Studies on Matter Production in Pineapple Plants: III. Effects of nitrogen nutrition on the gas exchange of shoots

Abstract

Using pineapple plants, a cultivar selected from the Smooth cayenne and grown in cultural solution, the effect of nitrogen (NO3-N) nutrition on the gas excahge of the plants was investigated. Six nitrogen treatments in culture medium contained 14, 28, 69, 138, 277 and 554 ppm of nitrogen concentration, respectively. The concentration of other elements except for nitrogen was same in the six treatments. The obtained results were as follows: 1. The CO2 influx occured in dark period (phase 1, after Osmond) and the last half of light period (phase 4) on every nitrogen treatment, and CO2 influx rate was different each other among each treatment. 2. Maximum CO2 balance for full one day and phase 1 was obtained in nitrogen treatments of 277 and 138 ppm. Maximum CO2 balance in phase 4 was obtained in 138 ppm plants (Fig. 2). 3. Total nitrogen, soluble protein, and chlorophyll content in leaves showed maximum value in 138 and 277 ppm nitrogen plants and decreased in 557 ppm plants (Fig. 3). 4. CO2 balance for full one day and in phase 1 showed positive and statistically significant correlations to total nitrogen, soluble protein, and chlorophyll content in leaves. CO2 balance in phase 4 did not significantly correlate to leaf nitrogen components (Figs. 4 and 5). 5. Correlation between CO2 influx rate and water vapour exchange coefficient was positive and significant in phase 1 and 4. The degree of correlation in phase 4 was particularly high (Fig. 7). Consequently, it appears that CO2 influx in phase 1 was mainly affected by factors related to nitrogen content in leaves, and that CO2 influx in phase 4 was regulated with the degree of stomatal aperture. 6. CAM ability, the ratio of CO2 balance in phase 1 to CO2 balance for full one day, increased as total nitrogen in leaves increased (Fig. 6). 7. Nitrogen use efficiency for one day in pineapple plant was as small as 1.9 to 1.2 mgCO2/mgN/day. In addition, maximum nitrogen use efficiency calculated from maximum CO2 influx rate in phase 1 and 4 was extremely small, showing the value of 93 to 120 µgCO2/mgN/h in phase 1 and 65 to 150 µgCO2/mgN/h in phase 4 (Fig. 9). © 1985, CROP SCIENCE SOCIETY OF JAPAN. All rights reserved.