An Earl’s-type melon (Cucumis melo L.) new variety ‘Expole’ which has long shelf life characteristic and resistance to powdery mildew (Sphaerotheca fuliginea (Schlecht. ex Fr.) Poll., race 2) and Fusarium wilt (Fusarium oxyporum f. sp. melonis (Leach et Currence) Snyder et Hansen., races 0 and 2) was developed using the test for ethylene sensitivity and Fusarium wilt resistance. The long shelf life gene and Fusarium wilt resistance gene were confirmed by these DNA markers in ‘Expole’. It was shown that DNA markers facilitated selection in melon breeding.
Orchid mycorrhizal fungi were inoculated on Habenaria radiata tubers in vitro, and we tried to make it clear whether the growth of the plants was promoted, and what kind of absorbed nutrients brought about the growth promotion. Based on these findings, the effectiveness of the mycorrhizal fungi inoculation in the growth promotion of the daughter tubers was discussed. 1. As for the orchid mycorrhizal fungi inoculation, it became clear that the orchid mycorrhizal fungi promoted plant growth and the enlargement of daughter tubers. 2. It was considered that plant growth was promoted by the mycorrhizal fungus inoculation because the plant absorbed carbon compounds from the oatmeal medium through the action of the fungi. 3. It could not be determined whether the plant absorbed carbon compounds directly through its own roots, or through the orchid mycorrhizal fungi.
Effects of overhead liquid fertilizer application on soil property, tree nutrition, yield and fruit quality of satsuma mandarin (Citrus unshiu Marc.) were investigated. Liquid fertilizer was prepared by dissolving solid fertilizer containing 15% nitrogen, 15% phosphorus and 10% potassium in water at 300-fold dilution. Eleven-year-old ‘Nichinan No. 1’ trees top-grafted on ‘Nankan No. 20’ (interstock)/trifoliate orange rootstocks were used. The soluble fertilizer was applied three times in March and five times from early October to early November at weekly or ten-day intervals. As controls, pellet-shaped solid fertilizer containing 50–60% organic materials, 8–10% nitrogen, 7% phosphorus and 7–8% potassium was applied on soil surfaces at a rate of 7 kg (early March), 8 kg (early October) and 5 kg (early November) per 10 a as nitrogen equivalents. In addition, plots in which nitrogen content was reduced by 30% in both liquid and solid fertilizer were allocated. The soil EC was slightly lower in the liquid than solid fertilizer application. The soil and leaf nitrogen content were also lower in the liquid fertilizer plots. These facts were further evidenced by leaf SPAD values representing chlorophyll concentrations. There were no significant differences in yield, fruit weight, Brix or titratable acidity of fruit juice among the treatments. Thus, liquid fertilizer application using sprinkler systems can be recommended since this method can greatly save labor cost compared with solid fertilizer application by hand.
To produce turnip rape (Brassica napus L.) with high concentrations of total calcium (Ca) and water-soluble Ca, we investigated the effect of defoliation on the form and levels of Ca (water-, 1N-NaCl-, 2%CH3COOH- and 5%HCl-soluble Ca) in the lateral shoots of turnip rape. By defoliation after pinching in November, the elongation of lateral shoots was inhibited and the yield of lateral shoots was reduced to 84~91% of the control without defoliation. Defoliation significantly increased total and water-soluble Ca concentrations in lateral shoots of turnip rape from November to December, but not those after January.
The effects of fruit position in the canopy, harvest date and covering fruit with bags of different colors on the development of reddish-pulp, skin and flesh anthocyanin concentrations and flesh firmness were investigated in ‘Takei Hakuho’ peach (Prunus persica Batsch) fruit. In the first half of harvesting, the rate of reddish-pulp development was higher in fruit harvested from the upper part of the trees than in those from the lower part, whereas in the last half of harvesting the rate of reddish-pulp development had no relationship with fruit position in the canopy. There was no significant difference in the rate of reddish-pulp development among unbagged fruit and those in white and orange bags, However, fruits covered with orange and black bags showed a lower rate of reddish-pulp development at harvest. However, when fruits were stored for four days at room temperature the rate of reddish-pulp development was as high as that in fruit covered with white bags. The relationship between skin and flesh anthocyanin concentrations and flesh firmness was investigated in fruits covered with bags of different colors. There was significant negative correlation (P<0.001) between flesh anthocyanin concentration and flesh firmness and there was no significant correlation observed between skin anthocyanin concentration and flesh firmness. The relationship between skin and flesh anthocyanin concentration in fruit harvested from ‘Shimizu Hakuto’ peach trees varied largely among the orchards. These findings indicate that anthocyanin accumulation in peach skin is significantly affected by light conditions, such as fruit position in canopy and modification of light quantity through bagging with different colors, although the bags had little or no effect on anthocyanin accumulation in the flesh.
The present study aimed to stabilize high tomato fruit yields with high soluble solids on long-term hydroponic cultivation using an organic substrate culture. The water holding properties of an organic substrate (made with cedar bark or coconut husk and bark compost) were investigated. Use of an irrigation control system based on solar radiation, and the effects of the irrigation interval on fruit yield and quality were also investigated. In the case of substrates drained after water had been absorbed, the volumetric water content decreased sharply in organic substrates compared to that in rockwool. The volumetric water content was higher in organic substrates compared to that in rockwool at pF2.7. The amount of leaf area changed only slightly after removing leaves under the second truss; a positive correlation was seen between total integrated solar radiation and the evapotranspiration rate in long-term tomato cultivation. Irrigation treatments were a function of the total integrated solar radiation with three thresholds (MJ·m−2); 1.71, 1.93, and 2.14 (1.50, 1.71, 1.93 before removing leaves under the second truss). Nutrient solution was supplied at a rate of 100 mL per plant during each irrigation. The marketable yield decreased and the soluble solids content increased as the thresholds increased. However, the yield of fruits with highly soluble solids (Brix 8% or more) was highest when irrigation thresholds were 1.93 MJ·m−2 (1.71 before removing leaves under the second truss).
We developed a Developmental Rate Model (DVR model) of Japanese persimmon (Diospyros kaki Thunb.), which was estimated by bud burst rate of cuttings chilled at constant temperatures (0, 5, 8, 11 and 18°C). Temperatures at 5–8°C were considered most effective for breaking bud endodormancy in ‘Tonewase’. Based on this model, the endodormancy completion stage of ‘Tonewase’ was assumed to be December 19–30 in Nara. Bud burst in forced culture, heated with the minimal air temperature in a greenhouse maintained above 15–18°C, can be estimated by the Developmental Index (DVI) at heating start time for bud burst. The DVR model was verified by comparison between estimated and observed bud burst stage in forced culture.
The conventional cultivation methods for sweet cherry involve two difficult problems; The trees become too tall and take over 10 years before bearing substantial fruit. We examined the Y-trellis training method to resolve these problems, and found that the Y-trellis training could solve the problems on a practical level; reducing the number of years until bearing fruit and lowering the height of the trees. In the present study, a new cultivation method by hedge-row training was tried to reduce the period till bearing fruit, create smaller trees and produce higher yields compared with those by Y-trellis training. In this training, the harvest started in the fourth year after planting; the target tree shape was attained in the fifth year; and the yield increased markedly. The fruits obtained from hedge-row training and the Y-trellis had higher quality, larger size and more favorable surface color, as well as their smaller variances, compared to those with open-center training.
To obtain early and high yield in the young filler trees of Japanese pear ‘Gold Nijisseiki’, the effects of different training systems on canopy development, yield, and fruit quality were investigated. Permanent trees with 3 scaffolds (PT) and filler trees with 6 different tree forms, that is, 3 scaffolds (3-SF), 4 scaffolds (4-SF), 6 scaffolds (6-SF), improved-two-branch 8 scaffolds (I-8-SF), 8 scaffolds (8-SF) and improved-two-branch 12 scaffolds (I-12-SF) were compared. The number of fruit and yield per tree increased earlier in the trees with larger numbers of scaffolds. The tendency was particularly pronounced for I-8-SF and I-12-SF. Cumulative yield of trees age 3 to 7 years was also higher for trees with larger numbers of scaffolds; the yield of I-12-SF surpassed that of PT by 76%. However, fruit quality was almost the same in the training systems. Highly positive correlations were observed between yield and some tree growth parameters, such as, total length of older wood, canopy area and LAI. These findings indicate that fruit yield strongly depends on the extension of older branches and consequent increase of canopy area or LAI. Therefore, training systems with a large number of scaffolds promote on increase in early fruit yield.
For the purpose of obtaining early and high yield in young filler trees of Japanese pear ‘Gold Nijisseiki’ the effect of different training systems on fruit production efficiency was investigated. Permanent trees with 3 scaffolds (PT) and filler trees with 6 different tree forms, that is, 3 scaffolds (3-SF), 4 scaffolds (4-SF), 6 scaffolds (6-SF), improved-two-branch 8 scaffolds (I-8-SF), 8 scaffolds (8-SF) and improved-two-branch 12 scaffolds (I-12-SF) were compared. Fruit production efficiency was evaluated by three indicators: yield per canopy area, yield per leaf area, and yield efficiency (yield per trunk cross-sectional area). Yield per 1 m2 of the canopy area was higher in the training systems with larger numbers of scaffolds. The average yield from 6–8-year old trees of I-12-SF was 4.1 kg, showing an increase of 44% compared to PT. Yield per 1 m2 of leaf area was also higher in the training method with larger numbers of scaffolds. Average yield from 6–8-year-old trees was 1.8 kg in the I-12-SF, which was 35% higher than in the PT. Yield efficiency was also higher in the training method with larger numbers of scaffolds. Average yield efficiency of 6–8-year-old trees was 1,232 g/cm2 in the I-12-SF, which was 60% higher than in the PT. These findings showed that fruit production efficiency was higher in training systems with larger numbers of scaffolds, due to higher density of spur bearing wood in the canopy, higher percentage of spur leaves which make a great contribution to fruit production, and lower shoot growth.
Ethephon (2-chloroethylphosphonic acid) was evaluated for its potential use as a flower thinner in several Japanese pear cultivars. In ‘Hosui’, ethephon at 100 or 250 ppm was applied to flower or fruit clusters 1 week before full bloom (WBFB) or 2 weeks after full bloom (WAFB). Ethephon treatment at 250 ppm at 1 WBFB resulted in a strong thinning effect. In ‘Kosui’, ethephon at 100-1,000 ppm was applied to flower or fruit clusters 2 or 1 WBFB, at full bloom (FB), or 2 WAFB. Ethephon treatments of 500 or 1,000 ppm at regardless of treatment timing showed a thinning effect. The thinning effect tended to increase when ethephon was applied at 1 WBFB. However, ethephon treatment of 1,000 ppm at 1 WBFB induced over-thinning. Ethephon treatments at 250 or 500 ppm at 2 WAFB decreased fruit weight at harvest. In ‘Wakahikari’, ‘Shinsei’ and ‘Niitaka’, ethephon at 250 or 500 ppm was applied to flower clusters at 1 WBFB. In these cultivars, fruit set was decreased when ethephon was applied at 500 ppm. It was concluded that ethephon treatment at 1 WBFB showed the thinning effect on ‘Kosui’, ‘Wakahikari’, ‘Shinsei’ and ‘Niitaka’ when applied at 500 ppm, and ‘Hosui’ when applied at 250 ppm. Thus, there seemed to be differences in the thinning effect of ethephon among the cultivars examined. The quality of fruits after these treatments was almost the same as that of control fruits.
Onion (Allium cepa L.) seeds were primed for 4–6 days at 15°C on a filter paper moistened with trehalose or raffinose solutions. These priming treatments accelerated the speed and uniformity of germination, and were comparable to the polyethylene glycol (PEG) treatment, which is used widely as a priming technique. Onion seeds stored at 5, 15 and 22°C for 9 weeks after priming with trehalose or raffinose still showed high germination speed and uniformity. The priming effect of trehalose was observed in all three onion cultivars tested even though there were differences in the effect based on their original germination abilities. Under stressful conditions such as NaCl (100 mM), PEG (10%) or low temperature (15°C), primed seeds treated by trehalose (0.4 M) or raffinose (0.4 M) showed germination rates as high as 30–50% after 2 days incubation. This is in contrast with germination rates of around 2% in the unprimed seeds. From these results, the trehalose and raffinose treatments are considered useful to improve seed germination ability in onion seeds.
The effects of calcium-chelate treatments on extending the postharvest life of carambola (Averrohoa carambola L.) fruit were examined. After harvest, fruit were dipped in 0, 250 and 500 ppm Ca-EDTA solution for 20 min with immersion of its peduncle during 7 days of storage at 30°C. The effects of calcium treatment on postharvest life, the concentration of calcium and the form of oxalate crystals were analyzed. 1) Fruit treated with 250 ppm Ca-EDTA solution were visibly acceptable for marketing after 7 days of storage. The fruit firmness and concentration of oxalic acid in these fruits were higher than those undergoing other treatments, whereas the respiration rate was lower in the oxalic acid-treated fruit. 2) In all portion of the fruit, the Ca concentration increased after treatment. The Ca concentration in the marginal portion was higher than those of the inner portion and peel. 3) The outer most cells of the cortex were filled with polyhedronous oxalic acid crystals, that were smaller than those of other crops. There was distasteful influence on fruit quality following calcium-chelate treatment. These findings suggested that the calcium-chelate application treatment is an effective method of extending the postharvest life of carambola fruit.
New cultivar of Japanese butterbur, ‘MY-20’ was selected from hybrid plants between ‘Mizubuki’ (native cultivar of Gunma pref.) and ‘Yatsugashira’. A head of ‘MY-20’ was composed of about a hundred female florets and several sterile florets. Therefore, it was considered a female plant. ‘MY-20’ produced a remarkable number of spikes and was superior to other cultivars in total spike yield. ‘MY-20’ showed a tendency for these spikes to concentrate near the bud planted. Marketable yield fell due to the opening bracts, but ‘MY-20’ showed a higher marketable yield than other cultivars in February, because the spike of ‘MY-20’ was wrapped by many bracts which began to open later. ‘MY-20’ developed less anthocyanin pigments at the bracts, spikes were tighter, which provided excellent quality. The length and diameter of the petiole were shorter than ‘Mizubuki’ (Gunma). ‘MY-20’ was mainly concerned with spike harvest.