By using two varieties with different growth habit. Norin No. 1 and Zosan No. 1,an experiment was made to examine at eath leaf stage the influence of air temperature on the tillering and tiller growth of rice plants. They were grown in the growth cabinets first at high (mean temp. 28.5°C.), then at low (mean 18.5°C.) temperatures and vice versa with the light intensity of 22.000lux and 0.275 cal/cm²⋅min. and the daylength of 12 hours. Temperature switching was carred out at 8th leaf stages of the respective main stem. The results were : 1) The high temperature conditions caused both the varieties to increase their tillers, while the low to inhibit their emergence. 2) Zosan No.1 (heavy panicle type variety) produced mach more tillers high to low temperature condition than under low to high conditions. The reason is that the formation of tiller buds in intensified by high temperatures, but that low temperature is suitable for them to grow up to be tillers. 3) To mention tillering aspect caused by the difference in growth habit, the production of high-position tillers was inhibited by high temperature conditions in both varieties, dut this influence was marked by observed especially in the heavy panicle type variety.

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1. The effects of low temperature on chlorosis expression in rice cultivars including 6 typical ecotypes, Aus, Aman, Boro, Tjereh, Bulu and Japonica, were studied in a controlled environments. 2. When temperature was kept 15°C, many cultivars in Southeast Asia, except Bulu ecotyp, showed a significant decrease in chlorophyll contents of leaves. Low day-temperature have a pronounced effect on chlorosis. The fact suggests that light has an important effect to induce the chlorosis at low temperature. 3. Aus and Tjereh cultivars were highly sensitive to low temperature and expressed typical chlorosis. Japonica and Bulu cultivars, espcially Japonica ones, have high tolerance to inducing chlorosis at low temperature. 4. Wild rice in Asia showed a remarkable chlorosis at low temperature, but cultivated and wild rice in Africa had high teolerance to low temperature inducing chlorosis.

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1. Chlorotic behaviors expressed under low temperature in relation to light intensity were studied using three rice varieties ; Dular as a chlorosis-sensitive variety, Norin no. 20 as a chlorosis-tolerant one and Chinsurah Boro II as an intermediate one. 2. Dular showed the typical chlorotic expression at 15°C. The chlorosis may be induced by depression of chlorophyll-precursor formation under low temperature. 3. In Chinsurah Boro II, chlorophyll contents decreased distinctly at low temperature under high light intensity. The decrease may be caused by inhibition of chlorophyll formation under high light intensity. 4. Norin no. 20 had the high chlorophyll content at 15°C, but the ehlorophyll contents considerably decreased until showed the chlorosis under the high light intensity. 5. From these results, Chlorosis expressed at low temperature might be induced by different physiological processes, i. e. the inhibition of chlorophyll formation at high light intensity and the depression of chlorophyll-precursor formation at low temperature.

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Using a respective clone of reed-canarygrass (RC) and orchardgrass (OG), the growth responses to different soil-moisture contents were compared between RC and OG. RC was more tolerant to water-saturated soil but more sensitive to water deficit than OG. The greatest dry matter production with the greatest accumulation of nitrogen and available carbohydrates were obtained at pF 1.0 in both grasses, where the water usage was most efficient. In both grasses, leaf-blade ratio increased with decreased moisture content, and dry matter percentage was smallest at optimum soil-moisture content, and TAC, fructosan/TAC ratio, and C/N ratio were greatest at saturated soil-moisture.

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In this paper, the reality of frost damage in North district of Iwate Prefecture, in July 1976 was described and the background of the causes that made the damage severer was discussed. The gist of the report was summarized as follows ; 1) It had been considered to be one of the causes by which the frost damage was increased that farmers grew crops without regards for the principle to grow crops adapted to environment of the district as the result of disordered extension of growing unsuitable cash crops. 2) It is the most necessary and important matter to make the cropping map classified according to district contour line to show the recommended crops to be planted to meet the demand for the reduction of frost damage.

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Leaf fresh weight per unit area (FW/dm²) was already reported to be significantly correlative with photosynthetic rate (P/dm²) in upper leaves, but it became less correlative as leaf position lowered to end in non-correlative in primary leaves. The experiment was carried out to confirm the above mentioned result with primary leaves and also to get the information about RuDP carboxylase activity (RuDPact/FW) in primary leaves. The results, including the informations about upper leaves, were summarized as follows. 1. P/dm² was devided into the following two components : P/dm²=FW/dm²×P/FW. where P/FW is photosynthetic rate per unit fresh weight of leaves. In primary leaves, FW/dm² was again non-correlative with P/dm²,but P/FW was highly and significantly correlative. Significant correlation between P/dm² and RuDPact/FW supported the relationship between P/dm² and P/FW. 2. As leaf position decame higher, leaves tended to be thinner and the correlation coefficient between P/dm² and FW/dm² got higher. The coefficient between P/dm² and P/FW, on the contrary, got lower. This was confirmed also by the change of coefficient between P/dm² and RuDPact/FW. 3. In lower leaves, photosynthetic activity per unit amount of leaf mesophyll seems to be an important factor for varietal differences in photosynthetic rate. In upper leaves, on the contrary, amount of leaf mesophyll per unit leaf area becomes more important. In the breeding of soybean plant for higher photosynthetic rate, FW/dm² of upper leaves may be used as a character for selection.

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The growth of tubers of elephant foot plants (Amorphophallus Koujac) was promoted by abscisin application to the petiole before or after the extensive growth of leaves have finished.

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