The effects of excessive moisture and dryness of soil on vine growth and fruit quality in passion fruit were studied. Under moistness treatment (pF 1.3–1.9), vine growth was inhibited and fruit set was decreased. The photosynthetic rate was markedly decreased from July onward. Leaf yellowing and root rot occurred. As a result, the starch content of roots was decreased. The fruit ripening period was the shortest in all treatments. Under drought treatment (pF 2.1–2.8), vine growth and flower bud formation were inhibited. The fruit ripening period was prolonged. The fruit size and Brix were smaller and lower than those of normal treatment, respectively. The reactions of plants differed based on the drying period. When plants were grown under early drought stress (until about 20 days after fruit bearing), the flower, ovary, and fruit size tended to be small. However, the leaf color and fruit set were improved. When plants were grown under late drought stress (from about 30 days after fruit bearing onward), vine growth, flower bud formation, and the photosynthetic rate were inhibited and the starch content of plants was also decreased. However, late drought stress improved the fruit peel color. These results indicate that excessive moisture and dryness of soil had adverse effects on vine growth and fruit quality in passion fruit. The results also suggest that temporal drought stress was effective for the improvement of fruit set and fruit peel color.
The effects of cold storage (i.e., 5°C storage until pre-treatment) and the pre-treatment temperature (i.e., 25°C or uncontrolled temperature storage between cold storage and planting) on bulb quality during storage and growth and scale leaf formation after planting in spring-harvesting cultivation of Allium × wakegi Araki ‘Kan Shirazu’ were investigated as compared with the conventional storage method of hanging under eaves. Cold storage of the bulbs after harvesting inhibited the deterioration of the bulbs as compared with the conventional method, and the quality of the seed bulbs was better with a longer cold storage period. The rate of softened bulbs at the end of December was approximately 45% under conventional storage, and cold storage of the bulbs at 5°C from mid-July reduced the value to less than 15%. On the other hand, cold storage tended to accelerate scale leaf growth after planting, but the pre-treatment at 25°C or an uncontrolled temperature after cold storage effectively reduced scale leaf formation. Pre-treatment at 25°C or long-term pre-treatment at an uncontrolled temperature after cold storage, however, resulted in deterioration of the bulbs during the pre-treatment. It is, therefore, recommended for seed bulbs to be stored at 5°C until the end of October or later, being shorter than 60 days before planting, and for them to be pre-treated at an uncontrolled temperature afterward.
‘Soshu’ persimmon is a very early maturing variety of the pollination constant non-astringent type, which has red skin color and excellent eating quality. Therefore ‘Soshu’ gets a high market valuation. ‘Soshu’ often exhibits physiological fruit drop in the early stage (June to July), and is known to have a variable fruit set. In this study, we investigated the effects of artificial pollination and grafting of the pollen cultivar on the physiological fruit drop of ‘Soshu’. The pollinizer cultivar ‘Saefuji’ was used because it was suitable for artificial pollination of ‘Soshu’. Artificial pollination with pure pollen of ‘Saefuji’ and grafting of ‘Saefuji’ had some preventive effects on physiological fruit drop; however, some variations in their effectiveness were observed due to annual changes. To identify a more stable prevention method, we examined the relationship between physiological fruit drop and the length of the shoot at the terminus of the primary scaffold branch. Shortening the shoot at the terminal of the primary scaffold branch prevented physiological fruit drop in June.
However, physiological fruit drop increased afterwards. From the above, we revealed that artificial pollination with pure pollen, grafting of the pollen cultivar, and shortening of the shoot at the terminal of the primary scaffold branch were efficient techniques for the prevention of physiological fruit drop. It is important to develop methods for the prevention of physiological fruit drop with an annual change by combining these techniques.
We investigated the effect of removal of flower lees (mainly corolla) using a hand “corolla winder” and the methods of gibberellin treatment on berry cracking of ‘Ruby-Roman’ grape. The rates of rust fruit and berry cracking were significantly lower in the treatment group when all the corollas were completely removed from the ovary on the day of full bloom than the control (unremoved) treatment group. There was no differences in rate of rust fruit or berry cracking between the treatments when all the corollas were completely removed from the flowers and another treatment whereby the corollas were removed using the “corolla winder” in about 10 windings. The results demonstrate that the removal of flower lees using a hand ‘corolla winder’ can reduce the occurrence of berry cracking as a labor-saving method. On the other hand, the method of gibberellin treatment had no effect on the rate of berry cracking. However, when the rate of pericarp cracking was significantly lower in the treatment group when the 2nd gibberellin treatment was conducted at an early rather than late stage. Furthermore, the rate of pericarp cracking was significantly lower with the single treatment of gibberellin than with the two-times treatment. From these results, we conclude that the removal of the flower lees using the “corolla winder” is effective for reducing berry cracking of ‘Ruby-Roman’ grape, and that single gibberellin treatment can reduce the rate of pericarp cracking.
To apply summer-autumn flowering of highbush blueberry to two-season harvesting and autumn harvesting, we investigated the timing and degree of flowering in summer-autumn for 78 highbush blueberry cultivars. ‘Bluetta’, ‘Puru’, and ‘Bluecrisp’ flowered readily during the summer-autumn. Moreover, summer-autumn flowering was observed at the tip of shoots from mid-July to mid-November. The shoot lengths were around 70–100 cm. One-year-old branches that flower in summer-autumn differed among cultivars, for example, ‘Bluetta’, ‘Patriot’, and ‘Spartan’ flower from shoots and suckers, but ‘Bluecrisp’ flowers from shoots only. Inflorescences that flowered in the summer-autumn showed a form unlike that of inflorescences that flower in spring. These did not form flower fruit clusters, and there were individual florets located in each leaf axil of the shoot. Moreover, the number of florets per shoot was 3.9–4.8. The day temperature was slightly lower, the duration of sun light was shorter, and summer-autumn flowerings were more numerous in July 2013 than in 2014–2015. Moreover, temperatures in September and October in 2013 were higher. The results suggest that flowering during the summer-autumn is related to climatic conditions.
The seed propagation type of strawberry cultivar ‘Yotsuboshi’ was investigated for the summer-to-autumn cultivation period in northern Japan. Plants sown on 27 January initiated the first inflorescence in mid-May, and the cumulative number of inflorescences was increased as a result of monthly two-week long-day (24 h) treatment, which was applied once between May and August. Plants sown on 27 February were still juvenile in May and were therefore not notably affected by the long-day treatment. Treatment in June or July led to the induction of flower buds, but since the resulting yield was insufficient, seeding in January was determined to be more effective. Then, two-week long-day (24 h) treatment in June and/or July was applied to plants sown on 13 January in 200-cell or 406-cell trays. There was little difference between the two with respect to cell size in growth at planting, the cumulative numbers of inflorescences, or monthly yield. Long-day treatment in June increased the yield and number of fruits in September, while the July treatment had the same effect after October. Two applications of the treatment in June and July increased the yield after October and the number of fruits after September. These results suggest that ‘Yotsuboshi’ sown in January with long-day treatment in early summer could be promising for summer-to-autumn production in northern Japan.
We investigated the effect of different seeding dates on direct sowing with or without phosphate fertilizer applied locally below the seeds of the onion variety ‘Tarzan’ in a temperate zone. The number of leaves was analyzed, and a significant correlation was found between the number of leaves at the beginning of foliage fall-over and yield. Therefore, in direct-sown cultivation, in order to obtain a stable yield equivalent to transplanting, it is necessary to have the same number of leaves at the beginning of the foliage fall-over stage as when using the transplant method. In addition, using regression analysis, a significant correlation was observed between the number of leaves and effective cumulative temperature. The results suggest that it is necessary to sow seeds in late September when using the direct sowing method to obtain yields equivalent to the transplant method in a temperate zone, but pest control and nitrogen supplementation must be performed in a precise and timely manner. In addition, the effects of locally applying phosphate fertilizer below the seeds were found to have little impact on yields of onion in brown lowland soil.
In a previous study (Tazuke et al., 2015), a sudden decline in the respiration rate was observed in cucumber fruits on vines under prolonged darkness. The study suggested that this was caused by an abrupt cessation of photoassimilate translocation to the fruit because the time course of the decline in the respiration rate was similar to that of fruits treated by heat-girdling of the peduncle. Here, we examined this hypothesis by detailed analyses of the time course of fruit respiration rates in plants treated prolonged darkness, cutting the peduncle, heat-girdling the peduncle, and total defoliation of the plant. All these treatments upregulated candidate marker genes of sugar starvation, CsSEF1, asparagine synthetase gene, and CsFDI1. Respiration rates of the fruits of cucumber plants (Cucumis sativus L.; cv. Tokiwa and cv. Tokiwa Hikari 3A) were measured in a growth chamber controlled at 25°C. Under prolonged darkness, the fruit respiration rate began to decline at about 12 h after the start of darkness. After some transition period, the fruit respiration rate was described well by the equation: y = a exp(–bt) + c, where y and t are the respiration rate and time, respectively, and a, b, and c are constants. In other treatments, the fruit respiration rate after some transition period following the treatment was also described well by the same equation. The value of the time constant of the decay, b, was about 0.003 min–1 under prolonged darkness and defoliation, whereas it was about 0.007 min–1 after cutting and heat-girdling of the peduncle. The similarity of the value of b with prolonged darkness and defoliation supports an abrupt cessation of photoassimilate translocation to the fruit. Possible explanations of the higher values of b in cutting and heat-girdling the peduncle are discussed.
In the present study, the effects of hydrogen cyanamide (H2CN2) on blooming, vegetative bud sprouting, the ornamental period, and characteristic blossom form of ‘Izutoi’ and Line “Toizakura Shirobana” cherry blossom (Prunus spp.) trees were investigated. In experiment 1, dormant branches were sprayed with 1.0% H2CN2 on October 22 and November 11, 2010. After the H2CN2 spraying carried out on November 11, blooming occurred 35 days earlier in both the strains than in the controls. There was no difference in the effect of spraying H2CN2 in the ornamental period between the two cultivars. In experiment 2, whole trees were sprayed overhead with 1.0% H2CN2 on November 8, 2011. In ‘Izutoi’ blooming occurred 44 days earlier than that in the controls. In “Toizakura Shirobana” blooming occurred 38 days earlier than that in the controls. Spraying both whole trees and only branches with 1.0% H2CN2 yielded similar results. No significant difference was observed in the diameter of the blossoms. In contrast, a significant difference was observed in blossom color. In conclusion, spraying ‘Izutoi’ and Line “Toizakura Shirobana” cherry blossom trees with 1.0% H2CN2 in mid-November promoted blooming to the greatest extent.
We investigated that effect of intermittent low-temperature storage on flowering acceleration and growth of Begonia × hiemalis ‘Netja’. The experiments were conducted from early August to early September in 2012 and 2013 under 50% shading in a greenhouse and refrigerator with the seedlings grown in 7.5-cm pots in diameter. The average temperature of the greenhouse ranged from 23 to 32°C, and the day length ranged from 12 hours 37 minutes to 13 hours 57 minutes. The first node number with a flower cluster of 2D/2D × 8 (processing of two-day refrigeration treatment at 10°C in the dark followed by two days under greenhouse conditions was repeated for eight cycles) and 4D/4D × 4 was decreased compared with that of plants grown only under greenhouse conditions (control). The timing of flowering of 2D/2D × 8 and 4D/4D × 4 was 3 to 14 days earlier than that of the control. In 4D/4D × 4, the first node number and timing of flowering of 10, 12.5, and 15°C refrigeration temperatures was significantly decreased compared with that of the control. Flowering timing accelerated as the refrigeration temperature increased from 10 to 15°C. Plant height at 10 and 12.5°C was more inhibited than that of the control. However, treatment at 15°C tended to cause spindly growth. In conclusion, we recommend 4D/4D × 4 at 10 and 12.5°C refrigeration temperatures as the timing of flowering significantly accelerated and potted plant quality was as good as the control plants.
This study investigated the effects of priming and low-temperature treatment durations of imbibed seeds on the growth and characteristic forms in Eustoma grandiflorum ‘Reina white’. This experiment used primed and non-primed seeds of this cultivar. The imbibed seeds were kept for 0, 1, 3, 5, 7, and 9 weeks at 10°C after sowing under dark conditions. The germination rate of the primed seeds was greater than that of seeds unprimed with the low-temperature treatment of the imbibed seeds for 5 weeks. The emergence rate of seedlings of the primed seeds for the duration from 0 to 5 weeks was the same or reduced compared with those that had not been primed in the low-temperature treatment of imbibed seeds for 7 and 9 weeks. The sizes of the seedlings that originated from the primed seeds were larger than those that were not primed at the time of planting. The bolting, flower-budding, and flowering rates of the primed seeds were greater than those that were not primed in the low-temperature treatment of the imbibed seeds for 0 and 1 week. The flowering rates were over 90% for primed seeds that had more than 1 week of the low-temperature treatment. The growth after planting was the same when the primed seeds were exposed for more than 3 weeks to the low-temperature treatment, although the growth was the same or slower when treated for 1 week. The characteristics of cut flowers were the same when the low-temperature treatment was administered for over 3 weeks. These results showed that 3–5-week low-temperature treatment was the most suitable treatment duration for primed seeds.
This study clarified suitable times for the single spraying of a fruit cluster with forchlorfenuron (1-(2-chloro-4-pyridyl)-3-phenylurea, CPPU) to reduce radial fruit cracking during tomato production under a rain shelter. We examined the relation between fruit development at the time of CPPU spraying and the occurrence of radial fruit cracking. The rate of occurrence was reduced in fruits that had been sprayed when they were 1.5–6.5 cm in diameter. The CPPU spraying time was regarded as the time when the maximum fruit diameter in the truss is 3.0–4.9 cm, with the minimum fruit diameter being about 1.5 cm. Actually, radial fruit cracking was clearly reduced by CPPU spraying at the time with a 3.0–4.9 cm maximum fruit diameter, although the reduction was somewhat unclear by spraying at the time of flowering or at the time with a maximum fruit diameter of 1.0–2.9, 5.0–6.9, or 6.0–7.9 cm. The reduction of radial fruit cracking by CPPU spraying was regarded as attributable to the increase in cell numbers near the fruit epidermis. The CPPU spraying did not significantly affect the harvested fruit number, average fruit weight, or total fruit yield. The marketable fruit yield increased along with the reduction of radial fruit cracking by CPPU spraying. The shape and quality of fruits sprayed with CPPU and untreated fruits were equivalent.
The new root-zone environmental control system (N.RECS) was developed by combining floor heating panels, an air-source heat pump cold/hot water supply system, and heat-insulating pot container. N.RECS has 2 modes, which are heating and cooling modes of root-zones. The heating mode was able to maintain the root-zone temperature at 25°C at a 10°C air temperature during the winter season, and the cooling mode could provide a 23°C root-zone temperature at a 40°C air temperature during the summer season. The effects of root-zone heating during the winter season on growth and flowering in dahlia (Dahlia × hybrida) were investigated. The plants were grown in plastic houses with minimum air temperatures/root-zone temperatures of 15°C/non-heating, 12°C/24°C and non-heating/24°C. The growth of plants cultivated at 12°C/24°C and non-heating/24°C were promoted compared with that of 15°C/non-heating. The flowering time of non-heating/24°C was 2 to 3 days late at 15°C/non-heating. The cost of the consumption of energy for heating was estimated to be 34 and 69% lower at 12°C/24°C and non-heating/24°C, respectively compared with that of 15°C/non-heating. Fuchsia (Fuchsia × hybrida), with poor heat tolerance, was used to investigate the effects of root-zone cooling on growth. When the plants were cultivated with non-cooling of the root-zone during the summer season, 48% of the plants wilted and died. However, root-zone cooling at 20°C or 23°C resulted in the healthy development of plants. Thus, it is indicated that N.RECS is useful for the growth regulation of pot flowers year round.
Annual changes and the lack of uniformity in the flowering period are recent problems in small-flowered chrysanthemum production shipped in early August in Japan. In order to improve the annual stability and uniformity in the flowering period, ‘Kasuga-no-beni’ was selected among the breeding lines where by the difference in the average flowering day under unheated plastic house and open field conditions was within five days for four years. ‘Kasuga-no-beni’ bloomed in early August every year under both conditions from 2010 to 2013. When ‘Kasuga-no-beni’ and the traditional cultivar ‘Hiroshima-beni’ were cultivated at constant temperatures of 10, 15, 20, and 25°C using growth chambers, we found that the unfolding rate and flower bud differentiation of ‘Kasuga-no-beni’ grown at 10 and 15°C were slower than those of ‘Hiroshima-beni’. Next, the effects of the normal year temperature ± 3.5°C for 2 weeks from the vegetative growth phase to the reproductive growth phase on the flowering period were investigated. In the vegetative growth phase, the node number of flower bud differentiation decreased as the temperature increased in the temperature range of 17 to 25°C, which is higher than that of ‘Hiroshima-beni’. In the reproductive growth phase, the flowering date of both cultivars was delayed with an increase from 22 to 29°C, however, the number of prolonged days in ‘Kasuga-no-beni’ was lower than that in ‘Hiroshima-beni’. As for the uniformity of flowering, the peak rate of flowering stems of ‘Kasuga-no-beni’ that bloomed in August 2–5 was higher than that of the control cultivars. The period from the beginning to the end of flowering in ‘Kasuga-no-beni’ was shorter than in the control cultivars.
The sweet, highly storable, yellow-skinned, and labor-saving apple cultivar ‘HFF63’ was bred on Fujisaki Farm, Hirosaki University. The parent cultivars of ‘HFF63’ were identified as ‘Fuji’ and ‘Toko’ by genotype analysis using DNA markers, but we could not identify the seed or pollen parent. At our experimental site, the suitable harvest season is the beginning to middle of November. The tree vigor and form are similar to those of the leading cultivar ‘Fuji’; and so the same horticultural care can be applied. The storability is very high and 1-MCP was not required for storage until 150 days after harvest, considering the fruit quality, including flesh firmness. One of the reasons for the high storability was ascribed to the low ethylene content of the fruit during storage. The fruit exhibits a strong, sweet taste because of its high sucrose content. The fruit also exhibits a fresh weight of about 350 g with a 15° soluble solid content and about 0.3% titratable acidity. We commercially registered ‘HFF63’ with the trademark KIMITO. Therefore, the fruit with suitable quality can use this trademark. ‘HFF63’ has the potential to be a leading cultivar suitable for gifting purposes.