Cluster dipping with the solution of SADH at 2, 500ppm 26-20 days before full bloom significantly increased the number of seeded berries per cluster and of seeds per seeded berry in Kyoho grape in 1975, 1976 and 1977. Shoot pinching leaving 8 leaves per shoot about 10 days before full bloom had no effect on the set of seeded berries but significantly promoted the set of seedless berries in both 1975 and 1976. Though this treatment promoted the set of seeded berries in the next year, it was less effective than the treatment with SADH. Flower thinning removing shoulder and tip parts of cluster about 10 days before full bloom was applied in 1975 and 1976, which exhibited the promotive effect on the set of seedless berries alone in both years alike shoot pinching. The application of SADH depressed the growth of floret, particularly of ovary wall in size before and during bloom, whereas shoot pinching enhanced and flower thinning did not affect it in the same period. Pollen germination on agar media and either pollen germination or pollen tube elongation in intact style and ovary tissues were not influenced by any of the treatments. Though no treatment had consistent effect on gibberellin activity in florets before and during bloom in 1975 and 1977, cytokinin level was raised by SADH application in both years and by shoot pinching in 1977 alone. Protein N and total N contents in florets before and during bloom were increased by SADH application but they were reduced or not so much affected by shoot pinching. Total sugar content in the same period tended to be raised by either SADH application or shoot pinching except at the beginning of bloom when it was slightly decreased by SADH application in both years. From these results, it is suggested that SADH application before anthesis in Kyoho grape promotes the set of seeded berries probably due to the improvement in fertilization ability of ovules and the effect of SADH may be causally related with the increased activity of cytokinin in developing florets. Further, it is shown that shoot pinching and flower thinning, as opposed to SADH application, promotemainly the set of seedless berries presumably resulted from the nutritional stimulation of parthenocarpic tendency.
It is important to investigate water transport through fruit trees because fruit production concerns greatly to water relationships in several aspects. In the present study, water transports in stems, peduncles and petioles in pear trees were investigated by a heat pulse method. The results may be summarized as follows: 1. The heat pulse velocities and the actual flow rates (sap velocities) in pear trees were obtained by Closs′ analysis. Further, the sap velocities and its possible shifts of the directions in the peduncles and the petioles were measured directly by a application of the analysis. 2. Heat pulse velocities were tested to detect the optimum depths of the installations in several pear stems using small thermal sensors (thermocouples of differential type) and heaters. Further, the effects of times of heat pulsing, voltages of source of electricity to the heaters and distance ratios of the 2 sensors (x:x') on the heatpulse velocities were measured in pear shoots. And measuring cautions were obtained in adapting the method for pear trees. 3. The heat pulse velocities in shoots were in proportion to numbers of attached leaves. And the sap velocities related to several factors concerning transpiration rate and transpiration demand. Especially it related greatly to the degrees of the slope of water potentials between the xylems in the shoot base and the mesophyll. The water potentials of the latter fell down as the result of the leaf transpiration. Different diurnal changes in the sap velocities were found among 4 directions in the canopy. The sap velocities in the shoots at the inner canopy were lower than that at the outer canopy (the latter was about 1.6 times as high as the former on the average of the all directions in the daytime). The inclinations of the shoots did not affect on the heat pulse velocities at the outer canopy. But since the almost horizontal and inclined shoots had fewer leaves than the upward ones and existed at the inner canopy, it seemed that these shoots would have lower velocities than the upward ones at the outer canopy. 4. Diurnal changes in water potentials in leaves, fruits and stems of Bartlett pear trees were measured. Further, diurnal changes in the sap velocities and the directions in peduncles and petioles of Bartlett pear trees were measured using the very tiny sensors. The reverse water transports from the fruits in the daytime were found and its typical velocities (about 0.8ml peduncle-1h-1 at maximum rate) were measured directly. These results coincided to the judgemental results from the authors′ model (“branched and confluent pipe stream model”) in the phenomena of competition of water between the fruits and the leaves. The pattern of watertranports between the two shifted in the fixed order, namely, the confluent stream to fruits in the nighttime→the branched stream in the early morning→the confluent stream to leaves in the daytime→the branched stream in the evening.
1. To clarify the role of photosynthesis in the rooting of hardwood cuttings of grapevines (cv. Delaware), the effects of the darkness and disbudding treatments started at various stages of the propagation period on rooting were observed. 2. Distinct differences in the rooting of cuttings grown in darkness throughout the propagation period were found between the disbudded and undisbudded cuttings. This indicates that functions of the buds other than photosynthesis may play a significant role in rooting. 3. Darkness treatments started later than the 45th day after planting had little effect on either the rooting percentage or the root number of the undisbudded cuttings. This suggests that root initiation may be mostly completed by the 45th day after planting, when the first root appears. Since the rates of apparent photosynthesis when rooting is initiated are quite low, as shown in a previous report (ref.), it may be assumed that root initiation is hardly affected by photosynthesis. 4. When darkness treatments were started later, better rootings were generally obtained through the latter half of the propagation period. Comparing the best rooted cuttings with the untreated controls, considerable differences were found in both root length and root weight. In view of these facts, it is possible that the root development is promoted by light during the latter half of the propagation period, and that photosynthesis may play a more important role in the development of roots after initiation.
The diurnal changes of solar radiation, air temperature and fruit temperature, and integrated solar radiation in all day were investigated at different locations on the trees of open center and hedgerow of satsuma mandarins (Citrus unshiu Marc. var Sugiyana) from late-July to mid-December, 1977. The results are given as follows. In the open center form, integrated circumglobal radiation (ICR) was the highest at the top in the south side of the tree and slightly lower in the other sides, but ICR of the hedgerow was lower even at the top of the canopy, when compared with the open center form. ICR at the skirt of a canopy was considerably low in both forms. ICR at the skirt in the north side of both trees was about 45% and 2% of that at the top of the south side in summer and in autumn, respectively. ICR at the interior of canopy was low in both forms, especially in the hedgerow, it was about 10-20% of the integrated value at the top of the south side. Ambient air temperature of the open center form rised more rapidly at the south side, the top and the skirt of the east side, and the interior than at the top and the skirt of the west and the north sides in the morning. The air temperature at the top of the west side on the canopy rised slowly until 14:00, then reached the maximum at about 16:00, thereafter fell gradually, but remained higher than that at the other locations. At the top of the north side, air temperature rised slowly from sunrise until 16:00, and then until sunset, thereafter gradually fell, keeping higher than that at the top and the skirt of the east side. At the interior, air temperature rised more rapidly than that at the top and the skirt of the west and the north sides in the morning, then kept constant from 12:00 to 16:00, and was higher than that at the top and the skirt of the east side after 16:00. Ambient air temperature of the hedgerow rised remarkably at the top and the skirt of the east side of the canopy in the morning, and that at the top and the skirt of the west side rised more slowly. Around noon, temperature on the west side was higher than that on the east side and fell down gradually keeping higher than the other locations. This was considered to be due to the westering sun. However, the air temperature at the top and the skirt of the east side fell rapidly after 14:00 and was the lowest of all locations at sunset. Air temperature at the interior canopy showed intermediate changes in the all locations all day. Fruit temperature rised more rapidly at the top and the skirt of the east side of the open center form than that at the other locations in the morning. After noon, fruit temperature at the top and the skirt of the west side was higher than that at the other sides. Fruit temperature at the south side was lower than that at the east side in the morning and was lower than that at the west side in the afternoon. At the top of the north side, fruit temperature was the lowest of all locations from sunrise to 15:00 and thereafter was higher than that at the south side. At the skirt of the north side and the interior of canopy, fruit temperature rised slowly and remained lower than that at the other locations all day. Fruit temperature rised more rapidly at the top and the skirt of the east side and the top of the west side of the hedgerow than at the other locations in the morning. At the skirt of the west side and the interior of canopy, fruit temperature rised more slowly than that at the other locations from sunrise to 15:00 and remained lower than that at the other locations all day. After 16:00, fruit temperature at the interior fell rapidly and that at the skirt of the west side fell gradually.
Development of loquat fruit was divided into two phases. The first was growth phase characterized by a growth of seed. The second was maturation phase characterized by decreasing acid content, color development and softening of the pulp tissue. In addition to these phenomena, sugar accumulation and a rapid increase in the fresh weight of the pulp tissue were also observed during maturation. This pattern of maturation is similar to that of fig fruit. The loquat fruit began to evolve ethylene at the beginning of the maturation phase. Sorbitol was a predominant component in the young fruits of loquat. Although sorbitol content increased during the fruit development, its percentage relative to total sugar decreased. Sugar accumulation was accelerated at the beginning of the maturation phase. Sucrose was accumulated faster than any other sugar during this phase, and was a major sugar in the ripe fruit, while sorbitol became a minor component. Ninety percent of the sugar present in the ripe fruit was accumulated within two weeks of maturation. This sugar is thought to be supplied by other parts of the plant.
Muskmelons were grown under the same environmental conditions to determine levels of salt tolerance in different media. Plant height at harvest decreased with increasing sea water concentrations in sand and soil cultures. The relative plant dry weight and fruit fresh weight were greatest in nutrient solution culture, followed by soil culture and least in sand culture. The relative fruit fresh weights at 1, 000ppm Cl as compared to 0ppm Cl in sand, soil and nutrient solution cultures were 66.2, 70.5 and 91.1%, respectively. Osmotic potential of leaves and roots decreased, and Cl content in each plant part, and Na and Mg in leaves increased with increasing sea water concentrations in each medium. The relative Cl and Na content in leaves was highest in sand culture and lowest in nutrient solution culture. Cl and exchangeable Na in soil and sand, and EC of soil increased with increasing sea water concentrations. Anion and cation content, and EC of media were greater in soil culture than in sand culture.
In order to clarify the relationships between the growth responses to K fertilizer and K concentration in radishes under various conditions, pot experiments with factorial design were carried out on the soil containing 91ppm exchangeable K. K treatments were consisted of 6 levels, 0g to 8g of K2SO4 per pot. Factors combined with K treatments were the light intensity, the soil water regimes, and the amount of N, P, lime, Mg and Na. All pots received 10g of ammonium sulfate and 40g of superphosphate except in the N and the P experiments. Twenty germinated seeds of radishes (var. Ooakamaru) were sown in plastic pots (25cm in diameter, 30cm in depth) filled with 6.5kg of soil (oven dry basis). Seedlings were thinned to six per pot after emergence and harvested at the time when the roots began to enlarge. The largest and the youngest unfolded leaves sampled for chemical analysis were the second and the third ones, respectively, at harvest time. 1. The fresh weight of both tops and roots usually attained to its maximum with application of 4g or 8g of K2SO4, which was regarded as the control levels of K treatments. 2. The amount of K2SO4 required to achieved the maximum growth increased with increasing rates of N or P, however, decreased with Na application or shading (see Table 21). 3. 3.2% of K (dry weight basis) in the largest leaves distinguished between K-sufficient and K-insufficient plants except in case where Na was applied (see Table 22). However, K concentration in the youngest unfolded leaves and roots. could not distinguish well between K-sufficient and K-insufficient plants. 4. K-sufficient plants sometimes contained less than 3.2% of K in their largest leaves in case where Na was applied. 5. From the above results, the critical K concentration in the largest leaves seemed to be a fixed value if Na concentration in leaves was low.
The experiments were carried out to clarify the effect of cyclic lighting on the bulb formation and the interrelationship between light stimulus and darkness associated with photoperiodism, using the cultivars ‘Kaizuka-wase’, ‘Sensyu-ki’ and ‘Sapporo-ki’. The plants were started from seed and grown under short-day in greenhouse for 2 or 3 months prior to experimental use. During treatment periods the plants received 8 or 12hr of sunlight followed by intermittent lighting (500lx) in light-dark cycle with incandescent lamp during long dark period. Intermittent light were applied for 50, 33.33 and 25% of time in light-dark cycles of various lengths. The shorter the cycles became, the more the bulb formation was induced. Moreover, it was found that relationship between the bulb formation and the logarithm of length of cycle was inversely proportional. The 15-15 light-dark cycle (min) was as effective as continuous light except for ‘Sapporo-ki’ when light applied for 50% of time in the cycles. When 1 sec lighting followed by various lengths of darkness, the dark duration less than 3 sec promoted the bulb formation as well as continuous light, whereas those of the dark duration more than 5 sec decreased with length of darkness. From above mentioned results, we made the assumption that the ratio of the duration of light stimulus in darkness to the duration of light applied was inversely proportional to the logarithm of duration of light. With this assumption, the expected values obtained by cyclic lighting were in satisfactory agreement with the observed values.
We investigated the effects of strongly reductive soil conditions and applying the growth regulators, ethephon, maleic hydrazide, and 2, 4-D on the browning of lotus rhizome surface. The results obtained are summarized as follows: 1) Rhizome browning increased by applying the growth regulators, ethephon or maleic hydrazide, and decreased by applying 2, 4-D or by giving strongly reductive soil conditions. 2) Oxidation potentials of rhizome tissue showed negative value in diurnal change all day. It increased from sunset and reached minimum at midnight, then began to decrease rapidly and reached maximum in the early morning. 3) The range of the fluctuation in diurnal change of oxidation potentials descended by the treatment of ethephon or maleic hydrazide, but ascended by 2, 4-D or soil reduction. 4) Generally, all the treatments induced CN- insensitive respiration in the rhizomes; whereas the increasing ratio of respiration under ascorbic acid substrates were inhibited by those treatments. 5) The change in the value of respiratory characteristics of CN- sensitive respiration under ascorbic acid participation showed almost negative correlation to brightness of browning. 6) In multiple regression analysis of the data, the (partial) potentials during the night contributed to browning by 72%, and both the values of CN- sensitive respirations under ascorbic acid substrate and Q values (respiratory quotient) contributed to browning by 67%.
Interclonal (compatible) crosses: In each species, in vivo pollen-tube growth after stigmatic pollination was remarkably accelerated as compared with in vitro growth on stigma-exudate medium. A certain stylar factor which accelerates pollentube growth appeared to actuate between 5 and 12 hours after pollination. Interspecific (incompatible) crosses: In vivo pollen-tube growth in the case of interspecific stigmatic pollination on L.longiflorum was the same as or a little better than that in the case of in vitro ‘interclonal stigma-exudate pollination’ and not accelerated as in the case of interclonal stigmatic pollination. This may indicate that the poor pollen-tube growth in interspecific crosses is not a result of ‘inhibition’ but rather results from impossibility of utilization of an accelerative factor in the style. In one species, however, pollen-tube growth was inhibited, showing abnormalities such as a swelled tube-tip between 12 and 24 hours after pollination.
The diffusible growth regulators from gladiolus plants were studied. 1. Development of the excised buds from non-dormant cormels was remarkably inhibited under light as compared with that in dark, when the sheath leaves or the leaf-bases were placed simultaneously in the same medium. 2 Diffusible growth inhibitors were not found in the diffusate from plants at the single-leaf and the two-leaf stages. Those were found at the subsequent stages. On the other hand the growth promoters were found in the diffusate from plants at the single-leaf, the two-leaf, and the three-leaf stages. When the leaf-bases of explants were wrapped with aluminium foil, the diffusible growth inhibitors in the diffusate from the explants remarkably decreased even at the three-leaf and the four-leaf stages. 3. At the three-leaf stage, inhibitors were found in the diffusate from the leafbases as well as the sheath leaves, but they were not identified in the diffusate from the top of leaves.
Effects of planting depth and soil covering at different stages on the dormancy of gladiolus corms were studied. 1. A significantly earlier sprouting was observed in corms from the plants planted 20 and 20cm deep. 2. The weight of corms from the plants deeply planted was found to be remarkably heavier than that of corms from plants shallowly planted. 3. The sprouting of corms from the plants covered with soil after the four-leaf stage was considerably promoted. 4. The amount of inhibitors was decreased in the leaves and corms from the plants deeply planted.
This work was designed to study the decrease in parent scale dry weight and the increase in newly formed plantlet dry weight during scale propagation (incubation). After a six-month incubation, the dry weight to fresh weight ratios both for parent scales and for scale bulblets were higher than that for roots or for stems and leaves. The increase in fresh weight of scale bulblets was accompanied by the increase in dry weight percentage. The growth of the newly formed plantlets resulted in a decrease in the parent scale dry weight percentage. Bolting from the scale bulblet also lowered the parent scale dry weight percentage. The parent scale dry weight percentage decreased more rapidly at 25°C than at 30°C during incubation. The dry matter percentage for the apical part of the parent scale decreased more rapidly than that for the basal part; this tendency was more noticeable at 25°C than at 30°C. The dry matter partitioning ratio between the parent scale and the newly formed plantlet organs at various times during incubation was also summarized.
This investigation was carrid out to clarify the mechanism of Chlorophyll degradation and the physiological function of ascorbic acid in the course of yellowing in leaf vegetables. 1) When parsley, spinach, and garland chrysanthemum were stored at 20°C, Chlorophyll and L-ascorbic acid content in the leaves, especially in parsley, decreased markedly with increased yellowing. 2) In parsley, the activities of Chlorophyllase and ascorbate oxidase showed a sharp decline with yellowing. Catalase activity did not show a marked change. On the other hand, peroxidase activity increaed remarkably with yellowing. 3) It was found that peroxidase degraded Chlorophyll in the presence of hydrogen peroxide. 4) The degradation of Chlorophyll by peroxidase was inhibited by the addition of L-ascorbic acid. These results indicate that the Chlorophyll degradation in parsley depends on the action of peroxidase in the presence of peroxide and that L-ascorbic acid inhibits such degradation.
Mechanisms which serve to suppress the ripening of fruits following the treatment with high concentrations of CO2 were investigated. When tomato fruit was treated with 100% CO2 for one day, CO2 exhaust remained at high level relative to nontreated fruit for several days after treatment. This phenomenon was also observed in banana and pear fruits. The ethylene production of tomato and banana fruits after treatment was also higher than that of non-treated fruits. However, the ethylene production of pear fruit decreased somewhat as the period of treatment became longer. When tomato fruit was treated with 100% CO2 for one day, the activities of enzymes related to respiratory metabolism changed remarkably during and after the treatment: glucose-6-phosphate dehydrogenase and malic enzyme were not activated following the ripening of fruit; phosphofructokinase showed a marked fluctuation after the treatment; alcohol dehydrogenase was activated during the treatment, and also was at high activity level after the treatment; and succinate oxidation in mitochondria was lowered during the treatment, but activated after the treatment. In addition, KCN inhibition of succinate oxidation decreased, and the respiratory control ratio of mitochondria was lowered for several days after the treatment; these results indicate the development of CN-resistant respiration through out the period.
In apple fruit, three types of sorbitol enzymes were certified by column Chromatography using Sephadex G-200gel. The first type was sorbitol-6-phosphate dehydrogenase catalyzing the conversion between sorbitol-6-phosphate and glucose-6-phosphate, which was active in the alkaline region (optimum pH 9.8) and a Km value of 7mM for sorbitol-6-phosphate. The second type was sorbitol dehydrogenase interconverting sorbitol and fructose, having optimum activity at pH 9.8 and a Km value of 125mM for sorbitol. The third was sorbitol oxidase converting sorbitol to glucose, which had a Km value of 70mM for sorbitol and was active in the acid region (optimum pH 4.0). The above three enzymes were also found in the apple cotyledon. Fifty-five and 66% of the sorbitol-6-phosphate dehydrogenase and sorbitol oxidase activities respectively were distributed in the subcellular fraction of 100-2, 000xg. The majority of the sorbitol dehydrogenase activity was contained in the supernatant. In the fruit flesh sorbitol dehydrogenase showed the highest activity of the three enzymes. In the cotyledon, sorbitol-6-phosphate dehydrogenase activity was highest among the activities of the three enzymes. Sorbitol oxidase showed the weakest activity of the three enzymes in both tissues. The roles of these three enzymes in the metabolism of sorbitol were discussed in relation to their distributions in subcellular fractions.
In order to investigate the differences in flavor quality of tomato fruit ripened on and off the plant, the concentrations of free amino acids and soluble nucleotides in the room ripened fruits were compared with those in the field ripened fruits, during ripening. Room ripened fruits were picked at the mature green, turning or pink stage, and ripened at 25°C. Glutamic acid was the predominant free amino acid in the fruit and progressively increased in quantity with advancing ripeness in every fruit studied. However, the content in room ripened fruit picked at the mature green or turning stage increased more rapidly than that in field ripened fruit. The major soluble nucleotide was identified as adenosine-5'-monophosphate (5'- AMP) by chemical and chromatographic analysis. The 5'-AMP concentration also increased with ripeness in every fruit studied. Again however, room ripened fruit picked at the mature green or turning stage had a higher 5'-AMP content relative to field ripened fruit throughout ripening process. These results indicate that deteriorating flavor quality in room ripened tomatoes can not be explained well by considering only the concentration of flavor-potentiating (umami) substances.