Sucrose phosphate synthase (SPS) activity of sugarcane internodes was measured in field-grown and greenhouse-grown plants. The concentration of sucrose increased and that of reducing sugars decreased at lower temperatures in plants both in the field and in the greenhouse upon ripening. SPS activity increased in winter and at lower temperatures in the greenhouse. These results indicate that the SPS activity increased under ripening conditions. The sucrose concentration and SPS activity of cv. NiF4 were higher than those of cv. F172 both in autumn and winter in the field. However, the results under the greenhouse conditions did not indicate a clear relationship between the SPS activity and sucrose concentration among the different varieties. Acid invertase (Al) activity, whose physiological function in sugar accumulation is opposite, was considered to play a more important role in the greenhouse. The results of this experiment supported the assumption that the SPS activity is one of the factors that control sugar accumulation in sugarcane.

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In a previous report, new methods of producing small tubers derived from TPS in potato (Solanum tuberosum L.) were described. In the new methods, four small tubers were produced per plant and their fresh weight was 6.9g. Small tubers which weighed more than lg accounted for 65.5% of the total and these tubers were lager than the micro-tubers obtained by the tissue culture method. These small tubers were divided into four class according to their weight and cultivated in plastic film greenhouse. As the size of the small tubers increased, the number and fresh weight of the new tubers per plant also increased. There was a considerable difference in the number and fresh weight of the new tubers between the use of small tubers above lg and that of small tubers below lg. Eighty five percent of the new tubers produced from small tubers above lg weighed more than 20g. These tubers could be distributed to farmers. Planting of 1-3g small tubers of different planting densities did not affect the number of new tubers per plant. However, the fresh weight of new tubers in sparse planting was heavier than that in dense planting. The number of new tubers per 1m² in dense planting was three times higher than that in sparse planting. And the fresh weight of the new tubers per 1m² in dense planting was two times that in sparse planting. Thus in sparse planting the number of new tubers above 20g increased. Dormancy of the small tubers could be effectively broken by soaking them at higher concentrations of GAs. However, as the period of GA treatment was long, the number of rotted tubers increased. Furthermore, at higher concentration of GA and during a longer period of treatment, succulent growth was observed in the potato plants. Therefore, the optimum treatment for breaking the dormancy of small tubers was to soak the tubers in GA 50ppm solution for one hour.

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The responses of two potato (Solanum tuberosum L.) cultivars to different levels of soil moisture stress at three growth stages (stage-I: vegetative to beginning of tuberization, stage-II: tuberization to initial tuber enlargement and stage-III: tuber enlargement to maturity) were studied in pot experiments in a naturally lit glasshouse. At 60% and 45% field capacity (FC), the cultivars May Queen and Dejima produced a smaller amount of dry matter than at 75%FC at all stages of growth. Dry matter production decreased relatively more in Dejima than in May Queen. The maximum reduction in Dejima (59%) was observed at stage-I and in May Queen (33%) at Stage-II at 45%FC. Plant height, leaf area, number of stolons and tubers per plant also decreased at lower moisture levels (45%FC) . Water-soluble carbohydrate (WSC) content in leaves increased due to the decrease of the moisture level, while the starch content decreased and the amount of total nonstructural carbohydrates (TNC) did not vary appreciably. Starch content of the tubers increased and leaf water potential (ψ_w) decreased at lower moisture levels. Nitrate reductase (NR) activity was also suppressed at these levels and the reduction rate was comparatively higher at 10 days after treatment (DAT) than at 20 DAT in both cultivars. Lower moisture level decreased the tuber yield too, and the maximum yield reduction was observed at stage-II in both cultivars at 45%FC. Depending on the severity of the treatments, stage-II at 45%FC was found to be most critical for potato yield. It was suggested that the decrease in tuberization and tuber enlargement due to moisture stress may be related to the decrease in the NR activity, leaf starch content and ψ_w.

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A study was conducted at the Teaching and Research Farm of the University of Calabar, Nigeria to evaluate the effect of three hedgerow species (Enterolobium cyclocarpum, Dialium guianense and Sesbania macrantha) on the growth and yield of plantain (Musa spp.), cowpea (Vigna unguiculata) and maize (Zea mays) in an alley-cropping system. The growth rate and biomass yields of the hedgerow species as well as the growth and yield of the associated food crops were determined. The highly branched, bushy species, E. cyclocarpum gave the highest biomass yield of 17.3 t/ha, while the fast-growing leguminous species, S. macrantha and the slow-growing D. guianense gave biomass yields of 11.9 and 7.4 t/ha, respectively. Compared with the other hedgerow species, alley-cropping with E. cyclocarpum generally enhanced the growth and bunch yield of plantain, while alley-cropping with S. macrantha decreased the bunch yield of plantain by 9%. The grain yield of cowpea was higher under alley-cropping with the hedgerow species, whereas that of maize was depressed. The overall results indicated the beneficial effect of alley-cropping on plantain and cowpea with the hedgerow species at the early stages of establishment.

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The germination percentage and tube elongation of freshly collected pollen of white sapote (a subtropical fruit tree) cultivars ‘Aoshima’, ‘Vernon’, and ‘Maltby’ were determined to identify the optimum agar medium conditions. Adequate germination percentage and tube elongation were obtained by using a 2% agar medium containing 5-10% sucrose at the incubation temperature of 20-30°C. The use of a 2% agar medium containing 10% sucrose, with a 100-500ppm concentration of boric acid was effective for pollen germination.
The germination percentage of the pollen which was stored for 45 days with silica gel (35% relative humidity) at 5°C was almost the same as that of freshly collected pollen. The germination percentage of the pollen stored at -60°C for one month was almost the same as that before the storage. It was possible to store the white sapote pollen without a decrease of germinability for one month under dry and low temperature conditions. Almost the same fruit-set percentage was obtained from hand-pollination with freshly collected pollen and pollen stored for about one month.

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Cultural and postharvest practices of banana grown without chemicals (hereafter referred to as “non-chemical bananas”) were surveyed in relation to fruit quality problems in the Philippines from April to May 1998 and September 1999. Farmer growing non-chemical bananas need to learn the importance of proper cultural management practices in their farms in relation to the occurrence of postharvest diseases. Inadequate classification of fruit maturity for the export market leads to a significant wastage of harvested fruits. Exposure to harsh environment, including careless loading, unloading and overloading, insufficient and poor cushioning, and poor truck suspension system and road conditions, seem to be the factors causing physical damage to and stress on non-chemical bananas. Limited source of water for washing bananas, unsanitary conditions at the packing centers and weak packing materials appear to be related to the high incidence of postharvest diseases in non-chemical bananas. Selection of good fruits, crown re-trimming and re-boxing of non-chemical bananas at the re-packing centers in Japan were performed to improve the appearance of non-chemical bananas before delivery to the consumers.

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Fruits of five pepper cultivars collected in Zimbabwe (Zimbabwe A, B, C, D and E) and three Japanese native cultivars (Shishitou, Takanotsume and Yatsufusa) were grown at the campus of the College of Bioresource Sciences, Nihon University. Contents of capsaicinoids in the flesh, placenta and seeds were analyzed by using high performance liquid chromatography (HPLC) . The chromatogram showed a typical pattern characterized by two major peaks corresponding to capsaicin and dihydrocapsaicin and other minor peaks representing nordihydrocapsaicin, vanillyl-decanamide, homodihydrocapsaicin and an isomer of homodihydrocapsaicin. The capsaicinoid contents were high in the placenta and low in the seeds regardless of the cultivars. Among the Japanese cultivars, ‘Yatsufusa’gave the highest value for the capsaicinoid contents (5105.2mg/100g D.W.) . Although the size of the fruits of the cultivars collected in Zimbabwe was smaller than that of the fruits of Japanese cultivars, the capsaicinoid contents were much higher with the exception of Zimbabwe A; the capsaicinoid contents of Zimbabwe B, C, D and E were 5 times higher than that of‘Yatsufusa’.

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