In the coldest season, uptake, reduction, organization and polymerization of 15N-nitrate by a satsuma mandarin tree (Citrus unshiu Marc.) were examined. A satsuma mandarin tree was capable of nitrate-uptake and reduction to amino acids in a low temperature regime (minimum temp. -4°C, maximum temp. 9°C. mean temp. 2.5°C in both air and gravel bed). Nitrate reductive activity of fine roots in vivo showed 24% of the maximum activity at 5°C and 10% at 0.5°C. No accumulation of nitrate was found in the fine roots. Asparagine was most abundantly formed from 15N-nitrate in the fine roots in cold conditions, followed by γ-aminobutyrate, alanine, aspartate and glutamate. Proline formation was relatively low as compared with that in summer. In the leaves 15N-amino acids were formed in negligible amounts in cold temperatures, showing a sharp contrast to the intensive incorporation of 15N into amino acids in summer. Incorporation of the newly synthesized amino acids into protein proceeded steadily in the fine roots. Leucine (+isoleucine), phenylalanine, arginine and proline were abundantly incorporated as compared with in summer. This indicates that protein formed in the cold season is qualitatively different from that formed in summer.
The amount of 15N-nitrate taken up by a satsuma mandarin tree (Citrus unshiu Marc.) in the coldest season (minimum temp. -3°C, mean temp. 3°C) was about one tenth of that taken up in summer (maximum temp. 28°C, mean temp. 23°C). In gravel culture, 90% or more of total nitrogen taken up during the cold season was kept in the roots, especially in the fine roots. A large portion of it began to translocate upwards after late February/early March and was used, preferentially, to build up new organs, such as flower, leaves and twigs. This accounted for 40% of the total nitrogen taken up during the cold season; another 36% was partitioned to the existing organs in the top and 24% to the roots. This partitioning pattern is close to that in soil culture. One-year-old leaves acted as a sink for 15N even at the developing stage of flushed shoots. Data on 15N abundances in the amino acids and nitrate indicate that nitrate, which is taken up in winter, translocate upward mainly as nitrate and asparagine in the following spring.
Changes of 0.2% ammonium oxalate and 0.05N HCl soluble K, Ca and Mg contents in ethyle alcohol and water insoluble fruit pulp with the fruit growth of “Yuzuhada” disordered and healthy Japanese pear cv. Nijisseiki trees were compared to clarify the relationship between the occurrence of “Yuzuhada” disorder and mineral nutrition. 1) K contents in 0.2% ammonium oxalate soluble fraction of fruit pulp of the disordered tree were remarkably higher than those of the healthy tree in the period from 30 to 40 days before symptom were visible on fruit rinds. In the same period, Mg contents in 0.2% ammonium oxalate soluble fraction of fruit pulp of the disordered tree showed a tendency to be slightly higher than those of the healthy tree. Ca contents in this fraction, however, showed no relationship to the occurrence of disorder. 2) Ca contents in 0.05 N HCl soluble fraction in fruit pulp of the disordered tree showed a tendency to be slightly higher in the late period of fruit growth than those of the healthy tree. No relationships were observed between Mg and K contents in this fraction and the occurrence of disorder. 3) These results imply that higher K contents in 0.2% ammonium oxalate soluble fraction in fruit pulp -K salt of pectic acid in the cell wall in the period from 30 to 40 days before symptoms are visible is closely related to the occurrence of “Yuzuhada” disorder.
The degree of occurrence of “Yuzuhada” disorder and its relation to the contents of inorganic elements in fruit pulp were compared among several Japsnese pear(P. serotina Rehd.) cultivars. 1) Japanese pear cultivars, Shinsui, Hosui, Kosui, Shinko, Chojuro and Nijisseiki were top-grafted on secondary scaffold branches of 12-year-old ‘Nijisseiki’ pear tree which was suffering from “Yuzuhada” disorder. 2) Three years after the grafting, the severe occurrence of “Yuzuhada” disorder was observed in ‘Shinko’, ‘Chojuro’ and ‘Nijisseiki’ fruits. In ‘Shinsui’ and ‘Hosui’ fruits, a slight occurrence of the disorder was observed, while in ‘Kosui’ fruits, no symptom was observed. 3) Contents of soluble K, Ca and Mg in fruit pulp were compared at an early stage of fruit growth. ‘Shinko’, ‘Nijisseiki’ and ‘Chojuro’ were rich in soluble K and poor in soluble Ca. On the other hand, ‘Kosui’, ‘Shinsui’ and ‘Hosui’ fruit pulps were lowor in soluble K and higher in soluble Ca than those of the former three cultivars. 4) 0.2% ammonium oxalate soluble K contents in fruit pulp were high in ‘Shinko’, ‘Chojuro’ and ‘Nijisseiki’. These cultivars were suffering from severe “Yuzuhada” disorder.
In flower clusters of grapevines, a large number of ovaries abscise at the base of their pedicels one to two weeks after anthesis. Using the cultivar ‘Muscat of Alexandria’, we studied the pollinated florets histologically from anthesis to setting or abscission. Such treatments as prebloom shoot pinching, cluster trimming and boron spray, widely applied to increase the setting rate, were also examined for their effects on the development of ovaries. The results are as follows. 1. Fluorescent microscopic observation of pollen tube growth revealed that in most florets, pollen tubes reached three or four ovules out of the four in an ovary penetrating through their micropyles even on the first day after pollination. The rate of such ovules showed no increase when examined two or four days after pollination. There was no significant difference in either the number of pollen tubes grown into ovaries or the rate of reached ovules between treated and untreated shoots, although the berry setting rate was much increased by the treatments, 28.6% for pinched and trimmed, 15.8% for boron sprayed, and 9.5% for untreated shoots. 2. Division of the primary endosperm nucleus, which occurs in the fertilized embryo sac, began two or three days after anthesis. Approximately 80% of the ovules contained two or more dividing free nuclei regardless of treatments four days after anthesis. This result indicates that ovules are fertilized easily if the pollen tubes reach into their micropyles, and that the severe flower shatter occurring in untreated shoots is not due to failure of fertilization of ovules. 3. Progression of the division of free nuclei, however, varied with the treatments. The percentage of ovules containing five or more free nuclei four days after anthesis was 41.5% for untreated, 52.6% for boron sprayed, and 69.4% for pinched and trimmed shoots. The effectiveness of these treatments for the development of fertilized endosperm was established. 4. Degeneration of nucelli occurred in many ovules from two to four days after anthesis. These ovules ceased to develop thereafter and aborted. The percentage of such aborted ovules amounted to 45% for pinched and trimmed, 54% for boron sprayed, and 67% for untreated shoots six days after anthesis, when ovary abscission started. Ovaries with three or four aborted ovules were likely to result in abscission, and those with either no or a single aborted ovule did set surely and developed as berries in either treated or untreated shoots. It is of interest that while ovaries with two developing ovules usually abscised in untreated shoots, half of them set in trimmed clusters on pinched shoots.
The purpose of this study to clarify the effect of night temperature on growth of bearing shoots and berries, and the number of days from budbreak to bloom of ‘Muscat of Alexandria’ (Vitis vinifera L.) grown in green houses and to find out the most suitable night temperature in order to save fuel oil. 1. Growth of bearing shoot was more closely related to mean temperature than to the temperature during a specific period of time. Growth of bearing shoot was closely correlated with heat summation above 2.9°C (the sum of the temperature subtracted 2.9°C from mean daily temperature). 2. The number of days from budbreak to full bloom was closely related to mean daily temperature. When heat summation above 2.7°C reached 661°C, flowers of cluster came into full bloom. 3. During growth period I, berry growth was promoted by higher night and mean daily temperatures. High temperature, however, did not affect the rate of berry growth during growth period II. 4. High temperatures did not always shorten the number of days from full bloom to veraison. 5. The percentage berry set showed a tendency to increase when the temperature from 0a.m. to 6a.m., or the mean temperature during blooming was low. There seemed to be no relationship between seed number per berry and temperature. 6. Althogh blooming under Low-Low treatment (low temperature treatments from 6p.m. to 12p.m. and from 0a.m. to 6a.m.) occured a few days later than that under Medium-Medium treatment, the amount of fuel oil consumed in Low-Low treatment was much less, and the retardation in blooming and berry growth was countered by proper vine management after blooming.
“Ajinashi” disease of Koshu grapevine (Vitis vinifera Linn. cv. Koshu) was first recognized in Yamanashi Prefecture in 1968. The disease shows no visible symptoms on the growth of vines and the yield of berries. But the berries are unsuitable not only for the table grape but also for the wine grape owing to a marked decline in sugar content, from which comes the name of this disease. In this paper, seasonal changes in diameter and weight of the berries, and in reducing sugar, glucose, fructose, titratable acid, tartaric acid and malic acid in the juice were investigated in comparison of the normal and “Ajinashi berries”. The results were summarized as follows: 1. The growth curve of the “Ajinashi” berry was almost the same as that of the normal berry, although the size and weight of the “Ajinashi” berry were somewhat greater than those of the normal berry. 2. The “Ajinashi” berry accumulated sugars as much as the normal one unti lthe 80th day after anthesis. At the harvest time, however, it had no more than 12% of soluble solids, 11.3% of reducing sugar, 5.2% of glucose and 5.7% of fructose in contrast to 19% of soluble solids, 18.0% of reducing sugar, 8.4% of glucose and 9.4% of fructose in the normal berry. 3. The “Ajinashi” and normal berries accumulated the highest titratable acid on the 60th day after anthesis, when they contained malic acid more than tartaric acid. After that, however, malic acid was consumed more rapidly than tartaric acid. As a result, titratable, malic and tartaric acid contents of the “Ajinashi” berry were 0.95, 0.40 and 0.70g/100ml and those of the normal berry were 0.86, 0.30 and 0.80g/100ml, respectively, at the harvest time. The ratios of the combined acid to the total acid were 17.4% in the Ajinashi berry and 24.6% in the normal berry.
Effects of benzyl adenine (BA), gibberellic acid (GA3 or GA4) and priming with polyethylene glycol (PEG) 6000 on the germination of celery seeds were investigated. In some priming treatments, BA and/or GA were added into the PEG solution. Concentration used for BA and GA were 10ppm and 50ppm respectively. In spinach seeds, too, germination promotion effects of PEG treatment were studied, and also possibility of storage of seeds air-dried after PEG treatment was investigated. PEG concentration used were -11.7 bars for celery seeds and -11.83--10.27 bars for spinach seeds. PEG solution was added to two sheets of blotting paper to full moistening in a Petri dish, and seeds were sown on the blotting paper. After 7 or 14 days of treat ment, seeds were washed with tap water, and sown on the blotting paper moistened with deionized water in a Petri dish, and incubated in a germinator. Results obtained are summarized as follows: A. Celery 1. Germination of celery seeds were depressed at the germination temperature above 20°C. BA was much effective in promoting the germination. GA4 was also effective to some extent, but GA3 had no effect. Combined treatment of BA and GA4 was most effective. 2. Priming with PEG solution enhanced the germination speed at 20, 25 and 30°C, and improved germination percentage at 25 and 30°C. 3. Remarkable effect was observed following 7 days of priming with PEG, but the larger effect was obtained by 14 days of priming. 4. As to the treatment temperature, one lot of seeds was favoured by the treatment at 15°C than at 20°C, but another lot of seeds was favoured at 20°C than at 15°C. 5. Treatment under light was more effective in promoting the germination than that under dark. 6. Addition of BA to the PEG solution enhanced the PEG treatment effect, but GA4 did not. 7. The difference in effectiveness of BA and GA4 between their use with and without PEG is considered to be due to the difference in treating methods. That is, in the case of treatment without PEG, seeds were continually in contact with such chemical(s) on the blotting paper till the end of germination experiment, but in the case of treatment with PEG, seeds were in contact with such chemical(s) only during the priming period, because seeds were thereafter germinated on the blotting paper moistened with pure water. B. Spinach. 1. Germination speed of spinach seeds was enhanced by PEG treatments at 20, 25 and 30°C, and germination percentage was improved at 30°C. 2. When PEG-treated seeds were air-dried and stored for 7 or 14 days, germination percentage did not change, and germination speed lowered only a little, showing preservation of priming effect.
Low temperature-induced fruit malformation in tomato was studied from plant hormonal view point. Treatment of TIBA (2, 3, 5-triiodobenzoic acid) and NAP (sodium N-1-naphthylphthalamic acid), auxin-transport inhibitors, increased locule numbers and induced severe malformation including catfaced and strawberry fruits with ovary splits, and oblate and fasciated fruits. Bendroquinone (2-benzimidoyl-3-hydroxyl-1, 4-napthoquinone), which is considered to have the similar action mechanism to TIBA and NPA, also showed the same effects. Auxins, PCPA (p-chlorophenoxyacetic acid), 2, 4-D (2, 4-dichlorophenoxyacetic acid) and 2, 4, 5-T (2, 4, 5-trichlorophenoxyacetic acid) reduced oblate and triangular types of malformation by decreasing locule numbers. Gibberellin (GA3) inducey ovary split but CCC [(2-chloroethyl) trimethylammonium chloride] and SADH (succinic acid-2, 2-dimethylhydrazide), which are considered to inhibit gibberellin synthesis, could not reduce low temperature-induced fruit malformation.
Muskmelons (Cucumis melo L.) were grown in sand with 7N form treatments (NO3:NH4; 10:0, 8:2, 6:4, 5:5, 4:6, 2:8 and 0:10) supplied daily at a concentration of 90ppm. A total of 78 liters of treatment solution was applied per plant throughout the experiment. The higher NH4 ratios caused plant growth and fruit fresh weight to decrease, while fruit soluble solids remained slightly higher. With increasing NH4 ratios N in leaves increased. NO3-N and NH4-N in the plant parts and medium (sand) reflected the form of N that was supplied. N uptake by plants at all NH4 ratios was greatest at 5, 137mg per plant. With increasing NH4 ratios NH4-N in soil solution increased, while NO3-N and Na, and pH and EC values tended to decrease.
Cabbage (Brassica oleracea L., capitata group) plants were grown in nutrient solutions containing NO3-N at 5, 50, and 500ppm. At the beginning of head formation, the outer leaves were removed in various ways, and the effects of the nitrogen supply and the defoliation on the head development were studied. The head weight increased greatly with an increase of the nitrogen supply from 5 to 50ppm N and decreased slightly at 500ppm N. At 50 or 500ppm N, the head weight decreased slightly following the removal of the middle and lower outer leaves (i.e. the upper outer leaves were kept intact), while greatly following the removal of the upper and middle outer leaves. At 5ppm N, the head weight was so small that no clear effect of the defoliation was recognized. The total N, 80% ethanolsoluble N, and NO3-N contents in the plants increased with an increase of the nitrogen supply and with the removal of the upper and middle outer leaves. The total sugar content was lower at 5 and 500ppm N than at 50ppm N, and decreased with the removal of the upper and middle outer leaves. The ratio of the total carbohydrate to the total N contents of the outer leaves was about 10 in the intact (control) plants which were grown at 50ppm N and had the largest head weight.
Green soybeans (Glycine max. Merr.) were grown in sand to determine the salt tolerance affected by salinization of sea water, NaCl, Na2SO4, MgCl2 and MgSO4 at osmotic potentials of -1.20, -1.70 and -2.70 bars as compared to a control of -0.70 bars of base nutrient solution. Dry weight of the whole plant, fresh weight of seeds and pods, and number of pole were greatest in the control and decreased in each salinity with decreasing osmotic potentials. Growth was greatest in the MgSO4 series, less in the sea water and Na2SO4 series, and least in the NaCl and MgCl2 series. There was a marked suppression of growth in the NaCl and MgCl2 series at -2.70 bars. Chloride-salinity caused markedly different symptoms from those caused bysulfate-salinity. In chloride-salinity treatments chlorosis and necrosis were observed on margins of leaves, and developed acropetally at the middle and late stages of growth. The lower the osmotic potentials the more pronounced the symptoms. In sulfate-salinity treatments at only -1.70 bars interveinal chlorosis was found. Na, Mg, Cl and SO4 content of leaves and sand solution (SS) tended to increase with decreasing osmotic potentials of treatment solutions in sodium-, magnesium-, chlo ride- and sulfate-salinities, respectively. EC values of SS increased and osmotic potentials of SS decreased as osmotic potentials of treatmentsolutions decreased. The values were similar at the isosmotic potential in each salinity.
Effects of BA (6-benzyl amino purine) and IAA (indole-3-aceticacid) on the redifferentiation and multiplication of callus were observed in Lilium maculatum var. bukosanense (Honda) Hara using Murashige and Skoog (M•S) medium. 1) Redifferentiation of shoots, phyllomes and adventitious roots and multiplication of callus were observed on M•S medium containing only 1ppm of IAA which gave the best result in this experiment. 2) Redifferentiation of shoots on the callus was observed rondomly during culture periods. 3) Ability of the redifferentiation was kept high until the fourth generation by sub-cultures of every 60 days on the medium containing 1ppm IAA. 4) In the histological observation, developmental features of shoots were distinguished between two types, bulblet and abulblet. 5) Procambial tissues in the adventitious roots had been differentiated when the root primordium was observed.
In order to examine the relation between the depth of dormancy and temperature for sprouting, gladiolus cormels harvested early in November and stored dry at room temperature were planted at different times in petri dishes containing about 0.6% agar alone as a substratum and placed at constant temperatures of 10, 15, 20, 25 and 30°C. Regardless of temperature, few cormels planted in December sprouted except bare cormels (shell removed) of ‘Professor Goudriaan’, in which sprouting took place at 10 and 20°C. This indicates that cormels are usually in a state of true dormancy about 2 months after harvest. On the other hand, cormels planted in January or later had been exposed to a long term of natural low temperature and were able to sprout at a wider range of temperature than cormels planted earlier. Namely, cormels first became able to sprout at lower temperatures of 10-15°C and then gradually at higher temperatures of 20-25°C. Bare cormels began to sprout at a wide temperature range earlier than intact ones (shell adherent). It may be concluded from these results that about 15°C or 20°C is optimal for the sprouting of cormels which are in a state of postdormancy or out of dormancy, respectively. For any planting date, few cormels sprouted at 30°C and therefore the maximum temperature for sprouting is presumed to be about 30°C. Moreover it was demonstrated that sprouting was promoted by storing cormels dry at room temperature for an extended period of 17 months and planting them in the early spring of the year after next. Cormels which were presumed to be in true dormancy at planting time remained in non-sprouting conditions for a year or longer, as long as they were placed in a wet condition at constant temperature between 10 and 30°C, especially between 20 and 30°C. However they gradually turned to a state of postdormancy during the non-sprouting period.
Some experiments were carried out to evaluate the role of light in rooting of softwood cuttings in Euonymus japonicus Thunb., The results were summarized as follows. 1. Among the cuttings grown under different light intensities by shading with different number of layers of cheesecloth during the propagation period, almost no difference in rooting percentage was found, while both the number and weight of roots per cutting were reduced with lowering light intensities. 2. Cuttings were placed in the dark at different times during the propagation period, and at the same time a half of them were defoliated and disbudded. When the treatment was started earlier than 14 days after planting, distinct differences in rooting percentage were found between the cuttings with and without leaves and buds. This fact indicates that functions of the leaves and buds other than photosynthesis may exert a significant influence on rooting percentage at the earlier stage of propagation. 3. When the treatment was started later, the number and weight of roots became greater in both cuttings with and without leaves and buds, although the values were usually much larger in the former cuttings than in the latter ones. This fact suggests that root development is promoted by lighting and affected by functions of the leaves and buds other than photosynthesis throughout the propagation period. 4. To clarify the role of photosynthesis in rooting, the effects of removal of carbon dioxide from the air during the first half and/or the latter half of the propagation period on rooting were obseved. As a result, it is clear that photosynthesis hardly affects rooting percentage, but has an important role in root development during the latter half of the propagation period.
Green Kabosu fruit (Citrus sphaerocarpa hort. ex Tanaka), a sour orange, tends to lose easily the external green colour and become poor in flavour during storage at room temperature. Therefore, it is important to keep green colour during storage of the fruit. In this study, physiological changes during storage at different temperatures ranging 1°C to 30°C were investigated to elucidate the optimum storage temperature for the fruit. 1. The most rapid degreening of the peel colour was found in the fruit held at 15°C and 20°C, while degreening of the fruit ceased within 1 month at 30°C. At 1°C, degreening was inhibited markedly and the fruit kept good green colour during storage for 4 months. 2. Fruit held at high temperatures tended to show a high rate of respiration during storage. Respiratory rate continued to increase gradually during storage at low temperatures (1°C-10°C). 3. A sudden rise of ethylene production was observed in the fruit stored for 15 days at 1°C, followed by a high rate of production. While the fruit continued to emit low rate of ethylene at temperature within the range 5°C to 20°C. 4. Break points were observed in the Arrhenius plots of respiratory rate of the fruit at 16°C and 4°C. 5. High rate of occurrence of chilling injury was observed in the fruit stored at 1°C for 4 to 6 months. On the other hand, occurrence of chilling injury was seldom in the fruit stored at 5°C and 10°C. Judging from the above results, it may be concluded that green Kabosu fruit is chilling sensitive and that shelf life of Kabosu fruit is less than 4 months at 1°C. If the fruit has to be stored for more than 4 months, the optimum temperature must be 4°C which is safe temperature from chilling injury.
Load resistibility to static pressure and the permissible limit of heaping height were examined on the fruits of tomato for processing in order to rationalize a method for the handling of the fruits after harvest. 1. The behavior of fruits of static pressure resembled closely creep of fourelement model in the visco-elastic body. 2. The hardness and elastic behavior of the fruits were high in the cultivars of ‘AT 70/24’ ‘TE-30’ and ‘ES-58’. A high correlation was observed between the creep characten and the color tone (Hunter a/b ratio) of the fruits with the significant level of 0.1%, and the hardness and elastic behavior decreased with maturity. 3. The observed relations of the degree of fruit deformation to the magnitude of load and to the loading time showed that the extent of occurrence of lacerated wounds in the fruits was low in ‘ES-58’ ‘TE-30’ and ‘AT70/24’ and high in ‘H-1409’ ‘KG-127’ and ‘Kurikoma’. The limiting deformation rate beyond which the fruits were lacerated was highest (36.8%) for ‘AT-70/24’ and lowest (7.5%) for ‘H-1409’. 4. The extent of fruit injury increased with an increase in heaping height of the fruits. Among the cultivars examined, ‘H-1409’ was injured most markedly, while ‘TE-30’ most slightly. The permissible limit of heaping height was very large for ‘AT70/24’ ‘ES-58’ and ‘TE-30’ and low for ‘H-1409’ and ‘KG-127’. These observations indicate that the cultivars with high hardness and elastic behavior are also have the high load resistibility to static pressure. Among the cultivars examined, load resistibility to static pressure was very high for ‘AT70/24’ ‘TE-30’ and ‘ES-58’.