Diurnal changes in nitrogen and potassium absorption rates of plants grown in a greenhouse

Yodai Okuyama, Kiyoshi Ozawa, Michiko Takagaki

研究成果: Article査読

9 被引用数 (Scopus)


In order to increase the efficiency of nutrient utilization in solution culture systems, it is indispensable to understand how plants absorb nutrients. A series of experiments were conducted using hydroponic culture system in the first to third experiments and soil culture system in the fourth experiment in a greenhouse in Okinawa, Japan. In the first experiment, changes in NO3-N absorption were measured every three hours during a 24-hour period on 40 days after transplanting (DAT) in cucumber. In the second experiment, daytime and nighttime NO3-N absorption were measured from 45 to 48 DAT in five crops including cucumber. In the third experiment, NO3-N, NH4-N, and K absorption in daytime, nighttime and shaded conditions were determined from 30 to 34 DAT in bitter gourd, a substitute crop for cucumber, and water spinach. In the fourth experiment, daytime and nighttime (NH4)2SO4-15N absorption rates were measured from 9 to 12 DAT in cucumber. The results showed that daily NO3-N absorption in cucumber peaked twice, just before midday and again just after the nightfall. The corresponding fluctuation pattern was observed in all other tested crops, with 20–41% of the total absorption occurring at night. Absorption rate of 15N in cucumber cultivated in soil also increased in daytime and decreased at night, with the nighttime rate accounting for 39–40% of the daily total absorption. The average nighttime NO3-N, NH4-N, and K absorption percentages of the daily total before shading the plant were 34–35%, 49– 51%, and 33–49%, respectively. During the shaded period, these nutrient absorption rates dramatically decreased, except for NH4-N which was not affected by shading. Across all experiments, 20–51% of total absorption took place at night, the majority of which may concentrate around the early nighttime. Furthermore, the absorption rates may be influenced by photosynthetic products.

ジャーナルJournal of Agricultural Meteorology
出版ステータスPublished - 10 12月 2015


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