A series of investigations was undertaken to obtain some useful indices for the rationalization of orchard practices which are closely related to environmental conditions. From this point of view, the present investigation was conducted from 1967 to 1969 to clarify the relation between seasonal patterns of diurnal fluctuation in fruit diameter, mainly transverse one, and climatic factors with respect to mature Nijusseiki pear trees. The results obtained are summarized as follows: 1) The seasonal trend of diurnal fluctuation in fruit diameter of Nijusseiki pear fruit was divided into four patterns according to its developing stages: namely Stage I (early growth), Stage II (retarded growth), Stage III (maximum growth) and Stage IV (nearly mature). The conspicuous characteristics at each stage are described as follows: Stage I: The diurnal growth was greater than the contraction, and the change in longitudinal diameter of fruit was greater than that of the transverse one. Stage II: This stage corresponds to the so-called June rainy season. Fruit showed. the least diurnal growth in contrast with the exceeding contraction. Stage III: The rate of growth was remarkable, and the diurnal growth attained to a maximum, though the degree of contraction was nearly the same as that of Stage II. Stage IV: The fruit continuously grew night and day, that is, the contraction in the daytime disappeared and the process turned into enlargement. 2) The typical diurnal fluctuation of fruit diameter was closely related to the change of atmospheric humidity but showed such an opposite tendency to that of solar radiation and temperature that a considerable increase in fruit diameter occurred at night and contraction usually appeared in the daytime. On fine days the contraction was usually conspicuous except when the fruit became nearly mature. By sprinkling with water, however, the enlargement, instead of contraction, was observed even on a fine day as well as on a rainy day. 3) Before Stage III, the phase of diurnal fluctuation in fruit size was greatly influenced by climatic conditions ; especially diurnal growth being affected quantitatively by the environmental conditions. Accordingly, in Stage I a highly significant positive correlation coefficient was obtained between temperature and diurnal amplitude of growth fluctuation. A significant correlation was also observed between diurnal hours of sunshine and diurnal growth increment of Stage III. 4) Similarly a high correlation coefficient was found between the contraction and the decreasing rate of atmospheric humidity. The magnitude of contraction became greater as the temperature rose. Under these experimental conditions, however, it was deduced that the fruit growth was not influenced by atmospheric humidity which is usually considered to be a dominant factor for the fruit growth, since the deficiency of soil moisture was not observed throughout the period of this investigation. 5) The diurnal fluctuations in fruit diameter were influenced not only by the concurrent fluctuation of climatic factors, but to some extent by the environmental conditions encountered several days before the measurement. 6) Types of fruit enlargement were classified in two categories according to the stagnation or rather slight decrease of fruit diameter which was usually observed at midnight. A highly significant positive correlation coefficient was obtained between the increase in fruit diameter attained before the stagnation and the daily growth increment. This enlargement before stagnation was scarcely influenced by the atmospheric humidity, while the enlargement after the stagnation was closely related to high atmospheric humidity. This fact implies that the former enlargement may correspond to the fruit growth which is due mainly to the accumulation of water-soluble photosynthates within a fruit, and the latter may be caused by the swelling of fresh pulp.
The effect of gibberellins on the setting and subsequent growth of peach and Japanese pear fruits has been studied after the embryos were destroyed or the seeds were removed mechanically at different stages of fruit development. 1. In the peach, 14-year-old ′Okubo′ trees were used. Among the growth regulators tested, GA3 was only effective on the fruit set and development following destruction of the embryos. 2. In young stages of fruit development, that is 5 and 9 weeks after bloom, the application of GA3 to embryo-killed peach fruit resulted in 8 and 6 per cent set of the mature seedless fruit, respectively. In advanced stages, however, embryo destruction 13 weeks after bloom, with or without application of GA3, resulted in 93 and 85 per cent set of the seedless fruit at maturity. 3. Injury to the fleshy pericarp without destruction of the embryo had little effect on the rate of fruit set when treated 5 and 9 weeks after bloom. 4. Seed removal and gibberellin application to the cut surface of the Japanese pear fruit, cv. ′Shinseiki′ were done at five different stages of fruit development. Only GA4+7, applied as a lanolin paste to the cut surface of seed-removed fruit, was effective in sustaining further growth of the fruit when treated 3 and 5 weeks after bloom. 5. At the stage of 7 weeks after bloom, however, not only GA4+7, but also GA3 application began to work effectively to sustain the treated fruit. In late stages subsequent to 9 weeks after bloom, GA3 in lanolin was more effective than G GA4+7 on maintaining the seedless fruit. 6. It was also found that a large number of treated fruit were infected with rot and fruit splitting in late stages of fruit development and they abscised before ripening.
1. Effects of different application time of nitrogen from January to April on the vine growth and the flower cluster development were studied with 3-year-old. Delaware grape vines grown in soils in relation to the nitrogen absorption, assimilation and translocation. 2. Well developed flower clusters were found to be fewer on the March or later applied vines than on the January or February applied vines, though no marked difference of berry set existed among treatments. Shoot growth of the late applied vines was very slow in its beginning and at the stage of flower development, but became rapid toward the blooming time as compared with that of the early applied vines. 3. The early applied nitrogen was absorbed soon by rootlets even when the soil temperature was still under 5°C and stored there mainly as protein. It was then, transported up to the buds with the commencement of the bleeding period namely nearly 20 days before bud burst. Thus in the early applied vines the nitrogen content of rootlets began to decrease rapidly, while it increased even after the bud burst in the late applied vines. 4. When the sap which was bled out at the cut end of the basal part of the shoot was analyzed, it contained more inorganic nitrogen in the late applied vines than in the early applied vines. Moreover, it held less amide, more glutamic acid and less bases of nucleic acid related substances in the former than the latter.
Hardwood cuttings of grape, Vitis labruscana BAILEY: cv. Niagara, Delaware and Campbell Early; and Vitis vinifera L.: Muscat of Alexandria and Neo-Muscat having a single mixed or compound bud were grown to examine the effects of different scion weights and leaf removal on the vine growth in normal sunlight during late winter and early spring. 1 Hardwood cuttings of cv. Niagara weighing 2.5g and 5.0g at the time of planting under glass developed into vines having fresh current shoot weight of 0.77 and 1.38g, respectively. Callus formation and rooting were more stimulated in cuttings weighing 2.5g-than in 5.0g-ones, however, total root growth of the latter was superior to those of the former. 2 The difference in the growth rate of shoot and flower clusters was compared using initial scion weight of 15g in Vitis labruscana (cv. Campbell Early and Delaware) and Vitis vinifera (cv. Neo-Muscat) grown outdoors. Final weight was heavier on Neo-Muscat vines than with those of Delaware and Niagara. On the contrary, the development of flower cluster in Neo-Muscat was poorest among three varieties, while that of Campbell Early was best. The ratio of flower cluster to current shoot weight per vine was highest in Campbell Early and decreased in the following order: Delaware and Neo-Muscat. Poor growth of flower cluster was seemingly correlated to vigorous shoot growth on Vitis vinifera vines. 3 To assess the degree of internal competition for reserve materials by the vegetative and reproductive organs, defoliation experiments were conducted with the above varieties. Each vine was manipulated to a system simple consisting of one bud from which the basal cluster on each developing shoot was selected; the others being removed as soon as they appeared. In the case of Delaware grape the secondary cluster was left because the lowermost cluster was undeveloped. Flower set and final cluster size were approximately proportional to initial fresh weight of cuttings. Independent of cutting weight, flower cluster development of defoliated vines was superior to vines left intact, indicating a diversion of reserve foods to the remaining organs. However, this diversion was more marked in European than in American species. The development of flower cluster was proportionate to the degree of defoliation.
The degree of competition for stored reserve substances and their utilization during flowering and berry setting periods in one-year-old grape vines were examined. The uppermost bud on each cutting was allowed to remain and others were cut off. Each experimental plant bore a single inflorescence on a woody cane. Plants were grown in a glasshouse in full sunlight during spring. 1 To assess the relative effectiveness of leaves, their position and time of defoliation on berry set, experiments were conducted with Campbell Early grape cuttings whose original weight was 15g. To assess the time of leaf removal on set, leaves were removed at three intervals: at bud break, 15 to 10 days before bloom, and full bloom. The manner in which leaf removal was accomplished was:(1) several leaves basal to a single flower cluster were left while the distal ones were removed (basal lot), (2) all leaves basal to flower cluster were removed and the distal leaves left intact (distal lot), (3) all leaves were removed (complete defoliation lot), and (4) all leaves were left intact (control lot). The average percent of fruited plants per treatment three weeks after full bloom was highest in the basal lot (42.2%). The effectiveness decreased in the following order: complete defoliated lot (24.5%), control lot (5.6%) and distal lot (2.2%). The presence of leaves is evidently not a prerequisite for berry set, although all berries in complete defoliated lot were shed before harvest time. This behavior suggests that the presence of leaves is evidently important for berry enlargement. Furthermore, the effects of leaf number and leaf position to flower cluster on berry set were examined. The presence of only 1 or 2 leaves basal to flower cluster was sufficient to obtain 40-60% of fruited plants. With increased number of leaves distal to flower cluster, the number of fruited vines decreased, which suggests that the competition for reserve substances and photosynthates during the critical period after anthesis may be an important factor for the fruit set and subsequent development. These experiments emphasize the interaction between vegetative growth and development of reproductive organs on utilization of the reserve substances in grape. The poor fruit set in cuttings in which expanding immature leaves were left above flower cluster is probably attributable to the diversion of reserve substances and photosynthates neccessary for setting and subsequent development. 2 In experiments with the cv. Delaware whose original cutting weight was 15g, the effects of defoliation and pinching of shoot and pruning of the tip of young inflorescences on subsequent flower and ovary development were investigated. Defoliation resulted in good flowering response and development of ovary while pinching and tip pruning of inflorescences had none. Ovary development for one week after bloom was enhanced by leaf removal as compared to the control vines in which ovary growth was reduced by the presence of immature leaves. Although the fruitlets on cuttings from which all leaves were removed was twice that of intact cuttings, they abscised prematurely. When 1 or 2 leaves were left at a node below the flower cluster, 20-30% of the treated plants fruited.
The experiment was conducted in the Horticultural Garden, Faculty of Agriculture, Banaras Hindu University, during the years 1968, 1969 and 1970. N, P, and K in the form of urea, double superphosphate and potassium chloride at 1 and 2 per cent oncentrations were sprayed singly and in combinations. Urea spray had significant effects in increasing the duration of flowering and fruiting, and percent fruit set and fruit drop, and also in decreasing the percentage of fruit retention and period of maturity in both the spring and summer flushes except the percent fruit drop and fruit retention which were affected significantly by 2 per cent urea spray in spring flush only. Double superphosphate spray at 1 and 2 per cent concentrations significantly increased the duration of fruiting in both the flushes, duration of flowering and per cent fruit set in summer flush and duration of flowering and percentage of fruit set under 2 per cent in spring flush only. Potassium chloride spray at 1 and 2 per cent concentrations significantly increased the duration of flowering and fruiting and percentage of fruit set in summer flush, and also duration of fruiting and period of maturity under 2 per cent spray in spring season. Combinations of N×P, N×K, and P×K also showed significant effects on duration of fruiting and percentage of fruit set.
Evidence for population-density effect on shoot and root growth was obtained through asparagus lateral bud culture. This effect may be due to some diffusing substance or substances from explants on the medium, and can be replaced with various cytokinins; kinetin, 6-benzylamino-9-(2-tetrahydropyranyl)-9H-purine (SD 8339) and benzyladenine provided with naphthaleneacetic acid (NAA). Good root growth was observed when explants were transplanted from modified Murashige and Skoog′s medium (the basal medium) containing 0.3mg/l NAA and 0.1 mg/l kinetin to the basal medium. The optimum root-inductive period on the basal medium containing NAA and kinetin was 2-3 weeks.
1. Tomatoes, cv. ‘Shin-Hogyoku No.2′ were grown under constant temperature regimes of 17°, 24°, and 30°C and at two levels of N, P and K during two growing seasons (1960, 1961) to study the interaction of those factors on flower bud differentiation and its subsequent development. 2. In 1960 the following results were obtained: a) The height and fresh weight of seedlings in 2(NPK) and NPK plots were: 24°, 30°, and 17°C in decreasing order. However, seedlings in 2(NPK) plots grown at the same temperature were larger than those in NPK plots. b) The time of morphological differentiation of flower buds and their subsequent development in both 2(NPK) and NPK plots in order of earliness were: 30°, 24°, and 17°C. Under the same temperature regime, seedlings in 2(NPK) plots differentiated flower buds earlier than those in NPK plots. c) The number of flower buds per seedling was 24°, 30°, and 17°C in decreasing order, that of 2(NPK) plots being consistently higher than that in NPK plots. 3. In 1961 the following results were obtained: The results in 1961 were essentially the same as those in 1960 except that in the second year, temperature had no influence on the development and the number of flower buds. This inconsistency with respect to the time of flower bud differentiation is attributed to the large difference in the amount of solar radiation as the sum total of the duration of sunshine per day and per growth period, between the two seasons. Total sunshine hours per growth period were 85.3 hours in 1960 and 116.4 hours in 1961.
The present studies were carried out to ascertain the influence of early environmental conditions and cultural treatments upon the development and the premature drop of flowers. 1. Effects of early environmental conditions and cultural treatments on the development and the premature drop of flowers. Egg-plant seedlings were grown at three different levels of soil fertilities and soil moistures, at four different light intensities (100, 75, 50 and 25 per cent of naturall day light) and at three different night temperatures (17°C, 24°C and 30°C). The higher night temperatures, the lower light intensities, the lower soil fertilities. and the lower soil moistures retarded the development of flowers. Smaller flowers with smaller sepals, petals, anthers and especially smaller ovaries with shorter styles were produced and heavy flower drop ensued (Tables 2, 3, 5, 6, 8 and 9). The less became the water supply, the smaller became the flowers, with smaller sepals, petals, anthers and ovaries. The flowers with shorter styles and the flower drop were not increased by the different water supply (Tables 11 and 12). The leaves which unfolded to a length of about 50mm were removed alternately or successively at the nodes 1 to 10, counting from the bottom of the plant. The defoliation retarded the development of flowers resulting in the formation of the smaller flowers with smaller sepals, petals, anthers and especially smaller ovaries with shorter styles and ensued the increased flower drop (Tables 14 and 15). 2. Relations between the development of flowers and the chemical constituents in the seedlings. The seedlings grown at the higher night temperatures and or at the lower light intensities and those defoliated contained the lower levels of total sugars, starch and polysaccharides, and had smaller flowers with smaller ovaries and short styles. The seedlings grown in the soils with lower fertilities contained the lower levels of nitrogenous constituents and had smaller flowers with smaller ovaries and short styles. The results of the present experimentss show that the lower levels of carbohydrates and or nitrogenous constituents in the seedlings are associated with the formation of the abortive flowers with short styles and ensued the increased flower drop (Table 16 and Fig. 4). If we express the percentage flower abortion as the coordinates, in a plane, of total nitrogen content as ordinate and total carbohydrate content as abscissa, the isogram with respect to the occurrence of smaller flowers with shorter styles may be given (Fig. 4).
The present investigation deals with in vitro growth of ovules on a half of the placenta of Petunia hybrida, W166H×K146BH (each clone is self-incompatible), with special reference to the influence of iron, boric acid, and sugars. The culture medium of NITSCH (1951), modified by the addition of 500mg/l KNO3 and 80mg/l NH4NO3, was used as a basal medium. The optimal initial hydrogen-ion concentration was at pH of 4.5-5.0 in the basal medium and at pH of 6.0 in the basal medium with Fe-EDTA at an iron concentration of ca. 2.5ppm instead of ferric citrate. The number of viable seeds per ovary increased with an increasing concentration of ferric citrate from 10 to 40mg/l in the basal medium. Iron complex Fe-EDTA composed of 50mg/l FeSO4•7H2O and 40mg/l disodium ethylenediaminetetraacetate, dihydrate (Na2-EDTA) was also an effective compound and was favorable for the viable seed production. 10mg/l or above boric acid should be added to the basal medium containing either ferric citrate or Fe-EDTA. Medium containing 50mg/l boric acid was superior for the viable seed production to those with any other concentration. The efficancy of boron was influenced by the organic forms of iron. The medium with Fe-EDTA at an iron concentration of ca. 2.5ppm was superior to that with 10mg/l ferric citrate. Basal medium containing 7.5 per cent sucrose or 5 per cent fructose produced the maximal viable seeds and that containing a mixture of sucrose and fructose or sucrose and glucose was inferior to the basal medium. From these results, experiments were conducted to clarify the interaction among three components, iron, boric acid, and sugars. About 5-6 normal seedlings with two cotyledons and roots per ovary were obtained in the medium containing ca. 10 ppm Fe as Fe-EDTA, 25mg/l boric acid, and 7.5 per cent sucrose. This was about six times as the number of seedlings produced in the basal medium. In the basal medium containing fructose instead of sucrose, however, the higher concentrations of boric acid and/or iron failed to bring about the noticeable effect.
The rest period of iris bulbs (cv. ‘Wedgwood’) and the effect of temperature on breaking of the rest were studied. Leaf formation at apical region suspended from mid June to mid August, and bulb weight increased until mid July continuously under the natural condition at Ina district. Bulbs harvested in Kyoto on June 6 and stored at 20°C on and after July 6 did not increased the number of new leaves until August 3, and increased thereafter. Bulbs which were shifted from 20°C to 15 or 10°C on August 3, as well as those shifted to 10°C and returned to 20°C after 28 days, on August 31, also formed new leaves thereafter. Bulbs shifted to 30°C, however, did not produce new leaves until August 31. The first leaves of bulbs stored at 20°C did not grow until August 3, and then began to elongate excepting those of bulbs shifted to 30°C. The latter bulbs began to elongate the first leaves on and after August 31. Bulbs stored at 20°C were planted in wet sand at 20°C on July 6, August 3 and 31, September. 28 and October 26. They began to sprout on September 10, 9, 16, October 8 and 31, respectively. The bulbs planted on August 3 at 10, 15, 20, 25 and 30°C required 37.6, 26.6, 36.6, 73.6 and 65.0 days from planting to 100% sprouting. On the other hand, those planted on September 28 took 12.4, 9.2, 9.8, 9.8 and 8.6 days, respectively. The results mentioned above, might indicate that the rest of ‘Wedgwood’ bulbs stored at 20°Cwas broken in late August. The bulbs seemed to be in the late phase of rest sprouted soon at about 15°C and very late at 25 and 30°C. After the rest had terminated, the bulbs sprouted in a short period at any temperature from 10 to 30°C.
Changes of the activity of chlorophyllase and PE during the ripening of tomato fruit were measured, and effect of packaging them with a polyethylene bag on the change of the activity was studied. 1) The optimum concentration of acetone, the optimum pH and the optimum temperature in reaction mixture for measurement of the activity of chlorophyllase in tomato fruit were about 45%, 7.0 and 25°C respectively. 2) The activity of chlorophyllase in tomato fruit on the plant increased with the ripening of them and reached the maximum at about the full-ripe stage, and then decreased. 3) In tomato fruit detached from the plant, the activity of chlorophyllase also increases with the ripening. In the packaged fruit stored at a room temperature, the activity of chlorophyllase was maintained on the original level, and the content of chlorophyll was kept under control and did not decrease. On the other hand, in the non-packaged fruit stored at 10°C, the enzyme activity fairly increased with the ripening of fruit and chlorophyll was decreased. 4) The activity of PE increased with the ripening of fruit. 5) The activity of PE in tomato fruit detached from the plant also increased with the coloring and softening of them, but its increase was controlled when fruit was packaged with a polyethylene bag.