Growing seasons of rice in tropical Asian countries can be divided into the wet (main crop) and the dry (additional crop) seasons. The first and second crops in Taiwan and Southern China correspond to the dry and wet season crops, respectively. Varieties grown in the wet season are mostly sensitive to photoperiod, while those of the dry season are insensitive. Since most wildrice forms (Oryza perennis) perform vegetative growth in the rainy season and are photosensitive, the wet season crop may be considered as primitive, the dry season crop being derived from it secondarily.
When a growing-season experiment with a photo-insensitive variety is conducted throughout the year, it is found in general that two peaks of grain yield occur a year, indicating that the two seasons are determined by natural conditions and the actual crop seasons largely consist with the natural seasons. The physiological basis for the occurrence of two rice seasons a year can be partly explained only by known evidence. When seeding is made between the adaptive seasons, either too proliferous growth giving rise to mutual overshadowing of the leaves, or a poor vegetative growth may bring about a decline of grain yield. Modern varieties adapted to intensive culture with fertilizers are mostly photoperiodically insensitive ones, which can be grown in both seasons. The Ponlai (or Horai) varieties of Taiwan afford an example for this. Such a wide seasonal adaptability might have been obtained from repeated selections in the first and second crop seasons which have different environmetal conditions. It is suggested that seasonal adaptability is correlated with regional adaptability.

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1) This study was carried out in 1962 to know the relation of the leaf age to the oil content and physicochemical properties of the oil of citronella in the greenhouse cultivation.
2) The oil content was highest in the young leaves and decreased with the age of leaves regarding the leaf-blades. On the other hand, the reverse relation was recognized in the leafsheaths. In the whole leaves, the relation between the age and the oil content was similar to that in the leaf-blades, because of the remarkably low oil content of the leaf-sheaths and relatively low proportion of the weight of the leaf-sheaths to that of the whole leaves.
3) The specific gravity, refractive index, acid value, acetyl value, and total geraniol content of the oil tended to be low in the young leaves and increase with the age of leaves.
4) The ester value and citronellal content of the oil tended to be high in the young leaves and low in the old leaves.

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The important points to utilize the Assum varieties for crossing are to introduce good characteristic and improve unfit characteristic in our culture. Utilization of the Assam varieties was investigated.
1. The rooting of cutting of the Assam varieties was more difficult than the other kind of tea plant.
2. As the lateral growth of the Assam varieties was very poor. It was necessary to select such varieties that have ample lateral growth in order to improve the vigor of the Assam progenies.
3. The size of mature leaf of the Assam varieties was so large that suitable varieties having corresponding leaf extent of the Assam varieties should be utilized in crossing.
4. The cold resistance of the Assam varieties was very weak, so it was not easy to get any resistant Fl progeny even though resistant variety was crossed with each other. It would rather breed the varieties fit for warm district than breed the resistant varieties in utilizing the Assam varieties for crossing.

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1. Presumably there is no definite season for the flower-bud differentiation of Hamaomoto in the pluvious tropics. In Japan's pluvious subtropical zones this plant has green leaves throughout the year, and flowers open on the smallest stocks. But in regions where many leaves wither in winter, flower buds may be formed on the largest axillae of about twenty-year-old plants having bulbs as big as ten centimeters in diameter, in June, July, August and September, when leaves grow thickest owing to the adequate temperature and much moisture. This presumption may be substantiated by the fact that if in the flower-bud differentiation season those whose flower buds have differentiated are deprived of their vitality by insufficient temperatures, leaf-sheath exfoliation, and other unfavorable conditions, the plants, when neglected, will later produce leaf buds and become deviational. It may also account for the fact that blooming large stocks grown in chilly regions become deviational on occasions.
2. In an unheated lower-temperature green house, Hamaomoto sends forth flower stems of 60 to 70cm in length and 1.5 to 2cm in diameter toward the end of June, and open flowers in about ten days, usually in the early part of July, at the rate of about two flowers on one flower system per day. The inflorescence of Hamaomoto is umbellar with four flowers on outer part, 4 in middle part and usually 4, sometimes n (e. g., 2, 5, 6...) in inner part, all undergo selffertilization. If pollinated by artificial crossing they will produce more seeds. All flowers blossom toward evenings and hold open for three days. Every flower lasts a fortnight. Seeds may be collected for a week, 40 to 60 days after flowering. When the fruit become ripe, their color changes from green to white-yellow. Every fruit is supposed to bear three seeds, but usually it bears only one seed or two. When the seed ripens, the position of its embryo moves to the underside of the leaning fruit because the embryo part is heavier. With this posture the seed drops of itself. When dropped on water, it floats holding that same posture. Every stock sends forth one flower stem or two, but bigger stocks give forth three stems. The flowering period is from the early part of July till that part of August, the hottest season of the year. The fruitripening time lasts from the early part of September till that part of October.

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