The Relationship between Environmental Factors and Behaviour of Stomata in the Rice Plants : VII. The relation between nitrogen content in leaf blades and Stomatal aperture

[摘要] The present investigation was undertaken to clarify the relationship between nitrogen content in leaf blades and stomatal aperture at different growth stages, by using rice plants with different nitrogen content. There were two plots prepared. One was a control, the other was a plot with additional nitrogen applied to soil several days before stomatal measurement (Table 1). The results obtained are as follows. For the plants, received additional application of ammonium sulfate, there was higher content of nitrogen in leaf blades regardless of leaf position on the stem and of growth stage (Table 2). On fine days the stomatal aperture was larger in higher nitrogen plot compared with that of the control especially from the morning until the aperture reached to the maximum of the day. After the stomata started to close in the afternoon the difference of stomatal aperture became very small or negligible due to more considerable extent of stomatal closure in higher nitrogen plot (Fig. 1). On the contrary, on cloudy days accompanied with lesser evaporation, the difference of the stomatal aperture between the two plots could be found from the morning to the evening even though it became smaller in the afternoon compared with that in the morning (Fig. 2). In addition, the larger difference of the aperture between two plots was found in upper leaves compared with lower leaves at all growth stages independent of weather condition (Fig. 3 and 4). A high positive correlation between nitrogen content and stomatal aperture was clarified in leaves on the different position of the stem at different growth stages (Fig. 5 and 7). In Fig. 5 and 7, examined in detail, it was found out that the stomatal aperture of lower leaves was smaller compared with that of upper leaves in the almost same nitrogen content and that the stomatal aperture of rice plants after heading stage was also smaller even in the same leaf position compared with that before heading stage (Fig. 6). It is assumed from these results that the difference of stomatal aperture between rice plants with higher and lower nitrogen content appears only in the case with sufficient water content of leaf blades, but that it cannot be found in leaves under water stress. Furthermore, it is also suggested that the increase of stomatal aperture owing to higher nitrogen content has much bearing on the increase of photosynthetic rate in leaf blades, considering high positive correlation between stomatal aperture and photosynthetic rate in rice plants.

[学科分类] 农业科学（综合）