Causes of low frequency in the production of triploid seeds in grapes were studied using two diploid ('Muscat of Alexandria', MA, 2x and 'July Muscat') and two tetraploid cultivars ('Kyoho' and 'Muscat of Alexandria 4x', MA 4x). The seedlings were obtained by culturing embryos from reciprocal crosses between these diploid and tetraploid culti-vars.
The formation of embryo and endosperm and the germination of the seeds obtainedfrom reciprocal crosses between diploid and tetraploid grapes were inferior to those of seeds obtained from open pollination. The inferiority was remarkably presented when dip-loid grape was used as a female plant. Hence, the development of ovules formed on 'MA, 2 x' and 'July Muscat' pollinated with 'Kyoho' and 'MA, 4x' was superior to those obtained by open pollination. However, the opposite results were obtained when 'Kyoho' and 'MA, 4x' were pollinated with 'MA, 2x' and 'July Muscat' pollens. The embryos at nine weeks after crosses of diploid × tetraploid were similar in size to those of open pol-lination, conversely embryos of the same age resulting between crosses of tetraploid × diploid were significantly smaller than those of open pollination.
The triploid embryos excised aseptically from the seeds 60 to 70 days after pollination were able to germinate on MS medium supplemented with 500 mg•liter^-1 of malt extract, and they formed seedlings on the culture medium. Root-tip cells of hybrid seedlings derived from diploid × tetraploid grapes had 57 chromosomes, confirming their triploid status (n=19).
In the production of triploid grapes, the use of tetraploid grapes as a female parent seems to be superior to using diploid female parents.

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The interrelationships between the development of watercore, fruit maturity, and diur-nal temperature during July, and the use of plant growth regulators, ethephon and GA, were studied in the Japanese pear (Pyrus pyrifolia Nakai cv. Hosui).
1. When potted pear trees were transferred to a phytotron in July to expose them to 23°/15 °C (day/night), severe watercore symptoms developed in four out of five years, as compared to fruits on trees exposed to 33°/25 °C or field-grown potted trees (control). In these afflicted fruits, the flesh was more physiologically mature than was the skin.
2. There is a high degree of correlation between the development of watercore and the exposure of pear trees to relatively cool temperatures 80 to 100 days after full bloom.
3. The percentage of fruits displaying watercore increased with the advancement of fruit maturity ; fruit with large affected areas in their flesh had lower specific gravity and softer flesh.
4. Treatments with ethephon and gibberellic acid which accelerated maturity also fos-tered the development of large watercores.

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The development of watercore in fruits of potted trees of the Japanese pear (Pyrus pyrifolia Nakai cv. Hosui) in relation to a change in the membrane permeability as influ-enced by diurnal temperatures was investigated. The levels of K ⁺ efflux through the membranes of fruits with watercore were compared with fruits without the watercore symptoms.
1. The optimal condition for measuring the K⁺ efflux through the membrane of flesh samples was to shake the tissues in 0.3 M or 0.5 M glycerin solution at 25 °C. The con-centration of Ca²⁺ in the shaking solutions had no relation to K⁺ efflux.
2. Tissue samples from fruits with watercore leaked K⁺ faster than did those without watercore.
3. When the ground color at the calyx end of fruits reached level 2 or 4, the mem-branes of fruits exposed to 23°/15 °C (day/night) in July were found to be more perme-able than were those from fruits on trees which had been exposed to 33°/25 °C or were continuously field-grown (control trees). Furthermore, the membrane permeability of fruits, exposed to relatively low summer diurnal temperatures, began at an earlier stage of fruit development than did that from the control fruits.
4. In those years during which there were more cool summer days, the membrane was more permeable in 'Hosui' fruits than it was in fruits which matured in warmer summer temperatures.
5. When fruits were treated with ethephon and GA, K ⁺ efflux was accelerated and occurred earlier than they did in control fruits.

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Flowering sequence and fruit setting were examined in a raceme inflorescence of orange, pummelo and grapefruit cultivars.
The flowering sequences in an inflorescence having 4-6 flowers of orange, pummel and grapefruit cultivars revealed similar patterns. The apical flowers opened first fol-lowed by basal flowers and then flowers at the middle part of the inflorescence. The sub-apical flowers opened at the end of flowering period.
The frequency of fruit setting in an inflorescence was not affected by the flowering sequences. Flowers among the second to the fourth from the apical flower readily set at higher frequency than the apical and basal flowers.

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Phytotoxic effects of the bark and sawdust extracts from several woody forest species were examined. We mainly used two kinds of bark : hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc. ex Endl.) and cryptomeria (Cryptomeria japonica D. Don). In Japan, the afforestation area of these species is on the increase in recent years. The results obtained are as follows :
1. Rice seedlings were cultured in water extracts of sawdust from Chamaecyparis obtusa, Cryptomeria japonica, Japanese red pine (Pinus densiflora Sieb. et Zucc.), Douglas fir (Pseudotsuga menziesii (Mirb.) Franco), western spruce (Tsuga heterophylla (Raf.) Sarg.), apitong (Dipterocarpus spp.) and red lauan (Shorea negrosensis Foxw.), or in water extracts of bark from Chamaecyparis obtusa, Cryptomeria japonica, Douglas fir, western spruce and apitong. Extracts of Chamaecyparis obtusa sawdust and bark, Douglas fir saw-dust and bark, western spruce sawdust and bark, Pinus densiflora sawdust and apitong bark inhibited the growth of rice seedlings. Particularly, inhibitory effects of Chamaecyparis obtusa sawdust and bark, Douglas fir sawdust and bark, and Pinus densif-lora sawdust were very severe. However, extracts of Cryptomeria japonica sawdust and bark, apitong sawdust and red lauan sawdust did not impede rice growth. Pretreatment of bark extracts of Chamaecyparis obtusa, Douglas fir, western spruce and apitong with insoluble polyvinylpyrrolidone (PVP) reduced inhibition which indicates that the inhibi-tory substances are phenolic compounds.
2. Water extracts of Chamaecyparis obtusa bark were fractionated with ethyl ether (EE), ethyl acetate (EA) and n-butanol (NB), and each fraction was examined by chroma-tography and spectral analysis. Every fraction inhibited the growth of rice and trifoliate orange seedlings. Several phenolic acids, such as benzoic acid and gallic acid, in EE frac-tion and condensed tannins in EA and NB fractions were separated and identified by chromatography. Condensed tannins, in particular, severely inhibited the growth of tri-foliate orange seedlings.
3. Volatile substances from Chamaecyparis obtusa bark inhibited root elongation of tri-foliate orange seedlings. Cryptomeria japonica bark, however, did not inhibit root growth. Volatile terpenes, such as a-pinene, 19-pinene and D-limonene, and ethylene evolved from the barks of Chamaecyparis obtusa and Cryptomeria japonica were detected by gas chroma-tography. In particular, the concentration of α-pinene was high, but in Cryptomeria japonica bark it was about one-third that of Chamaecyparis obtusa bark. Inhibitory effects of α -pinene and β-pinene on trifoliate orange seedlings were observed. The volume of ethylene evolved by soil to which the Chamaecyparis obtusa bark was incorporated was about twice as much as that evolved by soil to which Cryptomeria japonica bark was added.

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Unfermented barks of cryptomeria (Cryptomeria japonica D. Don) and hinoki cypress (Chamaecyparis obtusa Sieb. et Zucc. ex Endl.) were used as materials for citrus orchard mulch and as soil additives or conditioners.
1. Cryptomeria japonica bark, when used as a soil conditioner, inhibited the growth of citrus trees on trifoliate orange rootstocks. The inhibition is attributed to the ethylene evolved in the soil as the bark decays. No inhibitory effect, however, was observed when the bark was applied on the soil surface as a mulch. Mulching with the bark prevented the soil from drying rapidly and alleviated drastic changes in soil temperature. The mulch also kept the citrus trees vigorous, as compared with those in the clean cultivated plots where weeds were removed manually with hoes and herbicides. However, the amount of mulch applied annually should be kept below 4 tons per 10 ares. Otherwise fruit quality may be sacrificed.
2. Chamaecyparis obtusa bark contains a great deal of growth inhibiting substances. Therefore, it is difficult to make a high quality compost with it even though it is fer-mented and mixed with livestock manure. The bark also contains antibiotic substances, but heating and washing it with alkaline solutions effectively eliminated the growth in-hibitors. Washing with acid solutions was less effective. Condensed tannins, which se-verely inhibit growth of trifoliate orange seedlings, were washed out with the alkaline solutions : 0.1% CaO and 0.1% Ca (OH)₂. By treating the bark and leaching out the in-hibitors, the bark from cypress trees can be rendered safe for composting.

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Fruits of 98 different citrus species and cultivars grown on a hillside orchard of the Experimental Farm of Kinki University at Arita, Wakayama, were left on the trees from November, 1990 to June, 1991, as part of a delayed harvest project. The effects of delayed harvest on the appearance of fruit disorders and changes in sugar and total titratable acid contents were investigated.
1. Disorders that occurred among the citrus species and cultivars (except for 'Fukuhara orange' and 'Shunkokan') were classified as : 1) physiolgical, e. g. granulation followed by fruit dropping or pell puffing ; 2) external, e. g. frost injury, abscission and decay ; and 3) complex, e. g. frost injury, granulation and subsequent abscission. The disorders also seemed to occur earlier in the season in early maturing species and cultivars than in later maturing ones.
2. The species and cultivars were divided on the basis of sugar accumulation patterns into four groups : group A consisted of species and cultivars which accumulated more than 11% total sugars (TS) before spoiling ; members of group B accumulated a maximum of 10% TS and then it leveled off ; those in group C accumulated a maximum of only 8% before abscising ; and species and cultivars in group D had TS content of less than 5%. 'Miyagawa Wase', Kishu mikan and Ponkan (kosho) in group A accumulated more than 15% TS.
3. Fruit disorders were accompanied with a reduction in juice content and a concurrent depletion and/or changes in the relative levels of sucrose, glucose and fructose.
We found that the quality of early satsuma mandarin, 'Miyauchi iyokan' and 'Kiyomi' improved significantly and that they did not develop any physiological disorders attributable to delayed havest.

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Influence of flower location (distal, mid- or basal) on a shoot thinned to 3 flowers and whether or not the flowers were pollinated on the set of parthenocarpic fruit of kaki (Diospyros kaki L. f.) cvs. Fuyu and Hiratanenashi was investigated. The purpose was to clarify the relation between the set of parthenocarpic fruits and the relative sink strength of parthenocarpic and seeded fruits located at different positions on the same shoot.
1. Fruit set of pollinated and non-pollinated flowers was highest at the distal position and lowest at the basal one on a shoot.
2. The set of parthenocarpic fruits on the distal position on the shoot with non-pollinated 3 flowers was higher than that of seeded fruits at any position on the shoot with pollinated 3 flowers.
3. Seeded fruits set at a greater frequency than did the parthenocarpic fruits on the same shoot.
4. The parthenocarpic fruit set of non-pollinated 3 flowers on a shoot, especially at the upper position, decreased with decreasing length of shoot.
5. There was a significant difference in seedless fruit growth among the fruiting positions ; many smaller fruits tended to abscise.
6. Whether or not a parthenocarpic fruit set depended on its position and the presence of a seeded fruit on the same shoot. The variations in setting patterns of parthenocarpic fruits were very similar in 'Fuyu' and 'Hiratanenashi'.
We concluded that 1) a dominant factor of the variation of parthenocarpy in 'Fuyu' was more environmental than hereditary, 2) there was no significant difference in hereditary characteristics of parthenocarpy between 'Fuyu' and 'Hiratanenashi', 3) fruit drop of seedless fruit was induced by competition among fruits, and 4) the set of parthenocarpic fruits was achieved when the relative sink strength of seedless fruit was stronger than that of competing fruits.

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Embryo-sac development and fertilization processes of Japanese persimmon (Diospyros kaki L. f.) cv. Fuyu were histologically investigated to clarify the cause of variations inseed formation among the trees.
1. The embryo-sac was formed after meiotic division of the embryo mother cell about 2 weeks before anthesis. One nucleus in the embryo-sac divided into 8 nuclei and the embryo-sac was completed after the antipodal cell disappeared.
2. Abnormal embryo-sac formation was observed : a) presence of a nucellus but lacking an embryo-sac, b) multiplied embryo-sacs, c) aborted embryo-sacs, and d) embryosacs with more or less than normal 8 nuclei.
3. Pollen tubes reached the micropyles 24 or more hours after pollination, but their numbers were few.
4. Most fertilization of eggs occurred 3 days after anthesis. Without zygote formation embryo-sacs began to degenerate in about 7 days, followed by the inner walls of the nucellus fusing together.
5. On vigorous shoots, meiotic division of the embryo-sac mother cell began earlier and the development of the embryo-sacs was faster than on less vigorous shoots. However, there were no differences in the percentage of abnormal embryo-sacs at anthesis and seed numbers per fruit on shoots of different lengths.
6. The percentage of abnormal embryo-sacs was low in the tree which produced many seeds per fruit and, conversely, it was high in the tree which produced a few seeds per fruit.
We conclude that the variations in seed formation among the trees probably resulted from their difference in the frequency of abnormal embryo-sacs.

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Young 'Tosa Buntan' pummelo (Citrus grandis (L.) Osbeck) trees on trifoliate orange rootstock grown in a plastic house were used in this trial. The leaf to fruit ratio in each tree was adjusted to a range between 25/1 and 30/1 by hand-thinning in early June, 1991. The trunks were strangulated to 50 and 70 Kgf. cm with steel wire (1.6 mm diam.) in late October. The steel wire was removed 3 months later. The girdles left by the wires around the trunk disappeared completely after mid-June. The soluble solids contents and acid in the juice of fruits harvested in February, 1992, were highest in the 70 Kgf. cm treatment. As the wire tension was increased the carbohydrate content in leaves increased, whereas the nitrogen content decreased. This resulted in a higher C-N ratio in the leaves at harvest. The majority of flower buds which sprouted were leafy ones. The numbers of inflorescences and flower buds in the 50 and 70 Kgf. cm treatments were 4.9 to 6.4 times larger, respectively, than were those of the control. The percentage of fruit set ranged from 50 to 68 in each tree ; no significant difference was noted among the treatments. Spring shoots were slightly shorter in the 70 Kgf. cm treatment, but the number of spring shoots was almost the same in all treatments.

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Young 'Tosa Buntan' pummelo (Citrus grandis (L.) Osbeck) trees on trifoliate orange (Poncirus trifoliata Raf.) rootstock were sand-cultured in the pots and transferred to a growth chamber kept at 30°/25°C (day/night) from early November in 1991 to late May in 1992. The trunks of the potted trees were strangulated with wire at a tension of 30 or 40 Kgf. cm degree in mid-December, when shoot growth in the first flush had stopped. Shoot growth in the second flush was decreased by the strangulation treatments, but there was no significant difference between the two strangulation treatments. A part of the wire ring at 40 Kgf. cm degree was covered with bark callus after a 5-month treatment, but the ring at 30 Kgf. cm degree was not covered until early June. Water absorption and transpiration rates of the tree were decreased by the treatments as were the net photosynthesis rates of the leaves. Water absorption rate in the 40 Kgf. cm degree treatment was slower than that in the 30 Kgf. cm degree treatment until mid-February, but the rate of the former became faster than that of the latter thereafter. Flower buds sprouted not only on the previous year's shoots but also on the first flush shoots on strangulated trees ; but control trees failed to flower. The number of flower buds was not significantly different between the two strangulation treatments, but they abscised after flowering in late May. The shoots and leaves in the second flush weighed less on dry weight basis in the strangulation treatments than they did in the control. The dry weight of the small roots on strangulated trees was also lighter than it was in the control.

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The nature of anthocyanoplasts (ACPs) from colored skin tissues of 'Kyoho' grapes was investigated under a microscope in relation to their development, membrane and anthocyanin.
1. ACPs in the subepidermal cells enlarged rapidly by repeated coalescence of the smaller ones. The volume of a coalesced ACP was almost the same as the sum of volumes of respective ACPs before coalescence.
2. It was confirmed by using protoplasts and/or isolated ACPs that ACPs were located in the vacuoles and each possessed a transparent membrane which could be clearly observed under a microscope.
3. A few minutes after a piece of skin tissue was permeated with 40 or 70% ethanol, anthocyanin began to leak out from ACP into the vacuole of the epidermal cell, and the vacuole turned red. The ACP then decreased in size and eventually collapsed, leaving almost no trace. The vacuole also burst soon after the collapse of the ACP.
4. When a piece of skin tissue was permeated with redistilled acetone, ACP in the vacuole of the epidermal cell collapsed. However, the vacuole did not burst, and smaller ACPs soon reappeared in the vacuole and rapidly coalesced together, resulting in larger ACPs. Throughout the formation of smaller ACPs and their coalescence, anthocyanin accumulated in a few larger ACPs, while the vacuole became near colorless.
5. The data indicate that each ACP is surrounded by a membrane which maintains the concentration of anthocyanin within an ACP higher than that in the vacuole, and that the formation and coalescence of ACPs are means by which anthocyanin accumulates in ACPs.

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Root growth in Japanese persimmon tree was monitored through observation of cell division in the root tips of fifteen-year-old 'Nishimurawase' trees. Forty root tips from twenty trees were collected at every sampling date, cooled immediately to 0 °C, and fixed with aceto-alcohol for 24 hours. The root tips of the Japanese persimmon tree can be either white or black ; these can distinguished by the blackish dermatogen in the terminal 5 to 10 mm of the root tips.
Before May 20 th, all root tips in the experimental sample were black. By June 14 th, 58% of roots were white. The number of white root tips decreased gradually after that days, and no white tips were observed on September 28 th.
Cell division occurred in both black and white root tips, but in April and May most cell division took place in the black ones. From June to September, most cell division was observed in the white tips. The mitotic index was low in April ; it increased suddenly in June, then decreased gradually until October.
Cell division in the root tips began when the air temperature was 12 °C ; its rate increased as the temperature rose. No relationship was observed between the rate of cell division in the root tips and amount of precipitation during that period.

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The objective of this study was to investigate the effects of different rootstocks on berry growth and compositions of 'Fujiminori' grapes (Vitis vinifera × V. labruscana). Berry growth, sugar, organic acid, amino acid, and anthocyanin contents in the berries were determined in 3-year-old vines grafted on seven different rootstocks : V. riparia × V.rupestris 3309, 3306 and 101-14, V. berlandieri × V. riparia Teleki 5C and 8B, and V. berlandieri × V. riparia SO•4 and 420A. The vines were grown in plastic containers in anunheated plastic house. Berry growth was more vigorous in vines grafted on 3309, 101-14, and 3306 than on 8B and 420A stocks. The ratio of seeded berries to total berries was significantly lower in vines grafted on 8B stock. Berries of vines grafted on 8B had the highest total soluble solids (TSS) followed in descending order by 3309, 3306, SO•4, 420A, 5C, and 101-14, The predominant sugars in both berry pulp and skin were glucose and fructose, irrespective of the rootstocks. Glucose and fructose contents in the pulp were higher in berries of vines grafted on 3309, 3306, and 8B than on 420A and 101-14 ; their values in the skin of berries from vines grafted on 101-14 and 5C were higher than those grafted on 420A and 3309. Titratable acidity of the juice was higher in the berries of vines grafted on 101-14 than on 8B and 420A and 3306 stocks. Regardless of rootstocks, tartaric and malic acids were the predominant organic acids in the berry pulp and skin. No significant difference in malic acid content was observed among the rootstocks. However, tartaric acid content was higher in the berries of vines grafted on 101-14 than on 8B and 420A stocks. Berries on vines grafted on 3306, 5C, 8B and SO•4 had higher levels of amino acids in the pulp than berries of vines grafted on 3309. Alanine, arginine, glutamine, and γ-aminobutyric acid constituted more than 70% of the total amino acids in the berry pulp, irrespective of the rootstock. The highest level of anthocyanin in the skin was observed in vines grafted on 3306, followed in order by those on 8B and 3309, berries of vine grafted on 101-14 had the lowest anthocyanin content.

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Electroporation proved to be an efficient transformation method for Citrus including mandarins which had not been transformed by the Agrobacterium method. Protoplasts were prepared from embryogenic callus of 'Ohta' ponkan (Citrus reticulata Blanco) and electroporation with exponential decay pulses was carried out in the solution containing the β-glucuronidase (GUS) chimeric gene coupled to the CaMV 35S promoter (pBI221). At 24 hr after incubation, significant GUS activity was detected in the cells by fluorometric assay. To optimize the transformation efficiency the parameter of electroporation including the capacitance, the voltage, CaCl₂ and DNA concentrations in the medium, and the heat shock to protoplasts were investigated. The transformation signals by the histochemical assay were also detected in newly formed callus colonies after 2 month culture of protoplasts.

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The angle of divergence between each pair of neighboring leaves on wild tomato plants, Lycopersicon pimpinellifolium (Just.) Mill., was measured with a semicircular protractor with an accuracy of ± 2.5 degrees. Not only in individual plants but in different plants with 10 leaves, the angles between pairs of mature leaves that developed sequentially on the main shoot with left-handed phyllotaxis ranged widely, from a maximum of 154.7 degrees between the first leaf and the second leaf and a minimum of 119.3 degrees between the second and the third leaf. The angle between the each pair of neighboring leaves from the third and the tenth leaf was intermediate, ranging between 120.3 to 141.3 degrees. The mean angle of divergence on one plant was calculated to be 135.3 degrees. The same pattern was observed also in plants with right-handed phyllotaxis that developed 10 or 11 leaves on the main shoot.
The angle of divergence between the terminal leaf and the first inflorescence was almost identical as that of pairs of leaves on the main shoot. The arrangement of nodes 7 to 12 of leaf primordia on the main shoot was similar. These results indicate that the phyllotaxis of tomato plants was 3/8, with an angle of divergence of 135 degrees, as calculated by the orthostichy system. Because the accuracy of measurement was within ± 2.5 degrees, our results would also be compatible with phyllotaxis of 5/13 (about 138.4 degrees), 8/21 (about 137.1 degrees), 13/34 (about 137.6 degrees), or the limiting value of the main series in Schimper-Braun's law, (3-√5) /2, (about 137.5 degrees).

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Three experiments were conducted on the effect of abscisic acid (S-ABA, the natural form) on bolting of Japanese radish (Raphanus sativus L.).
Exp. 1. Dry or pre-imbibed seeds of Japanese radish (cv. Taibyousoubutori) were soaked in water (control), 100 or 1, 000 ppm S-ABA for 24 or 48 hr at 15 °C and sown immediately into small planter (6 x 6 x 6 cm3) filled with soil. The planters were kept at 8 °C for 10 or 20 days and then transferred to a growth chamber kept at 22 °C (day) and 18 °C (night). Treatment with 1, 000 ppm S-ABA significantly inhibited bolting of the seedlings.
Exp. 2. Four lots of seeds was soaked in water, 250, 500 or 1, 000 ppm S-ABA at 15°C for 24 hr, allowed to dry completely, stored at 4 °C for 5 months and then sown in planters as above. The inhibitory effect of S-ABA on bolting of seedling persisted throughout the drying and storage periods.
Exp. 3. Pre-germinated seeds of eight Japanese radish cultivars were dipped in water or 50 ppm S-ABA at 5 °C for 20 days and then sown. In another test, young seedlings of eight radish cultivars were sprayed with water or 250 ppm S-ABA during vernalization for 14 days at 8 °C. Thereafter, they were grown in the greenhouse. Seed-dipping or foliar spray applications of S-ABA inhibited bolting. The efficiency of S-ABA, however, was cultivar-dependent ; seeds and seedlings of 'Taibyousoubutori' and 'Natsuminowase No. 3' were most sensitive to S-ABA, whereas those of "Wakayama" and 'Kaiwaredaikon' were less sensitive. The treatment with 50 ppm S-ABA on pre-germinated seeds was more inhibitory than was the foliar application at 250 ppm.
These results show that S-ABA is useful in preventing bolting of Japanese radish.

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Effects of abscisic acid (ABA) applied to the culture solution on the growth, water relations and temperature stress in tomato plants were investigated.
1. Plant growth was strongly inhibited when plants were placed in culture solutions containing 5 and 10 ppm ABA ; it was slightly promoted in culture solutions of 0.1 ppm ABA primarily because root growth was stimulated.
2. ABA suppressed the water absorption by roots and reduced transpirational loss from detached leaves. The leaf temperature of ABA treated plants during the day was several degrees higher than that of untreated ones depending on ABA concentrations. At 0.1 ppm ABA, the a-naphthylamine oxidizing activity of roots and the formation and growth of adventitious roots were enhanced.
3. At 0.5 ppm ABA, cold hardiness of tomato seedlings increased with a corresponding smaller loss of water from detached leaves and higher a-naphthylamine oxidizing capacity of roots, as comparison with untreated plants.
4. On plants exposed to high temperature, ABA treatments advanced tomato fruit maturity with a concomitant increase in sugar content of fruit. It was obseved that 0.1 ppm ABA treatment tended to increase fruit yield.

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Effects of atmospheric humidity and soil moisture content on the relative intensity of chlorophyll fluorescence of cucumber (Cucumis sativus L.) exposed to high air temperatures were assessed as a measure of heat stress or injury.
1. After exposure to 25 °C (control) and 42°, 44° and 46°C for two to three hours, the intensity of fluorescence decreased a little at 42° and 44°C but markedly at 46°C. However there was no significant difference in seedling growth among those grown for 12 days at the three high temperature treatments and those at 25°C.
2. Chlorophyll fluorescence decreased significantly in plant kept at a humidity of 0.3 kPa of vapor pressure deficit (VPD) and 46°C, compared with those held at the same temperature but at 4.8 kPa VPD. The intensity decreased to 5% of that at 25js_°C immediately after a high humidity and 46°C treatment. It recovered to 55% of the control two days after the treatment was terminated but never attained more than 70% of control even after 5 days at 25°C. The reduction in chlorophyll fluorescence is attributed to the high leaf temperature and humidity which depressed transpiration.
3. Chlorophyll fluorescence intensity of seedlings exposed to 46°C and 55% soil moisture content for one to three hours decreased significantly, whereas it decreased just slightly when cucumbers were grown at the same high atmospheric humidity but in soils with 97% moisture content. The leaf temperature of plants grown at the low soil moisture level gradually increased and surpassed that of plants grown at high soil moisture content ; the transpiration rate was apparently higher in moister soil than in drier soil.
These results indicate that determinig chlorophyll fluorescence may be a method of detecting heat stress or injury to the photosyntetic apparatus. They support the idea that heat injury may be avoided by maintaining low atmospheric humidity and high soil moisture content which hasten the transpiration and thereby tend to keep the leaf temperahire low.

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We studied the influence of the nutrient solution concentrations on cracking of cherry tomato fruit grown hydroponically and the mechanism of cracking.
1. In 'Sugar Lump', 'Sun Cherry' and 'Mini Carol' the occurrence of fruit cracking increased as the concentrations of the solutions became higher. However in 'Akakokko', the concentrations of the solution had very little influence.
2. There were no differences in the cumulative temperatures (the number of hours above 0°C) from anthesis to full ripeness or the number of fruits cracking among the four cultivars.
3. It is postulated that the factors which promote fruit cracking are : 1) an increase in soluble solids content, 2) decrease in osmotic pressure of the pulp, 3) flesh firmness.
4. Less volume of injected water was required to induce fruit cracking artificially in fruits harvested from the high nutrient solution concentration than from that of the low concentration.
Fruits of 'Sun Cherry' seemingly import water more easily because of a lower osmotic potential of the fruit flesh (Ψ_flesh), compared to that of the external solution (Ψ_solution). In the water absorption test the occurrence of fruit cracking and the rate of expansion of fruit volume increased when plants were grown in solutions of high concentration. These results indicate that frutis can absorb water rapidly under these conditions.

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An experiment was conducted to investigate the effect of relative humidity (RH) in the culture vessel on the growth of potato plantlets In Vitro, especially on shoot elongation. Plantlets were cultured under four RH conditions obtained by using distilled water or different salt-saturated solutions. Culture vessels had number of air exchanges per hour of 0.95. The vessels containing the cultures were maintained in a culture room at 25°C and 75% RH under 16 hr•day^-1 photoperiod with 100 μmol • m^-2 • sec^-1 photo-synthetic photon flux density. The CO₂ concentration in the culture room was increased with time from 550 to 1400 μmol mol^-1 to maintain the concentration in the vessel at or above 350 μmol • mol^-1.
The actual measured RH in the vessel increased in all treatments except for the control with time as the explants grew into the plantlets, which decreased the differences in RH among the treatments. The shoot length of plantlets decreased with decreasing the initial (day 8) RH. The shortest shoot length, 35mm, was observed in the lowest RH treatment and the longest one, 52 mm, in the control. There were no significant differences in dry weight per plantlet among the treatments. Short and vigorous micropropagated transplants could be obtained by the slight reduction in RH without a significant reduction in dry weight of plantlets.

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Seed germination of spinach (Spinacia oleracea L. cv. Jiroumaru) was inhibited markedly at temperatures above 25°C. Exposure of the seeds to 36N sulfuric acid for 30 min or 18N for 60 and 120 min increased the final germination percentage at 25°C to 80-95%, compared to about 30% for the water-soaked control. In the de-coated seeds, the germina-tion percentage was increased to 90%; likewise, germination was also promoted by physi-cally cracking the pericarp. But at 30°C, the final germination percentage was 50% in the both acid-scarified and de-coated seed treatments.
The acid scarification followed by priming with polyethylene glycol 6000 solution (-1.3 MPa, 1 week at 10°C) increased the germination percentage even at 30°C to more than 80% within 8 days after sowing for 6 cultivars including 'Jiroumaru'. Treatment with PEG alone was less effective in promoting germination.
Scanning electron micrographs showed that the acid removed the pericarp cuticula, that the epidermal layer was pitted, and that some of pits had pores of 1-2μm in dia-meter on their bases.
After acid scarification, the use of priming using PEG had beneficial effect on the ger-mination of spinach at 30°C, but very little is known about the physiological process of priming.

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Effects of storage temperatures on polyamine content in buds of broccoli (Brassica oleracea var. italica, cv. Chaster), fourth leaf of senpo-sai (Brassica napus), and cotyledons of the Japanese radish, kaiware daikon (Raphanus Sativus L.) were investi-gated to ascertain the possibility of the polyamines, putrescine and spermidine, being in-dicators of chemical changes during storage. The combination of perchloric acid extrac-tion and post-column HPLC provided recoveries ranging from 84.5 to 105.2%, proving to be a useful procedure for routine assay for polyamines. Chlorophyll and polyamine levels in the broccoli and the kaiware daikon decreased during storage at 20°and 23 °C, re-spectively, whereas at 2 °C, chlorophyll and spermidine tended to remain nearly constant while putrescine increased. In the fourth leaf of senpo-sai, a decrease in chlorophyll and an increase in putrescine were observed during storage at 23 °C. These variations in polyamines in these vegetables during storage indicate that polyamines are not as good an indicator of chemical changes as chlorophyll.

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Expanding leaves of nine cultivars of caladium (Caladium Xhortulanum Birdsey) were cultured on modified MS medium supplemented with 1.0 mg•liter^-1 BA and 1.0 mg•liter^-1 NAA from which multiple shoot primordia were obtained. The multiple shoot primordia were in turn, cultured on modified MS medium without any growth regulators to regenerate plantlets.
Leaf color variations in the plantlets regenerated from the multiple shoot primordia were very different among the nine cultivars. Leaf color variants were not observed in the plantlets regenerated from their multiple shoot primordia of 'Aaron', 'Frieda Hemple', 'John Peat', 'Candidum Junior', and 'C. R. 5', but they were observed with high frequency in those of 'Pink Cloud', 'White Wing', 'Rosary', and 'Ginger Land'.
All leaf color variants in the regenerated plantlets changed from the white or red veins to the green. Variants regenerated from the multiple shoot primordia of 'Pink Cloud' and 'Ginger Land' had green veins and the laminas retained the color of the original parent plants. On the other hand, the variants regenerated from those of 'White Wing' and 'Ro•sa•ry' had both green laminas and veins.
When the green vein variants of 'Pink Cloud', and green leaf ones of 'White Wing' and 'Rosary' were cultured, the regenerated plantlets appeared similar to the parental stock.

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By monitoring the utilization of sugars by petiole segments of Begonia×hiemalis cultured in medium containing the plant grwoth regulators, kinetin (1 ppm), NAA (1 ppm), the optimum time for beginning the CO₂ enrichment treatment was established.
The total sugar concentration in the medium decreased rapidly after 40 days of culturing. The cessation of sugar depletion by the tissues after 60 days is attributed to the onset of photosynthesis by the plantlets. CO₂ administration at this time promoted leaf development, whereas CO₂ enrichment 10 to 20 days earlier halted the development of adventitious shoots. These observations suggest that the optimum period to begin CO₂ enrichment to promote shoot growth and to enhance photosynthesis is about 60 days after the culturing the petiole segments.

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This study was undertaken to demonstrate : a) the stimulatory effect of ethylene evolved by diseased kiwifruit on the ethylene evolution by sound ones, and b) that sound kiwifruit are unable to start evolving ethylene without this stimulus.
1. In the experiment using 'Hayward' kiwifruit packed in a carton at 20°C, some fruits showd ripe rot symptoms and coincidentaly started evolving ethylene soon after being transferred from 5°C to 20°C. About 12 days later, the other fruits within the same carton also started evolving ethylene without any ripe rot symptoms.
2. When fruits of 4 cultivars were packed a) individually in unsealed polyethylene film bags or b) in polyvinyl chloride (PVC) box with an ethylene absorbent to minimize the effect of ethylene evolved from diseased fruits, most sound fruits did not start evolving ethylene up to about 60 and 40 days, respectively. The carbon dioxide in the polyethylene bags or PVC boxes did not accumulate so much as to retard the induction of ethylene synthesis.
3. When sound fruits were placed at 20°C and separated physically from diseased ones, they had persistent low levels of internal ethylene concentration, 1-anciinocyclopropane-1-carboxylic acid (ACC) content, and ethylene forming enzyme (EFE) activity.
These results indicate that ethylene evolution in the sound kiwifruit is stimulated by ethylene stemming from diseased fruits packed in the same container, and also indicate that ethylene formation in the sound kiwifruit requires an exogenous induction factor such as ethylene gas or a diseased fruit nearby.

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Green bananas were treated with 0 to 60% CO₂ and 1 to 100 ppm C₂H₄ to study their interaction on the ripening process.
1. The CO₂ treatment did not block completely the initiation of ripening of banana by exogenous C₂H₄. When the concentration of applied C₂H₄ was kept constant and the CO₂ concentration high, the appearance of the yellow pigment in the peel was delayed.
2. The combination of various concentrations of CO₂ and C₂H₄ on the respiratory climacterics in green banana, monitored with an automated microcomputer system, revealed that the onset of the climacteric rise of bananas under any CO₂ concentration combined with 1 ppm C₂H₄ commenced simultaneously with fruits which were kept under air and 1 ppm C₂H₄. However, the progress of the climacteric rise was slower and the peaks were lower at high CO₂ concentration than they were at low CO₂ concentrations. With 60% CO₂ and 100 ppm C₂H₄, the fruit color remained green until the end of the gas treatment, in spite of the slow respiratory rise and ripening of the flesh.
Our results suggest that the elevated CO₂ concentration has no effect on the initiationtime of banana ripening induced by exogenous C₂H₄ but lowers the progress rate of ripening.

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Strawberry fruits (Fragaria×ananasa cv. Hokowase) were treated with 20% CO₂ for 12 to 48 hr at 1°C and then stored at the same temperature for an additional 24 to 48 hr; subsequently they were transferred to 20°C and held for 8 hours.
1. Berries exposed to CO₂, including those stored for 8 hr at 20°C were firmer than the control berries exposed to air.
2. The CO₂ treatment had a little effect on the evolution of methyl acetate and methyl butyrate, the predominant volatiles. However, the evolultion of ethyl acetate and ethyl butyrate, the minor volatiles, was increased sharply by the CO₂ treatment. These changesin the concentration of volatiles gave the berries an unnatural aroma.
3. In berries given the same CO₂ treatment for 24 hr but stored longer period at 1°C, the abnormal aroma formation persisted for at least 5 days.

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A commercially available Near Infrared (NIR) instrument was modified and fitted with fiber optics to measure NIR transmittance spectra in intact fruits. With this modification the potential of the NIR transmittance method to determine the Brix value in satsuma mandarin was examined. To reduce the fruit size effect which affected the NIR spectra, the 2nd derivative spectra were normalized by being divided by 2nd derivative value at 844 nm, which had a high correlation to the diameter of the fruit. Using 50 selected samples, multiple regression analysis was carried out to relate the Brix value to the normalized 2nd derivative spectra. The highest multiple correlation coefficient was 0.989 with a standard error of calibration (SEC) of 0.28 °Brix. The bias-corrected standard error of prediction (SEP) was 0.32 °Brix with a bias of -0.02°Brix. It is concluded that the NIR transmittance method yields an accurate estimate of the Brix value in intact satsuma mandrins.

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