Change in Activity of Enzymes, Soluble Carbohydrates, and Intensity of Respiration of Rice Seeds Germinating under Water.

In the world market upland rice (grain) occupies a very modest place, since its production is comparatively limited, and harvests are uncertain since they depend upon precipitation. For this reason upland rice cannot compete with lowland rice. Upland rice is used exclusively in those regions possessing insufficient water for irrigation purposes. CAMUS (2) identifies four types of rice. Of these, the type requiring least water is "Caingin" while that having the highest water requirement is "typical lowland." In spite of this classification, the two types do not possess definite characteristic qualities, so that certain "upland" varieties of rice grow very poorly on soil containing only ordinary amounts of water but grow very vigorously under irrigated conditions. There is little literature relating to upland rice, especially in relation to its physiological character. Among the latter is to be found the work of the following investigators: INOUYE (4), GILE and CARRERO (3), JIRO ONODERA (5), VILLEGAS (9) and NAGAOKA (7). The conclusions of these investigators indicate the existence of well defined differences between upland and lowla(ld rice. The present work presupposes a biochemical and physiological study of the first stages of development of the rice plant, namely, swelling and germination of seeds. The writer will here deal with the metabolism of soluble carbohydrates, changes of dry matter, activity of enzymes, and respiration. In these experiments seeds of the lowland variety Oobe and upland variety Bely were used. The seeds of these varieties were germinated under two sets of conditions: on filter paper, and under water. The stages of germination were: (1) air-dry seeds; (2) swollen seeds; (3) sprouting seeds; (4) seeds with stems 2 cm. in length; (5) seeds with stems 3 cm. in length; (6) seeds with stems 10 cm. in length.