Studies on the Effects of Soil Temperature on Rice Plant Growth : IV. Diurnal and nocturnal differences of water and nutrient absorptions and effects cf medium conditions upon nutrient absorption

Abstract

Diurnal and nocturnal differences of water and nutrient absorptions and effects of medium conditions upon nutrients absorption were examined using a rice plant, variety called Norin no. 41. It was experimented using four large-sized thermostats to keep root temperature at 30°, 25°, 20°and 15°C respectively. Results obtained are summarized as follows: (1) Elements absorptions during day and night time whether fine or rainy in weather, under the established root temperature conditions. But water absorption was superior in fine day to in rainy day. (2) Ratios of N and P absorption to water absorption were nearly equal in different temperatures except in 15°C plot, but during night it was higher in lower temperature plots, except in 15°C plot. Ratio of K-absorption to water absorption showed nearly equal tendeney in daytime in contrast to N and P absorption. During night, it was very different, that is, there was little difference between 30°and 25°C, but the ratio in 20°and 15°C, fell with the fall in the temperature, (3) Elements absorption was somewhat intensified by aeration under the established root temperature conditions except in 15°C plot. (4) Elements absorption was promoted with increasing the amount of elements given in media under the established root temperature conditions.