‘Sweet Pepper Parental Line Nou-1’ was selected from a cross between a male sterile plant of ‘Tokyo Piman’ and ‘101(2·4)-11-1-4’ (a seed parent line of ‘Beruhomare’). The cross shows genic male sterility, resistance to phytophthora blight and ToMV. It is suggested that genic male sterility is controlled by a recessive gene, and the resistance to phytophthora blight is controlled by a few incompletely dominant genes. Since genic male sterility is able to improve in F1 seed production systems, ‘Sweet Pepper Parental Line Nou-1’ is expected to be used as a seed parent for F1 cultivers of sweet peppers.
Floral scent compounds of 13 wild lines of Camellia lutchuensis T. Ito ex Matsum. collected from Okinawa, C. lutchuensis line 1118, which is one of the pollen parents of fragrant camellia cultivar, and 4 fragrant camellia cultivars were compared. Limonene and 6 aromatic compounds, o-anisic acid methyl ester, benzaldehyde, benzyl benzoate, eugenol, methyl salicylate and phenylacetaldehyde were newly identified as scent compounds of C. lutchuensis. The total amounts of scent compounds in most of 13 wild lines, especially lines 3 and 36, were more than those of line 1118. Floral scent of line 36 with a high composition ratio of 2-phenylethanol and phenylacetaldehyde with floral note was considered stronger than that of line 3. Floral scent compositions of fragrant camellia cultivars, ‘Himenoka’, ‘Minato-no-akebono’, ‘Shunpu’ and ‘Fragrant pink’ were also almost the same as that of C. lutchuensis. However, those composition ratios differed greatly in each cultivar, and the floral scent of ‘Himenoka’ and ‘Minato-no-akebono’ with a high composition ratio of floral note compounds was considered stronger than those of the other 2 cultivars.
This study confirmed the usefulness of fertigation based on cumulative solar radiation in order to establish a fertigation technique that would decrease the nitrate concentration in spinach leaves (Spinacia oleracea L.). The plant growth, the nitrate concentration, and the nitrate utilization/application ratio was determined using potted plants. When the nitrate concentration in the irrigation water was varied, and the water quantity applied to the plants was varied to equalize the nitrate quantity applied to the plants, the plant fresh weights increased and the nitrate concentrations decreased with increases in the irrigation water. The leaf color, however, turned yellow when the irrigation water was increased. In the next study, the nitrate quantity applied to the plants was simultaneously increased with the irrigation water. Plant growth was promoted without leaf yellowing or nitrate accumulation by applying 1.2 times as much as the standard fertigation. The nitrate utilization/application ratio was about 90%, which is considered very high. In conclusion, fertigation based on cumulative solar radiation was considered effective for supplying water and nutrient in accordance with the plant demand, and this technique was suggested to be effective for spinach production without nitrate accumulation in leaves and NO3-N discharge from the soil.
Spinach plants (Spinacia oleracea L.) were grown in a greenhouse using fertigation based on cumulative solar radiation, and effects on plant growth, nitrate concentration in the leaves, and nitrate utilization/application ratio were studied. The relation of water and NO3-N absorption to cumulative solar radiation was initially determined in hydroponically grown spinach, then the stepwise fertigation program was set to 1.0, 1.2 and 1.4 times the standard quantity. With 1.2 fertigation treatment, plant growth and leaf color did not differ from those of plants cultivated by conventional soil culture. Total nitrate supplied to the soil under fertigation treatment were about half of that at soil culture. The nitrate utilization/application ratio was increased from 44% in soil culture to 82% under fertigation treatment. The nitrate concentration in spinach leaves under fertigation treatments tended to be lower compared to those under soil culture. In addition, the production of spinach with lower nitrate and without effects on growth seemed to be feasible by the withdrawal of NO3-N in the drip solution for several days before harvest.
We compared changes in certain characters associated with fruit maturing such as fruit size, flesh firmness, sugar concentration and storability in ‘Akatsuki’ peach growing in Kumamoto and Ibaraki, under different weather conditions, to investigate the influences of temperature on the development of peaches. The average temperature of Kumamoto during the fruit growing period (from full bloom to harvest) was about 2°C higher than that of Ibaraki. The mean temperature during fruit maturing period (four weeks before harvest) was the highest in Kumamoto in 2004 (25.7°C), and the lowest in Ibaraki in 2003 (20.9°C). The time of the initiation of stone hardening, based on the degree of the endocarp lignification, was related to the temperature during young fruit (six weeks after full bloom), that is, the higher temperature tended to shorten the period until the initiation of stone hardening. However, the interval from stone hardening to harvesting time was similar in all years and places investigated, although the weather conditions differed. Furthermore, based on the harvesting time, changes in various characteristics of fruit maturity were similar regardless of the place or year. Moreover, the storability was not significantly different when fruit were harvested at firmness of around 30 N. These findings suggested that fruit maturing or ripening of ‘Akatsuki’ peach was unaffected by the temperature during the fruit growing season.
The effects of prolonged night chilling and short day treatment with fertilization on the growth of terminal inflorescence and differentiation of primary axillary inflorescence were studied in strawberry plants that already differentiated terminal inflorescence in early August. Eight to ten days interruption of the treatment after the initial differentiation of terminal inflorescence increased the number of flowers in the terminal cluster. Supplemental application of fertilizers during interruption and prolonged night chilling and short day treatment accelerated the differentiation of primary axillary inflorescence. Transplanting strawberry plants to a productive field in early September after prolonged night chilling and short day treatment it made possible to harvest fruits of terminal inflorescence from early October onward and fruits of the primary axillary inflorescence continuously. Therefore, early yield of strawberry fruits increased.
To examine re-growth and distribution of carbohydrates, this study measured the dry weight of leaves, bulbs, basal stem and roots, and the sugar concentration in each organ of Chinese chives (Allium tuberosum Rottler) grown by sand culture for 20 days after harvesting. The total dry weight first decreased for 12 days after cutting, followed by an increase. Nevertheless, the total dry weight recovered to only about 80% of its initial weight, when the leaf length became harvest size (40 cm and over) on the twentieth day after cutting. Especially, after the initial decrease, the dry weight of the root only reached about 50% of its initial weight. This finding indicated that the Chinese chive root plays a significant role as the carbohydrate storage organ. A high degree of fructose was demonstrated in the leaf, whereas sucrose was dominant in other organs (bulb, basal stem and root), showing the highest concentration in the basal stem. However, the great decrease in concentration of sucrose in each organ was shown from the fourth day after cutting. Total sugar contents within alcohol soluble solids of the plant were lowest on the fourth day after cutting, then, increased with re-growth of the leaf, and consequently, 20 days after cutting, exceeded the initial sugar content of the plant. During the examination it was also discovered that the total carbohydrate (saccharide) content declined to the minimum level (60% of the initial level) on the eighth day after cutting. A partial recovery up to 72% followed in the remaining 20 day period. The main cause of this is related to the content of polysaccharides, which increased only slightly after a significant decrease during the initial eight days after cutting.
The effects of I− and IO3− on the growth and iodine absorption of tomato and spinach plants were investigated using a non-recirculating hydroponic system. Tomato and spinach plants were grown under 4 treatments; containing iodine I− 0.1 mM, I− 0.2 mM, IO3− 0.2 mM and 0 mM (control) for tomato, and I− 0.05 mM, I− 0.1 mM, IO3− 0.1 mM and 0 mM (control) for spinach. The results indicated that I− treatment was more toxic to plants than IO3−. I− treatments reduced the absorption of nutrient solution. Spinach was more sensitive to iodine than tomato. Spinach grown with a higher I− concentration showed symptoms of necrosis and leaf abscission. Based on these findings, tomato and spinach showed clear differences between their sensitivity to iodine. Further research will be required to achieve the final goal of using iodine as the disinfectant for hydroponic systems while avoiding toxicity to plants. In both species, iodine was found in high concentrations in leaf tissue. Therefore, a leafy vegetable like spinach might be a suitable crop to increase dietary iodine intake. Similarly, tomato fruits were found to accumulate iodine, thus, this crop might also contribute to achieving that objective.
To stabilize the berry production in a dioecious Japanese wild grape, Vitis coignetiae Pulliat, we studied the flowering patterns in female and male plants and the effects of timing and frequency of artificial pollination on fruit set and berry quality. The flowering periods of female and male plants were ten and nine days, respectively. The highest fruit set in the fruit cluster (54.6%) after performing artificial pollination twice was obtained using the pollen of male plants on the second and fifth days of the flowering period. With a single artificial pollination, we obtained higher fruit set with pollination on the fifth day (46.2%) than with pollination on the second day (24.0%). The soluble solid concentration in berry juice was higher in fruit with pollination on the fifth day. We also found it useful to use pollen from Vitis cultivars with artificial pollination to obtain a high percentage of fruit set in Vitis coignetiae Pulliat.
To clarify the effects of girdling on the coloration of berry skins, treatment date, width of girdling and berry number were investigated in ‘Aki Queen’ grapes’ (Vitis labrusca L. × V. vinifera L.). In Exp. 1, girdling treatment on bearing shoots was conducted 13 days after full bloom (DAFB) and 30 DAFB, and the berry number of the clusters was thinned to 13, 32, or 50 berries on each treatment date. Clusters with 13 berries were more sensitive to girdling treatment than clusters with 32 or 50 berries. In clusters of 13 berries, girdling on 13 DAFB increased berry weight, total soluble solids (TSS), and anthocyanin content; and girdling on 30 DAFB also increased TSS and anthocyanin content. Anthocyanin content of 30 DAFB treatment was even more than that of 13 DAFB treatment. In Exp. 2, girdling treatment was conducted on 5 dates (35, 42, 49, 56, and 63 DAFB) and 4 widths (3, 5, 10, and 20 mm). Girdling treatments on 35 DAFB increased TSS and anthocyanin content more than later girdling treatments, regardless of the width of the girdle. The width of the girdle had little effect on TSS or anthocyanin content. Anthocyanin accumulation by girdling was accompanied by sugar accumulation, hence sugar accumulation from 30 DAFB was thought to be critical for anthocyanin accumulation. Moreover, a narrow width of girdle such as 3 or 5 mm is sufficient to improve berry skin coloration.
The antioxidative activity in Eleutherococcus sciadophylloides (Franch. & Savat.) H. Ohashi. was assessed by the β-carotene degradation method and DPPH radical scavenging activity. Its methanolic extract showed a high antioxidative activity and its component was chlorogenic acid. Effect of temperature, light and cutting length on the chlorogenic acid concentration in young shoots was tested in a growth chamber. Intense light and long cutting increased the concentration of chlorogenic acid. Based on these findings, culture conditions suitable for forcing were investigated in green house. Young shoots that contain a high concentration of chlorogenic acid could be harvested in forcing culture by planting 30~40 cm-long cuttings in 10~15 degree C water.
The effects of daytime heating on the quantity of fertile pollen were examined in forcing cultures of eggplants ‘Senryo’. Small greenhouses were installed within a greenhouse, and each small greenhouse was warmed to a different minimal day temperature using an electric heater. When the plants were cultivated while maintaining a daytime temperature above 25°C, the weight of fertile pollen increased during the winter and the yields of normal fruit increased. In addition, with regard to the heating time, heating the greenhouse for 3 h around noon showed an effect similar to that of heating for 9 h from 8:00 to 17:00.
To investigate characteristics of carotenoid biosynthesis in the Japanese persimmon ‘Fuyu’ fruit during maturation, carotenoids and gene expression for phytoene synthase (DK-PSY), phytoene desaturase (DK-PDS), ζ-carotene desaturase (DK-ZDS), lycopene β-cyclase (DK-LCYb), β-ring hydroxylase (DK-HYb), zeaxanthin epoxidase (DK-ZDS) and lycopene ε-cyclase (DK-LCYe) were analyzed. In the skin, lutein was the main carotenoid at the green stage. The level of gene expression of DK-LCYe was constant throughout the experimental period. In contrast, the level of carotenoid-biosynthetic enzymes with the exception of DK-LCYe was lower in the green stage than in the coloring stage. These findings suggested that during the green stage, DK-LCYe played an important role in carotenoid biosynthesis and was responsible for massive accumulation of lutein. In the coloring stage after October, β-cryptoxanthin (β-CRY) and zeaxanthin were mainly accumulated. At this stage, simultaneous increase of the gene expression for carotenoid-biosynthetic enzymes with the exception of DK-LCYe was observed. It was thought that the change in expression profile of the genes accelerated the accumulation of β-CRY and zeaxanthin in this stage. In the flesh, β-CRY and zeaxanthin were mainly accumulated in October. Lycopene was mainly accumulated in November. The lycopene accumulation was accompanied by a massive increase in expression of genes at the later stages of lycopene biosynthesis (DK-PSY, DK-PDS and DK-ZDS). This finding suggested that lycopene accumulation was caused by massive increase in the expression of genes at the later stages of lycopene biosynthesis.
To grasp the actual influence of global warming on fruit tree production in Japan, a questionnaire was sent to prefectural institutes for fruit tree research. All 47 prefectures responded. All prefectures replied that global warming had affected on at least one tree species. The impact had extended to almost all tree species. The tree species were classified in to two types by responses of fruit development to climate changes. One group was the earlier development type and the other was the prolonged development type. The former were tree species in which both flowering and maturation periods had accelerated; these included Japanese pears, peaches and Japanese apricots. The latter were tree species in which the flowering period had accelerated, while maturation period had not accelerated; this type included apples, Japanese persimmons, grapes and satsuma mandarins. Fruit qualities of the prolonged development type had clearly changed, for example coloring faintly, enlarging, reduction of acid, softening and spoiling rapidly. Freezing injury on evergreen fruit trees and figs had decreased, while it had increased on other fruit tree species. Late frost damage showed both increase and decrease by region.
‘Nishimura-Wase’ persimmon is one of the important cultivars for commercial culture in Japan. ‘Nishimura-Wase’ tends to bear many more staminate flowers but fewer pistillate flowers with age or weakening of tree vigor, which causes decrease yield. For this reason, it is very important to have well-nutritious shoots bearing numerous pistillate flowers to maintain stable yields. Water shoots must be pruned during growing season, because it disturbs both tree form and sunlight condition. In this study, we tried to form fruiting mother shoots from water shoots by pinching in springtime. Summer shoots growing from water shoots by pinching from May to June bear many pistillate flowers and fewer staminate flowers than normal shoots. Pinched water shoots that never sprouted a summer shoot also bear almost the same numbers of pistillate flowers and fewer staminate flowers as compared to normal shoots. Although there was no difference in the numbers of flowers among pinching date, pinching in early May is more recommended, because the percentage of summer shoots sprouted from water shoots is higher than that of after late May. There was no difference in the fruit quality among experimental plots. Based on these findings, pinching water shoots from May to June could be applied to form fruiting mother shoots for the next year.
‘Aki Queen’ (Vitis labrusca L. × V. vinifera L.) is a bright-red grape cultivar, but often bears undesirable colored berries that are not only poor but also deep. To improve the bunch color, the effects of abscisic acid (ABA) on coloration were investigated in ‘Aki Queen’ grape. ABA (1,000 ppm) was applied to seeded bunches on 54 (veraison), 63, 72 days after anthesis. In the 54-day treatment, ABA did not affect the coloration. In 63- and 72-day treatments, ABA application promoted total anthocyanin concentration in the skin of the berries, resulting in an increase of proper and deep colored berries. Different coloration of respective berries in the same bunch occurred in all treatment fractions. ABA application did not influence either the anthocyanin composition, sugar and organic acid concentrations in the juice, or the weights of the bunch or individual berry.
The effect of long chain fatty alcohol (LCFA) in a nutrient solution on the growth of tomato (Lycopersicon esculentum Mill.) seedlings was investigated under various controlled environmental conditions in a closed transplant production system. In 128-cell trays with LCFA solution, root dry weight increased by 18 to 30% compared to the control. This indicated that treating the LCFA solution in the closed transplant production system could promote root growth. With continuous application of LCFA solution, the dry weights of aerial and root parts increased by 9% and 23%, respectively, compared with those of control. The net photosynthetic rate of the LCFA treated plants also increased by about 30%, but the chlorophyll concentration in the leaf did not increase.
‘Andesu’ netted melon plants (Cucumis melo L.) were grown under shaded or unshaded conditions, and the relationship between the ethylene production and the development of ‘water-core’ in the fruit was studied. In the pre-ripe stage, ethylene production and fruit softening of the shaded plants were accelerated more than those of the unshaded plants, whereas ‘water-core’ in the fruit was formed only at and after the ripe stage. Although ‘water-core’ at the ripe stage was more apparent in the shaded than in the unshaded plants, some of the fruit developed the disorder even in the unshaded plants. In the unshaded plants, however, the number of ‘water-cored fruit’ did not increase even at the over-ripe stage. In the unshaded plants, both ethylene production and flesh firmness in ‘un-disordered fruit’ at the over-ripe stage were similar to those in ‘water-cored fruit’ on shaded plants at the ripe stage. Our results showed that the development of ‘water-core’ in ‘Andesu’ netted melon fruit was not due to the high ethylene production at the ripe to over-ripe stages.
To clarify suitable transport conditions of cut gypsophila flowers, effects of temperature (10 and 20°C), time (24, 48 and 72 h) and two types of transports (dry- and wet-transport) on vase life were investigated. In wet transport at 20°C for 72 h, fresh weight and rate of open florets increased during the transport, but wilted florets were not observed. In contrast, in dry transport, fresh weight decreased by 10% during the transport at 10°C for 24 h, indicating that the freshness of flowers deteriorated after transport. The vase life of cut flowers was influenced by transport temperature and time. The vase life of flowers was shorter with raising the temperature as well as increasing time of transport. The vase life of flowers in dry transport tended to be shorter than that in wet transport when transport temperature and time were the same. In particular, vase life was markedly shortened by dry transport at 20°C for more than 48 h. The results obtained in this study clearly showed that wet transport was better than dry transport for the vase life of cut gypsophila flowers. In particular, the vase life of flowers wet-transported was not shortened compared with those that were dry-transported when transport temperature was 20°C.
In ‘Le Lectier’ pears treated with either low-temperature (5°C 7 days) or ethylene (5000 ppm · 24 hours) after harvest, showed changes in peel color, flesh firmness, soluble solid concentrations and ethylene production rate were determined for fruits during ripening at room temperature. When the fruits in low-temperature or ethylene treatment were ripened, the percentage of edible fruit reached 100% 35 days after treatment (DAT). The ethylene production rate from fruits in both treatments started to increase 14 DAT and reached the maximum at 35 DAT. The peel color at the equatorial and calyx end position in ethylene treated fruit was significantly higher than that in low-temperature treatment at 49 and 56 DAT. In both treatments, the peel color index was 5.0 or more when fruits reached the ripe eating stage. When the index of the peel color was equal after low-temperature and ethylene treatment, the flesh firmness differed.
Pulse treatment with sucrose extends the vase life of cut Eustoma flowers, but leaf injury is sometimes observed following this treatment. To investigate the factors causing leaf injury, cut ‘Mira Coral’ flowers with 3 open florets and 3 buds were treated with DW, 2% and 4% sucrose at 23°C, relative humidity 53%, 71% and 86% in the dark for 24 h, respectively. The rate of leaf injury was 100% in 53%RH 4% sucrose, and 50% in 71%RH 4% sucrose, but other treatments did not cause leaf injury. The absorption of pulsing solution was affected more by RH than by sucrose concentration, and lower relative humidity condition caused greater absorption of pulsing solution. Sucrose absorption showed a greater increase with 4% sucrose treatment compared to that with 2% sucrose treatment under all RH conditions. Vase life was affected more by sucrose concentration than by RH, and a higher concentration of sucrose effectively extended the vase life. These findings indicate that a high concentration of sucrose was effective in extending the vase life, but excessive absorption of sucrose caused leaf injury.
A mutant peach (Prunus persica Batsch) cultivar ‘Shimizu Hakuto RS’, developed by radiation breeding, shows the same quality as the original cultivar, ‘Shimizu Hakuto’. However, it shows poorer fruit set than the parent strains. The fruit set of this cultivar only reaches 20 to 30% of the total numbers of flower; whereas the original one reached 50 to 70%. As a result of morphological observation, the higher ratio of morphological abnormalities in pistils, slowing degeneration or incomplete development of the ovary and embryo sac, causes poor fruit set. Furthermore, the numbers of normal pollen per anther were smaller in ‘Shimizu Hakuto RS’ than in the parent strains. We suggest that this number reduces the probability of pollination and thus results in lower percentages of ovule fertilization. Nevertheless, the poor fruit set did not cause lower fruit productivity. We find it is a very labor-saving variety because the labor hours for flower or fruit thinning from March to May were remarkably reduced.
In growing melons, tendrils at each node generally result in decreased labor efficiency for training vines. A new cultivar ‘TL Takami’ with a tendril-less phenotype has been bred using the tendril-less type ‘Chiba TL’ and ‘Takami’ as the parents. The cultivar ‘TL Takami’ has no tendril, but has either a lateral shoot or a leaf at the nodes. Other characteristics are the same as those of ‘Takami’ and the fruits were able to be sold as ‘Takami’ fruits on the market. This newly developed cultivar has a great advantage in a 20~40% labor-saving during vine management compared with previous cultivars, especially when crop management is delayed.