We studied the effects of root container volume on plant growth, carbohydrate concentration, and photosynthesis, and the effects of release from root volume restriction (RVR) on plant growth, carbohydrate concentration, and distribution of photoassimilates in cabbage seedlings. Plant dry weight increased with increasing root container volume from 9 mL to 300 mL. Dry matter allocation to leaves was lower in plants grown in a smaller root container volume. The photosynthetic rate was higher with increasing root container volume. Starch and soluble sugar concentrations in leaves were highest at 9 mL and lowest at 300 mL. Starch was not detected in roots, and the soluble sugar concentration in roots increased with decreasing root container volume. Plant growth was enhanced when plants were released from RVR by transplanting from 9-mL containers to 300-mL containers. The carbohydrate concentrations in leaves and roots decreased after release from RVR. Total activity of ¹⁴C-photoassimilates incorporating into leaves was much higher in released plants than in control plants. The distribution rate of ¹⁴C-photoassimilates from incorporated leaves to stems and roots was higher in released plants than in control plants. These results indicate that carbohydrate metabolism in cabbage seedlings was altered in response to RVR, which is closely associated with plant growth.

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It is important for process design to predict properly the effect of variation of main factors concerning composting processes on indexes for their success. These factors are initial microbial concentration X_i, initial substrate concentration S_i, initial moisture content w_i, and aeration rate u. Final moisture content w_f, maximum attainable temperature T_max, amount of substrate consumption ΔS, and time required for finishing the process t_f were chosen as indexes for the success of composting. These indexes represent characteristics of composting products and conditions for proper composting. Through numerical experiments, it was discussed whether variations of the indexes could be approximated by a linear combination of contributions of changes in the individual factors, on condition that arbitrary two factors would change simultaneously. Contributions of the changes in the individual factors to the indexes were estimated in advance, assuming that the value of each factor varies solely from its default value. Among four indexes, T_max seemed to be hardly influenced by the variation of factors, however, deviations of w_f, ΔS, and t_f could not be predicted well by the linear combination of the contributions of changes in individual factors, especially when S_i and w_i would change simultaneously.

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Heat stress damages under plastic house conditions in summer have caused low productivity of cherimoya (Annona cherimola Mill.) . Six-year-old‘Big Sister’ cherimoya trees were grown at 3 different shading levels under plastic house conditions to examine if the shadings improve cherimoya production. The plastic house was divided into 3 sections: regular plastic house condition as a light shading, middle shading condition which was provided by a combination of the plastic film of the house and shade cloth, and deep shading condition produced by the plastic film with two sheets of the shade cloth. Shoot length, shoot diameter, leaf number, and total leaf area reduced as shade increased, but inter-node length and single-leaf area increased. Leaf chlorophyll content increased at deep shading condition. Leaves at light and middle shading performed higher CO₂ assimilation rate (A_c) with higher stomatal conductance. Under high light, high leaf temperature caused high leaf vapor pressure deficit, resulting in a reduction of gas exchange rate. Throughout the daytime, A_c at light shading was maintained at a higher level than the other conditions except during midday, when stomatal conductance and leaf water potential were lowered. Under deeper shading conditions, fruit weight and quality were decreased and the harvest was delayed. Heavy shade using shade cloth under plastic house conditions appeared to detrimental to cherimoya production. A shading of 50-70% sunlight was thought to be adequate to obtain optimal light environment for cherimoya cultivation.

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Seasonal changes in dry weight, carbohydrate and total nitrogen content in the various organs of Japanese iris ‘Chihayajo’ were investigated. Leaf growth measured as dry weight peaked in early October, thereafter it decreased to near zero in November. Rhizome dry weight reached its maximum in mid November when the leaf dry weight began to decrease. The spring leaf growth started in March, whereas the increase in root dry weight was not detected until early May. Total sugar and starch content in a plant which distributed mainly in the leaves and roots increased up to early October. Total sugar and starch in the roots decreased rapidly during the sprouting period. A rapid increase in total sugar and starch content was observed in the scape due to its growth, while no major changes were detected in other organs. Total nitrogen content in each organ increased from August to early October, thereafter itt continued in the rhizome until November with leaf senescence. The nitrogen content in the rhizome decreased with the onset of spring growth of leaf and scape. From these results it appears that in Japanese iris the carbohydrate reserves in the roots and the nitrogen compounds stored in the rhizome and roots are utilized for growth resumption.

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We investigated the effects of microclimate under floating row cover materials on the growth of komatsuna (Brassica campestris L.) . Under a newly developed row cover film ‘Agrihot’ (spunbonded polyester non-woven fabric combined with polyethylene flat checker-patterned yarn), soil temperatures in the nighttime were higher, and lower in the daytime than those in the open field, while air temperatures was slightly higher than that under no cover condition. On the other hand, soil and air temperatures under PVA non-woven fabric ‘Tufbell3800N’ and polyester non-woven fabric ‘PASS LITE’ were higher than the open field. The stem and leaf fresh weight, the maximum leaf length and the number of leaves of komatsuna were largest under ‘Agrihot, ’ while the total sugar and nitrogen contents in the leaves were slightly lower than those of outdoors. These indicate that ‘Agrihot’ is useful to maintain air and soil temperatures adequately for komatsuna cultivation under hot conditions in earlysummer.

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Effects of 60 mM NaCl added into nutrient solution on the growth, concentrations of sugars, K, Na and Cl of cucumber (Cucumis sativus L. cv. Asomidori No.5) fruits were studied. In 1992 (Expt. 1) and 1993 (Expt. 2) springs, cucumber plants were solution-cultured in a greenhouse. The aeration rate of the nutrient solution was low and high in Expts. 1 and 2, respectively. When the 10th leaf was expanding, 60 mM NaCl was added to the solution. Both in Expts. 1 and 2, the initial growth of fruits was enhanced by NaCl. Thereafter, fruit growth at 60 mM NaCl was markedly suppressed in Expt. 1, whereas it was not much affected in Expt. 2. In Expt. 1, hexose concentration of fruits at 60 mM NaCI decreased with the suppression of fruit growth, whereas it was not much affected in Expt. 2. Possible involvement of the shortage of photoassimilate supply in the fruit growth suppression under salinity was discussed.

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In this study, the growth periodicity of Allium oreophilum ‘Zwanenburg’ plants grown outdoors was clarified. Simultaneously the effect of temperature on the initiation and development of flower buds was investigated. The inflorescences initiated in early September before planting. They formed tepals and stamens between early October and early December and bloomed in mid-May of the following year. After February, some plants that were moved from outdoors to a greenhouse kept at min. 10°C could flower in May. When bulbs were stored at 10, 15, 20, 25 or 30°C from August 13 to October 8, flower bud initiation occurred at 20 to 30 °C. Most of bulbs stored at 10 or 15°C formed new bulbs at the shoot apex instead of inflorescences. None of the bulbs developed inflorescence when they were grown in a greenhouse kept at min. 10°C. When bulbs were stored at 20, 25 or 30°C for 8 weeks from August 13 to October 8, followed by storage at 5 or 10°C for 8 weeks from October 8 to December 3, those stored at 10°C after 20, 25 or 30°C showed advanced flower bud development. However only bulbs stored at 5°C after 25 or 30°C could produce flowering inflorescences when they were grown in a greenhouse kept at min. 10°C.

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Grafted tomato (scion: Lycopersicon esculentum Mill. cv. Momotaro; rootstock: cv. Helper M) plug seedlings were stored at 10°C for different durations (7, 14 or 21 d) under the optimum combination of CO₂ concentration and photosynthetic photon flux density (PPFD) determined in a previous study (0.25% CO₂ and 1.9 μmol m^-2 s^-1 PPFD continuous red light from light emitting diodes) . The stored seedlings were transplanted and cultivated at 25°C and 200 μmol m^-2 s^-1 PPFD during the 16 h light period and at 20°C during the 8 h dark period for 28 d. The maximum storage duration was determined using strict criteria based on visual quality scores, aerial- and subterranean-part dry weights during storage, stem length, stem diameter, leaf number, aerial- and subterranean-part dry weights, required days to produce the first flower truss, first flower truss setting node and flower-bud number of the first flower truss during cultivation following storage. The results indicate that the maximum storage duration of grafted tomato plug seedlings stored at 10°C under the optimum combination of 0.25% CO₂ and 1.9 μmol m^-2 s^-1 PPFD was 21 d, and that the duration was at least three times longer than the duration for the seedlings stored at 10°C under conventional dark storage conditions.

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Carbon dioxide (CO₂) emission by peat and litter decomposition and by tree respiration were measured in a primary peat swamp forest of southern Thailand. The obtained emission rates from foliage, branch, stem, peat soil, litter and ponding water surface were integrated to estimate the total CO₂ emission from the forest ecosystem. The open-airflow chamber method with an infrared gas analyzer was employed for all the emission measurements except for litter decomposition. For litter decomposition, the mesh bag method was applied to estimate the emission. Root respiration was estimated from the difference between the CO₂ emission rate of ponding water and peat and litter decomposition. On the basis of unit surface area, the branch had the greatest respiration rate among the aboveground components. However, the foliage had the greatest rate per unit ground surface area. Annual CO₂ emission from the ecosystem was estimated to 8.84 t C ha^-1 year^-1 on the carbon weight basis. The breakdown of the value to each component was 6, 6, 28, 28, 18 and 14% for stems, branches, foliage, roots, litter and peat, respectively. This indicates that emission from underground plays quite important role to assess the carbon balance of the peat swamp forest.

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Effects of soil temperature on dry matter production and tuber growth of eddoe plants were examined. Potted plants were grown under non-controlled (N, 25.0-35.8°C), and controlled soil temperatures: low (L, 14.0-17.3°C), medium (M, 19.5-26.3°C) and high (H, 32.5-36.1°C) . Total dry matter and leaf area were the highest in plot N, followed by plot M, whereas those in plots H and L were low. Growth rate of a plant and tuber growth rate were positively correlated with leaf area. Leaf photosynthetic rates showed the maximum value of 12.8 μmol CO₂ m^-2 s^-1 at a root temperature of 27°C, and decreased by about 20% at 17 and 37°C. The tuber yield (daughter tubers) of plots M, H, and L was 74.6, 17.1, and 6.2% of plot N, respectively. Development of leaf area and growth of daughter tubers were promoted under soil temperature of around 25°C in the early period of growth. Increasing the soil temperature by means of mulching is effective in promoting the initial development of leaf area, and hence the growth of daughter tubers in eddoe plants.

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