ISSN:
1573-5036
Keywords:
acetylene reduction
;
Bradyrhizobium
;
chloroplasts
;
herbicides
;
lupins
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Field and laboratory investigations were carried out to determine the influence of two commercial herbicides Lindex and Simazine on symbiotic N2 fixation, the photosynthetic apparatus, percentage of proteins, and grain yield of lupins (Lupinus albus L. cv. Multolupa). The herbicides were added (3 kg commercial product in 9001 per ha) two weeks after sowing. The nodulated roots were tested for nitrogenase activity by the acetylene reduction assay (ARA) at the first and second flowering. The ARA values decreased with herbicide application. The decrease was smaller in the Simazine treatments with inoculated seeds. The ARA for plants treated with Lindex did not increase with inoculation. Nitrogenase activity was greater in the non-inoculated plants growing together with weeds. The effect of Simazine on the photosynthetic apparatus proved to be more toxic than that of Lindex, not only considerably reducing the size of the chloroplasts but also affecting the grana structure. The latter appeared as an electron-dense compact mass. There were no visible alterations in the photosynthetic apparatus of plants treated with Lindex. However starch, which was not present in the control leaves, accumulated. No ultrastructural changes were observed in the nodule cells treated with Lindex. Simazine altered nodule cells by causing vesicle formation, degeneration of bacteria, and by decreasing the number of N2-fixing bacteroids. The grain yield decreased with both herbicide treatments, the decrease being lower in the inoculated plants, especially in the Simazine treatment. Our results suggest that each herbicide had a different effect on N2 fixation, the photosynthetic apparatus and grain yield. Laboratory studies indicated that cyanazine and simazine did not adversely affect the growth of Bradyrhizobium.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02371036
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