In the first paper of this series, highly significant correlations were reported between hours of sunshine and diurnal increment of growth throughout the later stages of fruit development. Such a fact was confirmed with the results obtained on days of different hours of sunshine by comparing the diurnal increments of growth at each stage of fruit development. The present paper, however, deals with the results obtained by comparing the diurnal increments of growth on a given day at each stage of development. Cumulative effects of sunshine on the size and organic constituents of fruit were simultaneously examined. The fruit-bearing branches of mature Nijusseiki pear trees remained covered with cheesecloth, then diurnal fluctuations of fruit diameter under the screens and in normal sunlight were compared. The results obtained are as follows: 1) Prior to July, diurnal fluctuations (both growth and contraction) were considerably depressed by artificial shading. In and after August, however, seasonal pattern of diurnal fluctuation was altered, that is, the artificially shaded fruits exhibited the fluctuation pattern of Stage II though the fruits in full sunlight already showed the fluctuation pattern of Stage III. Such a tendency was more conspicuous of the foliage-shaded fruits. There was observed a daytime decrease of fruit diameter without moisture reduction. 2) After the end of June, fruit growth seemed to depend significantly upon the intensity of sunshine and more prominent decrease in fruit size was caused by shading after the middle of August. Relative transverse diameters of harvested fruits were 100, 85. 1, and 76.0 in normally irradiated, artificially shaded, and foliage-shaded branches, respectively. Likewise, relative fresh weight of harvested fruit was 100, 61.7, and 42.9 in normally irradiated, artificially shaded, and foliage-shaded fruits, respectively. 3) Chemical characters such as total soluble solids (refractometer readings), titratable acidity (malic acid equivalent), and ascorbic acid contents were highest in the fruit exposed to full sunlight, followed by those of artificially shaded and then foliage-shaded fruits in decreasing order. These facts indicate that restricted illumination exerted some retarding effects on the maturation of Japanese pear fruits. 4) On the basis of results obtained in the present investigation, it may reasonably be concluded that during later stages of fruit development the diurnal fluctuation of fruit diameter and consequently the progress of fruit growth are closely associated with the accumulation of elaborated materials, mainly sugars, within the fruit.
In the first paper of this series (6), it was reported that contraction of fruit size in the daytime was not observed on a rainy day, and, thus, the diurnal fluctuation of fruit size seemed to be closely related to the daily change of atmospheric humidity. Under moist soil conditions, however, fruit growth was not influenced by atmos-pheric humidity, which indicates that under these conditions the atmospheric humidity was not a dominant factor as to the fruit growth. In the present paper, the influence of aerial moisture on diurnal fluctuation of fruit size was investigated as an environmental factor. In 1968, daily change in the equatorial diameter of bagged and exposed fruits on ten-year-old Wase Nijusseiki (early type) and Nijusseiki (common type) pear trees grown in the orchard was examined under rainy conditions. Besides, the influence of water sprinkling on diurnal fluctuation of fruit was also examined with ten-year -old Wase Nijusseiki pear trees on July 31, August 4 and 11. The results obtained are summarized as follows 1)Under rainy conditions the size of exposed fruits was superior to that of bagged ones. The influence of rainfall was immediately exerted on the size of exposed fruit, while about two hours later it was confirmed on the bagged fruit. When it rained after a sequence of droughty days, cracking was brought about on many fruits unless they had been covered with bags. 2) Soon after the beginning of sprinkling, fruit diameter of sprinkled trees enlarged excessively, instead of contraction which was usually observed in the daytime. So the pattern of diurnal fluctuation in fruit diameter was like that of rainy day. The diurnal enlargement of bag-removed fruits was twice as great as that of bagged fruits, and consequently seven in ten measured fruits were cracked by moisture inhibition. The increment of water content in the bag-removed fruit amounted to twice that of the bagged fruit. Thus many injured fruits were brought about because the growth in volume of hypodermal tissue was extremely rapid due to the absorption of water through its surface. 3) Relative daily growth in fruit transverse diameter of sprinkled trees was 116.1, 154.3, and 130.2, in July 31, August 4 and August 11, respectively, as indicated by the non-sprinkled fruit of 100. As to the weight of harvested fruit, however, the difference was not significant among the treatments. So, the extreme fruit growth on the sprinkling day seems to be due to a temporary effect. 4) No difference in soluble solids, free acid, and maturation time of fruit was also observed between sprinkled and control plots. 5) The temperature of air, fruit and leaf inside the tree crown was lower in sprinkled than in non-sprinkled trees. Atmospheric humidity, on the contrary, was higher in sprinkled than in not-sprinkled trees.
The present experiment was carried out to estimate optimum degree of fruit thinning, using persimmon cultivars"Jiro, Monpei and Hiratanenashi", and a pear"Chojuro". The number of harvested fruits per one square meter of leaf area was counted on each tree for representing the fruit load ratio which was recognized as a major factor influencing the individual fruit weight. 1. The mean fruit weight per tree showed a negative correlation to the fruit load ratio, though it attained to a maximum when the fruit number per one square meter of leaf area was decreased to about two to three fruit in persimmon. Thus, the fruit load ratio at which the mean fruit weight attained to a maximum, was considered to be the upper limit of degree of thinning effective for promoting fruit enlargement. The fruit yield per unit leaf area had a positive correlation to the fruit load ratio. The coefficient of variation of fruit weight differed slightly among trees, but the fruit load ratio did not exhibit distinctive effect on it. 2. Marketable fruits are required to exceed a certain size and weight; the lowest limit of weight for marketable fruit in all varieties of persimmon is 136g, and that in"Chojuro"pear is 195g. For calculating yield of marketable fruits an equation was established from three main factors such as correlations of fruit yield and mean fruit weight to the fruit load ratio, and coefficient of variation of fruit weight. The quantity of marketable fruit differed depending upon the coefficient of variation of fruit weight. Even though the fruit yield per unit leaf area was the same, the larger became the coefficient of variation of fruit weight, the smaller quantity of marketable fruits there was. 3. The optimum range of fruit load was estimated by considering the fruit size and the yield of marketable fruits. The method of estimation of optimum fruit weight was established by considering the gross income and yield of marketable fruits.
1. Relationship between the resistance to the leaf burn and the drought resistance of detached leaves was studied, since the leaf burn seemed to be caused by dehydration. The drought resistance is devided into two components: (a) drought avoidance, which means ability to prevent water loss under a drought condition, and (b) drought tolerance, which means ability to remain alive at a low water content. The authors have made an attempt to evaluate the drought avoidance of leaves as the time required from saturation to 50 percent death by dehydration in a sealed chamber of which the water vapor pressure was controlled, and to evaluate the drought tolerance of leaves as the water saturation deficit at the death. 2. In preliminary, the changes of water saturation deficit and desiccation injury of detached Bartlett leaves were observed at intervals of 30 minutes under four conditions of 8 to 16mm Hg water vapor pressure deficit. When the water saturation deficit of leaves was over 30 percent, a desiccation injury began to occur, and when it reached about 60 percent, about a half of leaf area was injured under any condition of water vapor pressure deficit. The value of water saturation deficit when a desiccation injury occurred in the detached leaves was higher than in the intact leaves reported previously. 3. There were large differences in the ability of drought avoidance of leaves of pears, Japanese pears, apples, peaches and grapes. It was the lowest in pears and the highest in peaches. The ability of drought tolerance was highest in peaches, followed by apples, pears, Japanese pears and grapes in the order, but the differences among them were not so large. 4. Within nine cultivars of pear tested, there was a tendency that the leaves of resistant cultivars to the leaf burn had higher ability of drought avoidance than that of sensitive cultivars, but it was difficult to find out a certain relationship between the ability of drought tolerance of the leaves and the resistance to the leaf burn. 5. The resistance to the leaf burn varied among the trees within a same cultivar. In the Bartlett cultivar which is very sensitive to the leaf burn, the percentage of burnt leaves in a showed significant negative correlation with the ability of drought avoidance of leaves detached from the same tree. On the other hand, there was a very low correlation between the percentage of burnt leaves in a tree and the ability of drought tolerance of leaves detached from the same tree. 6. The abilities of drought avoidance and tolerance of the detached leaves of Bartlett pear, especially the former, showed a tendency to decline with age. This seemed to be closely related to the fact that the occurrence of the leaf burn was localized to the old leaves within a tree.
Effects of the addition of 2, 4-D and kinetin, each or both, to the Linsmair and Skoog medium on the callus induction from floral organs of Pyrus serotina culta REHDA cv. Nijisseiki and the root or shoot differentiation from the induced callus tissues were investigated. Although callus tissues were induced from sepals, stamens and petals of buds collected before anthesis on every medium with or without 2, 4-D or kinetin, only the callus induced with 2, 4-D grew well on every medium, especially on 2, 4-D media in the subculture. Root formation was recognized in the callus subcultured on the medium containing 2, 4-D at 0.1ppm and also in the callus transferred from the 2, 4-D medium onto the one containing adenine at 20ppm. Shoot formation from callus, however, did not occur on any kinds of media prepared in this experiment.
The combination effects of day-length and temperature on the growth and bunch differentiation of grapes were observed with one-year-old grafted vines of Delaware (V. labruscana) and Muscat of Alexandria (V. vinifera) in natural light growth cabinets by treating as follows; i) 20°C-short day (8-hour), ii) 20°C-long day (16-hour), iii) 30°C-short day (8-hour), and iv) 30°C-long day (16-hour). 1) In Delaware, shoot growth and bunch differentiation were greatly retarded on short days regardless of temperature, while promoted remarkably on long days, the trend being more marked at 20°C than at 20°C. However, shoots elongated so rapidly on 30°C-long days that most of lateral buds at their basal part became barren. 2) In Muscat of Alexandria, shoot growth and bunch differentiation were less sensitive to day-length than to temperature. Shoot growth was considerably ensured at 30°C even on short days, though it was greatly retarded on 20°C-short days. Bunch differentiation was best on 30°C-long days, followed by 30°C-short days, 20°C -short days, and 20°C-long days in the order. Particularly no bunch differentiation occurred on 20°C-long days all along the shoot. 3) Therefore, to utilize fully the room space in the vine growing under glass or plastic film, 20°C-long days seem to be best condition for Delaware, and 30°C-long days for Muscat of Alexandria from the stand-points of shoot growth and bunch differentiation. It is, however, noticeable that root growth and wood maturity were generally better on short days than on long days in both cultivars.
Vein-yellowing of leaves has often appeared at the basal part of shoots of the Campbell′s Early vines grown under wetting conditions during the rainy season in Kagawa prefecture, resulting in a serious damage for its production. To clarify the metabolic mechanism of this foliage disorder, the content of mineral nutrients was compared between the vein-yellowed leaves and the normally developed ones collected from other healthy vineyards. 1.The vein-yellowed leaves contained less N and P, and more Cu than the normal leaves. Particularly, the upward and downward trends of the element content were marked with N in petiole and vein and with P and Cu in mesophyll. 2. In the vineyards where leaves have shed in every rainy season, the N and P contents decreased and the Cu content increased in the leaves at the basal part of bearing shoots with their growth. This suggests that the vein-yellowing symptom is closely related to the Cu content of leaves which is affected through the change in soluble Cu content of soil. 3. When pot-cultured vines were submerged at the root zone, rootlets turned black and died before long. In the leaf analysis at the basal part of shoots, the vines treated with excess water showed less N, P and K and more Mn, Fe and Cu contents than the non-treated vines. However, no marked difference of the mineral nutrient contents was observed with the leaf at the top part of shoots between both the treated and non-treated vines.
Further experiment was conducted with Campbell′s Early grape to elucidate the effect of copper taken through roots on the vein-yellowing of leaves at the basal part of shoots. 1. Vein-yellowing of leaves was observed on the rooted cuttings of the grape treated with 50 to 2000ppm copper sulfate solutions. The symptom appeared earlier and more distinctly with increasing concentration of copper sulfate. But, when cultured with 0.1% KH2PO4 solution before the copper sulfate treatment, the vein-vein-yellowing decreased eased in developing rate and become less distinct. 2. The existence of copper surrounding the vascular bundle was clearly shown by staining with Diphenyl Carbazide solution in cross sections of the yellowed vein induced by the above treatment with 1000ppm copper salfate solution. 3. When the 6-year-old vines planted in the pots were submerged at the root zone after application of copper sulfate powder to the soil, the veins of leaves at the basal part of shoots turned yellow distinctly. From the result of leaf analysis, it was revealed that they contained more Cu and sometimes more Mn and Fe than the non-treated vines. Moreover, they contained less P, showing a lower ratio of P to Cu.
Changes in endogenous growth regulators shortly after the NAA application at 50 ppm about 20 days after full bloom were compared between large and small fruits of kaki"Fuyu". The size of the former was larger and that of the latter smaller than 2.21cm and 1.80cm in the cross diameter measured at the time of application, respectively. 1) Based on the three year′s experiments from 1970 to 1972, it was confirmed that NAA-induced fruit drop reached its peak 3 or 4 days after spraying and was nearly completed within another 4 days. A reverse relationship was found between fruit size of the application time and drop ratio; i. e., smaller fruits which usually contained fewer seeds were more sensitive to NAA than larger ones. 2) In either pericarp tissue including seeds of calyx tissue, higher activity of GA-like substances was detected in larger than in smaller fruits just prior to the application. Though their activity decreased in both large and small fruits in less than 3 days after application, the level of activity in large fruits was still higher than that of non-treated small fruits. The auxin-type promoters contained in large and small fruits were different from each other in the chromatographic behavior. No distinctive change in the promoter content was caused in large fruits by the application of NAA though a drastic decrease of them occurred in the small fruits. 3) The level of ABA-like inhibitors was higher in small than in large fruits just prior to the application. Almost no change in inhibitor content was observed in large fruits even 3 days after the application, while the small fruits exhibited a remarkable increase of them during the same period. 4) The thinning action of NAA was negated almost completely by the supplementary treatments with GA3 or GA7 24 and 40 hours after the application. 5) Based on the above facts, it is possible to assume that NAA acts as a thinner against kaki through its effects on the levels of endogenous growth regulators in fruit tissues, resulting in the accerelation of physiological drop of relatively smaller fruits.
1. The water extract from larvae of chestnut gall wasps exhibited cytokinin activity in tobacco pith callus growth test and barley leaf chlorophyll retention test. The larvae was fractionated with ether, water and a cation exchange resin, and the activity was detected in the basic water fraction. Paper chromatographic analysis of the fraction revealed that the active substances contained in the larvae were consisted of at least two components. 2. This extract had remarkable activity for callus formation by young stems of the susceptible (var. ne-17) and resistant (var. Ginyose) chestnut trees. On Linsmaier and Skoog RM ′64 basal medium and various media containing organic substances and plant growth regulators such as 2, 4-D or kinetin as additives, chestnut stems exhibited callus formation nearly in proportion to the concentration of the larval extract added into these media. Further, the amount of callus formed by stems at the same concentrations of the added extract did not differ clearly between the susceptible and resistant varieties. The active components in the basic fraction separated by the paper chromatography promoted the callus formation by stems showing similar Rf values to those obtained in the preceding analysis.
1) Fruits of 14-year-old satsuma mandarin trees (Miyagawa-wase) were thinned out at the leaf-to-fruit ratio (L-F ratio) of 30, 60, 100 and 300. As the L-F ratio increased, the total number and weight of fruits harvested and total soluble solids content of juice were decreased whereas the weight of individual fruit, transverse and longitudinal diameters, and weight of rind and fleshy pulp were increased. On the other hand, the weight percentage of rind remained almost constant as far as this investigation is concerned. 2) At harvest time, the carbohydrate content of leaves was fairly increased as the L-F ratio increased, but it was scarcely or not increased at all in the aerial parts such as green wood and primary branch. On the other hand, its content of the underground parts was remarkably increased, especially in starch of root which was proportionally increased with increasing L-F ratio from 30 to 300. 3) High L-F ratios markedly increased the blossom production of the following year, that is, the number of flowers in the 300-L-F ratio was about five times that of the L-F ratio of 30, which resulted in so marked decrease in number of emerging leaves that it seemed probable that the shift in the burden of fruiting might change the growth pattern of trees from vegetative to reproductive or from reproductive to vegetative according to their crop load. 4) The total-defoliation of 5-year-old Miyagawa-wase trees in December, February and April caused a decrease of blossom production and an increase of leaf emergence in the following growth season. On the other hand, half-defoliation in December resulted in the production of nearly the same number of flowers and leaves as that of non-defoliated trees. Every flower of totally defoliated trees, however, fell shortly after full bloom whereas half-defoliated trees bore a half in number of the fruits that were persisting on the non-defoliated trees.
The present investigation was carried out in order to find out the effects of irradiation on the flower organ formation in tulip and to elucidate the mechanisms of the morphological changes anatomically. The bulbs and plants of tulips at the various growing stages, from the early stage of the flower bud differentiation (July) to the late stage of appearance of flower bud (March) were irradiated with cobalt-60 gamma rays (Table 1, Fig. 1, 3). Dosages employed were 0.5, 1 and 3 krad at dose rates of 1.6×102 and 1.4×104 rad/hr (Table 2). The results of the observation are as follows:
Effect of light quality was investigated on the anthocyanin formation in detached carnation petals cultured using 4% sucrose liquid medium in vitro for 18 days. The cultures were treated with artificial light in all cases, and the results obtained are summarized in the following. 1. When the detached petals were irradiated with various pure colored fluorescent lamps, anthocyanin formation in the petals was more stimulated in the irradiation with fluorescent lamps than in darkness, and its content was highest under either red or blue light, becoming gradually lower in the order of orange, yellow and green lights. 2. The irradiation of far-red light at either short or long period gave rise to a markedly increased content of anthocyanin as compared with darkness. 3. The petals showed the formation of anthocyanin at a higher level when irradiated not only with light from white fluorescent lamp but also with a mixed light from red and blue ones than when irradiated alone with red or blue fluorescent lamp. 4. As to the irradiation with ultraviolet ray, anthocyanin formation in the petals was suppressed by its shorter wavelength region, and not promoted even by its longer wavelength region.
The relationship between the viscosity of satsuma mandarin (Citrus Unshiu MARC.) juice and some other chemical constitution was examined in this study. There was high or low positive correlation among the viscosity and non-reducing sugar amount, reducing sugar amount, total pectin, water soluble pectin, (NaPO3)6 soluble pectin, NaOH soluble pectin and was low negative correlation between the viscosity and organic acid amount. Their correlation coefficients of Wase Unshiu (early maturing cultivar) were 0.81, 0.75, 0.75, 0.82, 0.72, 0.60, -0.60, -0.59 and those of Futsu Unshiu (Medium maturing cultivar) were 0.75, 0.88, 0.78, 0.84, 0.76, 0.82, 0.85, -0.64, -0.57, respectively. On the other hand, free organic acid contents have high negative correlation with pH values. These correlation coefficients of Wase and Futsu Unshiu were -0.90 and -0.80. From the experimental results described above, the viscosity of juice was considered to play good index in determining the quality of citrus fruits and their products.