Sweet cherry (Prunus avium L.) cultivars; 'Valera', 'Schwartze Venus' and 'Mazzard' with low cracking susceptiblity, and 'Satonishiki', 'Napoleon' and 'Van' with high cracking susceptibility were examined for changes in exocarp cell length during the fruit enlargement at the apex, equator, stalk cavity and suture. Although fruit weight and fruit thickness varied among cultivars, growth curves based on these parameters exhibited a typical double sigmoidal pattern; however, differences existed in the lengths of each growth stage. Exocarp cell lengths also differed with equatorial lateral length, apical vertical and lateral lengths, and suture vertical length being particularly long. Large cultivar differences were noted in stalk cavity, apical lateral and vertical lengths, and equatorial vertical length. With ripe fruit, the exocarp cell lengths in the above parts are smaller in the 'Valera', 'Schwartze Venus' and 'Mazzard' than those in 'Satonishiki', 'Napoleon' and 'Van'. With some exceptions, significant positive correlations exist between exocarp cell length of each part versus fruit weight, fruit thickness and radial cell length of the mesocarp. We hypothesize that exocarp cell division occurs simultaneously with that in the mesocarp, but unlike the other three parts, it continues at the apex even after the cessation of mesocarp cell division. The duration of the cell division period also differs among cultivars, with 'Schwartze Venus', 'Valera' and 'Mazzard' having the longest cell division period as well as having small exocarp cell lengths compared with the other cultivars, from the immature to the ripe fruit stages. Lighter and smaller fruit with a late cessation of cell division of the apical exocarp cells resulted in the smaller length of apical exocarp cells and lower susceptibility of cultivars to cracking.

View full abstract

A series of one-season experiments were carried out with 'Fuji' and 'Jonathan' trees of different ages and with young 'Hokuto' trees. Twigs (1-year-old branches) on trees that were trained to the central leader or open center systems were headed to elucidate the twig-to-twig relatonships on terminal shoot growth. Terminal shoots were almost the same length between pruned and unpruned twigs in 'Fuji' and 'Hokuto' trees, whereas those of 'Jonathan' grew longer when headed. Unpruned twigs of 'Fuji' sent out a few shoots but the number of shoots and total shoot length that developed from headed twigs were almost the same as those from unpruned counterparts. Unpruned twigs of 'Jonathan' tended to develop a large number of shoots, whereas heading cuts caused a significant reduction in the number of shoots and total shoot length. The foregoing cultivar-specific responses to pruning also occured in experiments with water sprouts. The above observations were integrated into the following assumptions: (1) The strength of shoot growth on twigs is determined to a considerable extent by inherent twig conditions and the circumstances under which they developed. Twig location on the crown and distance from the tree base as well as length and thickness of the twigs seem to be important factors related to the shoot growth. (2) Terminal shoot length is a product of conditions determined by the individual twig and the mutual interaction between terminal and lateral shoots. (3) In cultivars with infrequent branching habits, such as 'Fuji', in which the terminal shoots have a strong dominance over lateral shoots, heading cuts do not encourage terminal shoot growth because growth relations between terminal and lateral shoots are little changed by pruning. (4) In cultivars having frequent branching habits, i.e., 'Jonathan', in which the terminal shoot is weakly dominant, heading induces the remaining terminal shoots to grow longer by reducing the number of active buds on the twig; it favors the early stage of terminal shoot growth and reduces subsequent inhibition of terminal shoots by lateral ones.

View full abstract

Ovules were removed from ovaries from mid-July to early August and cultured in vitro. As a result, all ovules which were sampled and cultured by July 19 in the central female flowers and by July 22 in the lateral female flowers died before early September. However, in ovules sampled and cultured on and after July 22 and 26 in the central and lateral female flowers, respectively, nearly one ovule per ovary survived and developed on the culture medium until mid-September. The development and enlargement of the embryos within the ovules were also observed. Differences in the weight between the largest ovule per ovary and the other ovules began to become clear after July 22 in the central and lateral female flowers. The differences increased rapidly on and after July 29. The longest pollen tubes which penetrated into the ovaries reached the nucelli on July 19-22 and July 22-26 in the central and lateral female flowers, respectively. The pollen tubes which reached the zone where the nucelli were located were observed on July 15 and 19 in the central and lateral female flowers; their numbers increased rapidly during July 15-19 and July 19-22, respectively. Subsequently, their numbers gradually decreased. In the central female flowers, the ovules with a single pollen tube per ovary numbered 5, 6 and 5 on July 22, 26 and 29, respectively. A pollen tube, which penetrated into the micropyle, reached the nucellus in only one ovule in the ovary during July 22-29. The pollen tubes which had penetrated into the micropyles of the other ovules stopped growing at the same length, about half of the length of the entire micropyle, on July 29 in particular. It was suggested that when one ovule had already been fertilized, the other ovules, into which pollen tubes had penetrated, could not be fertilized owing to the cessation of the pollen tube growth.

View full abstract

We investigated the chemical degradation and structural changes of cell walls of watercored tissues induced by GA paste treatment in Japanese pear (Pyrus pyrifolia Nakai) 'Akibae' and 'Housui'. Depolymerization of high molecular-mass trans-1, 2-cyclohexanediamine-N, N, N', N'-tetraacetic acid (CDTA)-soluble pectin occurred in severely watercored fruits, but there were no such metabolic changes in the Na₂CO₃-soluble fractions in both cultivars. Hemicellulose in 4% KOH soluble fractions, size-fractionated through a Sepharose CL-6B-100, revealed partial molecular-mass downshifts of total sugars in both cultivars, but considerable mol-mass change of xyloglucan only occurred in 'Akibae'. The polymers in 24% KOH soluble fraction showed no detectable alteration of molecular-mass in both cultivars, whereas 'Akibae' exhibited much higher cell wall-bound polygalacturonases and glycosidases activities compared with 'Housui'. The activities of β-galactosidase and β-glucosidase increased as the zone of watercore expanded in 'Akibae'. Total activity of cell wall bound glycanases was higher in 'Akibae' than in 'Housui'. Catabolism of carboxymethyl cellulose by cellulase was not different between sound and watercored tissues in both cultivars, but the activity against xyloglucan was higher in watercored tissue than the sound tissue adjacent to the watercore zones in 'Akibae'. Structural changes observed by light microscopy in sound and severely watercored tissue showed a greater extent of cell separations with the accumulation of pectic materials in the intercellular space of severely watercored tissues in 'Akibae' than in 'Housui'.

View full abstract

The effect of planting density on fruit size of vertically trained watermelon (Citrullus lanatus (Thunb.) Matsum. et Nakai) plants was investigated with regard to light-interception character-istics and photosynthetic production. Watermelon plants, grafted on bottle gourd, were grown in a glasshouse at different planting densities. Two vines per plant were allowed to grow and trained vertically. One hand-pollinated fruit per plant was set around the 15th node on either vine. The solar radiation and photosynthetic rate of individual leaves during fruit development period were determined by an integrated solarimeter film and a portable photosynthesis system, respectively. Fruit size was significantly decreased as the planting density increased, whereas soluble solids content of the fruits was affected little. The solar radiation and the photosynthetic rate of the individual leaves gradually decreased as the leaf position became lower at all planting densities on account of shading; those at lower leaves tended to decrease as the planting density increased. Fruit size was closely related to both the total solar radiation and the photosynthetic production per plant. In conclusion, the difference in fruit size among the planting densities is attributed to the photosynthetic productivity of the whole plant, which is mainly a function of the total solar radiation. This paper appears to be the first trial relating the influence of light interception and photosynthetic rates in high density plantings of vertically trained watermelon plants on fruit size.

View full abstract

Effects of high root-zone temperature (RT) on ABA content, photosynthesis and its related parameters in cucumber (Cucumis sativus L., cv. Suyo) were investigated. Plants were grown in water culture at a RT of either 30°C or 3°C for 10 days. Other growth conditions were 30/25°C air temperatures (day/night), a 14-hr photoperiod, and a light intensity of 250 μmol·m·s^-1. Plant growth was severely inhibited at 38°C RT as compared with that at 30°C RT. At 38°C RT, leaves did not wilt and the leaf color was normal green, but showed a marked increase in ABA content after day 6 with a significant decrease in stomatal leaf conductance. In both RT treatments, leaf water potential declined at day 6, which was more pronounced at 38°C RT than at 30°C RT, but the difference was relatively small. The photochemical activity of chloroplasts was not affected by high RT. However, the CO₂ exchange rate (CER) of leaves decreased linearly after day 4 in the high RT treatment. Peeling the epidermis of the abaxial leaf surface to eliminate the stomatal limitation to CER resulted in a significant but not complete recovery of CER, indicating that the high RT limited CER through a decrease in not only stomatal aperture but also photosynthetic capacity of mesophyll cells. After day 6 of high RT treatment, ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) exhibited a gradual decrease in the initial level and the activation state. The results indicate that ABA-induced stomatal closure and reduction in the activation state of Rubisco are responsible for impaired photosynthesis in cucumber grown at elevated RT.

View full abstract

Calli induced from bulb scales of Lilium X formolongi were bombarded with the plasmid pAct1-F, which harbors the uidA gene encoding β-glucuronidase (GUS) that is driven by the rice actin-1 promoter. Based on the frequency of GUS-expressing cells in the calli, bombardment conditions were optimized. Calli were bombarded with pDM302 harboring the bar gene, encoding phosphinothricin acetyltransferase (PAT) that is driven by the actin-1 promoter, and selected for bialaphos resistance. Regenerated bialaphos-resistant lily plants were obtained six months after bombardment. PCR analysis suggested that some of the bialaphos-resistant plants were transgenic. Transgenic bialaphos-resistant plants displayed PAT activity and resistance to bialaphos-based herbicide.

View full abstract

The effects of storage humidity on persimmon fruit deterioration and cell wall composition were investigated. Under a low humidity condition (20°C, 60% RH), fruits underwent a more rapid rate of water loss, ethylene production and fruit softening than did those stored under a high humidity condition (20°C, ≥ 98.5% RH). Arabinose (Ara) and galactose (Gal) in the pectic fraction of mesocarp cell walls decreased significantly under low than high humidity at the late stage of fruit softening as did the cellulose fraction. Fruit firmness is significantly correlated to contents of Ara and Gal of water-soluble (WS), pectic and hemicellulose and that of cellulose, which suggest that these components influence the integrity of mesocarp cell walls of persimmon fruit. Water loss and induced ethylene are involved in the decrease in contents of Ara and Gal in pectin and cellulose content, leading to fruit softening.

View full abstract

The effects of controlled atmosphere (CA) at 5, 21 (air, control) and 100 % O₂ on chilling injury, respiratory and antioxidative parameters at 5, 10 and 20°C in cucumber fruit were determined. The appearance of chilling injury symptoms in cucumber was delayed in both CA treatments; 100 % O₂ effectively reduced pitting than did the 5 % O₂ treatment. Respiration and ethylene production rates were suppressed in cucumber fruit stored at 5°C to a greater extent in 100 % O₂ than in 5 % O₂ and air. At 20 °C, however, 100 % O₂ increased the respiration rate to rates higher than in 5 and 21 % O₂. The respiration rate of cucumber fruit stored in 100 % O₂ at 10°C was lower than control but higher than the fruit stored in 5 % O₂. Analyses of fruit for changes in enzymatic antioxidant; superoxide dismutase (SOD) and catalase, and non-enzymatic antioxidant, ascorbic acid and glutathione revealed that those stored at 5°C, SOD activity temporarily increased on D-1 by 5 and 100 % O₂ treatments; at D-5, its activities in all storage atmospheres increased. Catalase activity in the control fruit was higher than those at both 5 and 100 % O₂, whereas glutathione concentration changed slightly from the initial level at different storage conditions. Ascorbic acid content in all storage atmospheres decreased, exhibiting the same trend throughout the storage period.

View full abstract

Twelve cultivars of cut flowering chrysanthemums (Dendranthema grandiflora Kitamura) were exposed continuously to air with or without 1 ppm ethylene and their leaf color was measured with a chromameter. When leaves of six cultivars, including 'Syuho-no-chikara' and 'Seiko-no-makoto', were exposed to ethylene, they turned yellow, but others did not respond to ethylene. Similar varietal sensitivity to ethylene and consequent leaf yellowing were observed in resetted and elongating vegetative shoots. Pulsing with 0.2 mM anionic silver thiosulfate complex (STS) completely inhibited leaf yellowing in the ethylene-containing atmosphere. These results indicate that yellowing of the leaves of some chrysanthemum cultivars is induced by ethylene.

View full abstract

A RAPD marker genome-specific to pink-flowered Freesia corymbosa (Burm. f.) N. E. Br., which was generated by using OPG-12 primer, is a DNA fragment with 837 bp nucleotide sequence. A pair of primers were also designed for generating a 637 bp SCAR marker. Both RAPD and SCAR markers were detected in all three accessions of Freesia corymbosa and absent in 32 accessions of eight Freesia species tested. The markers were detected in most cultivars having red, pink, blue, purple and violet perianths, which support our hypothesis that pinkishtone perianth color of freesia cultivars originated from the pink-flowered Freesia corymbosa. However, a SCAR band at 637 bp appeared in some yellow- and white-flowered cultivars. The lineage of freesia cultivars is discussed.

View full abstract

The origin of tendrils and inflorescenses on primry (main or trunk) and secondary (lateral) shoots in relation to the transformation of V. ficifolia, and 'Campbell Early' and 'Kyoho' grapevines from their juvenile through adult phases was studied. The effects of growth regulators on this transition were also investigated. In V. ficifolia seedlings, the nodal position where the first tendril on the secondary shoots formed depended on the origin of the branch on the main shoot. The tendrils and floral clusters emerged at lower nodes with increasing nodal positions on the main shoot. On mature vines cut back to a basal bud or on rooted, single-bud cuttings trained to the single stem derived from 'Campbell Early' and 'Kyoho', the first tendrils differentiated at lower nodes than those on the mother vine. Furthermore, the nodal position that formed the first tendril on cuttings taken from the juvenile part of the mother stem tended to be higher than those obtained from the adult region. The nodal positions that formed inflorescences on dehorned mature vines or cuttings were equal to or higher than those on the mother plants. The percentage of cuttings that formed inflorescences generally increased with increased nodal positions where the cuttings originated on the mother vines. The co-application of 6-benzylaminopurine (BA), gibberellin A3 (GA₃) and BA + spermidine with a liquid fertilizer had no influence on the rate of transformation from the juvenile to the adult stage in V. ficifolia seedlings. However, treatment with BA during the transition phase hastened it. Treatment of young vines with 1-aminocyclopropane-1-carboxylic acid (ACC) delayed the transition to the adult phase, whereas that with GA₃ inhibited the formation of inflorescences on mature vines.

View full abstract

Fruit and endocarp (stone) weights and their ratios in 57 Japanese apricot (Prunus mume Sieb. et Zucc.) cultivars grown at the National Institute of Fruit Tree Science were investigated. Large differences among cultivars were detected in the fruit and stone weights but a statistically significant correlation exists between the two parameters. In average, stones contributed 9.7 % to total fruit weight. Two cultivars closely related to apricot and plum, 'Takadaume' and 'Sumomoume' have particularly low percentages of stone weight. The coefficient of yearly variation of stone weight is low in comparison to that of fruit weight. Fruit that weigh between 25 and 35 g, with stones weighing 2.0 to 2.8 g or 8 %, respectively, or less, are desirable for the production of pickled fruits. Using these criteria, 'Baigo', 'Kensaki', 'Benisashi', 'Gecchibai' and 'Kairyo uchidaume' were identified as promising source cultivars for the development of lines that meet the requirements of pickled fruit producers.

View full abstract

The petioles of 37 Japanese taro cultivars (Colocasia esculenta (L.) Schott. and C. gigantea Hook, f.) which belong to 14 cultivar groups were examined to compare the densities and sizes of their calcium oxalate crystal idioblasts. Two types of raphide idioblasts were observed in petioles of all cultivars examined: the nondefensive raphide idioblasts, which are elongated cells containing a tightly connected raphide composed of many needle-like crystals; the defensive raphide idioblasts, also elongated cells, but containing a loosely connected raphide. The densities of raphide idioblasts differed among cultivar groups, whereas in some cultivar groups, they closely resembled each other. No definite differences in the densities of raphide idioblasts were recognized among the cultivars within the same cultivar group except for a few. The densities of druse idioblasts were higher than those of raphide idioblasts in all cultivars examined. Definite differences in the densities of druse idioblasts were recognized among cultivars within the same group. The 14 cultivar groups were divided into 2 types according to the density of raphide idioblasts in the petioles: the low density type, 'Migashiki', 'Mizu-imo', 'Shoga-imo', 'Tono-imo', 'Yatugashira', 'Hasu-imo', 'Egu-imo' and 'Akame-imo'; the high density type, such as: 'Hasuba-imo', 'Ishikawa- wase', 'Dotare', 'Kurojiku', 'Binroshin' and 'Takenoko-imo'. The densities of raphide idioblasts of cultivars with edible petioles were less than those of cultivars with edible corms. The size of the raphide and druse idioblasts was comparatively small in the cultivars with edible petioles. These results indicate that the densities and sizes of raphide idioblasts are useful as the selection indices in breeding of taro cultivars with edible petioles.

View full abstract

Diallel cross and ovule culture were carried out among 15 Alstroemeria species. Ovules harvested 14 days after pollination were cultured on 1/2MS medium containing 3% sucrose at 20°C under a16-hr photoperiod. Embryo germination occurred in 196 out of 210 combinations of the diallel. A. angustifolia, A. ligtu, A. magenta and A. pelegrina showed wide cross-compatibility with not only Chilean but Brazilian species as well. When A. aurea, A. diluta, A. garaventae and A. zoellneri each served as a female parent, the percentage embryo germination was low in some crosses, but some germination took place in all combinations. A. inodora, A. maginfica, A. psittacina and A. pulchra exhibited unilateral interspecific incompatibility in many combinations.

View full abstract

Effects of ancymidol sprays on summer-to-autumn-flowering chrysanthemum (Dendranthema grandiflorum (Ramat.) Kitamura) were studied. In plants sprayed 1.0-10 mg·liter^-1 ancymidol, flower bud differentiation was advanced compared to those treated with 0-0.1 mg·liter^-1 ancymidol in 'Seiun' and 'Summer-yellow'. Spraying with 0.1-1.0 mg·liter^-1 promoted early bud differentiation resulting in anthesis being 3 to 10 days ealier and the stems shorter by 2 to 7 cm than the control. However, when plants were treated with 10 mg·liter^-1, anthesis in all cultivars was delayed 1 to 8 days and the stems were 5 to 12 cm shorter compared to the control. We conclude that applications 0.1-1.0 mg·liter^-1 ancymidol can advance anthesis 3 to 10 days and cause some dwarfing in summer-to-autumn-flowering chrysanthemums.

View full abstract