Dianthus (Dianthus hybryda hort. cv. Sakuranadeshiko) shoot tips were automatically frozen by computarized programfreezer (FFP-190, Osaka Sanso Industry Co. Ltd.) . After pretreatment with 10% DMSO and 3% glucose for 10, 60, and 120 min. at 0, 20 and 30°C respectively, each sample of shoot tips set in 0.5 ml plastic straw were frozen according to freezing program (Table 1) . Hundred percent of shoot tips were survived by pretreatment of cryoprotectants, except pretreatment at 30°C. Hundred percent shoot tips which thawed rapidly in water 37 or 0°C were survived and regenerated shoots with 40 days culture on modified MS medium, but only 35.2% shoot tips which thawed slowly in air at 15°C were survived. In the process of rewarming in air, survival rate of shoot tips declined sharply during slow rewarming above -40°C. After 210 days of strage in liquid nitrogen (LN₂), more than 91.7% of shoot tips were regenerated into plantlets.

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Potted eleven street tree species (Aucuba japonica, Cinnamomum camphora, Daphniphyllum macropodum, Ginkgo biloba, Hedera rhombea, Ligustrum japonicum, Pasania edulis, Prunus yedoensis, Quercus acutissima, Rhododendron oomurasaki, Zelkova serrata) were treated with various concentrations of O₃ to investigate the heritable differences in the capacity of O₃ uptake. The rates of net photosynthesis and transpiration, and stomatal density were determined for every tree species. Some species showed a linear relationship between O₃ concentration and the uptake rate of O₃, while other species did not. The analysis using a gas phase diffusive conductance indicated that the nonlineality was assumed to be resulted from the stomatal closure. Concerning those nine tree species which showed the linear increase in O₃ uptake rate with O₃ concentration, the rate of O₃ uptake was ranked as follows: P. yedoensis=H. rhombea>Z. serrata=Q. acutissima>C. camphora=D. macropodum=G. biloba>A. japonica=R. oomurasaki. Those tree species with higher uptake rates of O₃ were not characterized with higher stomatal frequency but with higher gas phase conductance for water vapor. This result suggested that the heritable differences in the rates of O₃ uptake are determined by the interspecific differences in stomatal conductances.

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A continuous measurement system of photosynthesis rate, transpiration rate and leaf temperature by means of open assimilation chamber system for single tobacco leaf, was developed.
Changes in photosynthesis rate, transpiration rate, leaf temperature of tobacco leaf in maturing stage, and soil moisture tension after irrigation, were investigated, and the following results were obtained.
In the case of irrigation at pF 2.72, photosynthesis rate and transpiration rate at 90 minutes after irrigation were higher and leaf temperature was lower than those of the initial state.
On the contrary, in the case of irrigation at pF 2.41, photosynthesis rate, transpiration rate and leaf temperature waved highly, and were almost same as initial state after 90 minutes.
There were significant correlations among changes in photosynthesis rate, transpiration rate and leaf temperature, but no relationship between soil moisture tension and other measurement.
After the irrigation, the sum of stomatal resistance and boundary layer resistance once increased and graduary became constant value.
The net mass of CO₂ assimilated per unit mass of water transpired exprsssed per unit vapor pressure deficit was almost constant, 0.043 mb^-1 at the dynamis stage after irrigation.

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Tomato (Fukuzyu No.2), eggplant (Hayabusa) and sweet pepper (Sinsakigakemidori) were grown in water culture under grasshouse condition in order to clarify the influence of concentrations of nutrient solution on their water and nutrient absorption.
1. Dry weight of tomato with high T/R ratio was greater than that of eggplant and sweet pepper with low T/R ratio. Growth of plants was remarkably inhibited with high nutrient concentratian and significant differences among crops were not observed. High nutrient concentration increased nitrogen compound, starch and total carbohydrate in each crop and conversely reduced soluble sugar and insoluble nitrogen/total nitrogen ratio.
2.Although the amount of water absorption/hr/dm² leaf area in sweet pepper was greater than in tomato and eggplant, the amount of water absorption/hr/plant in tomato was highest followed by eggplant and sweet pepper. The water absorption of plants was decreased with high nutrient concentration and marked differences among crops were not observed.
3. High nutrient concentration enhanced N, P, K, Fe, Mn, Cu and Zn contents in each crop, and conversely decreased Ca and Mg contents, especially in Ca. Sweet pepper contained higher N and K and lower Ca concentrations compared with tomato and eggplant. The amount of mineral elements per plant corresponded with the growth of tomato, eggplant and sweet pepper, respectively.
4. Sweet pepper had lower base exchange capacity than that of tomato and eggplant. Divalent Ca²⁺ base exchange capacity in each crop was higher than monovalent cations where Na⁺showed the greatest followed by K⁺and NH₄⁺.

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Seeds of eggplant, cv.‘Hayabusa’were sown in sand bed. After cotyledon expansion, uniform seedlings were planted into 12cm polyethylene pots filled with three different media (soil, 1 soil: 1 bark compost, bark compost) under different soil moisture for 40 days and then transplanted to a vinylhouse.
1) Growth of seedlings, especially shoot growth, were suppressed under dry soil condition. Seedlings grown at low soil moisture showed lower value of stem weight to root weight (S/R) with a higher root and lower stem percentage of dry matter distribution than other seedlings.
2) The higher yield was obtained on the plants from seedlings grown under dry soil condition, which recovered quickly and developed a deeper and wider root system consisting mainly in thick roots over 1 mm in diameter after transplanting.
3) The yield was closely correlated to the number of thick roots over 1 mm in diameter. The more the number of thick roots, the higher the yield.
4) Plants with the lower S/R value at transplanting time showed both vigorous growth and higher yield. There also existed a correlation between the yield and S/R value.
5) It may be concluded that seedlings should be raised under the dry soil condition.

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In order to induce and select amino acid analogue resistant mutants, a protocorm-like body (PLB) was induced by a shoot apex culture in a banana (Musa acuminata, (AAA) ) . And the growth inhibition of the PLBs by proline analogue (L-hydroxyproline) was studied.
The meristem including adjacent corm tissue was removed from the cultured shoot apex and was transplanted to a fresh medium. PLBs were induced on the sliced corm. They were proliferated by separating into smaller pieces and subculturing on the same medium.
L-hydroxyproline (HYP) containing media were prepared by adding HYP into the culture medium, after filter-sterilization. The growth inhibition of PLBs by HYP was analyzed by culturing PLBs on the HYP-medium. It was observed that concentrations of HYP up to 4 mM completely inhibited the PLB's growth, i.e. prevented any increase of the fresh weight of the PLBs.
The results described here are being used for the selection of banana tolerant to the amino acid analogue.

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