Characteristics of root development of evergreen azaleas were evaluated quantitatively. ‘Oomurasaki’ and ‘Shiro-ryukyu’, which are vigorous in growth and often used for landscaping, had a greater root length density and developed root systems penetrating deep soil layers. Most azaleas developed greater root length density in a moderately wet soil moisture area than in a wet soil area. However, R. indicum which distributes in rocky riverside areas, demonstrated a greater root length density only in wet soil area and the root development was especially concentrated in the surface soil layer. Thus, differences in root development system and root adaptation to moisture environments observed between species and/or cultivars, would have originated from the adaptation of each species to the natural environment.
We studied the origin of Keraji (Citrus keraji hort. ex Tanaka), which is a local cultivar mainly grown on Kikaijima island located on the east side of Amami-oshima, Kagoshima prefecture. The proportion of common bands was calculated based on the results of inter simple sequence repeat (ISSR) analysis. For Keraji, that value was highest for Kunenbo (C. nobilis Lour.) (0.823), followed by Kikaimikan (C. keraji hort. ex Tanaka) (0.688). Of the 16 polymorphic markers that appeared in Keraji, all bands were shared with Kunenbo and/or Kikaimikan, and no extra bands were detected in Keraji. Therefore we can assume that Keraji originated from Kunenbo and Kikaimikan. Since Keraji, Kunenbo and Kikaimikan always showed identical banding patterns on chloroplast DNA analysis, those three accessions were not distinguished from each other. Since both self-incompatible Keraji and Kikaimikan were cross-incompatible on reciprocal crossing, the incompatible genotype of those two accessions was considered identical. However, cross-incompatibility was not found between those two accessions and self-incompatible Kunenbo. When Kikaimikan and Kunenbo, which are both candidates for parental accessions of Keraji, carry the same incompatible gene, Keraji and its pollen parent are cross incompatible. In accordance with this theory, there is a possibility that Keraji originated from Kunenbo and Kikaimikan as the seed and pollen parent, respectively.
Recently, the importance of DNA markers has been heightened further by its usefulness in breeding new agricultural cultivars. In this study, we tried to identify DNA markers for the breeding of parthenocarpic eggplant by AFLP analysis; smpc77 (primer combination [EcoRI-AGG, MseI-CTG], fragment size 168 bp) was selected as a DNA marker concerned with parthenocarpy in eggplant. The mean value of fruit number of doubled haploid (DH) lines showing this marker was significantly greater than the value shown by other cultivars. Ninety-five per cent of DH lines without smpc77 had no fruit or a low number of fruit, and were not practical for eggplant cultivation. These results indicate that smpc77 is a useful marker for the breeding of parthenocarpic eggplant.
Cell walls of scarious floral leaf cells in seven plant species were observed under a transmission electron microscope (TEM), a scanning electron microscope (SEM) and a polarization microscope. Generally, floral leaves are composed of parenchyma cells with only primary cell walls. However, it was clarified that there were secondary cell walls showing orientation of cellulose microfibrils for all cells of scarious floral leaves in the seven plant species investigated. The fine structures of secondary cell walls varied as follows: Helichrysum bracteatum L., Acroclinium roseum L., Rhodanthe manglesi L. and Xeranthemum annuum L. in the Compositae family formed a reticulate or striped structure similar in morphology to secondary thickening of tracheary elements or transfer cells. Gomphrena globosa L. and Gomphrena haageana L. in the Amaranthaceae family formed a layered structure similar to fiber. Limonium sinuatum L. in the Plumbaginaceae family formed a folded structure similar to the sclereid of seed coat.
Varietal differences in root development were evaluated using cuttings of three species and four cultivars of evergreen azaleas. More than 80% of cuttings were rooted in a shaded rain shelter, a closed-frame and a mist propagation system. Total root lengths of Rhododendron ripense and R. × pulchrum ‘Oomurasaki’ were long, while those of R. indicum ‘Osakaduki’ and Kurume azalea ‘Kirin’ tended to be short. Leaf number and leaf area of each azalea were increased in cuttings of shaded rain shelter and closed-frame system, compared to mist propagation system except for the leaf area of R. macrosepalum. R. macrosepalum, R. indicum ‘Osakaduki’ and R. × mucronatum ‘Shiro-ryukyu’ showed a wide rooting areas in the cuttings, having many and a wide range of extended roots out of cylindrical net in the nursery bed. R. kaempferi and Kurume azalea ‘Kirin’ showed a narrow rooting area, having a small number of roots extending out of the net. These varietal differences of root characteristics in rooted cuttings showed the same tendency as field-planted plants in a previous study and would be related to genetic traits originating from adaptation to the natural habitat environment by each original species and the varieties derived from them. Root characteristics of cuttings from evergreen azalea can be indicator of the root traits of field plants and would be useful information for application to the breeding of evergreen azalea.
The effects of soil or soilless culture of mother plants on the yield of cuttings and the quality of rooted cuttings were examined in the summer-to-autumn-flowering chrysanthemum ‘Seiun’. The yield of cuttings in soilless culture was about two times that in soil culture. Stem lengths of rooted cuttings taken from mother plants grown in soilless culture were longer and the number of leaves greater compared with those in soil culture. Especially, there was less premature budding of rooted cuttings taken from mother plants grown in soilless culture than those grown in soil culture. We also investigated the effects of cutting time, concentration of the nutrient solution, planting density, and shading treatment of mother plants cultivated in a soilless culture. The yield of cuttings grown in soilless culture was greatest for a planting density of 25.6 per m2 and with an intermediate concentration (nitrogen concentration was 142 ppm). It was clear that the stem length of rooted cuttings became shorter when cuttings from the mother plant were taken later and the concentration of nutrient solution was lower. Mother plants in the greenhouse were shaded from ambient daylight (control) using cheesecloth between June and August. The yield of cuttings taken from mother plants under the control conditions increased and the rooting of cuttings improved with increasing light intensity. The above results are considered applicable to the cultivation of mother plants of summer-to-autumn-flowering chrysanthemum.
Root-proof capillary wick culture is expected to eliminate water drainage. Application of controlled release fertilizer instead of liquid fertilizer may be economical because liquid fertilizer equipment would not be required. In this experiment, large-fruited tomato was grown at three fertilizer levels; 11.3 gN (LF), 16.2 gN (MF), 21.0 gN (HF) per plant to evaluate a suitable level of controlled-release fertilizer needed for the culture of 15 trusses between October and July. For HF, the experiment was terminated at the end of December due to severe wilting. There was no significant difference in marketable fruits weight between LF and MF, but the soluble sugar content was higher in MF. The stem diameter at the end of experiment was larger in MF. The amount of nutrient remaining in the substrate was lower for N, P2O5 and K2O, but greater for CaO and MgO at each fertilizer level. Each nutrient concentration in the substrate solution was low after the middle of February for both LF and MF. Therefore, enrichment of nutrients in the substrate solution did not occur in either LF or MF. In conclusion, the amount of 16.2 gN per plant may have been sufficient for 15 trusses of tomatoes undergoing forcing culture.
The influence of replacing Fe2+ with other divalent cations to inhibit ACC oxidase activity on ethylene production in fruit and on-tree fruit-softening of ‘Saijo’ persimmon was investigated. When studying the effects of spraying treatment of fruit calyx with 1,000 ppm of NiCl2, CoCl2, and CuSO4 solutions (2 days after ethephone treatment) against on-tree fruit softening induced by ethephone, it was determined that a NiCl2 solution at a concentration of 1,000 ppm was most effective for inhibiting fruit softening. Second, when studying the inhibitory effect of spraying NiCl2 solution to prevent on-tree fruit softening, it was observed that treatment during early or mid-September or early October had little effect on inhibiting fruit softening and spraying had no effect after on-tree fruit softening had already occurred. However, by combining the serial application treatment in early September and again in early October, the ethylene concentration in fruit decreased and one-in-three trees treated tended to show inhibition of on-tree fruit softening. The fruit hardiness of flesh receiving two treatments remained higher than that of non-treated fruit. While the possibility of inhibiting on-tree fruit softening by treatment with Nickel solution was shown in this study, further investigation is necessary to clarify and confirm the effect by replication experiments in future years and on other trees.
We investigated the effects of a soilless culture system for use on sloping land and root-zone heating in the early morning (MH; 3:00~9:00), daytime (DH; 9:00~15:00), and 24 h constant heating (CH) on celery growth in winter. When normal drip tubes were used, solution in the tubes leaked from the lower emitters. The growth of celery plants differed with differences in the amount of fertigation. In the soilless culture system for use on sloping land, there were no leaking lines. The growth of celery plants was almost the same among all lines. Therefore, the soilless culture system is available for celery cultivation. The weight of the marketable portion grown under MH was almost the same as that of plants grown under CH and higher than that of plants grown under DH, even though the average root-zone temperature was lower than that in CH and almost the same as that in DH. The root-zone temperature in MH was lower at night than that in CH and in the morning, it was higher than that in DH. Thus, root-zone heating from morning to evening may improve celery growth. The heating cost for MH was lower than other treatments. Therefore, MH was energy efficient because the increase in the weight of marketable portion per energy consumption and per cost was the largest for MH.
Artificial climate experiments were conducted to evaluate the effects of timing and period of low temperature treatment on petal coloring of picotee cultivar of Eustoma grandiflorum. After pistil formation of the first flower bud, low temperature treatment was carried out with the daytime temperature set at 20°C and the night temperature set at 15°C. The coloration rate of the petal increased with increases in the duration of low temperature treatment up to 6 weeks. And the coloration rate increased when low temperature treatment was started as soon as the pistil formation stage of the first flower bud. However, 2if daytime temperature was set at 30°C and the night temperature was set at 15°C during the 4 weeks after pistil formation of the first flower bud, the colored area of the petal was more than 40% in 0-2.9% of the flowers. In this case, the quality of cut flower was superior to the quality of cut flowers grown at consistently high temperatures throughout cultivation. Furthermore, the possibility that another factor besides the developmental stage of the flower bud participated in this phenomenon was suggested by the increasing petal coloration rate at low temperatures.
In order to reduce labor load in a greenhouse growing forced cucumber (Cucumis Satius L.) cultivated under high air temperature and high humidity, effects of air temperature on thermal environment, work load, branch length, fruit yields, quality and the incidence of two cucumber diseases were investigated. The air temperature in the greenhouse was adjusted by ventilation through a roof window. The Wet Bulb Globe Temperature and the heart rate of laborers at an air temperature of 25°C between 9:30 and 11:30 was lower than those of 29°C as a conventional control. The labor load in the greenhouse at an air temperature of 25°C was reduced compared with that at 29°C. When cucumber plants were grown at an air temperature of 38°C between 11:30 and 13:30, the marketable yields decreased, the bent fruit increased and fruit skin color became light. However, there was no difference in branch length, fruit yields, quality and skin color between time-dependent temperature management of 33°C and conventional control of 29°C from 11:30 to 13:30. The incidence of powdery mildew and downy mildew under a time-dependent temperature management of 33°C was reduced compared with that at 29°C. It was suggested that the frequency of fungicide application and production cost of cucumber could be reduced using this time-dependent temperature management method.
To determine the relationship between NIC (nitrate ion concentration in petiole juice) and fruit quality, sampling conditions of the petioles were investigated in ‘Kyoho’ grapes with a long-pruning system for seeded berry production. The results indicated that the average NIC should be determined using 3 petioles near the first spike from 5~7 shoots 45~60 cm-long obtained between 10:00 am and 1:00 pm. The NIC determined by the above conditions showed a significant negative correlation with sugar concentration in the fruit at harvest. Two other indices, SHT (length of current shoot at distal position of lateral branch) and BUD (percentage of sprouting buds on a mother shoot) were also established. When the relationships between these 3 indices and fruit quality were studied at harvest, high quality fruits with sufficient enlargement, high sugar content and low acid content were often produced by vines showing low NIC, long SHT and high BUD. The indices presented here will be useful for producing high quality fruit in ‘Kyoho’ grape culture.
Effects of low light intensity due to shading during high and low temperature seasons on the flower-bud appearance and fruit setting of the parthenocarpic tomato ‘Renaissance’ were examined. The flower-bud development of ‘Renaissance’ was hindered by low light intensity due to 70% shading during the high temperature season, but the flower-bud developed normally expressed parthenocarpy. The seeded fruit rate and numbers of seeds per fruit of ‘Renaissance’ were increased by low light intensity due to 70% shading during the high temperature season. Furthermore, low light intensity due to 45% shading during the low temperature season did not influence the flower-bud development of ‘Renaissance’ and the parthenocarpic characteristics of ‘Renaissance’ were very strong. Accordingly we conclude that reducing the shading to the minimum is important to be developed the flower-bud normally during high temperature season for the purpose of improving the productivity of the parthenocarpic tomato ‘Renaissance’.
Seasonal changes in the light-saturated photosynthetic rate (photosynthetic capacity) were investigated for spur leaves of Japanese pear, using a portable open-chamber instrument. Preliminary tests demonstrated that the chamber should be ventilated at a rate of 500 μmol·s−1, and the photosynthetic photon flux density should be kept at 1,500 μmol·m−2·s−1, to evaluate the photosynthetic capacity. Moreover, all the measurements were conducted before 9:00 a.m., because the photosynthetic rate was found to decrease thereafter, the photosynthetic capacity of spur leaves reached maximum (15-20 μmolCO2·m−2·s−1) 30-60 days after flowering, then maintained that level until at, or just before harvest. The photosynthetic capacity gradually decreased after harvest, and then rapidly declined after October. The seasonal change in the mesophyll conductance was very similar to that in the photosynthetic capacity. Therefore, it is suggested that the photosynthetic capacity is mainly regulated by mesophyll activity. Our experiments demonstrated that the photosynthetic capacity of spur leaves of Japanese pear is maintained at a high level throughout the fruit-bearing period.
We investigated the effect of photoperiod on the flowering of small-flowered spray chrysanthemum cultivars with July- and August-flowering. As a result, all of the August-flowering cultivars showed summer-to-autumn flowering type response to the photoperiod. However, we found both summer and summer-to-autumn flowering type responses in the July-flowering cultivars. Based on their photoperiodic response to flowering, a July-flowering cultivar, ‘Hotaru’, showed habits similar to those of ‘Iwanohakusen’, a major summer-to-autumn flowering disbudded chrysanthemum cultivar in Japan. Based on these results, the flowering of ‘Hotaru’ could be manipulated by lighting without the influence from annual climate changes. Here, we propose that breeding and selection of small-flowered spray chrysanthemum cultivars with a ‘Hotaru’ type flowering response would be efficient for stable summer production of a selected cultivar in each color.
The peel color index and soluble solid concentration of ‘Koshisayaka’ pears after harvest increased during ripening at 20°C, while the flesh firmness, elasticity coefficient, viscosity coefficient and elasticity index of the fruit decreased. When the fruit reached the edible-ripeness stage 12 days after harvest, the values of those characteristics were 9.3 (peel color index), 12.7 Brix % (soluble solid concentration), 1.4 N (flesh firmness), 1.8 × 106 (elasticity coefficient) and 1.1 × 107 (viscosity coefficient). In addition, the elasticity indices that were calculated from the frequency of second resonance and the third resonance were 9.5 × 106 and 17.4 × 106, respectively. Film packaging of the pear fruit resulted in inhibition of moisture loss, yellowing of the peel, softening of the flesh and saccharification of starch during ripening. The characteristics of the film-packaged fruit 12 days after harvest were 3.7 (peel color index), 20% (potassium iodide reaction), 12.5 N (flesh firmness), 15.0 × 106 (elasticity coefficient), 15.0 × 107 (viscosity coefficient), 29.5 × 106 (Emf2) and 66.2 × 106 (Emf3). These findings clarify the ripening characteristics of ‘Koshisayaka’ pear fruit and the delaying effect of film packaging on fruit ripening. The delaying effect on fruit ripening is suggested to be due to decreased level of oxygen in film. Furthermore, the possibility of a nondestructive method for estimating the ripening stage is suggested by the correlation between the elasticity index and fruit softening.
After harvesting, lemon fruit are transported to packinghouses where they are sorted by size and quality. We measured the shock that lemon fruit received during all of the harvesting and processing stages in order to determine the causes of shock generation. Shock was measured using a “dummy lemon” that contained a shock sensor imbedded in formed polystyrene. It was found that lemon fruit received the most frequent and strongest shock at the packinghouses. The second highest amount of shock was received during harvesting, while the amount received during truck transportation was not especially high. The occurrence of shock exceeding 5 G during harvesting was primarily the result of handling by the farmers. This shock resulted from numerous factors, such as the height from which harvested lemon fruit are thrown into the collection basket, and the method used to transfer the lemon fruit from the collection baskets to shipping containers. Shock in the sorting line was mainly generated by gaps in the drying process, rotation drum for size sorting, gaps in front of the light sensor and falling from the sorting line to the boxing line. During weight sorting, which requires a longer brush washing time, the amount of shock sustained by the fruit was many times higher than that produced by the light sensor sorter. It is suggested that it is necessary to improve the sorting lines in order to reduce shock.
To study the relationships between compositional feature and food functionality of the cell wall components of fruit, profiles of cell wall components (cellulose, hemi-cellulose, pectic polysaccharides, lignin and non-extractable procyanidins) and food function (bile acid-binding and DPPH radical-scavenging activities) of 6 fruits (blueberry, pear, apple, Chinese quince, quince and hawthorn) were investigated. The composition of cell wall components and their concentrations varied with the fruit, and the bile acid-binding activity and DPPH radical-scavenging activity of alcohol insoluble solids (AIS) prepared from each fruit also varied. Especially with regard to DPPH radical-scavenging activity, lignin and procyanidin concentrations in AIS correlated strongly with the activity. These findings suggest that cell wall-bound phenolics are important components as a portion of dietary fiber for increasing their health beneficial function.