To clairfy the mechanism of seedlessness in ‘Himrod Seedless’ grape, histological comparisons were made between unseeded ‘Himrod Seedless’ and seeded ‘Campbell Early’ berries. The development of berry and seed, pollen fertility, pollen tube elongation in the ovary, internal morphology of the ovule, and the nuclear division in the endosperm and fertilized egg (zygote) were studied.
1. Berry and seed (ovule) development: The berries of ‘Campbell Early’ clearly exhibited a double-sigmoidal growth curve, whereas those of ‘Himrod Seedless’ lacked the second stage of berry growth and, therefore, did not reveal the same growth pattern. Seeds of ‘Campbell Early’ increased rapidly in size from about 1 week through 4 weeks after flowering which coincided with the first stage of fruit growth. The size remained constant thereafter until harvest. Seeds of ‘Himrod Seedless’ grew slightly for 2 weeks after anthesis and then stopped growing.
2. Parthenocarpic ability: The percent sets of parthenocarpic berries resulting from emasculated flowers were 23.3 for ‘Himrod Seedless’ and 15.9 for ‘Campbell Early’, which demonstrate that both cultivars can set berreis parthenocarpically. The weights of seedless berries of ‘Himrod Seedless’ and ‘Campbell Early’ were 60% and 15% lighter, respectively, compared to those naturally pollinated berries.
3. Pollen fertility: The percentages of pollen which germinated on agar medium (20% sucrose, 1% agar) were 14.0 and 22.2 for ‘Himrod Seedless’ and ‘Campbell Early’, respectively. The percentages of pollen stained by acetocarmine were 90.4 and 45.6 for ‘Himrod Seedless’ and ‘Campbell Early’, respectively.
4. Pollen tube elongation in the ovary: The rate of pollen tube elongation in ‘Himrod Seedless’ was slightly slower than that of ‘Campbell Early’. However, in both cultivars, 80% of the pollen tubes reached the ovules within 48hr after flowering.
5. Internal morphology of ovule and embryo sac: At anthesis, ‘Himrod Seedless’ ovules had an abnormally long inner integument and a larger micropyle compared to those of ‘Campbell Early’. The embryo sac of many ‘Himrod Seedless’ ovules lacked the egg cell or the synergids, or exhibited degeneration of the egg apparatus. The percentage of ovules with these abnormalities was 88.4%.
6. Nuclear division in the endosperm and embryo formation: In ‘Campbell Early’, freenuclear division of the endosperm began 3 days after anthesis, whereas nuclear division of the zygote began about 18 days later. In ‘Himrod Seedless’, 93.3% of the endosperm did not exhibit free-nuclear division but degenerated. In the remaining 6.7% of the ovules, the endosperm nuclei divided only 2 or 3 times beginning 6 days after flowering. Cell division of the zygote was not observed.
We speculate that seedlessness in ‘Himrod Seedless’ berries is the result of abnormal double fertilization based on the high percentage of abnormal development of the embryo sac and egg apparatus and the limited nuclear division occurring in the endosperm. Polar nuclei may become fertilized but subsequent neclear divisions are abnormally low. This may hamper or limit the nutrient supply and lead to the degeneration of the zygote.

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Although ambient temperature is kept adequate, grape cultivation under covered facilities during winter months in Japan gives rise to low yields of poor quality berries because of low light intensities. This investigation was conducted in leaf chamber, using Vitis labruscana Bailey cv. Kyoho, to determine the influence of leaf age, light intensity, and CO₂ concentrations on photosynthesis. The effects of CO₂ enrichment on vine growth and fruit quality were also investigated in growth chambers.
1. The rate of photosynthesis per unit leaf area (Pn) between May 28 and September 19 rapidly increased with leaf growth, reaching a maximum of 18.9mg CO₂/dm²/hr, 37 days after the unfolding of a leaf. Pn then gradually decreased with leaf age. In young leaves, higher CO₂ concentrations and stronger light intensities resulted in a significant increase in Pn. Older leaves exhibited a similar enhancement of Pn upon exposure to high light intensity. Pn was saturated at 828ppm CO₂.
2. Administration of 1, 000 to 1, 100ppm CO₂ to vines for an 8hr/day at a late stage of berry development until harvest had no effect on berry size but resulted in an increase in sugar and anthocyanin contents but a decrease in organic acid content. Dry weight of newly developed roots doubled as a result of CO₂ enrichment.
3. Application of CO₂ under a long-day photoperiod at an early stage of berry development to a week before véraison markedly promoted shoot elongation. Furthermore, CO₂ enrichment gave a 36% increase in both berry and cluster weights and also a higher sugar-acid ratio at harvest.

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Growth and ripening processes of Japanese persimmon fruits, ‘Hiratanenashi’ (astringent type) and ‘Jiro’ (non-astringent type) were compared for three years at two different locations. One orchard was situated in Tsuruoka, the northern city of Japan, and the other was located in central Japan, Kyoto.
The average temperatures throughout the fruit growing season were higher in Kyoto than in Tsuruoka. Thus, full bloom for both cultivars was 2 to 3 weeks earlier in Kyoto, and consequently, fruit growth was faster than that of trees growing in Tsuruoka. However, harvest times were almost the same between the two sites. This shortening of the period from full bloom to maturity in Tsuruoka was due to the shortening of the second growth stage which was probably caused by the cooler summer weather. The yellowing of fruits started earlier in Tsuruoka but the final color intensity was more advanced in Kyoto. Total sugar and soluble tannin contents in the flesh at maturity were quite similar for the two locations.

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Chromosome numbers of the original tree and embryos exised from immature or aborted seeds of Japanese persimmon cv. Hiratanenashi were examined. The possible origin of the tree and the reason for seedlessness in ‘Hiratanenashi’ based on chromosome number are discussed.
1. The original ‘Hiratanenashi’ tree, a chance seedling, has a somatic chromosome number, 2n=135. Accordingly, the tree was considered to have originated from a union of an unreduced gamete (n=90) and a reduced gamete (n=45) of the same species; ‘Tone Wase’, a spontaneous bud sport of ‘Hiratanenashi’, also has 135 chromosomes in its somatic cells.
2. Differences in the degree of embryo development were observed among immature embryos 80 days after anthesis and embryos cultured on artificial medium. These differences indicate that the development and growth of ‘Hiratanenashi’ embryos are related to its genotype.
3. The somatic chromosome number of the embryos derived from immature or aborted seeds of ‘Hiratanenashi’ and ‘Tone Wase’ ranged from 106 to 114. This suggests that the embryos were aneuploid and that the gametes of heteroploidy were derived from their mother plants, ‘Hiratanenashi’ and ‘Tone Wase’.
4. We postulate that the main factor preventing normal seed development in ‘Hiratanenashi’ persimmon is the formation of abnormal embryo sacs and heteroploid gametes. The unbalanced chromosome numbers in gametes must lead to abnormal cell division and subsequently the degradation of endosperms and embryos.

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1. In order to determine avocado tree (Persea americana Mill.) bearing behavior in Japan, the cultivars ‘Zutano’, ‘Bacon’ and ‘Fuerte’ were studied in Yamada Orchard, Numazu, Shizuoka, during 1980-′88.
2. Fruits had a sigmoid growth curve, growing rapidly after late June and then slowly after mid August. Growth of seeds was steady June to October and slow thereafter.
3. Flower (fruit) drop had two peaks, first mostly flowers from early May to mid June, and a second peak of mostly small fruits from late May to late June. Flower drop was more severe than fruit drop.
4. Primary branches (bearing shoots) and secondary branches (lateral shoots) elongated rapidly after mid May, then very slowly after late June.
5. Leaf drop had two peaks, the first from mid May to mid June and a second for ‘Bacon’ and ‘Zutano’ from August to late September.
6. Inflorescences were of two types: Indeterminate (with growing tip) and determinate (no growing tip). ‘Zutano’ had more indeterminates; ‘Bacon’ and ‘Fuerte’ inflorescence type tended to alternate from year to year.
7. There were eight types of fruiting branchlets, based on different combinations of vegetative and bearing shoots. Successful fruiting percentage was higher for summer than for spring shoots, for first than for later branches, and for terminal buds than for secondary nodes of flowering branchlets.
8. Fruit set per flower ranged up to 0.038%, with ‘Fuerte’ highest and ‘Bacon’ lowest. Yield alternated from year to year. Both fruit size and number were smaller in years with lower temperatures.
9. Flower bud mortality increased with both time and lower temperature minimum in the -2.5° to -3.5°C range.
10. The major impediment to avocado growing in Japan is low temperature, both winter freezes and flowering period chilling. It is therefore important to select the warmest locations, and also to breed cultivars with greater cold resistance.

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The allocation of dry matter, reserve nutrients and flower bud formation of Japanese pear (Pyrus serotina Rehder) cv. Kosui grown under plastic house (PL) were compared with those grown in the open field (OF). Experimental trees were grown under frames covered with polyethylene vinyl-acetate film from early March to mid-May. Materials were sampled in late November and December.
1. Shoot: root ratio of tree under PL was higher when compared with that of trees grown in OF. It was notable that all organs, especially roots of covered trees had lower carbohydrate reserve contents than did those sampled from trees in OF. Mineral contents in most of the organs under PL were also lower than were those of OF.
2. Covered trees had 49% more axillary flower buds on shoots and 46% less flower buds on spurs than did those of OF. Current shoots under PL were thinner and shorter than were those in OF.

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Concentrated mechanical stress in the skin of a growing fruit may be a driving force behind fruit cracking and splitting. This paper deals with a new system that analyzes the distribution of surface stress of fruit and the relationship among the degree of fruit cracking of 8 sweet cherry cultivars and the fracture patterns and the distribution of the stress.
1. This system is based on the method of Considine and Brown (1981) who applied “Theory of Shells” to some model shells of fruits. It analyzes the distribution of surface stress of actual fruits. By reading the plane co-ordinates of an outline of a vertical section of an actual fruit using a digitizer, the system calculates the radius of the curvature at each point on the outline in the direction of the longitudinal and latitudinal arcs and other geometrical variables, and finally it produces the distribution of stress and that of the “factor of stress concentration”.
2. Epidermal stress of the cherry fruits rose rapidly at the beginning of June under the influence of increases in turgor pressure of the mesocarp tissue.
3. The stress, acting in the direction of a longitudinal arc, was concentrated around the fruit apex and the pedicel cavity in fruits of all cultivars. The other stress, acting in the direction of the latitudinal arc, was concentrated around the equator of fruit. Furthermore, an intimate relationship was found between the distribution of stress, and the degree of cracking, and the fracture patterns.
4. Significant differences were revealed in the relative values of the mean stress at several surface regions among some cultivars. There was a close correlation between the percentages of cracked fruits by forced immersion and the intensities of the stress at some regions among the 8 cultivars.

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Bean, spinach, lettuce, and radish were grown in solution culture to investigate the effect of form of N supplied and pH level of the nutrient solution on Cu toxicities. Copper was supplied at levels of 0.02, 0.3, and 1ppm. At each Cu level, NO₃, NO₃+NH₄ (1:1), and NH₄ were supplied, with the total N concentration being held constant at 12me/liter. The pH of the nutrient solution was adjusted to two levels, 4 and 6.
1. At the normal Cu level (0.02ppm), the growth of plants supplied with NO₃ and NO₃+NH₄ was excellent in any vegetable crops, but NH₄ plants produced inhibited growth except for lettuce. In vegetable crops except for bean, pH 6 produced better growth than pH 4. The growth reduction due to excess Cu in the nutrient solution was more marked at pH 4 than at pH 6. At pH 4, NO₃+NH₄ was more advantageous than NO₃ for reducing the Cu toxicity, while NH₄ treatment did not show the same effect because of NH₄ toxicity.
2. In any vegetable crops, roots were found to accumulate a larger concentration of Cu than leaves, the difference being more marked where excess Cu was supplied. The Cu accumulation in roots was generally larger at pH 4 than at pH 6. This was considered to be due to the markedly higher concentration of Cu²⁺ in the nutrient solution at pH 4 than at pH 6, as the result of the influence of pH on the extent of chelate formation of Cu with EDTA supplied as Fe-EDTA. The application of NH₄ had effects to suppress the Cu accumulation in roots. In NO₃ and NO₃+NH₄ treatments, there was a close relationship between the Cu accumulation in roots and the reduction of plant growth. The root Cu-plant growth relationship in NH₄ treatment was quite different from that in NO₃ and NO₃+NH₄ treatments; especially in spinach and radish, the plant growth was almost constantly poor regardless of the root Cu concentration.

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Plants of the strawberry cultivar ‘Reiko’ with an inflorescence consisting of a primary (1st) flower (fruit) or a primary and two secondary (2nd and 3rd) flowers (fruits) were grown in a chamber under controlled light and temperature conditions, and the size of each fruit was measured with a caliper at 2-day intervals from 5-7 days after anthesis. Each fruit grew rapidly in the early period (5-7 days) and late period of fruit growth, in showing a pattern characterized by a double sigmoid curve. The second peaks occurred at 35, 28 and 36 days for the 1st, 2nd and 3rd fruits, respectively, in the first experiment (16°C in the daytime (12hr, 315μmol m^-2 sec^-1) and 13°C in the night), and at 23 days for the 1st fruit in the second experiment (20°C in the daytime (14hr, 185μmol m^-2 sec^-1) and 17°C in the night). In the second experiment, at 5-9 days the achene on the 1st fruit grew rapidly. During 5-17 days the dry weight and sugar concentration per dry weight of the 1st fruit were very low, but thereafter they increased remarkably.
It is considered that in the first peak of fruit growth the receptacle started to grow and the fruit set was completed due to the rapid growth of the achenes after fertilization, while in the second peak a large amount of assimilates was transported into the receptacle which enlarged rapidly again.

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Effects of photoperiod on the length and number of epidermal cells in ‘Donner’ strawberry petioles were investigated.
The number of cells in petioles which were differentiated under natural daylength between May and June increased as the leaves emerged and petioles elongated later in 16-hr daylength (LD); concurrently, the average cell length became shorter. The mean cell length also decreased when leaves emerged under 9-hr daylength (SD); the numbers of cells per petiole of the first three petioles to elongate under SD conditions were not significantly different.
Petioles which differentiated and elongated under SD had shorter cell length and fewer number of cells compared to those growing under LD. Petiole cell length was controlled by photoperiod after emergence of the petioles, whereas cell number per petiole was independent of daylength.
The leaf emergence interval (days per leaf) was longer for leaves which differentiated under SD than that which differentiated under LD. As petiole length decreased, the formation of runners (stolons) was inhibited.
Cell division in leaf initials enclosed in the plant crown is inhibited by SD. This responce will be one of the reasons why petioles become short under LD at high temperatures at the beginning of the rest period.

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The purpose of this paper is to report susceptible strawberry cultivars and strains to Alternaria black spot of strawberry (Alternaria alternata strawberry pathotype) in Japan. The test for susceptible strawberry cultivars and strains to the pathogen was carried out by artificial inoculation with the spores (isolate OH-5) in June and September, 1988 and 1989. Natural infections under field conditions were also recorded.
Among sixty Japanese and foreign strawberry cultivars and strains tested, only two cultivars, ‘Morioka-16’ previously known as susceptible cultivar in Japan and ‘Robinson’ from the United States of America, were susceptible to the pathogen in Japan. The other cultivars including ‘Chiyoda’ and ‘Fairfax’, used as crossing parents of ‘Morioka-16’, were completely resistant.

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A rapid and simple method for determining 4-methylthio-3-butenyl isothiocyanate (MTB-ITC), a pungent principle in root of Japanese radish, was developed. Fresh root was grated by a food processor, and glucosinolates in the root tissue were hydrolyzed with endogenous myrosinase. Released MTB-ITC was extracted with methylene chloride, and analyzed by a gas chromatograph (GC) equipped with FID at constant column temperature.
Most of added sinigrin was quantitatively recovered as allyl isothiocyanate by the new modified method, indicating that the activity of endogenous myrosinase was high enough to hydrolyze all of glucosinolates to isothiocyanates. MTB-ITC contributed more than 95% of peak area detected on the chromatographic tracing. Methods of crushing root tissue affected the amount of MTB-ITC produced. MTB-ITC in methylene chloride was stable as long as it was kept at -20°C. Differences in MTB-ITC contents among radish cultivars were examined by the method.

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The contents of 4-methylthio-3-butenyl isothiocyanate (MTB-ITC) in roots of Japanese radish (Raphanus sativus L. ) were determined by gas chromatography to evaluate the relative pungency of cultivars. The relationship between the content of MTB-ITC and the taste of grated radish was also examined.
The contents of MTB-ITC in more than half of the commercial cultivars ranged from 200 to 300μmol/100ml juice. Among the cultivars examined, ‘Karami’ showed the highest content of MTB-ITC, reaching as much as 1735μmol/100ml, followed by ‘Shinshu-jidaikon’ group of 400-700μmol/100ml. ‘Ninengo’ and ‘Shiroagari’ groups also exhibited relatively high content averaging more than 300μmol/100ml. On the contrary, ‘Miyashige’ group or Chinese cultivars contained the lowest level of MTB-ITC ranging from 100 to 200μmol/100ml.
Coefficients of variance in MTB-ITC content among individual roots were 32-43% in oldtype purebred cultivars, and 12-14% in recently-released F₁ hybrid. A significant negative correlation (r=-0.789) was observed between the content of MTB-ITC and the water content of the tissues among cultivars.
The result of sensory evaluation on grated radish showed that a cultivar with higher content of MTB-ITC was proportionately more pungent, supporting the idea that this substance is the pungent principle in roots of Japanese radish.

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Flowering response in intergeneric hybrid Brassicoraphanus (Brassica oleracea×Raphanus sativus, 2n=36) and interspecific hybrid Hakuran (B.×napus, 2n=38) was compared to their parental species with respect to their endogenous gibberellin (GA) contents. Flowering response of both hybrids was similar to that of their seed vernalization type parental species, e.g., R. sativus and B. campestris, respectively, but sensitivity of progenies to vernalization treatment was lowered and still unstable. Endogenous GA increased in hybrids and parental species after seed vernalization, but the GA content in vernalized hybrid seedlings was not intermediate compared to levels in the vernalized parental species. Increase in the endogenous GA in the vernalized plants was independent of the flowering response to vernalization.

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Tomato plants (Lycopersicon esculentum Mill., cv. TVR-2) were grown in the nutrient film technique (NFT) system. The dissolved oxygen (O₂) concentrations of the nutrient solution flowing on the bottom of the channel were determined after the solution supply was interrupted. The interruption were made when the 3rd or 4th truss was flowering.
The O₂ concentration decreased with time after the interruption, but it began to increase after 10 to 30-min had elapsed. Therefore, the maximum O₂ concentration was higher, the longer the duration of the interruption. The increase of O₂ concentration after the interruption occurred sooner when the solution temperature was higher. At the same solution temperature, O₂ levels were higher at night than during the day.
Comparison of O₂ concentrations between interruption intervals of 15-min and 60-min followed by a 15-min flow revealed that the difference between the maximum and minimum O₂ concentration was much greater after a 60-min interruption than that of a 15-min.
The amount of O₂ absorbed by excised tomato roots was two-fold greater in air than in water.
When the method of intermittent solution supply was adapted during the entire growing period, plant growth was not stable in early flowering stage, but it improved if a sheet of non-woven fabric was laid on the bottom of the channel. Fruit yield was also increased by this treatment compared with that without the non-woven fabric.

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Germination of Wasabia japonia Matsum. seeds, typical recalcitrant crop seeds in Japan, was investigated. Wasabia seeds have deep dormancy, but during storage the dormancy weakens. In eight months after harvest, the dormancy almost all disappears, resulting in the heavy sprouting of stored seeds.
Optimum germination temperature is 15°C. In deep dormant period, 20°C or higher temperature cannot induce full germination. At 10°C, germination speed is very slow, though the similar germination percentage can be attained as in 15°C.
GA₄ is more effective than GA₃ in breaking the dormancy. Germination percentage is higher and mean germinating days is smaller in GA₄ than in GA₃.
BA and thiourea are effective to some extent for dormancy breaking. Combination of GA₃ and BA shows about as the same effectiveness as GA₄.
Decoated seeds show almost perfect germination even in the deep dormant period, showing the cause of dormancy is mainly due to seedcoat.

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Wasabia japonica, a kind of spices, produces typical recalcitrant seeds.
When dried seeds (moisture content 10-20%) are stored open at room temperature, they lose viability in two to three weeks, and within two months even at 5°C low temperature. However, when those seeds are stored in liquid nitrogen, viability can be retained about one year.
When moisture content of seeds decreases to less than six percent, their viability is almost lost at that time.
Seeds of high moisture content cannot survive in liquid nitrogen. The critical moisture content is between 20% and 15%, i.e., seeds containing more than 20% moisture lose viability at once in liquid nitrogen, and those containing less than 15% can be stored safely in liquid nitrogen.
Cryoprotectant (DMSO+glycerin+PEG) is not effective for preventing freezing injury of moist seeds in liquid nitrogen. However, when dried seeds (moisture content about 12%) are treated with cryoprotectant and then immersed in liquid nitrogen, freezing injury was prevented and the seeds retained viability for some period.
When seeds are stored in moist condition at low temperature of 5° to 10°C, critical point of moisture content of seeds is between 40% and 30%, i.e., seeds having less than 30% moisture content lose their viability in a short period, and those more than 40% can survive for a long time.
When seeds are stored in moist condition at low temperature, sprouting of seeds increases according to weakening of dormancy. Storage of seeds in PEG solution or storage of seeds pretreated with growth retardants (pachrobutrazol, uniconazol, ancymidol, CCC or CGR-811) is a useful method for storage of seeds without sprouting for a long time. Combination of PEG solution and a growth retardant is also useful for storage.
When moist seeds are stored embedded in vaseline or lard, viability decreased in two or three months, suggesting oxygen is necessary for surviving of moist seeds.

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The reasons why tertiary phosphates suspended radicle protrusion during priming of carrot seeds were examined.
During priming of seeds in petri dishes, the pH of K₃PO₄ solutions continued to decrease from the start of the treatment to day 7, and then it became constant between pH 9.1 and 9.5. Although the pH of NaCl solutions increased asymptotically for the initial 7 days, it became constant at pH 8. Osmotic potentials (OP) of K₃PO₄ and NaCl solutions decreased by 0.1MPa within one day after the treatment began. Subsequently, the OP of NaCl solutions changed little until the experiment was terminated, whereas, those of K₃PO₄ solutions decreased to a point lower than the final OP of NaCl solutions. The differences in the final OP between the two solutions were 0.1 to 0.2MPa for those which were initially -0.5 to -1.0MPa, and 0.3 to 0.4MPa for those initially -1.25MPa.
To minimize the influence of the changing pH and OP during the priming period, seeds were continuously drenched with fresh solutions. K₃PO₄ inhibited radicle protrusion at the same range of OP between -0.5 and -1.25MPa more so than did NaCl. Solutions having pH 12 had greater influence on suspending radicle emergence than did those of pH 6. At a fixed OP of -0.75MPa, there was a decreasing gradient of percentage of seeds with protruding radicle from pH 6 to 12. When pH of solutions was lowered from pH 12 to 6 on day 7, the percentage of radicles which emerged through the seed coat increased rapidly to overtake that of seeds kept continuously at pH 6.
We concluded that the high pH of tertiary phosphate solutions played an important role in suspending radicle protrusion of carrot seeds during priming and that the lower osmotic potential of these solutions appeared to favor suspension of radicle protrusion.

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Promotive effects of endogenous and exogenous cytokinins on the growth of cucumber fruits (Cucumis sativus L. cv. Chojitsuochiai No. 2) were examined.
Cytokinin activity in decreasing order was: N⁶-benzyl adenine (BA), N⁶-isoamyl adenine (iso Am), _??_²-isopentenyladenine (2iP), trans-zeatin (t-Z), cis-zeatin (c-Z) and kinetin (K).
The endogenous cytokinin levels in the cucumber fruits were examined in relation to fruit growth using the Amaranthus assay. The increase in the amounts of the cytokinins corresponding to zeatin in extracts as bioassayed on paper chromatogram coincided with the increase in fresh weight, suggesting promotive effect of the endogenous cytokinins for fruit growth.

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1. A survey of chromosome numbers of edible (Shokuyo-giku) and garnish (Tsuma-giku) chrysanthemum was carried out to elucidate the genetic characteristics and varietal differentiation in those cultivars. Cultivars of edible (137) and garnish (32) chrysanthemums were examined for this study.
2. Examination of entire plants revealed variations in somatic chromosome numbers ranging from 53 to 66 in edible chrysanthemums and from 51+B to 55 in garnich forms. Furthermore, the mode of the distribution in chromosome numbers was 54 for both edible and garnish forms. Variation frequency of chromosome number in both forms agreed well with that of ornamental chrysanthemums. Therefore, according to chromosome variation, edible and garnish chrysanthemums were duly considered to have been derived from ornamental cultivars grown for exhibition or cut-flower use.
3. Different number of chromosomes were observed among root tip cells within the same individual. A similar chromosomal variation was found between individual plants or clones of the same cultivar, some cells possessing 54±1, 2, or 3 chromosomes.
4. B chromosomes were recognized in both forms of chrysanthemums.
5. This investigation revealed confusion in nomenclature; for example, among 26 cultivars examined, some had 2 to 9 synonyms. Therefore, the actual number of edible chrysanthemum cultivars was 65, and that of garnish forms was 30.
6. Correlations between chromosme number and flowering period or flower size were ascertained among edible chrysanthemums.

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1. To elucidate the mechanism of conspicuous aneuploidy in different forms of garden chrysanthemums, the situation of B chromosomes with respect to their morphology, transmission into offsprings and behavior at meiosis was surveyed.
2. A total of 284 different forms of chrysanthemum cultivars were examined.
3. Occurrence of B chromosomes. 1) The frequency of B chromosomes differed significantly among different forms of chrysanthemum cultivars. The B chromosome was observed in 10.9% of the general population; within a given cultivar, it was detected in 1.5% of the plants examined, whereas in other cultivars as many as 21.3% of the population possessed the B chromosome. 2) An appreciable intimate relationship could be ascertained between the frequency of B chromosome and autosome number, i.e., B chromosome occurred more frequently in aneuploid cultivars than in euploid ones. 3) B chromosomes were recognized in all cells and whole plants in a number of cultivars examined. But in other cultivars, B chromosomes appeared randomly within individual somatic cells, especially in cells of root tip tissues.
4. Frequency and morphology of B chromosomes. 1) Of the cultivars (individuals) examined, 90.7% possessed one B chromosome, the rest (9.7%) had two. 2) Size was about one half of the shortest autosome. 3) The morphology was separated into three types by the position of the constriction; sub-median, median and sub-terminal; their frequency, respectively, was 54.6, 27.3 and 18.2%. All B chromosomes were euchromatic.
5. Behaviour at meiosis and transmission of B chromosomes into the offsprings. 1) Via cross-pollination: In crosses between three cultivars with B chromosomes and seven normal ones, no seed was obtained. When five cultivars were cross-pollinated (four combinations), B chromosomes were observed in some hybrid seedlings. 2) By open-pollination: Of seedlings resulting from open-pollination of one cultivar possessing B chromosome, none inherited the B chromosomes. 3) Via self-pollination: Progenies resulting from self-pollination among four cultivars having B chromosomes, only one of two inherited the B chromosomes. It had the same morphology as that of its parent. 4) Meiosis: B chromosome did not pair with auto-somes and behaved as an univalent.
6. Judging from the above results, the existence of B chromosomes seems to be related to the occurrence of aneuploidy in garden chrysanthemum. However, the degree of relationship between the presence of B chromosomes and aneuploidy differs with forms, strains, and cultivars of chrysanthemum.

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Flower bud initiation and development in Gypsophila paniculata L. ‘Bristol Fairy’ grown under field conditions were observed by means of a scanning electron microscope.
In plants which were exposed to a sufficient amount of chilling during the previous winter, flower bud initiation took place when the stem attained 18cm in length. Subsequently, differentiation of sepals and petals occurred. Stamen primordia in the terminal floret were initiated around April 30. Between May 5 and 10, when the shoots were in the visible bud stage, the pistil primordium appeared in the terminal floret. Following differentiation of floral organs, the style elongated and the petaloid stamens appeared. The petals and petaloid stamens expanded in succession which led to the dehiscing of the sepals, resulting in anthesis of the terminal floret on May 30.
In plants which were exposed to a limited amount of winter chilling, flower bud initiation of the terminal floret was delayed. It did not take place in buds located from middle to basal nodes of the main stem. However, after the apical meristem enlarged, differentiation and development of the floral organs in the terminal floret were unaffected by the amount of exposure to previous chilling.

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To identify the factors affecting inflorescence development of Begonia semperflorens, seasonal changes in plant growth and inflorescence composition were investigated. Experiments were started in March, May, July, and September. Branched plants and unbranched ones were used to clarify competition for assimilates between inflorescences and vegetative parts.
The plant growth rate was evaluated by the rate of leaf emergence, derived by calculation of 5-day means of the plastochron index. The plant growth rate was higher in summer. The growth rate of unbranched plants, which had fewer competing sinks, was higher than that of branched plants.
The inflorescence composition was recorded as the highest order of visible flowers and the number of biparous branches. The former seemed to be mainly controlled by temperature and the latter by the amount of photosynthetic assimilates available to the inflorescence.

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A technique for improving in vitro growth of bulblets of Lilium rubellum Baker was developed. When bulb scales were cultured in a modified Murashige and Skoog′s basal medium (3) for 8, 12, 16 and 20 weeks, there were scarcely any differences in the number of bulblets developed, except for those cultured for 20 weeks. At 20 weeks, the number of bulblets per cultured explant was largest and the average weight was heaviest compared to other three durations. Bulblets grew slowly as long as they were cultured on the original explants However, growth of bulblets was improved when they were isolated from the original explants and recultured. A liquid basal medium enhanced growth but the bulblets grown in it were more apt to rot than were those grown on agar when stored at 4°C for 22 weeks or transplanted to soil.

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A stable, annual production of Japanese apricot fruit has hitherto been desired in Japan. To realize this target, the present investigation was conducted to obtain possible clues. For that purpose, the internal constituents, amino acid, sugar, and starch, were determined quantitatively in shoots collected from different aged branches of young, adult, and old trees. Bearing spurs, 4-6cm in length, possessed higher levels of these substances in comparison with longer bearing shoots or succulent water sprouts. Amino acid content of bearing shoots borne on old trees was higher than that from young or adult trees. Sucrose and starch contents also increased with tree, age. Spurs which are highly productive, and bearing shoots sampled from old tree, had higher levels of amino acid, sugar and starch. Hence, there was a close relationship between productivity and amino acid, sugar, or starch content. Current shoots gathered from three- or four-year-old lateral branches which set large sized fruits had higher amino acid content than did the other different aged branches. In conclusion, three-or four-year-old lateral branches were determined to be the most productive units in Japanese apricot trees.

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‘Beniaka’and‘Beniazuma’are major sweet potato cultivars (Ipomoea batatas L.) in the fresh vegetable market. Their roots have good quality profiles as to shape, surface color, and flavor. Freshly harvested roots of‘Beniaka’and‘Beniazuma’contain 23-26 and 27-30% starch, 0.5 and 1.0% organic acids, respectively, and 2% sugar.
Sucrose content of both cultivars increased by 2.5% during curing (held for 7 days at 30°C and 98% RH) or during storage for 1 month at 13°C. After storage for 4 months at 13°C, sucrose content of uncured‘Beniaka’roots increased, whereas it changed slightly in uncured ‘Beniazuma’and cured‘Beniaka’roots. Sucrose content of‘Beniaka’roots also changed little when stored at 15°C and/or 98% RH. Changes in sugar contents and enzyme activities indicate the possibility that sucrose synthase was more active in sucrose metabolism than was sucrose phosphate synthase.
Starch in‘Beniaka’and‘Beniazuma’roots cooked immediately after harvest was converted to 7 and 14% maltose, respectively. The amount of starch converted to maltose by cooking increased in‘Beniazuma’roots which were previously stored at 13°C.
Texture of‘Beniazuma’roots was mealy when cooked immediately after harvest but the roots gradually became more moist with storage at 13°C. Textural properties of cooked ‘Beniazuma’roots did not correlate well with sugar and starch contents of the fresh or cooked sweet potatoes.

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Some physiological responses of tomato fruits infected withBotrytis cinerea which were observed with respect to storage temperatures.
1. Fruit ripening was accelerated at 5°, 15°and 25°C but not at 35°C.
2. The rate of development of disease symptom was fastest at 15°C; the rate diminished in the following order: 25°, 5°, 35°C. A green ring, a green islands-like zone, remained green around the inoculated part as fruits ripened. The fungi grew best at 15°and 25°C in intact fruit and in pericarp slices, respectively.
3. Two peaks of C₂H₄ evolution were observed in infected tomato stored at 25°C. The first peak was associated with the normal climacteric phenomenon, whereas the second peak reflected a physiological response to the fungal infection. The latter was considerably higher than that of the uninoculated fruits. The green ring and its marginal pericarp tissue had the highest rate of C₂H₄ evolution. They also contained an unusually elevated level of 1-aminocyclopropane-1-carboxylic acid (ACC). The infection was less effective in causing evolution of CO₂ as compared to that of C₂H₄.
4. The C₂H₄ evolved by the inoculated fruits was derived from the fruit tissue rather than from the fungi. Thus, ethylene generation is a likely response to a physiological stress caused by the fungal infection.

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In an attempt to understand the mechanism of ethylene biosynthesis induced suddenly at the onset of ripening, banana [Musa (AAA group, Cavendish subgroup) cv. Giant Cavendish] fruit were ripened under these conditions: a) hypobaric pressure, b) three temperature regimes, c) treatment with 2, 5-norbornadiene (NBD), d) treatment with manganese (Mn) and e) exogenous ethylene. Changes in the rate of ethylene production, contents of 1-aminocyclopropane-1-carboxylic acid (ACC), and 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), and the activity of ethylene forming enzyme (EFE) were measured during different fruit ripening stages from preclimacteric to early climacteric rise in respiration.
About 0.20nl/g•hr of ethylene and 0.25nmol/g ACC were detected in immature banana in all the treatments during the preclimacteric period. Their levels remained nearly constant until the onset of ripening. Both ethylene production rate and ACC level was increased markedly with the onset of ripening, while MACC level was increased slightly as the fruits ripened. In contrast, EFE activity increased linearly during the preclimacteric period and reached a peak in all treatments shortly before the onset of ripening. When NBD, a competitive inhibitor of ethylene action, and Mn, an ethylene adsorber, were applied to preclimacteric fruit, the process of increase of EFE activity was prolonged and the number of days until the onset of ripening were extended, but the maximum value of the EFE activity was unaffected, being similar to that of untreated fruit. In fruits treated with ethylene, EFE activity increased rapidly, reaching to the MTT (minimum ethylene exposure time needed to induce ripening); the activity decreased after 24hr to the previous level in spite of continued treatment.
These data suggest that a trace amount of internal ethylene existing in banana fruit during the preclimacteric stage may be a causal factor to the elevation of EFE activity as bananas begin to ripen.

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This study was to determine both the contents of chlorophyll (Chl) and potato glycoalkaloids (PGA) in which the cortex tissues (the outer 1-3mm thick), prepared from‘May Queen’ potatoes, were stored at 1°, 5°, 10° and 15°C under white fluorescent light (5, 200-5, 800 lx) or in the dark. Further, the effects of light exposure on changes ofChland PGA contents in the cortex and the pith tissues of potato tubers coated half with aluminum foil were also examined.
1. The cortex tissues stored at 1°and 5°C under light exposure showed no color change and both of theChland PGA contents showed no change throughout the storage period. At 10°C-storage, they turned green from the 4th day accompanied by increases in theChland PGA content. On the other hand, the samples stored at 15°C turned green from the 2nd day. As the storage period was prolonged, the green color of this sample became deeper and the Chl content increased. The PGA content also increased with an increase of theChlcontent. It was found that the light exposure would accelerate the content of α-chaconine and α-solanine and that the increase of the latter compound was particularly remarkable.
2. A lengthwise half of potato tubers was coated with aluminum foil and subjected to light exposure at 15°C for 7 days. TheChlcontent in the cortex tissues of the coated half was fairly higher than that stored in the dark, but it was lower than that of the lightened one. On the other hand, the PGA content in the cortex tissues of the coated half was lower than that of the lightened half, and it was almost the same amount as that stored in the dark.
3. It is desirable to store potato tubers at a temperature of 10°C or below while insulating light as strictly as possible.

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To reduce limonoid bitterness in citrus fruit, the biosynthesis and metabolism of nomilin in stems of Yuzu (Citrus junos Sieb. ex Tanaka) and Sudachi (Citrus sudachi Hort. ex Shirai) were studied by using ¹⁴C-acetate.
Biosynthesis of nomilin from acetate was more active in the stems of seedlings than in shoots of citrus tree. The rate of nomilin biosynthesis in shoots was faster when the leaves were expanding to full size than at budbreak. It was relatively fast in the stem, reaching a maximum in 5.5hr, whereas after a 10-day incubation period, its activity decreased rapidly.
Biosynthesis of nomilin in stems of Sudachi was slightly more active than that of Yuzu stems. Nomilin was converted mainly to deacetylnomilin; the rate of nomilin metabolism being more active in the shoots than stems of seedlings.
It may be concluded that stems of Yuzu and Sudachi synthesize nomilin from acetate, and then convert it to deacetylnomilin, obacunone, and nomilinic acid.

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Ethylene production of‘Jonagold’apple (Malus domestica Borkh.) at an immature stage (60 to 140 days after full bloom (DAFB)) remained at low level until the fruits matured (150 DAFB) and over. The rate of C₂H₄ production increased dramatically in the harvested fruit (150 DAFB) kept at 20°Cand 90-95% RH, peaking at harvest+20 days. Thereafter, C₂H₄ evolution declined rapidly as the fruit began to senesce. The respiration rate of whole fruit showed a typical pattern of a climacteric fruit during its maturation.
The activities of ethylene-forming enzyme (EFE) in peel and pulp were very low during the early growth period. Increases in EFE activity were detected between 130 and 160 DAFB and conspicuously observed in the harvested fruit kept at 20°Cfor 20 days. The peel consistently showed greater EFE activity than did the pulp. ACC contents of peel and pulp during the fruit growth and maturation on the tree were low compared to levels during the post-harvest period. Trends in ACC content paralleled those of EFE activity and C₂H₄ production.

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