pnut pnut Peanut Science 0095-3679 0095-3679 American Peanut Research and Education Society 10.3146/i0095-3679-10-2-17 Articles Effect of Leaf Removal on Symbiotic Nitrogen Fixation in Peanut1 A. K. Osman , J. C. Wynne , G. H. Elkan , and T. J. Schneeweis 2 Former graduate student (presently with Agronomy Section, Agricultural Research Corp., P. O. Box 126, Wad Medani, Sudan) and Professor, Crop Science Department; Professor and Research Associate, Microbiology Department, North Carolina State University, Raleigh, NC 27650

1Paper No. 8861 of the Journal Series of the North Carolina Agricultural Research Service, Raleigh, NC 27650. This research was partially supported by USDA-SEA-CR grant 801-15-93 under A.I.D. PASA AG/TAB 610-9-76.

 7 1983 10 2 107 110 10 12 1983 American Peanut Research and Education Society 1983 American Peanut Research and Education Society Abstract

The effect of varying levels of leaf defoliation on the nodulation and nitrogen fixation of a Virginia and a spanish-type peanut (Arachis hypogaea L.) cultivar was investigated in the greenhouse. Five leaf defoliation treatments - (a) control (no leaflet removal), (b) 25%, (c) 50%, (d) 75%, and (e) 100% - were carried out every 3 to 5 days throughout the growing period.

All nitrogen fixation measurements were affected by the defoliation (leaflet removal) treatments. Increased leaf defoliation reduced nodule formation and N2 fixation. The reduction in plant dry weight, nodule number, nodule dry weight, and nitrogenase activity was most severe for the 100% defoliation treatment. Correlation coefficients (r) of N2 fixation measurements and leaf areas and weights were highly significant.

The defoliation effect was similar in both experiments and cultivars; however, the Virginia type achieved higher values for all N2 fixation measurements.

 Key Words Arachis hypogaea; , nodulation; , defoliation; , leaf area