5 and 6.5. As indicators of taste, the titratable acid content was lower and total soluble solid content was higher at pH 4.5 and 5.5, indicating preferable palatability. The sugar/acid ratio was highest at pH 4.5. The numbers of flowers and fruits, vegetative growth, and photosynthetic rate were also higher at pH 4.5 and 5.5. Conversely, soil with a near-neutral pH of 6.5 yielded fruit with a pale peel color, severe peel wrinkles, and a low sugar/acid ratio. Vegetative growth was inhibited, and the photosynthetic rate and leaf water potential were lowest at pH 6.5. The leaf/fruit ratio was lower at pH 6.5. A shortage of photosynthate may have reduced fruit quality. Leaf nitrogen, manganese, and zinc contents, as well as the chlorophyll content (SPAD index), were lowest at pH 6.5. Deficiencies in these minerals may have led to a low photosynthetic rate and SPAD index under the higher pH condition. With excessive acidic soil (pH 3.5), vegetative growth, photosynthetic rate, and the number of flowers were as high as those at pH 4.5, although the fruit-set percentage and fruit quality were lower. Thus, strongly acidic soil around pH 4.5 is recommended for producing high-quality passion fruit.
The field performance of ‘Taishuu’ Japanese persimmon trees grafted onto clonally propagated rootstocks, ‘MKR1’ and FDR-1, was investigated over 10 years. These results were then compared with the performance of trees grafted onto seedling stocks (S) and own-rooted trees derived from micropropagation (O-R). ‘Taishuu’ scions on ‘MKR1’ and FDR-1 rootstocks grew well initially, but stopped growing taller at seven years after planting. Total shoot length and trunk cross-sectional area (TCSA) increased annually in all trees, while the differences in these parameters between S or O-R trees and ‘MKR1’ or FDR-1 trees continued to increase year after year. The graft union of trees grafted onto ‘MKR1’ swelled, and FDR-1 rootstock overgrew the ‘Taishuu’ scion. Trees grafted onto both ‘MKR1’ and FDR-1 bore female and male flowers soon after planting, and the percentage of shoots with female flowers relative to total shoots in ‘MKR1’- and FDR-1-grafted trees were higher than that in S and O-R trees each year. The numbers of shoots with male flowers varied from year to year in ‘MKR1’- and FDR-1-grafted trees, but did not appear to increase yearly. ‘MKR1’- and FDR-1-grafted trees almost completely inhibited secondary shoot occurrence in mid-June, and the percentages of dropped fruitlets between the middle of May and the end of July were almost always lower for ‘MKR1’- and FDR-1-grafted trees than for S and O-R trees. Cumulative yield efficiencies according to TCSA, canopy area, and canopy volume showed that ‘MKR1’- and FDR-1-grafted trees produced fruit most efficiently, although the total yields per tree were not significantly different between rootstocks. There were no significant differences in fruit quality between the rootstocks, except for the number of seeds. Concentric cracking and stylar-end cracking occurred in fruit of trees grafted onto ‘MKR1’ and FDR-1. However, the differences between the rootstock types were not large. The harvest date of ‘MKR1’ trees was significantly earlier than that of S and O-R trees. In conclusion, ‘MKR1’ and FDR-1 are both satisfactory dwarfing rootstocks for ‘Taishuu’, with high yield efficiency and inhibition of early fruit drop.
The effect of non-woven fabric floating row covers on the growth and yield of spring-sown, direct-seeded onions was investigated in Hokkaido, a subarctic island of Japan. Field experiments were carried out in 2014, 2015, and 2017. The seeds were sown in late April in each year. Floating row covers were installed a few days after seeding and kept in place until the end of May. During the treatment period, average daily maximum and minimum soil temperatures were approximately 4–5°C and 1–3°C higher, respectively, under covered compared with uncovered treatment. The effect of row covers on soil moisture varied annually. Emergence was obviously accelerated by floating row covers, as evidenced by an emergence date that was 1 to 4 days earlier than that of the uncovered treatment. Growth during early stages was promoted by floating row covers; however, the difference in plant growth between covered and uncovered treatments gradually decreased, with an almost non-significant difference observed by the beginning of bulb formation. The effect on growth earliness differed between years and an earlier lodging time was observed in 2015, in which the sunshine duration during the covered period of about 40 days reached 350 hours and the soil temperature difference between covered and uncovered treatments was larger than the other 2 years. Floating row covers had little effect on bulb yield. As for other growth aspects, decreased survival under floating row covers due to heat injury was observed when high temperature and drought simultaneously occurred. Floating row covers also tended to decrease onion maggot feeding damage. Non-woven fabric floating row covers effectively promote the emergence and early growth of spring-sown, direct-seeded onions mainly by elevating soil temperature. Although the degree differs depending on the year, earlier bulb formation and lodging, and a decrease in onion maggot feeding damage are also expected. These results suggest that non-woven fabric floating row covers may be a viable option to reduce the risks of delay in emergence, growth suppression caused by low temperatures, delay in lodging time and feeding damage due to onion maggot.
Light quality is an important environmental factor that regulates stem length of the tomato (Solanum lycopersicum). Previously, we showed that the stem length of tomato seedlings grown under red (R) light emitting diodes (LEDs) was significantly longer than that of seedlings grown under blue (B) LEDs or a mixture of B and R LEDs; further, the light intensity of B LED negatively correlated with the stem length. This study aimed to elucidate the mechanism of how B and R lights affect stem elongation. We analyzed the levels of gibberellins (GAs) and the expression of genes associated with their metabolism in tomato seedlings grown under different B and R light conditions. The level of bioactive GA, GA4, was significantly higher in the seedlings grown under R LED than in those grown under other light conditions. In addition, an increase in the B to R light ratio increased the transcript level of the GA inactivation enzyme gene, SlGA2ox7. Moreover, the transcript level of SlGA2ox7 increased with the intensity of B light, and was negatively correlated with the stem length of the seedlings. These results indicated that the B light intensity controlled GA inactivation of the seedlings, and endogenous GA contents may affect stem elongation. Further, we found that the transcript level of the GA biosynthesis enzyme gene, SlGA3ox3, in the seedlings grown under R LED was significantly higher than that under other light conditions. This could be due to depletion of B light and suggests that GA biosynthesis may be involved in the stem elongation of seedlings grown under low B light conditions.
The Cauliflower mosaic virus 35S promoter (P35S) induces transgene expression with insufficient activity and stability in some plant species, including lettuce. To develop a system to provide sufficient gene expression, a polyubiquitin promoter (PLsUbi) and terminator (TLsUbi) were isolated from lettuce, and this system was functionally compared with the conventional P35S-NOS terminator (P35S-Tnos) system by using a β-glucuronidase (GUS) reporter gene. In transgenic Arabidopsis, PLsUbi induced higher GUS activity than P35S, and the PLsUbi-TLsUbi combination induced higher GUS activity compared with the PLsUbi-Tnos combination, suggesting that the polyubiquitin terminator promotes transgene expression in concert with PLsUbi. The PLsUbi-TLsUbi combination induced less accumulation of GUS mRNA but > 10-fold higher GUS enzyme activity than the P35S-Tnos combination, suggesting that the PLsUbi-TLsUbi combination translationally promoted GUS expression in Arabidopsis. In transgenic lettuce, PLsUbi-TLsUbi transcriptionally and translationally promoted GUS expression, inducing approximately 16-fold-higher accumulation of GUS mRNA and > 800-fold-higher GUS enzyme activity compared with those induced by P35S-Tnos. Bisulfite sequencing methylation analysis of the introduced promoter sequences indicated that, for PLsUbi, the mean percentage of methylated cytosines in lettuce was 3.5 times that in Arabidopsis. For P35S, the mean percentage of methylated cytosines in lettuce was > 10 times that in Arabidopsis, and this methylation may be a major reason underlying the transcriptional inactivation of P35S in lettuce. Together, our results indicate that PLsUbi-TLsUbi promotes transgene expression in lettuce and Arabidopsis and may have broad applications in genetic engineering of additional plant species.
Flowering induction in Amorphophallus muelleri Blume is required for mass production of seeds within a short period of time. Hence, the objective of this study was to evaluate the effect of gibberellic acid (GA3) application on flowering induction for non-flowering-aged corms (immature corms) in A. muelleri. Research was conducted at Leuwikopo Farm, Bogor-Indonesia in May 2015–August 2016. Dormant corms of bulbils (0 year), 1-, and 2-year-old were treated with 0, 500, 1000, 1500 and 2000 ppm GA3. A 3-year-old corm was used as an additional control. Results demonstrated that GA3 application effectively induced flowering in 2-year-old corms. Bulbils flowered at a rate of 1.7–6.7% and 1-year-old corm at a rate of 2.8–16.7% irrespective of GA3 levels; 100% and 50–100% of inflorescences, respectively, were abnormal leading to low seed production. The GA3 application caused erratic flowering in bulbils and one-year-old corms, indicating age-dependent-flowering in A. muelleri. The erratic flowering caused a detrimental effect on seed production. In this experiment, 2-year-old corms produced larger inflorescences and a lower number of abnormal inflorescences. Thus, application of GA3 at a level of 1500 ppm on 2-year-old corms is recommended for mass production of A. muelleri seeds within a short period of time. In the future, it will be interesting to study the physiological mechanism of the erratic flowering phenomenon across corm age in A. muelleri.
In this study, we investigated the effect of high temperature on spear sprouting and elongation in asparagus to explore new approaches to control the harvest period in asparagus production. Four-year-old rootstocks of ‘UC157’ were grown in chambers in the dark at 30°C (30°C treatment), 34°C (34°C treatment), 38°C (38°C treatment), and 42°C (42°C treatment) for 14 days, and then at 25°C for 18 days. In the 42°C treatment, no spear sprouting was detected, and all rootstocks died. During the high temperature period, the number of sprouted spears was significantly lower in the 38°C treatment than in the 30°C treatment, whereas after the high temperature periods, the number was significantly higher in the 38°C treatment than in the 30°C and 34°C treatments. The total number of sprouted spears during and after the high temperature periods was not significantly different between the 30°C, 34°C, and 38°C treatments. The elongation rate of the spears during the high temperature period was significantly lower in the 38°C treatment than in the 30°C and 34°C treatments, whereas there were no significant differences in the mean spear elongation rate after the three high temperature treatments. These results suggest that a temperature of 38°C can be used to control spear sprouting reversibly by its application and cancellation.
Cut dahlia (Dahlia variabilis) flowers have recently become popular in Japan, but have the disadvantage of only having a short vase life. Here, we sought to clarify which factors are responsible for this by investigating the effects of an antibacterial (CMIT/MIT) treatment and a combined glucose plus antibacterial (Glc + CMIT/MIT) treatment on the vase life of the cut flowers of 10 dahlia cultivars, as well as the bacterial growth kinetics in their vase solutions and the soluble carbohydrate contents of their petals. We found that the CMIT/MIT treatment extended the vase life of ‘Kamakura’, ‘Magic Pink’ and ‘Purple Stone’, all of which had relatively high numbers of bacteria in their vase solutions. By contrast, the Glc + CMIT/MIT treatment significantly extended the vase life of three cultivars and also increased the fresh weight of nine cultivars. A comparison of two cultivars with relatively long and short vase lives (‘Moon Waltz’ and ‘Port Light Pair Beauty’, respectively) showed that a longer vase life was related to a higher carbohydrate content in the petals. Together, these findings suggest that maintaining the carbohydrate level is important for extending the vase life of cut dahlia flowers.
Bud-mutation carnation cultivars of the “MINAMI series” have a diversity of flower color in which the directions of bud sports are recorded. ‘Poly Minami’, which is the origin of the “MINAMI series”, produced the eight cultivars with various petal colors through continuous bud mutations. Flavonoid pigments analysis showed that the flower color variation is produced by the difference in the quantitative ratios of pelargonidin-typed anthocyanin and chalcononaringenin 2′-O-glucoside (Ch2′G). Acyanic cultivars; ‘Poly Minami’, ‘Lemon Minami’ and ‘Vanilla Minami’ had Ch2′G showing a yellow coloration as a major flavonoid with different concentrations in the petals. Cyanic cultivars with pinkish petals; ‘Orange Minami’, ‘Minami’, ‘Passion Minami’ and ‘Feminine Minami’ had different ratios of 3,5-di-O-(β-glucopyranosyl) pelargonidin 6′′-O-4,6′′′-O-1-cyclic malate (Pg3,5cMdG), showing a pink coloration, and Ch2′G as major flavonoids in the petals. The variegated cultivar ‘Sakura Minami’, with deep pink sectors and flecks on pale pink petals, accumulated a small amount of Pg3,5cMdG. The red-flowered cultivar ‘Tommy Minami’ accumulated pelargonidin 3-O-malylglucoside (Pg3MG) showing a red coloration as a major anthocyanin in the petals. The gene expression analysis through flower-bud development showed that the ratios of Pg3,5cMdG and Ch2′G are produced by the difference in the expression levels of flavonoid biosynthesis-related genes; the dihydroflavonol 4-reducatse gene (DFR), the chalcononaringenin 2′-O-glucosyltransferase gene (CHGT2) and the chalcone isomerase gene (CHI2) and the acyl-glucose-dependent anthocyanin 5-O-glucosyltransferase gene (AA5GT) and an anthocyanin transportation-related gene; the glutathione S-transferase-like gene (GSTF2). This study revealed that the flower color variations in the “MINAMI series” are caused by genetic and metabolic changes associated with flavonoid biosynthesis and identified five candidate genes for flower color changes in the “MINAMI series”.