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Competition Between Upland Rice and Purple Nutsedge for Nitrogen, Moisture, and Light

Published online by Cambridge University Press:  12 June 2017

L. I. Okafor*
Affiliation:
Dept. of Agronomy, International Rice Res. Inst., Los Baños, Laguna, Philippines
S. K. De Datta*
Affiliation:
Dept. of Agronomy, International Rice Res. Inst., Los Baños, Laguna, Philippines
*
Mail address P.O. Box 933, Manila, Philippines
Mail address P.O. Box 933, Manila, Philippines

Abstract

Field experiments were conducted on clay and clay loam soils at the International Rice Research Institute to investigate the effects of competition between upland rice (Oryza sativa L.) and varying populations of purple nutsedge (Cyperus rotundus L.) for nitrogen, moisture, and light on the grain yield of upland rice. ‘IR5’ was used in 1972, while the experimental line ‘IR442-2-58’ was used in 1973. Grain yields of ‘IR5’ and ‘IR442-2-58’ increased with 60 kg/ha of nitrogen, and decreased with increased purple nutsedge population. The application of nitrogen to weedy upland rice fields benefited the purple nutsedge more than the rice. Purple nutsedge and upland rice competed extensively for moisture and the competition was much more serious with increased nitrogen fertilization. Purple nutsedge competition reduced the light transmission ratio (LTR). The reduction was proportional to the increase in purple nutsedge population density. Reductions in the LTR were greater at higher nitrogen levels during the three seasons.

Information

Type
Research Article
Copyright
Copyright © 1976 by the Weed Science Society of America 

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