In order to look into classification of rice varieties, Oryza sativa L., 14 strains of Sikkimese rice varieties and an indica and a japonica strain were used, and diallel crosses were carried out constituting 240 cross-combinations. In the present report, ; heading date and growing period were mainly described. The main points obtained were summarized as follows:
1) Growing periods of parental plant ranged from 99 to 167 days. Those of F₁ hybrids ranged from 97 to 172 days at plant level and from 99 to 170 days at cross-combination level. The range of growing period at the parental and cross-combination levels markedly differed in according to the parent.
2) In reciprocal combination, the all strains and all cross-combinations showed significantly positive correlations. The reciprocal differences did not indicate noteworthy cytoplasmic influence on the growing period.
3) Differences in growing period of Sikkimese rice for indica and japonica types used as female and male parents ranged from 3.3 to 23.7 days and from 11.0 to 28.7 days, respectively. Correlation coefficient between them was+0.898, which was significant at 0.1% level. The variations found in those characters showed extensive differentiations of Sikkimese rice varieties.
4) A heterotic expression and / or a dominance of genes on the growing period was assumed both for earliness and lateness of growing period.

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The influences of gibberellin on the growth and alkaloid content were studied in Duboisia myoporoides R. BR.
1) The effect almost was never observed on the growth and the morphology.
2) The content of total alkaloid had the reverse correlation with the percent of scopolamine per total alkaloid in leaves. With aqueous spray treatment containing 10 ppm gibberellin, the former was maxmum and the latter was minimum.
3) On the treatment with 10 ppm concentration of gibberellin, hyoscyamine only in leaves was demonstra-ted.
4) The changes of concentration of total alkaloid and scopolamine in stems were similar to the changes seen in leaves.
5) The percentag of hyoscyamine per total alkaloid in stems was higher than in leaves and similar level to that of scopolamine per total alkaloid in any treatments.
6) The content of total alkaloid in roots was apt to be a little lower than in leaves and higher than in stems. But the difference in roots with concentration of gibberellin was not apparent.
7) The contents of scopolamine and hyoscyamine in roots tended to more increase with higher concentration of gibberellin.

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In confirmation of the influence which the variation of heading rate exerts on the herbage yield in some tropical grasses throughout the season of utilization, Guinea grass, Panicum maximum Jacq., Coloured guinea grass. P. coloratum L. and Makarikari grass, P. coloratum L. were grown in the experimental field of the Faculty of Agriculture, Miyazaki University, and were cut back to a stubble height of 10 or 20 cm at the plant height of 90 cm and to 10 cm at 40 cm.
The results obtained are summarized as follows.
1. From the changes of heading rate as expressed by the ratio of heading tiller numbers to total tiller numbers, Guinea grass tested was infered of its growth habit as a late flowering type, Makarikari grass as early and Coloured guinea grass as intermediate.
2. In the case of cutting at the higher plant height, yield of every one of tested grasses decreased in autumn. This seasonal change of yield was less in Guinea grass than in the other two grasses. In plants cut back to the lower stubble height at the lower plant height, however, yields of Guinea grass and Coloured guinea grass increased and that of Makarikari grass did not increase.
3. Decreasing the stubble height or plant height at harvest resulted in the lower yield in summer, and hence in the lower total yield.
4. It was supposed that the changes of heading rates exerted a great influence on the changes of herbage yield throughout the season of utilization. Thus, it will be preferable for high yield to utilize the tropical grasses in a way fitting the growth habit of each grasses.

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The effect of N fertilizer applied at various growth stages on the yield of the following three varieties of Panic grass was investigated : Makarikari grass, Panicum coloratum L., Coloured guinea grass, P. coloratum L., and Guinea grass, P. maximum Jacq.
In a pot experiment, plants were protected from rain and were supplied with N fertilizer in the following method after each cutting at different growth stages : Plants were fertilized with the same total amount of N. but each top dressing treatment was different. Amount of N applied was increased in one plot (F₁ plot) and decreased in another plot (F₃ plot) gradually, and in the remaining plot (F₂ plot), N was applied constantly.
The results obtained were summarized as follows.
1. In accordance with the assumption in the previous paper that Makarikari grass might be an early flowering type, Guinea grass a late one and Coloured guinea grass an intermediate one. It was observed in the undefoliated plants of this experiment that the time of heading commencement was earlier and the heading tiller numbers in autumn were less in the order, Makarikari grass, Coloured guinea grass, Guinea grass.
2. In connection with the difference in the growth habit of each grass, the increase of the heading tiller numbers due to the increase of the amount of N applied was significant after the first cutting in Makarikairi grass and after the second cutting in Coloured guinea grass and even after the third cutting in Guinea grass.
3. In the F₃ plot of Makarikari grass and Guinea grass, tiller numbers were increased after the first cutting and plants maintained more tillers until the third cutting than that in the other plots. In Coloured guinea grass, the effect of N on tiller numbers was less until the third cutting than in the other grasses. After the third cutting, this effect of N was significant in every one of tested grasses.
4. In every kind of tested grass, the effect of the amount of N fertilizer on the herbage yield was significant when temperature was high and plant grew vigorously.
5. From the above mentioned, it might be considered that in choosing N fertilizer schedule, it would be preferable for high yield to lay emphasis on the earlier application in the grasses of the earlier flowering type than in those of the later flowering type.

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