In order to clarify the mechanism of flower bud formation in Japanese pear (Pyrusserotina Rehd.), the effects of SADH application and bending of shoots on nutrient elements and endogenous growth regulators in shoot tips and axillary buds were studied in relation to the differentiation and development of flower buds. 1. SADH application or bending of each shoot in ‘Shinsui’ was carried out on June 10; after application of SADH shoot growth stopped one month earlier than in controls, and after bending, shoot growth stopped twenty days earlier than in controls. 2. In both treatments there was a rapid increase in the number of nodes (scales and bracts) in axillary buds ten days after treatment. On June 30, twelve scales were formed, after which the first visible signs of flower initiation were found. Thereafter the flower buds differentiated and developed in both treatments. The final percentage of flower bud formation was about 60%. 3. On the other hand in controls the number of nodes in axillary buds increased slowly, so that only a few of the first visible signs of flower initiation were found on July 30, which was one month later than in both treatments. Thereafter differentiation and development did not occur, so that the final percentage of flower bud formation was 15.2%. 4. Both treatments led to a marked decrease in sorbitol and amino acid contents in the shoot tips, but to increases in axillary buds. 5. Both treatments caused a decrease in IAA and cytokinin contents in shoot tips, but caused rapid increases in axillary buds. 6. Both treatments markedly decreased the gibberellin content of shoot tips and axillary buds. From these results, it was suggested that flower initiation in Japanese pear is determined by the active state of buds, giving an increase in the number of nodes followed by formation of twelve scale. Endogenous growth regulators are closely involved in these processes, particularly gibberellin and cytokinin, which play a major role in flower bud formation.
In order to investigate the self-incompatibility reaction in the Japanese pear (Pyrus serotina Rehd.), fruit setting was examined in the trees blooming at 12 different times within a year from February to September by selfing and crossing the flowers at bud and full bloomed stages. When self-pollinated in full bloom, there was little or no fruit set at all the flowering times, suggesting the presence of strong self-incompatibility in the flowers. When self-pollinated at the bud stages, about 10% of the total flowers pollinated were set throughout the season, indicating weak incompatibility. Pollen tube protrusion from the excised-styles cultured on agar media was also studied. At all flowering times, the percentage of mature styles protruding pollen tubes when cross-pollinated was higher than that when selfed, except in the styles obtained on January 20, soon after rest. The number of immature styles in the floral buds with pollen tubes was similar regardless of whether were self or cross-pollination performed. These results may indicate that the pollen tubes passed through immature styles more easily than did through mature one, even though self-pollination had taken place. The length of styles in the floral bud which was capable of setting fruit was about one half that of styles in the opened flowers. This fact support the possibility that the physical length of styles in the flowers might be one of the factors responsible for a breakdown of self-incompatibility after bud self-pollination in P. serotina.
Although the total phenol content in the berry of grape (Vitis vinifera L. cv. ‘Muscat of Alexandria’) was kept constant during period II and III, the qualitative changes of the phenols could be found before and after veraison. Three of 7 fractions, which were separated from the berry by several organic solvents, exhibited growth inhibitory activity in the avena coleoptile straight growth test. By the 1-demensional paper chromatogram, the activity was found at the Rf differing from that of ABA in period II, while it was found at the Rf corresponding that of ABA late in period III. Nineteen spots were detected on the 2-dimensional paper chromatogram and 13 of them showed phenolic reactions to UV light and some reagents. Among the 13 phenolic spots, 5 were large in area on the paper chromatogram in period II, but they were small or none in period III. The reverse was true for other 3, excepted the 5, among the phenolic spots. Among the phenolic spots, 4 showed no change in area on the paper chromatogram during period II and III. The phenolic spot, which remained at the original point on 2-dimension paper chromatogram, exhibited the growth inhibitory activity and it showed large in area in period II but small after veraison. Four spots did not show phenolic reactions with all reagents, and 2 of them were large in area during period II including veraison, and none in period III. One or 2 of them may have the growth inhibitory activity. From this experiment, it may assumed that the berry growth is retarded during period II by phenols as immovably associated tannin and nonphenolic compounds, and late in period III by ABA like substance.
The factors presumed to control the susceptibility to berry splitting caused by rainfall were examined in 6 grape cultivars which were experientially known to differ in their susceptibilty. Judging from the soluble solids contents in juice, the amounts of rainfall during ripening and the proportion of split berries occurring under field conditions, the most susceptible cultivars seemed to be ‘Portland’ and gibberellin (GA)-treated ‘Delaware’, followed by ‘Campbell Early’ and ‘Muscat Bailey A’, while the least susceptible were ‘Kyoho’ and ‘Muscat of Alexandria’, just as predicted from previous observations. Neither the firmness of berries, as measured by a curdmeter, nor their critical turgor pressure exhibited any clear relationship with the susceptibility. The histological observations of berry skin revealed that the thickness of cell wall and the size of cells in the sub-epidermal region were highly related to the susceptibility. Other parameters, including the thicknesses of the cuticlar layer and the epidermal cell wall, and the size of epidermal cells did not show such an obvious relationship.
Several viticultural characteristics of the 3 wine-grape cultivars, changes in chemical composition of the berries during ripening, and quality of the wines from the grapes were investigated over 3 years from 1980 to 1982. The cultivars tested were ‘Seibel 9110’, ‘Seibel 13053’ and ‘Seibel 8745’ belonging to french hybrid, cultivated on the experimental vineyard of Yamanashi University. The results are summarized as follows: 1. The mean weight and diameter of berries, and the mean weight of clusters reached the following maxima, 2.8g, 16.0mm and 480g in early September for ‘S. 9110’, 2.0g, 15.0mm and 230g in late August for ‘S.13053’, and 2.8g, 16.0mm and 250g in early September for ‘S.8745’. These cultivars were small berry types (i.e. a berry weight below 3.0g). 2. At full maturity, the pH values of all the musts from the cultivars tested were 3.4. 3. It was known that the two cultivars ‘S.9110’ and ‘S.13053’ were low-acid types, and that their harvest times might be decided by acidity rather than °Brix. On the other hand, ‘S.8745’ was a medium-acid type and the acidity of the must was more than 0.8g/100ml at full maturity. 4. The maximum °Brix of ‘S.13053’ and ‘S.9110’ were 16.0%, in late August, and 17.0%, in mid-September, respectively. The °Brix of ‘S.8745’ reached 20.0% in late September in warmer years but in cooler years the °Brix was very low. 5. At full maturity, the glucose-fructose ratios and the tartaric-malic acid ratios of ‘S.9110’ and both ‘S.13053’ and ‘S.8745’ were 0.9 and 1.5, and 1.0 and 2.0, respectively. Cultivar ‘S.9110’ was a high-fructose type, while ‘S.13053’ and ‘S. 8745’ were high-tartaric acid types. 6. In both ‘S.9110’ and ‘S.13053’, the summation of temperature necessary for reaching full maturity was low, so these cultivars seemed to be adapted to cultivation in cool areas. 7. All the 3 cultivars tested were productive and easy to cultivate, so it was necessary to regulate the cropload. 8. The ‘S.9110’ wine had a fruity aroma, a slightly acid taste, and the color changed rapidly to brown. The ‘S.13053’ wine had a slightly noble aroma, but a flat or insipid taste due to low acids and tannins. The ‘S.8745’ wine had tart, astringent and tough tastes, but lacked a noble aroma.
Seasonal changes in growth, chemical composition, peel color, respiration and ethylene production of satsuma mandarin (Citrus unshiu Marcovitch) fruit were investigated in relation to maturation. Two cultivars of satsuma mandarin, ‘Okitsu Wase’, an early maturing cultivar and ‘Silverhill’, a common cultivar, were used in this study. The results obtained were as follows. 1. Fruit weight and diameter of ‘Okitsu Wase’ increased gradually until early December and decreased thereafter. The maximum weight and diameter of ‘Silver-hill’ occurred between early and mid-December. 2. Fruit of ‘Okitsu Wase’ reached full color in early December while in ‘Silver-hill’ full color was reached in mid- or late December. 3. The total sugar content and °Brix of the juice increased markedly until early December in ‘Okitsu Wase’, and until mid-December in ‘Silverhill’. 4. A rapid reduction in the acidity of ‘Okitsu Wase’ fruit occurred in mid-October or early November, while the acidity of ‘Silverhill’ fruit declined rapidly until early November. 5. The respiration rate of ‘Okitsu Wase’ fruit decreased slightly up to early October, and thereafter increased until January or March of the following year. The respiration rate of ‘Silverhill’ fruit increased slightly until mid-October or early November and continued to increase steadily in the following year. 6. The rate of ethylene production decreased until early October in ‘Okitsu Wase’ fruit, and decreased up to mid-or late October in ‘Silverhill’ fruit. Thereafter, the rate of ethylene production in both cultivars remained constant at a low level up to early January of the next year, and then increased.
Arginine and proline, which are the major forms of soluble reserve N, were fed singly in uniformly labelled 14C-form to excised 2-year-old stem sections with a new shoot, to wood sections, and to burst buds from a 21-year-old satsuma mandarin tree. Metabolism was studied by radioassay and autoradiography. In stem sections with a new shoot, both 14C-compounds were metabolized to acidic and neutral components, insoluble components, and 14CO2. This conversion occurred to a greater extent in sections fed with arginine than with proline. When 14C-arginine was fed, the highest 14C-activity in the cationic fraction of stem sections, bark, wood and new shoots was found in γ-guanidinobutyric acid, followed by γ- aminobutyric acid and proline; low levels of 14C was also found in ornithine and trace amounts in citrulline. These findings demonstrate that arginine is metabolized by at least two routes: via ornithine and via γ-guanidinobutyric acid. In every organ, the major metabolic products of 14C-proline were pyrrolidone-5-carboxlic acid, glutamic acid, aspartic acid, asparagine, an unidentified compound(U5 in Fig. 4), γ-aminobutyric acid and arginine. The basic metabolic pathways in the conversion of both 14C-compounds were the same in burst buds, new shoot, bark and wood, although there was a slight difference autoradiographically.
Using 3-year-old wase satsuma mandarin (Citrus unshiu Marc.) trees grafted on trifoliate orange (Poncirus trifoliata Raf. ), 8-month-old natsumikan (Citrus natsu-daidai Hayata) seedings, and 6-month-old avocado (Persea americana Mill.) seedings, the effect of low root temperatures on cold hardiness was examined in relation to whole-plant water status, changes in carbohydrate and proline concentrations, and endogenous hormone activities in plant parts. Transpiration and leaf water potential in all species were reduced at low root temperatures (5° and 13°C), leaf water potential being most markedly affected at the lower temperature. Total sugars and proline in the leaves, stems, and roots accumulated while starch was reduced at low root temperatures. Cold hardiness in all species was greatly augmented at 5°C root temperature compared to 13°C and the control. Endogenous gibberellin and cytokinin activities in the roots (trifoliate orange) of wase satsuma mandarin were increased when exposed to 5°C root temperature. In conclusion, in both citrus species and avocado lowering root temperature restricts water uptake and then induces cold hardening together with accumulation of sugars and proline in the plant tissues.
Six species of vegetable crops were grown in solution culture in order to investigate the effect of form of N supplied and pH level of the nutrient solution on Zn toxicities in vegetable crops. Zinc was supplied at levels of 0.05, 3 and 10ppm. At each Zn level, NO3, NO3+NH4(1:1) and NH4 were supplied, with the total N concentration being held constant at 12me/l. The pH of the nutrient solution was adjusted to two levels, 4 and 6. Plants were grown under different treatments for about three weeks. 1. At the normal Zn level (0.05ppm), plants supplied with NH4 developed various NH4 injury symptoms. In some vegetable crops excess Zn associated with pH 6 and NO3 developed Zn-induced chlorosis, which was not observed in NO3+NH4 and NH4 treatments. Under pH 4 this symptom was scarcely observed. 2. At the normal Zn level, the growth of plants supplied with NO3 and NO3+NH4 was almost equally good, but NH4 plants produced much more inhibited growth. Excess Zn in the nutrient solution inhibited the growth of plants supplied with NO3and NO3+NH4, but in most cases NO3+NH4 produced better growth than NO3.The growth of plants supplied with NH4 was almost constantly poor regardless of the Zn level in the nutrient solution. Under Zn excess condition, pH 4 often produced better growth than pH 6 in NO3 and NO3+NH4 treatments. 3. Increasing proportion of NH4 supply and low pH had effects to inhibit the accumulation of Zn in leaves. In NO3 and NO3+NH4 treatments, the more the accumulation of Zn in leaves increased, the more the growth was inhibited regardless of N treatments. In NH4 treatment, however, the growth of plants was almost constantly poor regardless of leaf Zn concentration. 4. It may be concluded that NH4+ and H+, unless their own levels are injurious, exert marked effects in reducing Zn uptake and Zn toxicities in vegetable crops.
The mode of inheritance of male sterility, discovered in Allium fistulosum by Nishimura et al. (1972), was investigated by three successive backcrossings and crosses between the second backcrossed plants and 7 varieties. The segregation ratio of sterility and fertility in the pollens and seeds was tested to determine the genes involved in male sterility. The materials used were male sterile plants MS, hybrids F1, families backcrossed to ‘Kaga’ (B1 B2 and B3) and 7 other varieties (‘Kaga’, ‘Choju’, ‘Koshizu’, ‘Towada’, ‘Kujo’, ‘Kincho’ and ‘Ishikura esu’). The male sterile plants were usually used as the female. The male sterile plants obtained by the backcross were used in the cross with the pollinator (recurrent parent ‘Kaga’) or the 7 other varieties. Polle and seed fertility was determined by shape and color when stained with acetocarmine, and by the presence of mature seeds. All plants obtained by the three successive backcrossings had sterile pollen and seeds, indicating that the male sterility of plant MS is controlled by cytoplasmic factors. In these experiments, segregation ratios of 1:3, 0:1, 1:1 and 1:0 for the sterility and the fertility of the pollens and seeds were observed in the progenies of the cross between the male sterile plants (B2) and 7 varieties and in the selfed progenies. From these results, it is apparent that male sterility is controlled by the interaction between the cytoplasm and nuclear genes and that the recurrent parent ‘Kaga’ is a maintainer. From the segregation ratios obtained in these experiments, the genotypes of the male sterile plants and the maintainer are assumed to be Sms1 ms1ms2ms2 and Nms1ms1ms2ms2. Male sterility may be used for the breeding of hydrid varieties of Allium fistulosum.
Seven cultivars were planted at different locations and dates to obtain estimates of genotypic and environmental variability. The characters tested were found to be significantly affected by both location and planting date. The β carotene and ascorbic acid were found to be heritable to an appreciable degree, and are suspected to be under multigenic control. β carotene was significantly and negatively correlated with colour while the ascorbic acid contents were significantly and positively correlated with the reducing sugars of the seven cultivars.
Photosynthesis (Pn) and transpiration (Tr) of rakkyo, a plant which can be cultivated without irrigation in sandy soil, is measured under several kinds of meteorological conditions, i. e., air temperature, relative humidity (RH) and light intensity. Several leaves of rakkyo were inserted into a small plastic assimilation box in a growth cabinet. The air temperature and relative humidity of the assimilation box and the growth cabinet were controlled. Experimental conditions were as follows: (1) Light intensity was constantly adjusted to 22klx by artificial lamps. Air temperatures were increased from 15°C to 35°C in 5°C steps. (2) Light intensity was charged from zero to 45klx. Four combinations of two air temperatures and two relative humidities were controlled in an assimilation box. These four combinations of environmental conditions were 15°C 50% RH, 15°C 70% RH, 30°C 25% RH and 30°C 70% RH. Photosynthesis and water use efficiency were high under conditions of low air temperature and high relative humidity, while transpiration showed the opposite tendency. In the case of 15°C 70% RH, 40klx, photosynthesis was 26mg CO2/dm2•h, transpiration was 0.6g H2O/dm2•h, and water use efficiency (Pn/Tr) was 38mg CO2/gH2O. At 30°C 25% RH, Pn was 19mg, Tr 2g and Pn/Tr 8mg/g, respectively.
A method and apparatus were described for estimating the volume and mean pressure of gas in vapour phase in plant tissues, using a plot of volume versus reciprocal of pressure. This was achieved by using a pressure chamber in which the pressure was increased stepwise from 1.0 to 11.0 bar. Volume of the gas space, which consists of compartments at various pressures, was partitioned by pressure, on the assumption that all the gas spaces dissolve completely at the same pressure. This method revealed a peak of gas space at 1.3 bar (0.3 bar above atmospheric pressure) as well as at 1.0 bar in pericarp tissue of freshly picked cucumber fruit.
1. Cucumber fruits were conditioned at 18°C for 1, 2, 3, 6 and 9 days before cold storage at 5°C. The chilling injury and the respiratory rate of the fruits were apparently reduced by pre-storage conditioning for more than 6 days, although senescence of the fruits was enhanced. 2. Pre-storage warming for 24h at 36 to 40°C, but not lower than 30°C, considerably reduced the chilling injury and the respiratory rate of the cucumber fruits during subsequent storage at 5°C. 3. Cucumber fruits harvested in different seasons were given pre- and interposed warming at 37°C for 24h before or during their cold storage at 1°C. The interposed warming was given after 1 to 3 days in cold storage. These treatments greatly reduced the chilling injury. However, in the fruits harvested in July, the prewarming was more effective than the interposed warming, and the effectiveness decreased as the time of application was delayed. The reverse was the case for the fruits harvested in March. Pre- and interposed warming were equally effective in the fruits havested in October. When warming treatments were applied to the fruits stored at 1°C, subsequent respiratory rates were considerably decreased. 4. Pre- and interposed warming at 37°C for 24h reduced electrolyte leakage from the flesh sections of cucumber fruits during the cold storage at 1 and 5°C.
This study was carried out to clarify the difference between climacteric and nonclimacteric type fruits in their ethylene producing activity, especially in the pathway from 1-aminocyclopropane-1-carboxylic acid (ACC), during growing and ripening stages. In tomato fruits harvested 28 and 34 days after anthesis, carbon dioxide production was stimulated when 10ppm of ethylene was applied to the fruits for 24 hours. After the ethylene treatment, the carbon dioxide production decreased temporarily; thereafter, ethylene and carbon dioxide production increased in fruits harvested 28 days after anthesis but in fruits harvested 34 days after anthesis only ethylene production increased. In cucumber fruits harvested 5, 8, and 20 days after anthesis, carbon dioxide production was stimulated during treatment with 10ppm of ethylene for 56 houus, but after the treatment, the rate was reduced to the pre-treatment level. Thereafter the rate of ethylene production only increased in fruits harvested 5 days after anthesis, which may have been due to the fruit decay. To observe the effect of D-, L-methionine or ACC on ethylene synthesis, these reagents were fed to tissue slices of tomato and cucumber fruits at several growing or ripening stages. Ethylene forming enzyme (EFE) activity was estimated by the rate of ethylene production due to the addition of ACC. In tomato pericarp tissue the rate of ethylene synthesis was least at the mature green stage and was greater at immature and ripening stages. The addition of ACC stimulated ethylene production in tissue slices of tomato fruits at all stages. In tissue slices of cucumber fruits, ethylene synthesis was stimulated by addition of ACC, but the rate of ethylene synthesis did not vary greatly with the development stage of the fruit. When D- and L-methionine were applied, it was found that the D-isomer enhanced ethylene synthesis in cucumber tissue slices. ACC content of tomato and cucumber fruits was measured at various stages. In tomato fruits the ACC content was least in fruits harvested 36 days after anthesis, and was greater in fruits harvested at immature or ripening stages, whereas in cucumber fruits it decreased with the advancement of fruit growth. Propylene was administered to cucumber fruit tissue slices to elucidate whether this analogue of ethylene had any effect on the activity of EFE. After treatment with 1000ppm of propylene for 42 hours, ACC was supplied to the tissue slices. The slices treated with propylene resulted in a greater production of ethylene than the untreated controls. These results indicate that tomato fruits at ripening stage synthesize a larger amount of ethylene, due to an increase in ACC content and to sufficient activity of EFE. Cucumber fruits at the growing stage produce only a small amount of ethylene, due to a reduced ACC content, in spite of having sufficient EFE activity.