For breeding Hydrangea, it is an advantage to breed new hybrid cultivars in as short a time as possible. To this end, we used ovule culture and regulation of flowering to shorten the breeding period of hybrids produced from crosses between Hydrangea serrata (Thunb.) Ser. and H. macrophylla (Thunb.) Ser. Interspecific crosses between H. serrata and H. macrophylla were carried out in June. One year after crossing, hybrid plants were induced to flower by cool temperature treatments of 15°C for 60 days (under ambient daylight). Dormancy of hybrid plants was broken by low temperature treatment at 5°C for 50 days. Hybrid plants flowered in December, 18 months after crossing. The flowering rates among the four hybrid combinations ranged from 77 to 96%. Interspecific hybrid ‘04MaP1’ which flowered in December was crossed with H. macrophylla ‘Sumida no hanabi’. Sixty days after crossing, ovules were excised from capsules and cultured on 1/2 MS medium. Germinated seedlings were raised in a culture/acclimation room at 25°C with a 16-hour light/8-hour dark photoperiod. These hybrid plants were transferred into a greenhouse without temperature regulation in July (7 months after crossing), and flowered the following April or May (18 months after crossing). Using these methods, we obtained flowering Hydrangea hybrids at the second generation, 3 years after the first crossing.
The usefulness of scaly rhododendrons in hybridizing with Kurume azalea (cultivar group of Rhododendron × obtusum) cultivars was examined in order to expand the variations of the Kurume azalea group. One R. keiskei and one R. mucronalutum var. ciliatum were used as pollen parents for pollination of eight Kurume azalea cultivars. The degree of post-mating barriers and the characteristics of hybrid seedlings were compared with those of previous crossings using R. japonicum f. flavum as a pollen parent. Hybrid albinism was remarkable for pollination with pollen of R. keiskei. Both the lack of seed germination and hybrid albinism were remarkable following pollination with pollen of R. mucronalutum var. ciliatum. We considered that these crossings had stronger post-mating barriers than crossings using R. japonicum f. flavum as a pollen parent. Of the 16 cross combinations we examined, only Kurume azalea ‘Gofuku’ × R. keiskei produced 12 healthy hybrid seedlings, and five of these flowered five years after pollination. The flower size of seedlings was equivalent to that of Kurume azalea cultivars. The leaves of the seedlings were coriaceous with better gloss that shown by either of parents. These useful traits did not appear in the hybrid seedlings obtained from crossings using R. japonicum f. flavum as a pollen parent. PCR-SSCP analysis demonstrated that ptDNA of the four hybrid seedlings examined was inherited paternally.
‘Izu Midori’ is a new autumnal edible pod pea variety (Pisum sativum L.) with resistance to white top disease caused by Pseudomonas, which occurs frequently in Izu peninsula. White top symptom resistance was introduced in ‘Azumino Sanjyuniti PMR’, which has with high heat tolerance. We then started to produce ‘Izu Midori’ by backcrossing ‘Azumino Sanjyuniti PMR’ with ‘Izu 1 Gou’. It is suggested that white top symptom resistance is dominant on the nucleus genome. After two backcrosses, this cultivar was selected. This cultivar shows a higher resistance to white top symptom than ‘Izu 1 Gou’. ‘Izu Midori’ was characterized by adequate plant heights, nodes, branches, first node position, as good as ‘Izu 1 Gou’. In addition, this cultivar has the similar pod quality with ‘Izu 1 Gou’, and gives heavy yield as well. For these reasons, this cultivar is expected to be cultured widely on the Izu peninsula.
The S-phenotypes (self-incompatibility phenotypes) of Japanese pear (Pyrus pyrifolia Nakai) ‘Chikusui’, ‘Shinseiki’, ‘Seigyoku’ and ‘Housui’ determined their S-genotypes by molecular markers were verified by cross pollination test. As an indicator plant for S3S4 phenotype, FC-14 was selected from progenies of ‘Kikusui’ (S2S4) × ‘Choujuurou’ (S2S3) by cross pollination and progeny tests. ‘Chikusui’, ‘Shinseiki’ and ‘Seigyoku’ showed incompatibility with FC-14, therefore the S-phenotype of these cultivars were identified as S3S4. ‘Housui’ indicated cross incompatibility with Nashi Hiratsuka No.24 [Nashi Hiratsuka No.1 (‘Ishiiwase’ × ‘Nijisseiki’) × ‘Kousui’] on cross pollination test. The S-phenotype of Nashi Hiratsuka No.24 and ‘Housui’ was presumed S3S5 based on the S-phenotype analysis of Nashi Hiratsuka No.24 and its parents, Nashi Hiratsuka No.1 and ‘Kousui’. This presumption was confirmed by segregation for S-phenotypes in progenies of ‘Housui’ × ‘Hakkou’. Thus, the S-phenotypes of ‘Chikusui’, ‘Shinseiki’, ‘Seigyoku’ and ‘Housui’ were consistent with the S-genotypes determined by molecular markers.
Polymorphic analyses of simple sequence repeat regions on chloroplast genomes in 34 vegetables were conducted using a set of consensus SSR primer pairs. A sufficient number of DNA markers were obtained in this study and could be available for polymorphic analyses at the species level. The most successful result was obtained from the polymorphic analyses of cultivated and wild species in Allium. The DNA fingerprints of Allium facilitated the identification of each species except in one difficult case. The fingerprint of a natural hybrid, A. × wakegi, could not be distinguished from that of its estimated seed parent, A. fistulosum. The DNA markers obtained from this study seem to have potential not only for breeding purposes but also for cultivar identification in various species of vegetables.
The effects of a rice husk charcoal (RHC) covering on the growth, nitrogen uptake and post-transplant growth were investigated in lettuce plug seedlings under organic fertilization during the cool season. The RHC covering had no effect on the medium temperature. However, the growth and amount of nitrogen uptake were greater in seedlings when the medium was covered by RHC than when it was covered by vermiculite or left uncovered. Growth immediately after transplanting was more rapid in the RHC seedlings than in the other two seedling groups. The head fresh weight at harvest was about 20% higher in the RHC seedlings than in the other seedling groups. The nitrogen concentration in the seedlings increased with increasing RHC volume, but there was no significant relationship between the RHC volume and the seedling growth. A mixture of RHC with medium at equal volumes promoted less seedling growth and nitrogen uptake compared with those with RHC covering alone. The benefits of RHC covering were lost when we shielded the surface of the medium with aluminum foil wrapped in a paper towel.
We examined the physiological factors causing reduction of seed germination under a high temperature of 24°C in Lilium × formolongi hort.. High temperature inhibited the saccharification of storage starch to glucose in the seed during germination with a reduction of α-amylase activity. Ethylene production and abscisic acid (ABA) concentration in the seed increased under a high temperature condition. Ethylene inhibitor, STS (Silver thiosulfate complex) and 1-MCP (1-methylcyclopropene), and wing removal treatments recovered the germination reduction at a high temperature. Furthermore, 1-MCP treatment during seeding in the soil was also effective in that recovering of germination reduction at a high temperature. We concluded a decrease in a-amylase activity with increases in ABA and ethylene is related to the inhibition of seed germination under high temperature in Lilium × formolongi hort.
In earlier research, we developed a system to measure the volumetric water content in the branches and trunks of satsuma mandarin (Citrus unshiu Marcow.) by portable Time Domain Reflectometry (TDR). However, there were some problems, such as temperature dependency or the unevenness of the values at the beginning of the measurement because of errors in the insertion of the probe. Therefore, in this research, a revised equation was used to adjust for the temperature dependency; and to remove the unevenness of the values, a relative evaluation based on the annual point time at which the stem water content became stable was examined. Concerning the revised equation, we recognized a strong correlation between the temperature and the TDR value through which we obtained the revised equation. During the measurement period, from early and mid-July to mid-September, when the temperatures were above 30 degrees and the soil was wet, the standard value was determined to be the point at which the stem water content reached an annual peak. Thus, the relative value of TDR (Rrev) could be fixed, and the correlation between that value and the leaf water potential (LWP, φmax) was demonstrated month by month. The correlation coefficient in July was 0.888, and that in August and September was about 0.7, but, in October and thereafter, the coefficient decreased to 0.435. However, the TDR value converted into volumetric water content (VWC) maintained its correlation coefficient with LWP 0.3 and under every month. The predicted value of LWP from Rrev and temperatures showed a strong correlation (r2 = 0.712) with the observation LWP value. In this way, the method used in this research seemed to be able to measure the water status of the stem with high precision.
Limited nutrient supply control of tomato grown in substrate culture using a double trough bed was investigated. Two experiments were conducted to determine the effect of a reduced amount of nutrient supply. Experiment 1. Treatment with 50 me NO3-N·plant−1·week−1 was considered in the cultivation and management of limited nutrient supply control. As a result, the yield till 4th truss was not significant compared with that under an EC-based control method. However on the 5th to 6th truss, the yield was decreased. At the late growth stage of 6th truss pinching of tomato, the results showed that 50 me NO3-N·plant−1·week−1 should be increased. Experiment 2. The influence of the amount of NO3-N applied at the 6th truss pinching tomato growth stage was investigated. In limited nutrient supply control, the blooming periods of the 2nd, 4th and 6th flower clusters were treated with increasing amounts of 50, 70, 90 me NO3-N·plant−1·week−1, respectively. Compared with that under an EC-based control, these treatments reduced the inorganic component rate by 33% (NO3-N), 56% (NH4-N), 53% (PO4-P), 41% (K), 22% (Ca) and 76% Mg, respectively. These results show that it is possible to apply limited nutrient control on tomatoes grown by substrate culture using a double trough bed, resulting in the reduction of the inorganic component, particularly NO3-N.
To investigate the suitable amount of potassium supplied to tomato plants through a limited nutrient supply control on substrate culture, tomatoes were grown until the 6th truss pinching stage in a substrate culture using a double trough bed with granulated rockwool. In the EC-based control method (control), nutrient solution was applied using a free drainage system. In the limited nutrient supply method, 250 mL of nutrient solution containing 3 levels of potassium (15, 30, 50 me K·plant−1·week−1) was supplied to each plant. Results showed that there was no significant difference in the yield of the 1st to 3rd trusses. In the 4th to 6th cluster, the yield was lower in plants receiving 15 me K·plant−1·week−1 treatment compared with that of controls, but there was no significant difference in plants receiving 30 and 50 me K·plant−1·week−1. However, in plants receiving 30 me K·plant−1·week−1 treatment, vascular browning was observed from the 2nd cluster to the 6th cluster with an incidence of 16 percent in the latter. The ratio of the total amount of potassium applied during the experiment at 15, 30 and 50 me K·plant−1·week−1 treatment to that of control was 28, 56, 98%, respectively. Based on these findings, in the 6th truss of tomato grown on substrate culture considerable reduction of potassium supply caused a physiological disorder in the tomato fruit. Therefore, in the EC-based control method supply, it was necessary to increase the potassium supply from 30 me K·plant−1·week−1 to 50 me K·plant−1·week−1 during the early stage of the 2nd truss of fruit development.
Photosynthetic characteristics measured with the leaves of ‘Weymouth’ highbush blueberry (Vaccinium corymbosum L.) and ‘Tifblue’ rabbiteye blueberry (V. ashei Reade) in phytotron were compared with regard to their responses to light intensity (0-2,000 μmol·m−2·s−1) and temperature (15-35°C). As temperature increased, photosynthetic rates of both cultivars increased. Photosynthetic rates of ‘Weymouth’ were higher than those of ‘Tifblue’ under low temperature conditions (15-20°C). However, there was no difference in photosynthetic rates measured under high temperature conditions (25-35°C), but ‘Weymouth’ showed higher transpiration rates and lower water use efficiencies (WUE) than ‘Tifblue’. Furthermore, photosynthetic characteristics of ‘Blueray’ highbush blueberry under high temperature conditions (28 and 35°C) were similar to those of ‘Weymouth’ under high temperature conditions. These findings show that photosynthetic characteristics of leaves could be related to the suitability of highbush blueberries to cool conditions, and to the heat tolerance and drought resistance of rabbiteye blueberries. WUE values measured at high temperature >35°C and high light intensity >1,000 mmol·m−2·s−1 could be helpful as indices for evaluating and selecting blueberry plants with heat tolerance. Transpiration rates increased at high temperature and high light intensity, which suggested that shading in summer to control light intensity under 1,000 μmol·μ−2·s−1, a light saturation point, could be useful for preventing water loss of the plants.
To verify the possibility of growing muskmelons by limited nutrient supply control (LNSC) based on the changing pattern of nutrient uptake, muskmelons were grown in double trough substrate bed from April 28 to July 14, 2006. Three treatments consisting of a combination of fertigation methods and kinds of substrates were as follows; 1) EC-based control in granule rockwool (EC·RW), 2) LNSC in granule rockwool (LNSC·RW), and 3) LNSC in an organic substrate (LNSC·OR). The results showed that the leaf and stem fresh weights under EC·RW were greater than those under LNSC·RW. However, fresh weight and soluble solid content of the fruits did not significantly differ between EC·RW and LNSC·RW. The amounts of total N, PO43−-P, K, Ca and Mg during the whole growing period under LNSC²RW were 883, 362, 492, 398 and 157 me plant−1, and the rates to those of EC·RW were 50, 88, 60, 48 and 38%, respectively. Thus, it was confirmed that muskmelons could be grown successfully without reducing the yield and quality by applying a reduced amount of nutrient elements using LNSC. It was also suggested that the suitable amount of nutrient differs depending on the kind of substrate, because the fruit yield and quality were found to be markedly lower for LNSC·OR than for LNSC·RW.
We evaluated the effects of training and culture methods on tree growth, yield and dry matter production in the Japanese pear ‘Kousui’. We adopted two culture methods: conventional culture and rhizosphere restricted culture, and two training systems: pergola and Y-shape, to make four test plots: 1) pergola/conventional (P/C), 2) Y-shape/conventional (Y/C), 3) pergola/rhizosphere restricted (P/R), and 4) Y-shape/rhizosphere restricted (Y/R). Leaf Area Index (LAI) in Y/R was 4.9, more than double that of the other test plots. Brix in Y/R was the highest. Fruit bearing rate per m2 in Y/R was 18.5, about double that of the other plots. When the leaf/fruit ratio (L/F) was set to about 35 in all the plots, yield in Y/R was as high as 61 t·ha−1, being 2.2 times P/C. Though shoot number and tree vigor in Y/R were between those of the other test plots, Y/R trees demonstrated superior shoots and the greatest number of flower buds per m2. Dry matter production per ha in Y/R was the greatest. Partitioning rate of the assimilates to the fruit was 43.0% in Y/R and 39.1% in P/R. Assimilate partitioning rates to fine roots in the rhizosphere restricted culture methods were higher than those in the conventional methods. It was concluded that a high yield of 61 t·ha−1 and a high Brix of 12.5% was attained as a result of 1) increase in fruit-bearing shoots due to an increase in fine roots by appropriate irrigation methods, 2) increase in dry matter production due to an increase in LAI and 3) increase in partitioning rate of assimilates to the fruits due to a compact tree.
The effects of treatment with gibberellin and MnSO4 solution on berry splitting in ‘Delaware’ grape were investigated. The density of berries in a bunch treated with the first gibberellin (GA, 100 ppm) dipping at the 7~8 leafing stage decreased by 0.5~2.3 berries·cm−1 compared to that at the 9~10 leafing stage. However, GA treatment appeared to have no suppressive effect on berry splitting due to the lack of calyptra shedding, low level of surface wax adhesion, and low degree of pericarp intensity. For the prevention of berry splitting, bunches of berries that still contained many non-removed calyptras demonstrated both an increase in surface wax adhesion and decrease in berry splitting. This was achieved by a second GA (100 ppm) treatment 5 days after full blooming and a double MnSO4 solution treatment: MnSO4 (0.5-1.0%) simultaneously with the first GA treatment and MnSO4 (0.5-1.0%) just before full blooming. Correlations between the level of adhesion of surface wax and the intensity of pericarp or percentage of berry splitting were positive and negative, respectively.
Pruning of Budousanshou (Zanthoxylum piperitum (L.) DC. f. inerme Makino) trees was investigated to determine whether the pruning degree influences sprouting and fruit set. First, the mother branches were divided into three groups by length, and then the four degrees of pruning were set up, i.e. no pruning, cutting back 1/3, cutting back 1/2, and cutting back 2/3 for each mother branch group. The sprouting rate, spike-bearing shoot rate, flower number and berry number in the fruit cluster were compared next spring. As a result, there was a greater tendency toward higher many flower numbers, berry numbers in the fruit cluster and berry numbers per mother branch after cutting back 1/3. These numbers tended to be higher than those in the other pruning groups for the medium mother branch length. The sprouting rate increased when trees were pruned by cutting back 2/3 and the spike-bearing shoot rate tended to become higher after cutting back 1/2 or 2/3.
The antifungal effect of postharvest treatment of Artemisia capillaris Thunb. extract on diseases that cause fruit rot in peaches after harvesting was examined. It is known the A. capillaris extract has a potent antifungal effect, and the principal ingredient of this extract is capillin. First, the antifungal effects of purified capillin on Moniliniafructicola, Phomopsis sp., Rhizopus sp., Gloeosporium sp. were investigated. As a result, extremely high antifungal effect on M. fructicola was observed, and the MIC (minimal inhibitory concentration) value was 0.25-0.5 ppm. However, relatively low antifungal effects on other fungi were observed, with MIC values ranging from 2-4 ppm. When peach fruit treated or untreated with A. capillaris extract were inoculated with M. fructicola, which causes brown rot disease, the diseased areas in treated fruits were smaller than those in untreated fruits. The effects of treatment on the quality of peach fruit were also investigated. The fruit quality was almost equal between fruit treated with A. capillaris extract and those that had not been treated.
Temporary rise in groundwater level and flooding period experiments were carried out to examine excess moisture injury in pot-cultured carrot. Thickened roots showed rotting and suppressed thickening in the low parts when groundwater level was kept at 15 cm for 14 days but thickened roots showed no damage at a groundwater level of 20 cm. Flooding for three days did not cause rotting of thickened roots but flooding for five days or longer caused thickened the roots to rot.
We developed automatic segmentation software for efficient measurement of area on digital images of plant organs. This software enables to measure area size of plant organs from a large number of images with less effort. The developed software has following two features. (1) We developed the technique for dividing plant organs and background using color difference of digital images. An accurate region extraction of plant organs can be executed compared with a conventional binarization method. (2) We developed software functions automating repetitive tasks to improve the task efficiency of image analysis. The developed functions enable efficient software operations and the processing of large number of image analysis. We applied the developed software to analysis of differences in the senescent pattern of petals in Ipomoea nil (L.) Roth. We found that the software effectively detected differences compared with conventional visual comparison methods. The developed software is available for use free of charge by downloading at http://www.kazusa.or.jp/picasos/.