We irradiated 17 cultivars of large-mum, 19 cultivars of small-mum, and a single cultivar of spray-mum. As a result of inducing flower color mutation, there was a cultivar-specific difference in mutation frequencies, regardless of the flower type. The mutation spectrum of the flower color varied according to the color of the used cultivar. Various colors were obtained from pink or reddish purple cultivars. They had a wide mutation spectrum. On the other hand, a specific color was obtained from yellow, brown, or white cultivars. In pink or reddish purple cultivars, there was a cultivar-specific difference in the obtained flower color or the number of mutation varieties. In this report, we show that the selection of a cultivar as a material is the most important to obtain flower color mutants by C-ion irradiation. It is also important to check the flower color of the material cultivar, in order to get the expected flower color mutants. The results of this research are useful for the selection of the cultivar as a material for C-ion irradiation. So, ion-beam breeding of flower color in chrysanthemum could be conducted efficiently.
In order to grow Habenaria radiata (Thunb.) K. Spreng. seedlings in their natural habitat, they must be pollinated by insects (natural crossing) and form numerous seeds. We investigated the rates of capsule formation and seed germination in H. radiata in a natural habitat in Aichi Prefecture. Seed capsule formation and the germination rate of the formed seeds in H. radiata individuals growing in their natural habitat were widely altered. Subsequent investigations of the factors affecting seed germination rates revealed that H. radiata germination was not affected by the nutrient status. The presence of relatively few H. radiata pollinators in the study area was considered to be responsible for the low pollination rate. In addition, the rates of seed capsule formation and germination varied markedly depending on the timing of pollination (days after anthesis: DAA), with the highest rates of capsule formation and germination observed when pollination occurred in the middle term of flowering at 4 to 5 DAA. These findings suggest that H. radiata flowers are the most susceptible to pollination at 4 to 5 DAA, and that pollination by insects during this period results in the formation of capsules containing the most viable seeds.
The objective of this study was to investigate the effects of the planting distance, system, and planting time on seed yield of the pumpkin (Cucurbita pepo L.) cultivar ‘Stripe pepo’ for edible seed production in Hokkaido. The effects of row width on the seed yield were the same at 150 and 300 cm. This can contribute to labor-saving in the case of ridging at a 300-cm row width compared with a 150-cm row width. Decreased intra-row spacing, from 52 to 35 cm, resulted in a significant increase in the seed yield. In addition, the intra-row spacing of 35 cm was suggested to be more appropriate for planting than two-row zigzag planting with an intra-row spacing of 70 cm at a row width of 300 cm. Furthermore, the number of fruits and seed yield per unit area increased further when the planting time was set earlier, between late-May and mid-June.
There has been an increasing demand for small-sized (cherry) tomatoes because they contain lycopene and other functional constituents, last for a long period of time, and are delicious to eat. However, since conventional cherry tomato cultivation methods involve guiding the vines upward and downward and other tasks that are labor-intensive, it is necessary to develop new cultivation techniques to save the energy required for cultivation management and reduce the labor required. In 2010, the authors developed a new method for open-field cherry tomato cultivation, in which the seedlings are planted more sparsely compared with conventional cultivation methods and most lateral shoots are left as they are. Although the new cultivation method, which is referred to as the sauvage method, is becoming popular across Japan, no studies have been conducted to compare the yield, quality, and growth rate of tomatoes between the sauvage and conventional cultivation methods. The present study aimed to establish the sauvage cultivation system as a new open-field cultivation method for summer-autumn-harvest cherry tomatoes. Two cherry tomato varieties with different characteristics were raised for two years using the sauvage and conventional cultivation methods, and the results were compared. The total yield and vendible crop yield per stock produced from the sauvage cultivation were larger, compared with conventional cultivation methods. In addition, the yield per area produced from the sauvage cultivation was expected to be equivalent to that from conventional cultivation methods, although the number of stocks per area was approximately one sixth. Furthermore, the sauvage cultivation method prevented the fruit from being sun-damaged. The sugar content of cherry tomatoes produced with sauvage cultivation was the same or lower, and the lycopene content was the same or higher, compared with conventional cultivation methods.
Tomato ‘CF momotaro yoku’ was sown 6 times in 2014 and 2015 to investigate the relationship between the emergence date and flowering date of the first truss of tomato with low node-order pinching and high-density planting. When tomato was sown in April, June, August and September, the time from emergence to flowering (DEF) was 36.4~39.6 days. When tomato was sown in December, DEF was 49.8~62.0 days, being significantly extended. The emergence rate at 4 or 5 days after sowing (DAS) was negatively related to the periods between the flowering day of the first and last plant (r = –0.88). The emergence rate at 3 DAS was affected by the volume of irrigated water: the rate was 82.3, 72.9, 59.4, and 29.2% when irrigated with 3, 6, 9, and 16 mL/cell of water, respectively. Moreover, matric priming shortened the time required for an emergence rate of 80% by approx. 24 h, and for a flowering rate of 80% by approx. 5 days compared with the control without priming. For these reasons, the emergence rate until 4 or 5 DAS was important for the simultaneity of flowering, especially in winter cropping. The water content of the medium affected the emergence rate. Matric priming improves the simultaneity of both emergence and flowering.
The effects of daily air temperature control in greenhouses on forced cultivar cucumber fruit growth and yield were investigated. Two methods of control were compared in two greenhouses. One has been applied practically in Saga Prefecture, Japan: the air temperature in the morning is maintained higher than that in the afternoon. The other has been applied in advanced countries for greenhouse horticulture: the air temperature is maintained higher in the afternoon than in the morning (PMHT) and decreased quickly (quick drop: QD) in the early evening. The latter method shortened the growing period from anthesis to harvest and promoted fruit growth. On the other hand, the growth of vegetative parts was restricted, and the number of harvested fruits decreased, because of the priority given to fruit growth. Thus, there was no difference in the total yield between the two methods. The temperature differences between leaves and fruits in the early evening were observed under PMHT·QD and the conventional method. The temperature differences were greater in PMHT·QD. These suggested that a higher temperature of fruit than leaves after sunset by PMHT·QD is one of the reasons for the promotion of fruit growth rather than the growth of vegetative parts.
We studied the germination and sprouting of onion seeds that had been immersed in a phosphorus solution from 0 to 5.0%. In cases of localized fertilization, we hypothesized that the phosphoric acid concentration in the soil would prevent or impede germination. Furthermore, we investigated the impact of fertilization with superphosphate on the emergence of onions. Fertilizing treatment with phosphorus of 4.66 g per pot decreased the emergence rate compared with no fertilization of 7 days after seeding, but afterwards it had no negative effect. The results suggest that the effects on germination and rooting of onion seeds immersed in a phosphorus solution are limited to just after germination. Therefore, even if seeds come into contact with superphosphate with localized fertilization, the effects on the emergence of onion decline over time. When superphosphate was locally applied, at a rate of 50 to 200 kg phosphate content per ha, the emergence rate 10 days after sowing was not affected.
This study was carried out to investigate the effects of covering with near ultraviolet ray-absorbing (UVA) film on the growth and coloration of spring red leaf lettuce and to evaluate the subsequent coloration after removal of the film. The daily mean temperature and light quantity under the UVA film were similar to those under ultraviolet transmitting film. The growth of ‘Variety-nouaka’, ‘Black rose’, and ‘TLE-496’ was promoted by covering with UVA film, while that of ‘Red fire’, ‘Red falder’, and ‘Early span’ was not affected. Covering with UVA film decreased the leaf anthocyanin content by 30 to 40% in ‘Red fire’, ‘Red falder’, and ‘Early span’, and by 60 to 70% in ‘Variety-nouaka’, ‘Black rose’, and ‘TEL-496’. The leaf anthocyanin content at 3 days after the removal of the UVA film was higher than that just before removal in all varieties except ‘Red fire’. In ‘Variety-nouaka’ and ‘Black rose’, the increase in the leaf anthocyanin content occurred mostly until when the integrated light quantity of near ultraviolet rays reached around 600 W∙h∙m–2 after the removal of UVA film.
This study was initiated to investigate the effects of exposing imbibed seeds to low temperatures on the growth and characteristics of Eustoma grandiflorum. Two cultivars with different rosette characteristics were used in this experiment, ‘Rococo Marine’ and ‘King of Snow’. Imbibed seeds of both cultivars were stored at a low temperature (10°C) for 5 weeks after sowing or before sowing under dark conditions. After the low-temperature treatment, the seedlings were grown at the natural temperature in the greenhouse for about 1 month. In this period, the daily minimum temperatures ranged from 21.0°C to 25.5°C and the average value was 23.0°C. Moreover, the daily maximum temperature remained in the range of 26.0°C to 43.5°C, within an average temperature of 37.2°C. Irrespective of the rosette characteristics, both cultivars had bolting rates of 100% when the low-temperature treatment was applied. The flower budding and flowering rates were higher than those without the low-temperature treatment in both cultivars. In ‘Rococo Marine’, which has a strong tendency toward rosette formation, the days to bolting, flower budding, and flowering decreased compared with those without the low-temperature treatment. The characteristic forms of the cut flowers were the same irrespective of the low-temperature treatment method. These results demonstrate that it is important to carry out low-temperature treatment of imbibed seeds in the high-temperature season, and that the different low-temperature treatment methods do not affect the growth and characteristics of Eustoma grandiflorum.
Sweet corn is one of the perishable vegetables that demonstrate rapid postharvest quality losses. Shriveling causes kernel denting that generates interstices between kernels on a corncob, raising particular concerns regarding its production and distribution. Harvested fresh ears of sweet corn can be prepared as husked or less-processed products without removing the shank or stalk. In the present study, we investigated the storage behavior of three varieties of sweet corn ears stored in different forms, with their husk leaves and other external parts being removed to different extents. Samples were stored at 10°C and 70–80% humidity, and evaluated in terms of changes in the score of shriveling, percentage weight loss, moisture content by part, and sugar content during 14 days after harvest. In all varieties examined, samples stored in the form of husked cobs (“husked cobs”) had a significantly higher score of shriveling from postharvest day 3 compared with those stored in other forms, indicating that shriveling occurs more rapidly in husked cobs. “Husked cobs” of the ‘Gold Rush’ and ‘Mirai 390’ varieties showed a significantly greater (or a trend toward a greater) percentage weight loss and a significantly lower moisture content of kernels from postharvest days 3 and 7, respectively, compared with their counterparts stored in a conventional form. Shriveling occurred in “husked cobs” within three days after harvest, irrespective of the sowing time and variety of the plant, although the weight loss and moisture content of kernels, factors that may contribute to shriveling, varied depending on the sowing time and variety. Therefore, further investigations are needed to examine longitudinal changes in the firmness, respiration rate, and carbohydrate content of kernels using more varieties to identify potential factors that influence shriveling.
The effects of pulse treatment with the silver thiosulfate complex (STS), sucrose, and their combination on the quality and vase life of cut flowers of Delphinium elatum were investigated. Cut flowers of D. elatum ‘Aurora Blue Imp’ were treated with STS solution at 0.1, 0.2, and 0.25 mM for different durations. The vase life of flowers was the longest when the Ag content in the florets was 3 μmol・100 g–1 FW or higher. The vase life of cut flowers was not influenced by the STS concentration or duration of treatment as long as the Ag content in florets was more than 3 μmol・100 g–1 FW. For the florets whose abscission layer had already formed, even if Ag had accumulated over 3 μmol・100 g–1 FW in the florets by pulse treatment with STS, the vase life of the florets was not extended sufficiently. Cut flowers of D. elatum ‘Blue Bird’ were treated with 0, 2, and 4% sucrose in combination with 0.2 mM STS. Treatment with 4% sucrose in combination with STS significantly extended the vase life, increased the anthocyanin concentration in the sepals, and improved the pigmentation of the flower color compared with that of STS alone. The effect of improvement of the pigmentation of the flower color was marked when cut flowers were held at 10°C for 48 h to simulate long-distance transport.
In the present study, ‘Murasaki L4 Daisuke’ was bred as a new cultivar for the rootstock of pepper (Capsicum annuum L.), showing resistance to both bacterial wilt caused by Ralstonia solanacearum and to mosaic caused by Pepper mild mottle virus (PMMoV). Moreover, ‘Murasaki L4 Daisuke’ had the marked advantage of easy identification between the scion and rootstock at the time of grafting because of the development of anthocyanin on the hypocotyl. In the inoculation test of a highly virulent strain of R. solanacearum, ‘S’, ‘Murasaki L4 Daisuke’ showed resistance similar to ‘Dai-Power’ and ‘Daisuke’. In the inoculation test of PMMoV, which is classified as pathotype P1.2.3, ‘Murasaki L4 Daisuke’ was recognized to have an L4 gene. By the quantification of anthocyanin, ‘Murasaki L4 Daisuke’ was confirmed to develop an approximately three-fold greater amount of anthocyanin on its hypocotyl compared with conventional cultivars. ‘Murasaki L4 Daisuke’ showed the same fruit productivity compared with ‘Daisuke’, when accompanying the scion ‘Miogi’.
The large, triploid, yellow-skinned apple cultivar ‘Hirodaimisaki’ was bred at Fujisaki Farm, Hirosaki University. The parent cultivars were elucidated by genotype analysis using SSR markers. This analysis revealed that ‘Hirodaimisaki’ might be obtained from a combination of ‘Golden delicious’ × ‘Delicious’ strains. At our experimental site, the suitable harvest season for this cultivar is at the beginning of October, 150 days after full bloom. The skin color index at this time is around 2–3, remaining greenish in color. The fruit exhibits a flesh weight of over 450 g with a 12–14% soluble solid content and around 0.4% titratable acidity, which constitutes an appropriate balance between sweetness and acidity suitable for raw consumption. It is possible to alter the skin color to red using fruit bagging treatment. ‘Hirodaimisaki’ shows the potential to become a popular labor-saving, yellow-skinned cultivar suitable for gifting purposes.
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