Quantitative estimation of lateral roots in rice plants (Oryza sativa L.) grown with different amounts of nitrogen application
2002
Sasaki, O. (Kagoshima Univ. (Japan). Faculty of Agriculture)
The present study was conducted to elucidate the effect of different levels of nitrogen fertilizer application on the lateral root formation along the axis of the primary (nodal) root in rice plants. Two kinds of treatment plot were provided as follows; N1-plot (5g ammonium sulfate was applied per 1/2000a Wagner pot), N2-plot (10g was applied per pot). The results are summarized as follows: In both treatment plots, two types of lateral roots were found according to their diameter and length. Thick and long lateral roots branch higher order laterals on their axis, while thin and short ones do not. The number of both thin and thick secondary lateral roots per primary root in the N2-plot was more than that in the N1-plot, and this tendency was prominent in the case of thick secondary lateral roots. However, their average length in the N1-plot was longer than that in the N2-plot. The average length of thin tertiary lateral roots in the N1-plot was longer than that in the N2-plot, but the numbers of thin tertiary lateral roots in each plot were almost equal. Total surface area of the whole roots (the primary root and the each order lateral root) in the N1-plot and in the N2-plot was 55.4 square cm and 61.2 square cm, respectively. Lateral roots in both treatment plots accounted for about 90% of the surface area of the whole root. The difference in the surface area of the thin secondary lateral roots in both treatment plots were slight. These results indicated that the greater total surface area in the N2-plot was due to the high level of development of the thick secondary and thin tertiary lateral roots.
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