The effect of Chinese milk vetch (Astragalus sinicus L.) as a green manure was studied on rice yield and the utility of no-tillage rice transplanting. No-tillage transplanting with a rice-transplanter was compared with strip-tillage transplanting. Experimental plots comprised with a no-tillage plot and two strip-tillage plots. In no-tillage cultivation, rice seedlings were transplanted through the Chinese milk vetch crop growing in flooded plots. In the strip-tillage plots herbicide was applied about one month before transplanting. One plot was then left covered with weeds and Chinese milk vetch and the other (control plot) was covered only with weeds. The results of three years of experiments showed that although the growth of Chinese milk vetch declines with years, and by applying half the basal dressing, no-tillage cultivation can be continued for about 3 years. Furthermore, the results of our study suggested that no-tillage transplanting is possible with the conventional rice-transplanter.

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The low temperature requirements for flower bud differentiation of Brussels sprouts were investigated. Five cultivars of plants were treated at 6 or 10 weeks old with a low temperature of 4℃ for 4 or 6 weeks. The plants were grown in a 16 hr day-length under fluorescent lights (PPFD 35 μmol・m^<-2>・s^<-1>) during the treatment. Budding of 'Family Seven' plants occurred when they were treated at 6 weeks old for 6 weeks, and at 10 weeks old for 4 weeks. Budding of 'Cluster', 'Early Green', and 'Wase Komochi' plants did not occur when they were treated at 6 weeks old, but did occur when they were treated at 10 weeks old for 4 weeks. Budding of 'Kodakara' plants occurred only when they were treated at 10 weeks old for 6 weeks. Flower buds of 'Family Seven' plants treated at 6 weeks old were differentiated at lower nodes and earlier than plants treated at 10 weeks old. When 'Family Seven', 'Cluster', 'Early Green', and 'Wase Komochi' plants were treated at 10 weeks old for 4 or 6 weeks, no difference was found in the number of nodes bearing first flower buds. From these results it was shown that Brussels sprouts have a low temperature requirement of plant vernalization for flower bud differentiation, and there were cultivar differences in low temperature requirement for flower bud differentiation.

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The objective of this study was to develop a sorting method for sugar cane seedlings using a laser sensor. Five shapes of experimental seedling were selected according to the presence of a seedling leaf, the presence of seedling node and the node-angle of the seedling. Seedlings of each shape were measured by a laser sensor attached to an inclined cylinder-shaped shooter. The different seedling shapes had almost no influence on the accuracy of shape measurement by the laser sensor. The rate of correct sorting was 100% using data obtained from the central part of a seedling. The results indicate that the laser sensor has good potential as a sorting method for sugar cane seedlings.

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To clarify the suitable applied nitrogen level for conducting experiment of the paddy-upland rotation cropping system at the paddy field existing large spatial variability of soil productivity, rice cultivar, Koshihikari was grown under 20, 0, 80 and 40 kgN・ha^<-1> conditions in 2000, 2001, 2002 and 2003, respectively. There were no significant differences in yield and its components among plots in 2002 with 80 kgN・ha^<-1>. Coefficient of variation of yield was smallest in 2002 with 80 kgN・ha^<-1>. These results indicated that 80 kgN・ha^<-1> was the suitable applied nitrogen level for minimizing the effect of spatial variability of soil productivity on rice yield, and that yield data obtained from experiment in 2002 were the suitable criteria for assessing the change of rice yields under the paddy-upland rotation cropping system.

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The effect of temperature, light condition and scarification on seed germination in Lathyrus latifolius L. was studied using 'Pink Pearl'. Optimum temperature range for seed germination of 'Pink Pearl' was 15 to 20℃ under dark condition. Germination percentage at 20℃ under light condition was slightly lower than under dark condition. Soaking seeds in concentrated sulfuric acid for 16 minutes increased the final germination percentage to 100% at 20℃ as compared to about 30-50% for the water-soaked control. The acid scarification followed by priming with polyethylene glycol 6000 solution (-1.3Mpa) for 1 week at 10℃ increased the germination percentage to more than 85% within 8 days after sowing even at 30℃.

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A survey in the southern part of the Satsuma Peninsula in Kagoshima Prefecture, Japan, found 63 host plant species from 15 families associated with Liriomyza trifolii and 53 species from 10 families associated with L. sativae. The two Liriomyza species co-occurred in most greenhouses (inside) and also on open vegetable fields near greenhouses (outside). Outside greenhouses, the number of host plant species mined by larvae declined from February to April, although mining larvae were found even in winter. In greenhouses containing Chrysanthemum and qing-geng-cai, L. trifolii was dominant. The two Liriomyza species co-occurred at equal density in greenhouses containing ornamental flowers and cherry tomato, while L. sativae dominated in greenhouses containing squash and leaf vegetables. Outside greenhouses, L. trifolii was dominant around Chrysanthemum greenhouses, and, in spite of cultivated plants, the two species co-occurred at equal densities around ornamental flower greenhouses; L. sativae was dominant around squash and cherry tomato greenhouses. The relative dominance of L. trifolii or L. sativae depended on the cultivation management and the existence of suitable host plants. Exceptionally, on some species of squash cultivated around greenhouses, we found L. trifolii in the 2005 and 2006 surveys, but not in the 2004 survey.

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Effects of liquid fertilizer application on soil chemical properties of satsuma mandarin (Citrus unshiu Marc.) trees grown in pots filled with granite soils were investigated under a plastic house. The effects of a liquid fertilizer were compared with those of three types of pellet-shaped solid fertilizers. For preparing the liquid fertilizer, water-soluble solid fertilizer (N-P_2O_5-K_2O=15-15-10) was diluted 1:150 with water. It was applied as overhead spray or as soil drench at a rate of 231 mL in a pot equivalent to 1.39 mm water 18 times in a year. The repeated liquid fertilizer application lowered soil pH. In the upper soil layer, the liquid fertilizer application increased inorganic nitrogen and exchangeable potassium content, while exchangeable calcium and magnesium contents were decreased. The available phosphorus content in the upper soil layer in the liquid fertilizer plots was among those of three types of pellet-shaped solid fertilizer plots. Our results by pot tests indicate the possible alternative way of fertilizer application but further experiments in the commercial satsuma mandarin orchards by using sprinkler systems are needed.

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