Seasonal changes in the types of bud, vegetative, mixed or generative (reproductive), and carbohydrate contents in three satsuma mandarin (Citrus unshiu Marc.) cultivars, 'Yamakawa Wase', 'Okitsu Wase' and 'Aoshima Unshiu', were investigated. Shoots from these very-early, early and late maturing cultivars, respectively, were excised and examined for bud types from the pre-harvest period of the previous year to just before bud break in the spring (2001-2002). Tree growth of each cultivar in 2001 showed aspects of nearly the heaviest on-year of alternate bearing for the previous 10 years, so that a poor return bloom was expected in 2002. Shoots that sprouted in the spring of 2001 were sampled at monthly intervals from early-November to mid-March, 2002, defoliated, placed in a vase and sprayed with 100 ppm benzyladenine (BA) to force them into growth in a chamber kept at 28°C. After 8-14 days of incubation, developing buds were tallied whether they were vegetative, mixed or generative. In every cultivar, nearly all buds of shoots excised in early-November were vegetative; those with an inflorescence constantly increased up to mid-March. Shoots of 'Yamakawa Wase', whose trees were harvested in late-October, progressed from the vegetative to the generative phase most rapidly, followed by those of 'Okitsu Wase' and 'Aoshima Unshiu', whose trees were harvested in mid-November and mid-December, respectively. There was no significant difference in the bud types between 'Okitsu Wase' and 'Aoshima Unshiu' throughout the experimental period. From December to February, the starch concentrations in the spring shoots of 'Yamakawa Wase' were significantly higher than those of the other two cultivars. Spring shoots of 'Okitsu Wase' had the highest total sugar contents from December to January, but the least number of inflorescences. Higher total sugar accumulation in spring shoots after harvest seemed to have no promotive effect on flower-bud formation. Our data indicate that earlier harvest of satsuma mandarin induces rapid starch accumulation in spring shoots, resulting in a progressive differentiation of flower buds on inflorescences.
Cell wall ingrowth, an unusual secondary cell wall thickening, in several layers of cortical tissue adjacent to the endodermis and the development of the Casparian strip within the endodermal cells were observed. The cell wall thickened inwardly, but unevenly until it had the appearance of an oblong ball. These cells exhibiting the ingrowth formed a single layer ring adjacent to the endodermis of young roots. Cell wall ingrowth subsequently occurred in several layers of the cortex as the roots aged. Using fluorescent microscopy, the Casparian strip in the endodermis became visible during vascular bundle development, concurrently with secondary vascular cylinder formation when a separation zone occurred between the cortical cells with ingrowths and the endodermis. Upon separation of the cortex and new cells within the endodermis increased laterally and the Casparian strip appeared. Following cortical separation, the outer region of the endodermis began to form cork-like tissue. The anatomical changes, relating to cortical cell ingrowth and the formation of the Casparian strip in the endodermis may play an important role in protecting loquat roots from water and solute loss.
The interaction between 8- and 24-hr photoperiods and plant growth regulators (PGR) (gibberellin A3 (GA3) and uniconazole-P (Uni)) on the development of the main shoots, aerial tubers (bulbils) and new tubers (below ground), and inflorescences (spikes) in Japanese yam (Dioscorea japonica Thunb.) plants was examined. Within the same PGR treatment, the main shoots of plants grown under the 24-hr photoperiod (constant light, LD) were longer than those grown under the 8-hr photoperiod (SD) in all season; under LD and SD, the main shoots of the GA3-treated plants were the same size as shoots sprayed with water (control), whereas the main shoots of the Uni-treated plants were significantly shorter. Under LD, whereas the control and PGR-treated plants produced a negligible amount of aerial tubers, under SD, their development was severely inhibited by GA3 treatment. During the early growing period, the fresh weight of new tubers and that of the combined fresh weight of aerial and new tubers in plants grown under SD were heavier than those grown under LD. From the middle to the end of the growing period, the development of aerial and new tubers in plants grown under LD accelerated so that the difference between the final fresh weights of the combined fresh weight of aerial and new tubers in plants grown under SD and those grown under LD at harvest became small. Although, there was not such LD promoting effect of those growth as would be observed in D.opposita cv. Ichoimo and Nagaimo. Under SD, the new tubers development were significantly promoted by GA3 treatment because the inhibition of aerial tubers development by GA3 treatment promotes the diversion of photosynthates stored in shoots to growth of new tubers. Under SD, plants grown developed one flush of inflorescences in June, whereas those grown under LD developed a flush in June and again in August through October. We conclude that the GA3 and Uni had no significant effects on the ratio of plants that initiated flowers, the nodal position of the first and final spikes, and the total number of spikes per plant in both season of spikes development in the main shoots were not clear.
The objective of this study was to investigate morphologically flower bud differentiation during floral organ development of 'Green Rocket' okra by using a scanning electron microscope (SEM). Flowers were formed at the axillary positions and were initiated successively from the node bearing the first flower up to the node below the shoot apex. Flower buds were divided into 8 developmental stages: 0) vegetative stage; 1) dome stage; 2) epicalyx initials; 3) calyx initials; 4) petal and stamen primordial appear; 5) carpel and stamen differentiating; 6) further carpel and stamen development; 7) anthesis. Formation of the epicalyx in okra revealed that it is the first floral organ to differentiate, such that the onset of floral differentiation is signaled by the appearance of epicalyx initials. The characteristic staminal column is formed whose base is fused with calyx and petal. These fused calyx, petal and stamen simultaneously wilted and abscised soon after anthesis. From the fusion of these floral organs and the elevated position of these fused parts other than the ovary, an okra flower is classified as being perigynous. A large number of anthers are formed on the staminal column. Five loculi with anatropous ovules are present in an ovary, exhibiting a central marginal placentation.
The recent increase of root rot of lettuce (RRL) in Nagano, a major lettuce producing area in Japan, is becoming a serious problem because there are no suitable cultivars for summer cropping of crisphead-type lettuce (crisp-lettuce) resistant to RRL. We bred 'Shinano Hope' crisp-lettuce that is resistant to Fusarium oxysporum f. sp. lactucae (FOL) Race 1 that is adaptable for summer cultivation. 'Shinano Hope' is a hybrid between two crisp-lettuce lines: one is from a slow bolting selection line, whereas the other is from a breeding line resistant to FOL Race 1. 'Shinano Hope' is field-resistant to FOL Race 1, similar to its paternal plant. It's resistance is superior to those of other lettuce cultivars that can be grown in mid-summer in Nagano. The leaf color of 'Shinano Hope' is lustrous green. The leaf margins have relatively shallow incision, indentation, and mild undulation. The quality of the head in appearance upon harvest was categorized as "good-superior"; it matures similar to 'Patriot' and tends to bolt slowly in mid-summer.
Embryogenic calli were induced from cotyledons of 'Pacific Giant' Delphinium hybridum (white line) in MS medium containing 1.0 mg-liter-1 2, 4-D, 0.1 mg-liter-1 BAP and 30 g-liter-1 sucrose. Embryogenic cell suspension cultures were established from these embryogenic calli by using a liquid N6-based medium (N6 inorganic salts and MS organic constituents), containing 1.0 mg-liter-1 2, 4-D, 1.0 mg-liter-1 TDZ and 30 g-liter-1 sucrose. The cell aggregates increased about eight-to ten-fold after one week of culture under fluorescent light at 25°C. When suspension cell clusters were transferred to a N6-based medium that lacked plant growth regulators, many somatic embryos were formed. When these somatic embryos were transferred to the same medium, the shoots that differentiated were transferred to 1/2 MS medium to root. About 20 plantlets were produced from 1 g of suspension culture.
Petunia (Petunia X hybrida Vilm.) 'Baccarat Blue' under high pressure sodium lamp (HPS) exhibits, dwarfism compared with one grown under a daylight type metal halide lamp (MH). The role of gibberellin (GA) in this growth change, caused by artificial lighting was investigated. The amounts of GA20 and GA1 were lower in petunia grown under HPS than those under MH, but, the levels of GA19 were similar in both treatments. Plant height of petunia was decreased by treatment with uniconazol, but the difference in plant height between treatments was small. GA3 application promoted stem elongation of uniconazol-treated petunia; the magnitude of stem elongation was independent of light source. These results indicate that dwarfism in petunia under HPS is caused by lower GA20 and GA1 contents, but not by GA sensitivity. The GA biosynthesis step of GA19 to GA20 may be affected by the light quality of these lamps.
Crosses between Lilium × formolongi 'White Lancer' and four Asian trumpet species (L. centifolium, L. sargentiae, L. wallichianum, and L. regale 'Album') were conducted using the cut-style pollination method. In all cross combinations, more hybrids were produced by ovary-ovule culture than by the embryo rescue method. PCR-RFLP analysis of rDNA was applied successfully to determine the hybridity of the resulting progenies. These hybrids had pure white trumpet flowers with low pollen fertility.
The nature of cross incompatibility between evergreen azaleas (Rhododendron section Tsutsusi) × R. japonicum (A. Gray) J. V. Suringar f. flavum Nakai, on intersubgeneric crossings, was examined using 22 plants of 13 species in section Tsutsusi. Pre-fertilization barriers were: 1) the arrest of pollen tube growth and 2) the failure of pollen tubes to penetrate into the ovules, whereas the post-fertilization ones were: 1) the failure of fertilized ovules to develop, 2) lack of seed germination, and 3) death of young seedlings. In 22 cross combinations, the number of pre-, post-, and both pre-and post-fertilization barriers that played the principal roles in cross incompatibility were fifteen, six, and one, respectively. Thus, we conclude that the variation in the propensity for the cross incompatibility existed in this intersubgeneric hybridization, and that it differed among individuals rather than among species.
Distributions of molecular weights of cell wall fractions of persimmon 'Fuyu' fruit (Diospyros kaki Thunb.), stored under low and high humidities, were measured. The molecular weight of total sugar of water-soluble (WS) polysaccharides from alcohol-insoluble solids under both low and high humidities shifted to lower molecular mass during storage. The amount of larger sized polymers in fruits kept at low humidity was less than that at high humidity during late stage of storage. Weight-average molecular weights of pectic polysaccharides under high humidity were higher than that under low humidity condition. Coefficient between fruit firmness and the level of individual polysaccharides was higher than those between fruit firmness and weight-average molecular weight of WS, pectin or hemicellulose fraction. These results were confirmed by multiple regression analysis. Hence, fruit firmness of persimmon mesocarp is not influenced by changes in a single cell wall fraction but by all cell wall fractions, i. e., the content of cell wall polysaccharides plays a grater role in determining fruit firmness than do their molecular weights.
Effects of streptomycin (SM) spraying on seed production in open pollinated fruit and effects of thinning time and trunk girdling on the set, development and fruit quality were investigated to develop a practical technique for producing seedless 'Tosa Buntan' pummelo. Three spray application of 500 ppm SM to whole trees at 1-5%, 50% and 100% full bloom significantly decreased the number of perfect seeds to 4.5 seeds per fruit. Fruit thinning with leaf/fruit ratio of 90-100 in June 24 (6 weeks after full bloom) promoted the development of open pollinated fruit, yielding mature fruit weighing about 470 g with 5.7 seeds and the soluble solid and citric acid contents statistically the same as those of the hand pollinated control fruits. Trunk girdling on May 1 was ineffective. The combination of three, 500 ppm SM treatments and fruit thinning on June 24, yielded fruit averaging 464 g with 5.7 seeds. Our analysis of the relationship fruit size in June 24 to seed number and fruit size in harvest time, indicate that fruit weighing 450-530 g with about 4 seeds was possibly produced by keeping fruits large as 42-48 mm in diam. when thinning is done about June 24. Our results demonstrate that commercial production of near seedless 'Tosa Buntan' pummelo fruit is possible by 1) three spray treatments with 500 ppm SM at 1-5, 50 and 100% full bloom, 2) fruit thinning in late June, 3) retaining only fruits large as 42-48 mm in diam. and 4) maintaining a leaf/fruit ratio of 90 to 100.
The cause of leaf chlorosis that occurred recently on greenhouse-grown cucumber plants in the northern district of Fukuoka Prefecture was investigated. The leaf chlorosis occurred only in greenhouses where virgin soils of granodiorite origin were used as a soil-dressing material. Soil chemical analysis revealed that these soils are rich in exchangeable Mg, particularly those excavated from the lower soil strata as compared with those of granitic and basaltic origins. The leaf chlorosis was more severe in the greenhouses with higher contents of exchangeable Mg in the cultivated soil. Leaf chlorosis was evident in leaves with the Mg content above 2.0%; the higher the Mg content, the greater was the severity of leaf chlorosis. In a preliminary water culture experiment, cucumber plants displayed leaf chlorosis similar to that observed in commercial greenhouses when the Mg concentration in the nutrient solution was above 20 me-liter'1. From these results, it is concluded the leaf chlorosis of cucumber plants that occurred in the northern district of Fukuoka Prefecture was mainly caused by excess accumulation of Mg in the leaves, which is attributed to dressing of virgin soils of granodiorite origin with having a high content of exchangeable Mg.
Discrimination between plants diseased by Verticillium wilt of cabbage and healthy plants was tried by using the super soft X-ray apparatus and computed tomography (CT) system. The X-ray photograph of clear contrast were obtained by dipping roots in the undiluted solution of Gastrografin 76% and Urografin 60% (medical X-ray contrast media) for 15 to 20 hr, without any detrimental influences on cabbage tissues. Nondestructive fluoroscopy using the super soft X-ray apparatus did not discriminate discolored vascular bundles from diseased plants, whereas a nondestructive CT system coupled with the X-ray contrast media yielded a clear photograph in the transverse section of vascular bundles. On the early and middle stages of growth, the vascular bundle parts absorbing the contrast media and not absorbing were appeared on the CT photograph of the diseased plants. These not absorbing parts and vascular browning parts coincided on some but not on others. The parts that did not coincide were the early diseased vascular bundle before the browning. Therefore, it was expected that early diseased plants cannot be discriminated by the naked eye. On diseased plants at harvest, the vascular bundle parts that did not absorb the contrast media coincided with vascular browning parts by the naked eye. Therefore, when the sample was made to absorb the medical X-ray contrast media, the use of nondestructive photograph analysis using CT system may discriminate Verticillium infected plants from healthy ones. Furthermore, the method may be usable for breeding disease resistant cabbage cultivars.
To investigate the relationship between aging and antioxdative levels of fully developed, aging cucumber leaves, we measured the contents of protein, malondialdehyde, chlorophyll, reactive oxygen species (superoxide and hydrogen peroxide), and antioxidative compounds (ascorbic acid, β-carotene and flavonoid), then analyzed the activities of antioxidative enzymes, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD). Protein, malondialdehyde and chlorophyll contents in the leaves decreased linearly for 22, 35, and 55 days, respectively, whereas superoxide and hydrogen peroxide contents accumulated for 35 and 25 days, respectively, and then decreased. These results suggest that the aging process after leaf development could be divided into two periods, the earlier one representing a growth process lasting until 25 to the 30th day, the later one is the senescence process beginning about the 35th day. Thus, SOD, CAT, and APX decreased rapidly after 35 days of development, while ascorbic acid and flavonoid contents decreased with time for 25 days. Our data indicate that SOD, CAT and APX, are closely related with the senescence process, whereas ascorbic acid and flavonoid are related with the growth process in developed cucumber leaves.
Twenty five varieties of Cattleya walkeriana, including one with an obscure original source and phylogenetically unidentified, C. nobilior, C. loddigesii, and their hybrids, were examined by RAPD analysis in an attempt establish their phylogenetic relationships and to distinguish varieties with different flower colors. Eight 12- and 10-mer primers generated 176 polymorphic bands between 100 and 2000 bp, out of which 65 bands were used for cluster analysis. Three dinstinct clusters representing C. walkeriana, C. nobilior and C. loddigesii were obtained, indicating that C. nobilior was clearly a different species from C. walkeriana in accordance with the classification of Brieger et al. (1981). C. walkeriana var. alba Tendentive' is a presumed variety of C. nobilior or a hybrid of C. loddigesii, but fell into the same cluster as other varieties of C. walkeriana var. alba. C. walkeriana varieties with different flower colors were distributed into different clusters by RAPD analysis when only one primer was used.