Experiments were carried out to obtain further information about self-incompatibility in Hyuganatsu, Citrus tamurana hort. ex Tanaka. The results obtained were as follows. 1. Using disc electrophoresis, sequential changes in buffer soluble proteins and peroxidase isozymes in self-pollinated pistils were compared with those cross-pollinated with Hassaku, Citrus hassaku ex. Tanaka. Remarkable differences in the band distributions of buffer soluble proteins were observed in samples from stigmas, styles and ovaries at any time within 24 hours after pollination. Differences in peroxidase isozyme distributions between self-and cross-pollinations appeared first in the ovaries, second in the styles and last in the stigmas. 2. Several treatments were tried in search of an effective method of overcoming self-incompatibility. Self-pollination after smearing the stigma exudate of mature Hassaku flower buds onto the stigmas of immature Hyuganatsu flower buds, half the length of mature ones, was found to be the most effective of the treatments tried. Repeated pollination of immature flower buds for 4 continuous days was nearly as effective as the preceding treatment. With both treatments, a number of small seeds, 1/3 size of normal ones, developed; these might be expected to be seedless triploids.
These investigations were carried out from 1973 to 1977 in order to clarify the conditions of occurrence and the quality of “yellowish fruit” in crops of satsumamandarins, because of the problems raised by their occurrence in recent years in Nagasaki. 1. The “L” and “b” values for the rind surfaces of yellowish fruit as measured on Color-Difference Meter were higher than for those of “reddish”, but the “a” values were lower. The ranges of “L”, “a” and “b” values were 60-63, 17-20 and 34-38, respectively for yellowish fruit, and for reddish fruit, 56-60, 22-27 and 32-37, respectively. 2. The juice of the yellowish fruits was lower in sugar content and higher in acid content than that of the reddish ones, and the proportion of small yellowish fruit below “S” size was greater than that of small reddish fruit. The rind surface of the yellowish fruit was smooth, less susceptible to injury, and showed a lower occurrence of puffing and wilting during storage. 3. The ratio of yellowish fruit in the packing house ranged from 10% to 30%, varying according to the year and the regions. 4. The occurrence of yellowish fruit in the lower part of the bearing area of the tree crown was greatest, especially that on the hill side of the tree. A relationship was found to exist between the occurrence of yellowish fruit and light intensity. 5. There was a quantity of yellowish fruit in light-deficient orchards facing north-east. 6. It was concluded that yellowish fruit was less colored, smaller fruit produced in the inner or lower parts of the tree crown, and that its occurrence depends largely on light conditions in the bearing part of the tree crown.
An attempt was made to clarify the processes and mechanisms which bring about changes in acid concentration during fruit growth by comparing various strains. The results obtained are as follows: 1. The period of maximum free acid concentration for Sugiyama was earlier than that of Imamura and equal to Miyagawa. Thus, the period of maximum free acid concentration seemed not to correlate well with the difference between wase unshiu (Miyagawa) and futsu unshiu (Sugiyama and Imamura). 2. The concentration of combined acid was comparatively high in young fruit pulp, but remained at a fixed value as the fruit matured. No differences in combined acid concentration attributable to the variation of strains were found. There fore, differences in total acid concentrtion among the various strains were mainly brought by variations in free acid concentration. 3. The total amount of free acid per pulp increases with fruit growth to reach a maximum, after which a steady decrease was observed. This clear decrease in total free acid may be a specific feature of the satsuma mandarin which has the earliest maturing in the genus Citrus. 4. The total amount of combined acid per pulp increased throughout the fruit development, and no differences were found in total combined acid when comparing the various strains. 5. The fact that wase unshiu synthesize less free acid in young fruit, and total amount of free acid per pulp begins to decrease earlier than in futsu unshiu may explain the fact that the acid concentration of wase unshiu fruit decreases earlier. Differences in free acid concentration between Sugiyama and Imamura, both of which belong to futsu unshiu, were attributable to differences in the acid synthesis. The acid in Imamura was synthesized at a higher rate and for a longer period than that of Sugiyama. This may explain the fact that the acid concentration of Imamura fruit decrease latest among the futsu unshiu fruits.
The first rapid increase of organic acid concentration in very young satsuma mandarin fruit (C. unshiu Marc.) may be related to transformation of sugars into malic acid via the addition of CO2 to pyruvate. The decrease in organic acid concentration after the maximum is caused by both the dilution from fruit enlargement and an actual reduction in the absolute amount of citric acid. Differences in the characteristics of maturity among strains of satsuma mandarin are associated more with changes in the absolute amounts of citric acid in the pulp than with its concentrations. The late-maturing Fukuhara attained a maximum in its absolute amount of citric acid later in the season than the early-maturing satsuma strains.
Seasonal changes in the mean values of solar radiation, air temperature and fruit temperature for a ten day period were measured at different locations on satsuma mandarin trees (Citrus unshiu Marc. var Sugiyama) of the open center and hedgerow formes during the period from late-July to mid-December in 1976 and 1977. And the correlation between cumulative solar radiation, cumulative air temperature and cumulative fruit temperature were investigated. The results are given as follows. 1. Each location on the open center form tree was grouped into four, according to the seasonal changes of mean flux of solar radiation, expressed as the mean of each ten day period. The south side and top of the west side were continuously exposed to the highest amount of solar radiation. The tops of the east side and north side were next, and were followed by the skirt of the east and west sides. The skirt of the north side and interior received the lowest amount of solar radia tion. This suggested that the south side and the tops of the east, west and north side were more strongly exposed to direct solar radiation than the skirt of the north side and interior. Each location on the hedgerow form tree was grouped into three. The tops of the east and west side belonged to the highest group. The skirt of the east side and all of the west side were in the intermediate group, and the interior was in the lowest group. The mean air temerature for ten days of a month was almost the same in all locations of both form trees. And for the open center form tree, the cumulative air temperature in the interior and top of the west side were higher than those for all of the north side and the skirt of the west side. The mean fruit temperature for ten days of a month was generally higher at the top locations than at the skirt locations in the canopies of both form trees. The cumulative fruit temperature was high at the tops of south and east side, and was low at the skirt of north side. 2. In both form trees, the regression coefficient of the cumulative solar radiation to the cumulative fruit temperature was low at the location with high solar radiation flux. A high positive correlation coefficient was also found between cumulative solar radiation and cumulative fruit temperature. The regression coefficient of cumulative solar radiation to cumulative fruit temperature was higher in the open center form tree than in the hedgerow form tree. This suggested that the fruit temperature was more strongly influenced by solar radiation in locations with thick leaf layers than in other locations. 3. The regression coefficient of the cumulative air temperature to the cumulative fruit temperature tended to be higher at locations exposed to direct solar radiation. At such locations, the cumulative fruit temprature was influenced much more by the cumulative air temperature. On the other hand, the regression coefficient was lower in the interior. This suggested that the fruit temperature in the interior was influenced more strongly by solar radiation than by air temperature.
Two methods of injecting phosphorus into the trunks of citrus trees, which we termed the “ringer-injection method” and the “pressure-injection method”, were studied using 14-year-old satsuma mandarin trees. 1. Only abut 60ml of a 0.1M-KH232PO4 solution was incorporated into a tree after 30 days by the ringer-injection method. Five hundred and twenty milliliters of a 0.1M-KH232 PO4 solution were pressure-injected by application of 5kg/cm2 for 3 days, and 750_??_1, 000ml of a 0.2M-KH2PO4 solution were injected by application of 10kg/cm2 for about 1 day, in field tests. 2. The phosphorus concentration in the pulp and leaves of the tree injected with 0.1M-KH232PO4 by application of 5kg/cm2 for 3days respectively increased by 7% and 64% after 1 week. However, 8 weeks later, the phosphorus concentration in the pulp had increased by 19%, while that in the leaves had decreased to 43%. 3. The phosphorus concentration in the leaves of the trees injected with 0.2M-KH2PO4 by application of 10kg/cm2 for about 1 day increased by 113% after 1_??_2 weeks.
Application of SADH at 2, 500ppm to clusters alone of Kyoho grape 25, 18 or 11 days before full bloom significantly increased the number of seeded berries per cluster but no influence on it was detected when applied 4 days before full bloom. The latest treatment, however, considerably increased the number of seedless berries per cluster and the application 11 days before full bloom also had a tendency to increase it. When CCC was applied at 200ppm to clusters alone of Muscat of Alexandria grape from about 25 days before full bloom to just after full bloom in the successive experiments for 3 years, the applications from about 25 to 10 days before full bloom consistently increased the number of set berries most of which are supposed to be seeded. Moreover, the number of seeds per berry significantly increased with the increment of berry number per cluster in Muscat under the influence of CCC applications in the 1st year′s experiment but it did not necessarily increase in the following 2 years. None of the CCC applications to clusters at different times before anthesis had detectable effect on shoot elongation measured just after full bloom through the 3 years′ experiments. The applications of SADH to clusters before anthesis, particularly the early applications significantly depressed floret (berry) growth in weight at blooming and setting stages in Kyoho but the applications of CCC during the similar period did not show such clear effects on it in Muscat. The activity of cytokinin in florets at the beginning of bloom and soon after full bloom tended to be raised by the early applications of SADH in Kyoho though such a consistent effect was not found in the gibberellin activity. All of the applications of SADH at different times before anthesis increased the amount of protein-N and total N in florets and on the contrary decreased the amount of reducing sugar and total sugar in them when measured soon after full bloom. The early applications of CCC in Muscat also exhibited similar effects on these components in florets (berries) sampled 2 and 9 days after full bloom. Based on these and other evidences, the mechanism of the promotive effect of growth retardants on the set of grapes is discussed.
In order to clarify the mechanism of the growth of an apple shoot, the authors aseptically cultured shoot apices (about 0.5mm in length) on an agar medium con taining Murashige and Skoog′s inorganic and organic substances. The effect of growth regulators and sucrose on the growth of the shoot apex was investigated. The results are summarized as follows. 1. The effect of α-Naphthaleneacetic acid (NAA) was not observed in the differ entiation and elongation of leaves, and the growth of the shoot apex was inhibited by high concentration of NAA. 2. The differentiation and elongation of leaves was enhanced on a culture medi um with N6-benzyladenine(BA), whereas the length and number of leaves increased according to the increase in BA concentrations within a range of 0.01 to 10μM. The apical shoots cultured on a medium with BA continued growing for six weeks. The number of leaves differentiating at 10μM BA was three fold, and the length of the longest leaf was seven fold as large as those of control respectively. 3. Gibberellic acid (GA) had no effect on the internode elongation, but enhanced the differentiation and elongation of leaves. However the effectiveness of GA became stronger with the increase in concentration within a range of 0.01 to 0.1μM, and was observed slightly at above 0.1μM. But the differentiation and elongation of leaves was not enhanced by prolonging the culture period beyond four weeks. Therefore, it seemed that GA affects the growth of shoot apices within four weeks. 4. In treatment of BA combined with NAA, the effectiveness of BA on the differentiation and elongation of leaves was observed at higher concentrations of NAA, suggesting that the effect of NAA was antagonistic to that of BA. 5. No callus formation was obtained on a media containing NAA, BA or GA alone, but under treatment of both BA and NAA callus formation was observed remarkably. The induction and growth of callus increased with the increase of concentrations of both NAA and BA. 6. The differentiation and elongation of leaves was inhibited by decreasing the sucrose concentration regardless of BA concentration. It is considered that sucrose is a limiting factor of the differentiation and elongation of leaves.
Cambial tissues from the twigs of a mature Japanese persimmon, Diospyros kaki Thunb, cv. ′Tsurunoko′, were used as the starting material in this experiment. Callli were induced on various callus induction media. Root formation in the calli was observed on Murashige and Skoog′s medium containing 1ppm NAA. KIN in combination with NAA did not inhibit to the root formation at 1ppm. Root formation in the callus depended largely on the type of medium on which the callus was isolated and subcultured and the number of successive subcultures on a given medium. When the callus was isolated on Murashige and Skoog′s medium containing NAA and KIN, roots were formed in the first passage, whereas when the callus was isolated on Murashige and Skoog′s medium containing 0.1% yeast extract or 0.1% phytone, NAA, and KIN, the first root formation was not observed until the callus was subcultured on the medium several times. Roots were never formed in calli which were isolated and subcultured on Murashige and Skoog′s medium containing 2, 4-D or IBA instead of NAA, nor were either Wolter and Skoog′s medium or a modified Wolter and Skoog′s medium containing NAA and KIN suitable for root formation. Bud initials were formed in callus which was subcultured several times on Mura shige and Skoog′s medium containing NAA and KIN. KIN was effective in promoting bud initiation in combination with NAA. These initials turned green under continuous light conditions, but they did not succeed in developing themselves into plantlets on various media. Abnormal structures were initiated in callus cultured on Murashige and Skoog′s medium containing NAA and KIN, but these structures were not identifiable as either root or bud initials.
In order to make comparison among vegetables in growth response to nitrogen source and accumulation of NH4-N and NO3-N in leaves, potato, carrot, radish (Raphanus sativus L. radicula group), turnip, and japanese radish (Raphanus sativus L. daikon group) were cultured in nutrient solution containing NO3, NO3+NH4(1:1), NH4, NO3+NO2 (1:1), and NO2 as nitrogen sources. The experiment consisted of 4 kinds of treatment conditions where 2 levels of nitrogen concentration (2meq/l designated as low-N and 12meq/l as high-N) and 2 levels of solution pH (5 and 7) were combined. Plants were grown under each treatment for about 3 weeks. 1. All root vegetables fertilized with NO3 and NO3+NH4 showed normal appearance with healthy leaves and grew well under all treatment conditions. The growth of root (edible portion) was often considerably better under NO3+NH4 than NO3 nutrition. 2. When plants were supplied with NH4, the top growth of potato and carrot was relatively good and the NH4-N concentration in their leaves was low. On the contrary, the top growth of turnip and japanese radish was inhibited extremely in NH4 nutrition and the NH4-N concentration in their leaves was high. The highest NH4-N concentration, however, was detected in leaves of radish which showed intermediate growth between aforesaid 2 groups. The concentration of NH4-N in leaves of plants which showed markedly restricted growth in NH4 was a few times as much as the concentration of amide-N. 3. Nitrite toxicities were more intensive under lower solution pH and higher N concentration. The difference of growth response of root vegetables to nitrogen sources was not clear under NO3+NO2 or NO2 nutrition. 4. The concentration of NO3-N in leaves was scarcely affected by solution pH but was affected markedly by N forms and levels in nutrient solution Under high-N treatment, the concentration of NO3-N in leaves of turnip and japanese radish was more than 2% on a dry weight basis. The concentration of NO3-N in leaves of NO3+NH4 plants was, in general, lower than NO3 plants under low-N treatment, while no difference was detected between them under high-N treatment. Apparently low NO3-N concentration was detected in roots(edible portion)as compared in leaves.
Effects of the storage period and fruit portions on the resistivity of ‘Kokko’ apples to impact and compression were investigated. 1. In the fruits stored for 2 to 3 weeks, the mechanical injuries caused due to impact by dropping onto the board from the height of 5-10cm, or compression by loading to 20kgW at a speed of 2mm/min, seemed to be alleviated. However, in case the impact was given by dropping fruits from the height of 30-50cm, no differences of injuries were observed among the lots with different storage periods. 2. The resistivity to mechanical injuries showed some relation with the percentage of permanent deformation, but not with fruit stiffness or the flesh firmness within the scope of this experiment. 3. Concerning the resistivity of fruit portions to impact, cheek, equatorial portion of fruit was somewhat susceptible compared with calyx and stem ends.
The resistivities to impact and compression of Japanese pear, ‘Kikusui’ and Chojuro and oriental persimmon, ‘Fuyu’ were investigated. 1. As for resistivity of ‘Kikusui’ pear to compression, fruts were injured more severely as the fruit stiffness lowered 15 days after storage at 20°C. How ever, the resistivity to impact was not connected with flesh firmness. 2. ‘Kikusui’ fruits were more sensitive than ‘Chojuro’, to impact and compression. 3. Concerning the impact position on the fruit, ‘Kikusui’ fruits were apt to be injured more severely at the stem end of fruit. 4. In ‘Kikusui’ pears, shapes of bruised portions by impact were different from those by compression. In both cases, however, fleshy tissues immediately under the skin were very sensitive to bruising. On the other hand, shapes of bruised portions in persimmon changed with fruit maturation, and fleshy tissues immediately under the skin were not injured except those of overripe fruits. 5. When ‘Fuyu’ fruits were dropped onto a hard board 2.7cm thick from the height of 20cm, the allowable flesh firmness for resisting impact injuries with sodden brusises was about 15lb. by Magness-Taylor pressure tester with 5/12 in. diameter plunger. In case fruits were loaded to 20kgw at a speed of 2mm/min by Instron material testing machine the allowable fruit stiffness for resisting compressed injuries was about 2.3-2.4kg/mm.
Recently interest has increased in strawberry fruits harvested at the full-ripe stage (complete coloring) and shipped at low temperature to obtain strawberry fruits with higher quality. The present experiments were designed to study the influence of ripening of strawberry fruits upon their quality. The ripe stage was determined by color development. Strawberry fruits were harvested at various stages of coloring: quarter-colored, half-colored, three-quarters-colored and fully-colored. The quality of fruits harvested at the various stages was determined on the basis of anthocyanin content, total sugar, titrable acidity, total ascorbic acid and firmness. Four studies were made, in January, February, March and April. Two cultivars, ‘Hokowase’ and ‘Donner’ were used as material. A relationship between fruit coloring and quality was found. As fruit color deepened, anthocyanin content and the sugar-acid ratio increased markedly, and the fruit tissue became soft. Total sugar and total ascorbic acid content increased slightly, and titrable acidity decreased slightly, during color development. In fruits harvested on January 18 and February 21, respectively, the correlation coefficients between the anthocyanin content and the sugar-acid ratio gave correlations of -0.61 and -0.69, regression of anthocyanin content vs. total sugar gave correlations of -0.28 and -0.48, and anthocyanin content vs. titrable acidity gave correlations of -0.62 and -0.12. Further experiments were designed to simulate conditions in transportation and distribution facilities. Strawberry fruits were harvested at the fully-colored stage and held at 3°C for two days, or at the half-colored stage (conventional maturity for shipping) before being held at room temperature (15-20°C) for two days. Their taste was tested by 100 panelists, and other quality changes were again determined by measuring total sugar, titrable acidity, total ascorbic acid, anthocyanin content and softness. These experiments were carried out three times (in March, April, and May). The taste of strawberries harvested at the fully-colored stage and held at 3°C was judged to be superior to that of those harvested at the half-colored stage and held at room temperature. Sixty-eight %, 91%, and 65% of the panelists attested the superiority in sweetness and freshness of fruits held at 3°C in taste tests in March, April, and May, respectively. Fruits held at 3°C for two days contained 5.67% total sugar and 0.42% titrable acidity, whereas those held at room tern perature for two days contained 4.9% total sugar and 0.55% titrable acidity. However, there was no difference in total ascorbic acid and anthocyanin content between the two groups. The fruits which were harvested at incomplete coloring colored completely during storage at room temperature for two days, but total sugar content scarcely increased, and titrable acidity decreased but little. In test simulating transportation conditions, bruising was found in less than 20% of the fruit held at 3°C, whereas bruising occurred in more than 50% of the fruit held at room temperature.
The physical behavior under drop impact of the fruits of tomato for processing was investigated to elucidate the resistivity of the fruits against impact load. 1. Impact force and impact energy accompanied by the dropping increased with increasing drop height or fruit weight. The impact energy was relatively large in the varieties of oblate fruits (H-1409, Kagome 70, ES-58) and the smallest in those of pear-shaped fruits (Super Roma V.F., Chico) among the examined varieties. 2. The hardness of the fruits was decreased by suffering the drop impact, and the decrease in the hardness became pronounced with an increase in impact. The degree of deformation accompanied by impact was distinguished in the varieties of round or oblate fruits, whereas it was not distinguished in those of pear-shaped or lengthy fruits. 3. The frequency of occurrence of injured fruits increased with increasing drop height. The damage index of the fruits increased with increasing fruit-shape index and fruit weight. The critical impact energy for the occurrence of injured fruits was comparatively high in Chico, AT 70/24, and Super Roma V. F. among the examined varieties. Accordingly, the resistivity against impact load was higher in the varieties of pear-shaped or lengthy fruits than in those of oblate or round ones. The resistivity of each variety decreased with a progress in maturity of fruits.
Ripening characteristics of mume (Japanese apricot, cv. Nanko) fruits on and off the tree were investigated from the pit-hardening stage to the fully-ripe stage. To study ripening off the tree, fruits were picked at four stages of development and stored at 20°C. Climacteric patterns were observed in the carbon dioxide production rate of fruits both on and off the tree. In fruits ripened off the tree, earlier onsets and a higher maximum values of the climacteric were observed as harvesting time was delayed. The rate of ethylene production in attached fruits remained below 0.1μl/kg•h until the first yellow coloring appeared on the skin surface, and then increased rapidly to reach a maximum value above 500μl/kg•h at the fully-ripe stage. A similar rise in ethylene production occurred during ripening in detached fruits, in which case production began earlier and reached a higher peak value as harvesting time was delayed. The free abscisic acid content of attached fruits increased rapidly after the skin color yellowed. In detached fruits, abscisic acid also increased once, after harvest, and then decreased, but levels were considerably lower than those in fruits ripened fully on the tree. Sucrose content showed a steady increase until fully-ripe stage in fruits on the tree, and a similar rise in detached fruits, to a lesser extent. The concentrations of fructose, glucose, and sorbitol in attached fruits also increased as the fruit ripened, but in detached fruits concentrations slowly declined after harvest. A linear increase in citric acid and, contrarily, a linear decrease in malic acid was found in attached fruits from the pit-hardening stage to the fully-ripe stage, which caused a slight change in total acidity. Similar trends were observed in detached fruits, where citric acid increased until some time after picking, whilemalic acid was steadily declined during ripening. It seems that the internal preparations for ripening of mume fruits are complete at the pit-hardening stage, after which detached fruits show a ripening pattern similar to that which occurs on the tree, and that ripening is more rapid as har vesting time is delayed.
The changes in respiration rates, ethylene production, internal ethylene concen trations and flesh firmness were investigated during the maturation and ripening periods of pear fruits, using 3 species and several cultivars, as follows: Pyruscommunis L. var. sativa DC. (Bartlett, La France and Winter Nelis), Pyrus serotina Rehd. var. culta (Yakumo, Nijisseiki, Niitaka and Kikusui), Pyrus ussuriensis Maxim. var. sinesis Kikuchi (Ya-li, Rai-Yan-Tsu-li and Auto-li). The fruits were picked 2-3 times at different stages of maturity and stored at 20°C. 1. Three cultivars of P.communis, Bartlett, La France, and Winter Nelis showed a typical climacteric pattern of respiration. Respiration and ethylene production in both La France and Winter Nelis were much lower than in Bartlett. 2. Among P.serotina, Yakumo and Kikusui fruits picked at two different stages of maturity showed a rise in respiration; respiration didn′t rise in Nijisseiki and Niitaka fruits picked at commercial harvest maturity, but did in fruits picked at the immature stage. Ethylene production in Yakumo increased with rising respiration, but the other 3 cultivars maintained a very low level of production during the experimental period. In Nijisseiki, exogenous ethylene treatment caused a rise in respiration immedi ately after picking. This effect continued only in the presence of exogenous ethylene, and could be reproduced in the same fruit when re-treated with ethylene after a month of storage. It was concluded that Yakumo and Kikusui can be classified as climacteric fruits, while Nijisseiki and Niitaka are non-climacteric fruits. 3. Three cultivars of P.ussuriensis; Ya-li, Rai-Yan-Tsu-li and Auto-li showed a typical climacteric accompanying a rise in ethylene production.