When compared to Anoka inoculated with USDA 31, the same cultivar inoculated with USDA 110 showed increases in total dry matter, per cent nitrogen, and total N2 fixed of 24, 7, and 31%, respectively. Cowpeas in symbiosis with the hydrogenase-producing strain 176A28 in comparison with the same cultivar inoculated with the H2-evolving strain 176A27 produced increases in plant dry weight and total N2 fixed of 11 and 15%, respectively. This apparent increase in the efficiency of N2 fixation for nodulated legumes capable of reutilizing the H2 evolved from nitrogenase is considered and it is concluded that provision of conclusive evidence of the role of the H2-recycling process in N2-fixing efficiency of legumes will require comparison of Rhizobium strains that are genetically identical with the exception of the presence of hydrogenase.
相似文献The rate of spread was much greater in tomato than in potato plants, and virulent strains of the virus, which achieve a high concentration in infected plants, spread more rapidly than avirulent strains. In only one experiment with potatoes did more than 10% of the healthy potato plants exposed to infection become infected during one season.
Datura stramonium and tomato plants became infected when growing in soil containing sap or residues from X -infected plants.
It was common in the field for potato plants whose foliage gave no reaction for virus X at the end of the season to yield a mixed progeny of healthy and infected tubers. Such infections are thought to result from underground spread.
Attempts to transmit virus X from infected to healthy potatoes by means of Rhizoctonia solani failed. No examples of infection were found except when healthy plants came into direct contact with sources of the virus. 相似文献