Six-year-old trees of‘Miyagawa Wase’, an early ripening satsuma mandarin, bearing various fruit loads under natural condition were selected (non-fruit-thinning tree group). Trees in almost the same range of fruit load as in the non-fruit-thinning tree group were obtained by thinning fruits on heavily loaded trees (fruit-thinning tree group). The influences of fruit load and fruit thinning treatments on the fruit character, flower bud formation in the following season and the other components were investigated.
1. The Brix of juice was higher with an increasing index of fruit load (No. of fruits per 10, 000 leaves) in the fruit-thinning tree group. However, the changes in Brix with increasing index of fruit load were small and the correlation between these two components was very low in the non-fruit-thinning tree group.
2. In the lower range of index of fruit load, the Brix of juice in fruit-thinning trees was lower than that in non-fruit-thinning trees which were similarly loaded. When fruits were mixed and classified by fruit size, the Brix of larger fruit was lower in both group. Also the Brix of fruit in the fruit-thinning tree group was lower than that of the same size fruits in the non-fruit-thinning tree group.
3. The more severe fruit thinning resulted in a lower Brix value independent of the fruit load in both groups of trees (the intensity of fruit-thinning treatment in non-fruit-thinning tree group was considered as zero percent).
4. Acid concentration of juice correlated positively with index of fruit load in both tree group. When fruits were mixed and classified by fruit size, the acid concentration of similar size fruit was almost the same in both group. Fruit thinning therefore, seems to have little affect on the acid concentration of juice.
5. The average weight per fruit decreased with increasing fruit load in both tree group, with no clear difference between the two tree group.
6. In the non-fruit-thinning tree group, the summer shoot leaves in that year sprouted considerably regardless of fruit load. There was less sprouting in the fruit-thinning tree group and this decreased with increasing fruit load, to almost no sprouting at a index of fruit load of above 600.
7. Trees of both groups having a low fruit load flowered abundantly much in the following year. The flowering in the fruit-thinning tree group was lower than that in the non-fruit-thinning tree group at similar fruit load. The flowering was insufficient to expect a normal yield at a index of fruit load of more than 550 in the non-fruit-thinning tree group, and more than 450 in the fruit-thinning tree group.

View full abstract

In 1967, two-year-old trees of‘Miyagawa Wase’, an early ripening satsuma mandarin, were planted at various planting densities and grown under different cultural treatments until 19 years old.
Planting densities were 1, 250, 2, 500, 5, 000 and 10, 000 trees/ha. Cultural treatments adopted were shallow plowing+less fertilization, or deep plowing+standard fertilization and non pruning+non fruit thinning, or pruning+fruit thinning.
The effect of planting density on fruit yield per unit area was determined from data obtained during the period from 1969 to 1984 (tree age from 4 to 19 years old). The effect of the cultural treatments on yield was also determined.
1. The yields of high density plots, 5, 000 and 10, 000 trees/ha, increased rapidly with tree age, and then started to decrease gradually. The yields of the lower density plots, 1, 250 and 2, 500 trees/ha, gradually increased in the early years, but soon exceeded those of the high density plots.
This trend was almost the same under all of the cultural treatments.
2. Planting densities which gave the maximum yield were 10, 000 trees/ha after 4-5 years; 5, 000 trees/ha after 6-7 years; 2, 500 trees/ha after 8-13 years; 1, 250 trees/ha after 14-19 years. The average maximum yield for the planting densities at each tree age (4-19 years old) was 68t/ha.
3. With non pruning+non fruit thinning, the trees allowed to bear the first crop showed the alternate bearing habit as early as the following year.
With the pruning+fruit thinning, the lower the planting density, the later the alternate bearing habit occurred.
4. The yield fluctuations from year to year were larger with the deep plowing +standard fertilization. There was no significant difference in the average yield between the two treatments.
The yield fluctuations were apparently larger with the non pruning+non fruit thinning than with the pruning+fruit thinning. The average yield was slightly higher in the former than in the latter.

View full abstract

Investigations were carried out in order to clarify the effect of root temperature on the budbreak, shoot growth and development of flower clusters of‘Muscat of Alexandria’vines. Six-year-old vines were grown in the greenhouse under confined rhizosphere conditions. Forcing was started on December 18. The air temperature was kept above 18°C and 4 plots were used with root temperatures adjusted to 13, 20, 27 and 20-27°C. In the 20-27°C plot, the root temperature was kept at 20°C for 18 days until the start of forcing and thereafter at 27°C. In addition to these plots, two treatments were set to see their effect on budbreak promotion; 1) the air temperature near the branches was kept at 25°C and 2) garlic juice was painted on the cane sections.
1. Budbreak began earlier at 27°C than at 13°C, and elongation of shoots and development of flower clusters was more active in the former. Growth at 20 and 20-27°C was similar to growth at 13 and 27°C, respectively. Differences in the percentage of budbreak among the plots were slight. However, the number of sprouted buds per arm was greater at 27°C than at 13°C. Rooting occurred first at 20-27°C followed by 27°C and 20°C. Rooting in these plots occurred before sprouting, while in the plot at 13°C it occurred 2 weeks after sprouting.
2. High temperature treatment of the branches as well as painting of garlic juice promoted budbreak. Garlic juice in particular showed a significant effect on budbreak in all the plots. At 27°C, cluster development was so conspicuous that fully developed florets were observed even at the top of the cluster, while at 13°C development of the cluster was depressed. At 13°C garlic juice was less effective on cluster development and few florets per cluster were observed.
3. There were no significant differences in the percentage of berry set, total sugar content and titratable acidity of berries at harvest among the plots. Although the temperature control of the rhizosphere was terminated 3 weeks after full bloom, berries at harvest were larger at 27°C than at 13 and 20°C.

View full abstract

The purpose of this study was to determine the accumulated chilling temperature necessary for sprouting of‘Muscat of Alexandria’(Vitis vinifera L.) grapevines. Mature grapevines in greenhouses were subjected to various cold temperatures at different times of the winter.
1. When the start of heating was delayed, which prolonged the duration of natural chilling, the accumulated temperatures from the beginning of heating to budbreak, as well as those calculated from November 21, were low. The accumulated temperatures were considerably decreased when vines were subjected to low chilling temperatures during the period from late November to late December. Thereafter, however, the low temperature did not reduce the accumulated temperatures.
2. The winter season from November 21 to February 28 was divided into 9 periods and the simple correlation coefficient between the mean temperature of each period and the accumulated temperature, which was summed up from the first day of each period to the day of budbreak, was calculated. The correlation coefficient was positive until early January but become negative thereafter. From November 21 to January 10, the lower temperature of each period contributed to a decrease in the accumulated temperature while after January 11, the higher temperatures caused the accumulated temperature to decrease.
3. Five periods were set from November 21 to January 10, and to each period was assigned a weighted seasonal factor. The hourly temperatures were collected to make a frequency distribution with a class interval of 2.5°C. A weighted chilling factor was given to each class of temperature, and the chill unit was then calculated as follows;
Chill unit=Number of hours of classified temperature
×Weighted seasonal factor
×Weighted chilling temperature factor.
A high negative correlation coefficient (r=-0.968) was recorded between the chill unit and the accumulated temperatures for budbreak. When heating was started on any day from early December to mid April, the chill unit was highly effective for predicting the accumulated temperatures from the beginning of heating to budbreak.

View full abstract

The relationship between ethylene biosynthesis and cyanide metabolism was investigated in apple fruit during their development and during storage after harvest. The rate of ethylene production and the activity of β-cyanoalanine synthase, which catalyzes the reaction between cysteine and HCN to form β-cyanoalanine, were very low in young immature apple fruit but increased markedly with the onset of ripening. At the same time, corresponding increases in the ACC and cyanide content were also observed, although the changes in the cyanide content were not so large. The rapid parallel increase in β-cyanoalanine synthase activity with the increase in ACC content and rate of ethylene production clearly demonstrates that an active cyanide metabolism begins to operate with the onset of ripening of apple fruit. Since the development of cyanide-resistant respiration has so far been recognized in ripening fruits, the active cyanide metabolism by β-cyanoalanine synthase may be involved in the development of the alternative pathway. The localization of cyanide in the tissues of apple flesh was tentatively investigated. Some component(s) which react with bromine to yield BrCN were found in the precipitated fraction of the apple flesh homogenate indicating that the cyanide is closely associated with membrane structures. Its function and subcellular localization are, though, not clear at present.

View full abstract

Changes in pectic substances and calcium during ripening of tomato fruits on vine and after harvest were followed.
(1) Firmness and viscosity of the ripening fruits decreased. Protopectine also decreased, while soluble pectine increased.
(2) The total Ca content in tomato fruits was almost the same at all stages of maturity. There was a marked increase in the water soluble fraction and decrease in the 1 N-NaCl soluble and 2%-acetic acid soluble fraction between breaker and light pink stages. The increase of the water soluble form of Ca was attributable to an increase of Ca²⁺
(3) ⁴⁵CaCl₂ solution was administered to tomato fruits through the peduncle at each ripening stage. In immature fruits, high specific activity was observed mostly in 2%-acetic acid soluble and 5%-HCl soluble fractions. The percentage distribution of incorporated ⁴⁵Ca in the water soluble fraction increased during ripening.
(4) After applying ⁴⁵Ca at the mature green stage, the tomato fruits were ripened off the tree. The specific activity of ⁴⁵Ca increased in the water soluble fraction and decreased in the 2%- acetic acid soluble fraction between mature green and breaker stages.

View full abstract

The composition of carotenoids in three different flesh colored watermelon cultivars was studied. The carotenoids were separated by column and thin layer chromatography and identified by order absorption affinities on the column and by their absorption spectra. The contents and kinds of carotenoids were as follows;
1. The red fleshed watermelon cultivar‘Asahiyamato’contained about 35-50μg/g lycopene as the major pigment; a small amount of xanthophylls and a slight amount of phytofluene, β-carotene, ρ-carotene and γ-carotene were present.
2. The major pigment in orange fleshed watermelon cultivar‘Kaho’was β-carotene (14μ/g); phytofluene, ρ-carotene, γ-carotene, xanthophylls and lycopene were also present in small amounts.
3. In the yellow fleshed watermelon cultivar‘Ogon, ’the main components was β-carotene (0.5μg/g) and xanthophylls(2μg/g); phytofluene and lycopene were detected in trace amounts.

View full abstract

In most cucumber cultivars, the proximal nodes (especially the first node) of the lateral shoots stably bear pistillate flowers and this is of great practical importance in the“pinching cultivation of cucurbits”where, to achieve yield of pistillate flowers from the proximal nodes, the primary lateral shoots are pinched, leaving only two or three nodes to enable the secondary lateral shoots to outgrow. The present investigation was carried out to clarify the mechanism of sex determination on the proximal nodes of the lateral shoots. The results, summarized below, indicate that the rigid sex expression on the proximal nodes of the lateral shoots appears under the influence of apical dominance.
1. The first node of the lateral shoots, which developed on up to the fifteenth node on the main shoots, stably produced pistillate flowers in all four cultivars of different genotypes, but the formation of pistillate flowers on the second to fifth node of the lateral shoots declined dramatically in three monoecious cultivars, except for a gynoecious cultivar, ‘Higan-fushinari’. However, a number of the lateral shoots which developed on the proximal location, the second to third node of the main shoots, produced staminate flowers even on the first node in monoecious cultivars.
2. When the lateral shoots of a monoecious cultivar, ‘Otone No. 1’were released from apical dominance as early as possible by pinching the main shoots under a stereoscopic microscope, the first node of the uppermost lateral shoots formed no pistillate flowers, although pistillate flowers are usually borne on those nodes in nonpinched plants. The production of pistillate flowers on the first node of the lateral shoots increased as the location of the node of the lateral shoots became farther from the pinching site on the main shoot.
3. When the main shoots of a monoecious cultivar, ‘Natsusairaku No. 3’were pinched just above the fifth, tenth or fifteenth node as early as possible, a number of the uppermost lateral shoots produced staminate flowers on the first node, whereas those of nonpinched plants regularly produced pistillate flowers. When pinching just above the fifth node was delayed until immediately after the fifth, tenth or fifteenth node became visibly detectable, there was a less pronounced effect on the production of staminate flowers on the first node of the uppermost lateral shoots.
4. A foliar spray of GA₄₊₇ and AgNO₃ to‘Otone No. 1’ at the 3-leaf stage caused the production of staminate flowers on the first node of the lateral shoots which had developed on the sixth to twelveth node of the main shoots, whereas pistillate flowers were produced on all those nodes in control plants. Silver ions had a greater effect on the modification of sex expression and also caused a substantial production of bisexual flowers on the first node of the lateral shoots.
5. Simultaneous treatment of GA₃ or CEPA with pinching strongly modified the pinching effect on sex expression. GA₃ promoted the pinching effect, increasing the production of staminate flowers on the first node of the uppermost lateral shoots, while CEPA increased the production of pistillate flowers, nullifying the pinching effect.

View full abstract

Asatsuki is a bulbous Allium species and is cultivated for its edible leaves, which are harvested in late winter and early spring. Asatsuki grows from autumn to spring and dies down after producing dormant bulbs in early summer.
Innate dormancy of roots of asatsuki bulbs ended in early July, and that of leaves in early August. However, hot summer temperatures of 25°Cor higher inhibited rooting and sprouting of the bulbs in the field, so that the bulbs rooted from early August onwards and sprouted from late August onwards.
Optimum temperatures for root growth after rooting were 21 to 25°C, and those for leaf growth after sprouting were 17 to 25°C.
After termination of innate dormancy, root growth activity (which comprises rooting and root elongation after rooting) and leaf growth activity increased gradually; the former reached a maximum in late August and the latter in mid-September. Asatsuki plants grew vigorously in September and early October. During this period the mean air temperatures are close to the optimum temperatures for growth.
After reaching their maxima, both growth activities decreased; root growth activity reached a minimum in mid- or late October and leaf growth activity in mid- or late November. Thus, growth was suspended in late autumn. In early or mid-December root growth activity began to increase again and in early January leaf growth activity began to increase again. Root growth activity reached a maximum in February and leaf growth activity in mid-March. In late January some plants initiated storage leaf primordia, but the plants appeared to be in a state of imposed dormancy until early spring.
Roots resumed growth in, late March but in mid-April rooting activity was lost and there was no increase in root weight per plant from mid-April onwards. Leaves resumed slow growth in early or mid-March, but vigorous growth of leaves did not occur until after the continuous snow cover had melted off (in early April). Leaf growth activity almost ceased in late May, and growth of tops ceased in late May. All storage leaf primordia were initiated by mid-April and those developed into cloves. The cloves grew rapidly from mid-April to mid-June. Browning of tops and dying of roots progressed rapidly from mid-June onwards, so that tops had almost died down by late June.
Leaf and root growth activities varied considerably from month to month (except for the dormant summer months). Growth activities became extremely low during late autumn and early winter, and asatsuki plants hardly grew at any temperatures between 9 and 25°C, showing that the plants were in the state of innate dormancy. Accordingly, it is concluded that asatsuki plants fall into innate dormancy twice a year, both in summer and in late autumn or early winter. However, the late autumn (or early winter) dormancy was not so deep as the summer dormancy. It is assumed that cool temperatures in October induced the late autumn dormancy in asatsuki plants.

View full abstract

Cymbidium goeringii Reichenbach fil. and Cymbidium kanran Makino are native Cymbidia of Japan and are important Oriental terrestrial orchids. When their shoot-tips are cultured, rhizomes are formed. Factors affecting rhizome formation were discussed in this paper.
1. Culturing of shoot-tips of Cymbidium goeringii at intervals of 2 months showed that rhizomes could be formed at any time throughout the year. However, rhizome formation depended on the starting time of cultures and the culture media. Maximum rhizome formation occurred in April when cultured in either MS or RM media both containing 1ppm NAA and 0.1ppm kinetin, and in June by culturing with modified Cymbidium-culture medium (Hyponex medium) devoid of plant growth regulators.
2. Culturing the shoot-tips of Cymbidium goeringii in darkness at 25°C hastened rhizome formation, and increased rhizome formation to almost twice the level obtained under conventional culture conditions with artificial illumination for 16 hours.
3. RM medium containing 1/5 concentration of inorganic components and 10% coconut water was found to be suitable for shoot-tip culture of Cymbidium kanran.
4. When shoot-tips of Cymbidium kanran were cultured in agitated liquid medium, all explants died.
5. The use of plant growth regulators was found to have no effect in cultures of Cymbidium goeringii and Cymbidium kanran.

View full abstract

To determine the optimum range of N in the medium for normal growth, in particular to establish the lower critical level, the chrysanthemum plants were grown on soil media and nutrient solutions with various concentrations of N.
In an experiment with soil media (Expt. I), the plants were supplied with 12.5, 25, 50, 100, 200 and 400g of NO₃-N per m³ soil on July 14, 1985, 16 days after pinching, and were grown for 15 days, receiving a small amount of liquid NO₃-N every day. All plants initially supplied with 12.5-50g/m³ N grew well, but higher levels of N inhibited growth.
In Experiment II, the plants were grown on nutrient solution at 50, 100, 200 and 300ppm of NO₃-N for 16 days from the 15th day after pinching (Aug. 12, 1985). Another group of plants did not receive N for the initial two days, and then on every other day they received the same amount of NO₃-N as absorbed by the plants receiving 100ppm during the previous two days. In that case the N concentration was maintained at 0-21.1ppm. The N level of the nutrient solution had no effect on the rate of plant growth. Even at a concentration of 0-21.1ppm the plants grew vigorously, and two days later their fresh weight reached the same level as that of plants grown at 100ppm.
When the plants grew normally, the N level of the medium did not affect the concentration of N in the plant tissue, but at higher N levels, which inhibited growth, the concentration of N in the tissue increased.
From these results, it can be concluded that the optimum range of N in the medium for normal growth of chrysanthemum plants is relatively wide, and that the lower critical level is very low. Normal growth can be achieved if the plants steadily receive as much N as they absorb.

View full abstract

The chromosome numbers in fifty-eight cultivars of Camellia vernalis MAKINO and fifty-six open-pollinated seedlings from those cultivars were studied in an attempt to understand the process of varietal differentiation of C.vernalis group.
For those cultivars whose chromosome number had already been reported, exactly the same results were obtained. Among the other cultivars, 2 triploids (2n=45), 1 tetraploid (2n=60), and 2 pentaploids (2n=75) were newly obser ved.
Some of the seedlings gave good results, consistent with Tanaka's hypothesis on classification of C.vernalis, for chromosome numbers and morphological characters of flower and leaf, but many others had different chromosome numbers which did not agree with the hypothesis. Various polyploids were also derived from the basic chromosome number (X=15) of the genus Camellia; in particular, a wide variation was observed, from triploid to decaploid (2n=150), within the seedlings from triploids that hardly ever set fruit. As for the seedlings from pentaploid and hexaploid cultivars, they showed to be hexaploids and heptaploids (2n=105), respectively.
These results indicate that the variation of C.vernalis has been extended within the relatively short time since an F₁ hybrid was produced between C.sasanqua THUNB. and C.japonica LINN.

View full abstract

The present study was carried out to improve the method of removing astringency from persimmon fruits by ethanol. Experiments to remove astringency on a large scale within a short period were performed by packing the fruits into well-ventilated plastic containers, stacking the containers in the de-astringency room and heating the room to about 30°C while adding ethanol.
1. It was necessary to insulate the de-astringency room using insulations such as urethane foam 25mm or more in thickness.
2. The addition of ethanol was accomplished by introducing an ethanolic solution into the de-astringency room at a given rate of flow and vaporizing the ethanol with a sufficient amount of air passed. The amount of ethanol penetrating into fruits reached about 80% of the added ethanol.
3. The room was heated by a composite unit of blower and heater, which had a surface temperature of lower than 200°C. Fruit temperature was increased to around 30°C within 1 day after heating started. In order to prevent the development of peel discoloration, the differences in heating rates throughout the load needed to be kept as slight as possible.
4. Ethylene treatment had a strong effect on hastening the ripening of fruits which became non-astringent within a short time. Fruits treated with ethylene produced good marketing qualities such as a melting flesh texture and a sweet taste.
5. The fruits receiving the 3-day de-astringency and ripening treatment using a manufactured equipment were graded, packed and shipped to market. There was no significant difference in market value between these treated fruits and those which became non-astringent after about 2 weeks using a conventional method.

View full abstract

Effects of dropping and vibration received during distribution process on the volatiles accumulated in satsuma mandarin fruit were studied. Gas chromatograms of volatiles from extracted fruit juice were analyzed by principal component analysis (PCA). Results obtained are as follows:
(1) Gas chromatography gave ten major peaks of volatile components within 30 minutes of retention time. Of these, ethanol is the most predominant, accounting for 80% of the total peak area, followed by acetaldehyde.
(2) In dropped fruit, volatile components such as ethanol, acetaldehyde, and others are accumulated. The same tendency is also observed in vibrated fruit. However, the accumulation in the fruit is not so appreciable as that in dropped fruit.
(3) Gas chromatograms were analyzed by the PCA, in which peaks from 1 to 6 on the gas chromatogram were used as independent variables. Consequently 80% of total information of the gas chromatogram data can be interpreted by the first (Z 1) and the second (Z 2) principal component.
(4) The first principal component indicates the amount of volatiles while the second one shows the relative contribution of each component.
(5) Dropped and non-dropped fruits are clearly discriminated between in the plane with axis of Z 1 and Z 2. Also, fruit dropped 30 times can be distinguished from fruit dropped less than 20 times. However, there were no differences between vibrated and non-vibrated fruits.
(6) The effect of dropping on the volatiles of fruit juice is more significant than the effect of vibration.

View full abstract

With the purpose of utilizing tropical and substropical fruits more effectively, abundant polyphenols found in guava (Psidium guajava L.) fruit and leaves were examined seasonally in both qualitative and quantitative aspects.
1) The method reported by Peri and Pompei was recognized to be highly useful for determining various polyphenols in crude extracts of guava.
2) Young guava fruit (picked on 18th August and weighting 2.9g) contained 620mg of total polyphenols per 100g fresh weight and 68% of the polyphenols was shown to be condensed tannin. Ass the fruit grew up, their contents of condensed tannin decreased remarkably.
3) Proanthocyanidin levels in the guava fruit also decreased with the increase in fruit weight from August to October.
4) Gel permeation chromatographic analyses of polyphenols suggest that high molecular weight polyphenols of more than 14, 000 disappeared with fruit development.
5) The polyphenol level of guava picked on 3rd August was about 10 times that of young fruit (picked on 18th August) and 84% of the total polyphenols was found to be condensed tannin. The levels decreased markedly at the late of August.
6) (+)-Catechin and (+)-gallocatechin were identified by a reversed phase HPLC in the extracts of guava fruit and leaves.
These results indicate that a large percentage of polyphenols in guava fruit and leaves is a type of flavans, especially proanthocyanidin heteropolymers that are composed of (+)-catechin and (+)-gallocatechin, and these compounds decrease remarkably at the early stage of fruit development or at the late of August in the leaves.

View full abstract