摘要
Greenness and nitrogen content of each leaf on main stem of different japonica and indica rice varieties under different nitrogen levels were investigated. Results showed that the fourth leaf from the top exhibited active changes with the change of plant nitrogen status. When the plant nitrogen content was low, its color and nitrogen content were obviously lower than those of the three top leaves. With the increase of plant nitrogen content, the color and nitrogen content of the fourth leaf increased quickly, and the differences of color and nitrogen content between the fourth leaf and the three top leaves decreased. So, the fourth leaf was an ideal indication of plant nutrition status. In addition, color difference between the fourth and the third leaf from the top was highly related to the plant nitrogen content regardless of the variety and development stage. Therefore, color difference between the fourth and the third leaf could be widely used for diagnosis of plant nutrition. Results also indicated that the minimized color difference between the fourth and the third leaf at the critical effective tillering, the emergence of the second leaf from the top, and the heading was the symbol of high yield. Plant nitrogen content of 27 g kg-1 DW for japonica rice and 25 g kg-1 DW for indica were the critical nitrogen concentrations.
Greenness and nitrogen content of each leaf on main stem of different japonica and indica rice varieties under different nitrogen levels were investigated. Results showed that the fourth leaf from the top exhibited active changes with the change of plant nitrogen status. When the plant nitrogen content was low, its color and nitrogen content were obviously lower than those of the three top leaves. With the increase of plant nitrogen content, the color and nitrogen content of the fourth leaf increased quickly, and the differences of color and nitrogen content between the fourth leaf and the three top leaves decreased. So, the fourth leaf was an ideal indication of plant nutrition status. In addition, color difference between the fourth and the third leaf from the top was highly related to the plant nitrogen content regardless of the variety and development stage. Therefore, color difference between the fourth and the third leaf could be widely used for diagnosis of plant nutrition. Results also indicated that the minimized color difference between the fourth and the third leaf at the critical effective tillering, the emergence of the second leaf from the top, and the heading was the symbol of high yield. Plant nitrogen content of 27 g kg-1 DW for japonica rice and 25 g kg-1 DW for indica were the critical nitrogen concentrations.
