The growth of ‘Kyoho’ (Vitis × labruscana Bailey × V. vinifera L.) grapevines grafted on colchicine-induced autotetraploids of two grape rootstocks, ‘Riparia Gloire de Montpellier’ (‘Gloire’, V. riparia Michx.), and ‘Couderc 3309’ (‘3309’, V. riparia × V. rupestris), was compared with the original diploids. Micro-propagated rootstock and ‘Kyoho’ grapevines were grafted in vitro and rooted. During the rooting and acclimating stage, ‘Kyoho’ grapevines grafted on tetraploids had much shorter shoots and internodes than those grafted on the counterpart diploids. In the nursery period in pots, ‘Kyoho’ grapevines grafted on each tetraploid rootstock also showed weaker growth than those grafted on the corresponding diploid rootstock. After planting in the vineyard, lateral shoot growth after primary shoot-tipping, the trunk cross-sectional area and pruned cane weight of ‘Kyoho’ grapevines grafted on each tetraploid rootstock were also smaller than those grafted on the corresponding diploid rootstock. The berries of ‘Kyoho’ grapevines grafted on tetraploids showed much deeper skin coloration than those of vines grafted on diploid rootstocks.

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The flux of nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂) from brown lowland soils in a satsuma mandarin (Citrus unshiu Marcow, ‘Silverhill’, 31 years old) orchard located in Okitsu, central Japan facing the North Pacific Ocean, was measured once a week from March 2001 to February 2002 using the closed chamber method. Two categories of treatment, mulching and non-mulching, were used in the experimental field by covering the soil surface with a moisture-permeable and waterproof sheet in the latter half of fruit growing season from mid-September to mid-December in 2001. The annual N₂O emission and the amount of total nitrogen fertilized were 93 mg N/m²/year and 27.0 g N/m²/year for the non-mulching treatment and 55 mg N/m²/year and 18.9 g N/m²/year for the mulching treatment, respectively. No significant difference was found in the N₂O emission factor between mulching (0.34%) and non-mulching (0.29%) treatment. These emission factors were much lower than the average value (0.62%) for upland fields in Japan and the IPCC default value of 1.25%. On the other hand, a small amount of atmospheric methane was absorbed into the surface soils throughout the year. The annual uptake of CH₄ was 24 and 17 mg CH₄/m²/year for the non-mulching and mulching treatment, respectively, with no significant difference between the two treatments. Annual CO₂ emission with the non-mulching and mulching treatment was 1.45 and 0.89 kg CO₂/m²/year, respectively. The difference in the amount of each gas emission between the two treatments was discussed with respect to the soil temperature, water-filled pore space (WFPS), the timing and amount of nitrogen fertilized, and the effect of mulching.

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Effects of interstocks on the growth and fruit quality of ‘Fuyu’ Japanese persimmon (Diospyros kaki Thunb.) were investigated to select an effective dwarfing interstock of this species. The performance of four interstocks (Ac-1, Ac-2, Y clones, and a seedling of Diospyros rhombifolia) was evaluated in combination with ‘Aogaki’ (D. kaki) seedling rootstocks and ‘Fuyu’ scions over a six-year period. Ac-1 and Y interstocks moderately reduced the tree size without influencing yield efficiency (yield per unit of crown area). In contrast, Ac-2 and D. rhombifolia interstocks reduced both tree size and fruit yield (kg/tree), and many of these trees died within a few years after planting. Annual fluctuations and no consistent trends were observed in the fruit weight among control and interstock trees. These results show the possibility of dwarfing ‘Fuyu’ trees by using Ac-1 and Y as interstock.

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Using real-time reverse-transcription polymerase chain reaction (real-time RT-PCR) and in situ hybridization, we investigated the temporal and spatial expression of LEAFY (LFY) and TERMINAL FLOWER 1 (TFL1) homologs in Japanese pear (Pyrus pyrifolia) and quince (Cydonia oblonga) buds, in order to elucidate their roles in the flower and inflorescence development of fruit trees in the subfamily Maloideae (Rosaceae). Japanese pear and quince were selected because they are very close phylogenetically but develop distinct inflorescence architectures. Floral differentiation in Japanese pear began in late June to early July in Osaka, Japan, forming a raceme inflorescence with about eight flowers, whereas that in quince took place from late October to November in Nagano, Japan, forming a solitary flower in each floral bud. LFY homolog expression levels in both species increased at the floral differentiation stage and remained at relatively high levels in flower meristems after the flower organ differentiation stage. In contrast, TFL1 homolog expression levels in both species were high in vegetative-stage buds, but decreased significantly just before floral differentiation. Japanese pear TFL1 homologs were expressed in the subepidermal layer of the apical meristem before floral differentiation, whereas those of quince were expressed in the epidermal layer of the apical meristem and leaf primordia. We discuss the possible involvement of maloid LFY and TFL1 homologs in triggering floral differentiation, as well as the involvement of the different spatial expression patterns of TFL1 homologs in the inflorescence architectures of Japanese pear and quince.

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The occurrence of internal browning (IB) was more frequent in sublimed sulfur applications at the levels of 0 and/or 10 g·m⁻²; however, an increase in the severity of IB symptoms was not nearly so marked when sublimed sulfur was applied, approximately at the level of 30 g·m⁻². The activities of L-phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) became low in proportion to the increasing application of sublimed sulfur from 0 to 30 g·m⁻². Conversely, a pronounced increase in ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GSHR) activities were detected with a larger amount of this element. These observations suggest that the application of sublimed sulfur resulted in an increase in H₂O₂ decomposing capacity via the ascorbate-glutathione cycle, so that IB symptoms seldom intensified because of inactivation of the peroxide detoxifying pathway derived from PPO.

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The present study was carried out to clarify the effect of the exogenous supply of 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU), 6-benzylaminopurine (BA) or Na-salt of α-naphthaleneacetic acid (NAA) on the occurrence of hollow cavity (HC) and vessel arrangement in roots of Japanese radish, ‘Gensuke’. Relative to untreated controls, fewer roots exhibited HC when plants were sprayed with 10 mg·L⁻¹ CPPU or BA solutions of > 1 mg·L⁻¹ during the middle of the growth stage. Conversely, HC occurred more frequently relative to controls when plants were sprayed with 5 mg·L⁻¹ NAA during the first half of the growth stage. On the other hand, the application of CPPU during the late growth stage or NAA during the second half of the growth stage produced little or no effect in terms of the occurrence of HC. Vessels in the roots were more sparsely arranged relative to controls when 10 mg·L⁻¹ CPPU was applied during the middle of the growth stage. Application of 5 mg·L⁻¹ NAA during the first half of the growth stage resulted in a high density of vessels relative to controls. From these observations, it was concluded that the exogenous application of cytokinin during the middle of the growth stage or auxin during the second half of the growth stage strongly affects vessel arrangement in the roots and this morphological change is closely correlated with the occurrence of HC.

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The genetic control of resistance to cucumber green mottle mosaic virus SH isolate (CGMMV-SH) in melon (Cucumis melo L.) ‘Chang Bougi’ was studied in progeny from crosses between ‘Chang Bougi’ and the susceptible cultivar ‘Perlita.’ F₁, F₂, and BC₁ plants were mechanically inoculated with purified CGMMV-SH under controlled (30°C) and greenhouse (average temperature of 24.9°C) conditions. All F₁ plants were susceptible to CGMMV-SH. The segregation ratios in F₂ and backcross progeny indicated that resistance to CGMMV-SH in ‘Chang Bougi’ is dependent on two independent complementary recessive genes, which we propose to call cucumber green mottle mosaic virus resistance-1 (cgmmv-1) and cucumber green mottle mosaic virus resistance-2 (cgmmv-2).

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To clarify suitable media for the mass production of phalaenopsis orchids, five potting media, New Zealand sphagnum moss (SM, as the control), coir mixes (CM), CM partially mixed with SM, granular rockwool mixes and perlite mixes were examined using clonal plants of two cultivars, ‘Stripe’ and ‘White Red Lip’, at two-month-old and eight-month-old stages. In pots filled with 100% SM, water retention and total porosity were the greatest, while pH and EC were the lowest. In perlite mixes, water retention and total porosity were the lowest. The CM partially mixed with SM yielded significantly greater number of leaves, and fresh and dry weights of both cultivars at the two growth stages. Scanning electron micrographs showed no differences in the shape of stomata or transversal cells of roots among plants in pots with five different media, while leaves of granular rockwool mixes produced abundant wrinkles on their epidermis. The CM partially mixed with SM was a practical potting medium replacing SM, because of its higher potential to support the superior growth of phalaenopsis.

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The effect of plant density and variety on allometry in Gypsophila paniculata L. was studied. Increasing plant density significantly reduced fresh weight, total branch length (the sum of the lengths of all primary branches), number of dichasia, number of florets per dichasium, and total number of florets in cut flowers in ‘New Face’. The relationships between fresh weight and the total branch length, number of dichasia, and total number of florets were negatively allometric, isometric, and positively allometric, respectively. There were allometric relationships between fresh weight and the number of dichasia, number of florets per dichasium, and total number of florets on each branch order. The allometric exponents of regression relating the number of dichasia and the total number of florets to fresh weight increased from lower- to higher-order branches. On the other hand, the allometric exponents of regression relating the number of florets per dichasium to fresh weight were similar in almost all orders. Significant differences were found in fresh weight and parameters of inflorescence architecture among varieties grown under identical plant density. Allometric exponents relating the total branch length and number of dichasia to fresh weight, varied, and those relating the total number of florets to fresh weight were stable among varieties grown under identical plant density.

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We assayed for Chrysanthemum stunt viroid (CSVd) in cultivated chrysanthemum (Chrysanthemum morifolium) collected from 10 prefectures in Japan and 8 wild species (Chrysanthemum spp.) cultivated at the National Institute of Floricultural Science (NIFS), Japan and determined complete nucleotide sequences of CSVd isolates infecting plants. CSVd was detected in 80 of 89 samples of cultivated chrysanthemum, and samples from all prefectures were infected. Since all 8 wild species had CSVd in RT-PCR results, they were recognized as hosts of CSVd, even though no stunt symptoms were observed. Five sequence variants of CSVd were distinguished among the 21 isolates based on the difference of the nucleotide sequences. Mutations were common in the P (pathogenicity) domain. Variant 5 from C. morifolium, and variant 4 from C. yoshinaganthum had different nucleotide sequences from those reported previously. Variant 1 was most frequently detected from samples in 6 prefectures and is assumed to be the predominant CSVd variant distributed in Japan.

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The effects of heat treatment on the formation of chlorophyll (Chl) derivatives and Chl-degrading enzyme activities in stored broccoli (Brassica oleracea L. Italica Group ‘Ryokutei’) florets were determined. The Chl a level barely changed during heat treatment, but each Chl a derivative level changed. Chlorophyllide (Chlide) a, pheophorbide (Pheide) a, C13²-hydroxychlorophyll (C13²-OHChl) a, Chl a′, an isomer of Chl a, and pheophytin (Phy) a were detected as a Chl derivative during heat treatment and during storage after treatment. Chlide a, Pheide a, and C13²-OHChl a levels decreased during 2-h heat treatment (50°C), whereas Chl a′ and Phy a levels increased. Chl-degrading enzyme activities, in particular, Mg-dechelation activity, were effectively suppressed after 2 h of heat treatment. The content of Chls a and b in control broccoli florets decreased greatly during storage at 15°C, while the content in heat-treated broccoli florets hardly changed at all. In Chl derivatives, the Pheide a level in broccoli florets treated with or without heat treatment, especially the former, increased appreciably during storage. The Chlide a level in control florets decreased markedly during storage. On the other hand, the Chlide a level in heat-treated broccoli florets did not change during storage. Mg-dechelation activity in control florets markedly increased after 4 days of storage at 15°C, but the enhancement of the activity was suppressed by heat treatment. These findings suggest that Chl derivatives, especially Pheide a, are accumulated as intermediates in heat-treated broccoli florets, and Mg-dechelating action, in conjunction with that of chlorophyllase and Chl-degrading peroxidase, could be involved in Chl degradation in stored broccoli florets.

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The physiology of starch degradation in relation to ripening and ethylene was investigated using ‘Tsugaru’ (early-maturing) and ‘Fuji’ (late-maturing) apples (Malus domestica Borkh.). Fruits were harvested at immature and mature stages, and treated with ethylene and 1-methylcyclopropene (1-MCP). In immature fruit of both cultivars, starch content rapidly decreased during storage at 25°C, and 1-MCP had little effect on this change. Ethylene treatment slightly stimulated the degradation of starch, but differences in starch among treatments were small. The respiration rate gradually decreased and ethylene production remained low during storage irrespective of the treatments and cultivars. These results showed that fruit at this stage could not respond to endogenous and exogenous ethylene for inducing the climacteric, and starch degradation did not relate to the climacteric or ethylene. In mature ‘Tsugaru’, 1-MCP treatment significantly inhibited ethylene production and reduced the respiration rate and starch degradation. The effects of 1-MCP and ethylene on starch degradation in mature ‘Fuji’ were small, and starch content decreased drastically in all treatments, although 1-MCP significantly inhibited ethylene production and the respiration rate. It is suggested that ethylene is partially involved in starch degradation in mature ‘Tsugaru’, but not in ‘Fuji’. These results showed that the role of ethylene in starch degradation differs between cultivars and their harvested stages, relating to ripening and physiological characteristics of the fruit.

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