Tohoku Journal of Crop Science

In the present report, the authors examined the subsequent development of the rice seeds which were exposed to high temperature for some time. The results obtained are summarized as follows ; 1. The soaked rice seed which was left for 48 hours at the neibourhood of 37.5°C showed almost similar growth as that left for 48 hours at about 32.0°C. The former also showed somewhat better growth (0.4 sheets more in total number of main culm leaves) and equal heading date as compared to non-treated plot. 2. The sowed rice seed which was left for several days at high temperature (at about 35-45°C, about 6 hours per a day) in vinyl-tunnel-nursery, showed normal germination percentage when cultivated thereafter under normal condltions, however showed bad growth and development, decrease of the total number of main culm leaves, decrease of the number of tillers from low and middle node order, increase of delayed tillers from high node order and the accompanying delay of the heading date. 3. At germination stage, sate and critical maximum temperature should be determined more accurately, considering the time interval at that temperature.

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Under 35-30°C, the ripening at early stages was promoted and more carbohydrate and nitrogen in the straw were transported into panicles, but at later stages they were retained in the straw as a result of early ceases of the panicles to receive them. The respiration of both grains and leaves at 35-30°C was higher at an early ripening period, but was lower at the later period than that at 25-20°C (Fig. 4 left). However, the respiration rate estimated at 30°C of grains being ripened under 35-30°C was always lower than that of grains under 25-20°C (Fig. 4 right). The respiration rate similarly measured of the boot leaf grown at high temperature was higher at early stages, but a little lower at later stages than that of the leaf grown at lower temperature (Fig. 5). It was considered that the earlier drop of physiological activity in the plant treated under high temperature had a keen relation with the earlier stop of ripening.

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The relationship between the directional growth of lateral buds and the auxin in shoot apices of potato seedling was studied and the results obtained were summarized as follows, 1. The directional growth of lateral buds in potato seedling was charactarized as follows : coty. - 4th node - downward growth, 5th & 6th node - horizontal growth, above than 7th node - upward growth. 2. The downward growth of lateral buds was suggested to be determined morphologically with two factors, increase of cell length and cell number in upper side of lateral bud. 3. The directional growth of lateral buds changed from downward to upward, with removal of the shoot apices. 4. The role of shoot apices was suggested to be combined with auxin in shoot apices. 5. Endogenous IAA activity (Rf 0.4-0.5) in upper parts of seedling was higher than that in lower parts.

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1. The writers researched the relation of the leaf types and the sizes of the top to the thickening growth of "Amorphophallus konjac."2. There is a great difference both in the distribution of the sizes of the top and in the distribution of the tuber weights in the various leaf types. 3. The normal type group or the abnormal one only in the leaf color (pale, deficient in minor elements) has more members big in the size of the top and heavy in the tuber weight than another group. 4. The abnormal foliation groups (willow-leafed, dwarf-leafed, and rod-leafed) have less members big in the size of the top and heavy in the tuber weight than the normal group. The more these abnormalities are serious, the more this tendency is marked. The tendency is also marked in the case that the abnormalities are complicated. 5. The tuber weight and each size of parts of the top are highly correlated with each other in the following cases. (1) Simple correlation among the 4 factors : The tuber weight is correlated with each of the other 3 factors, the thickness of petiole, the length of petiole, and the width of expanded leaf. (2) Partial correlations among the 3 factors (the primary partinl correlation) and among the 4 factors (the secondary partial correlation) : The tuber weight is correlated with the thickness of petiole and with the width of expanded leaf. (3) Multiple correlation among the 4 factors : The tuber weight is correlsted with all of the other 3 factors.

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