排序方式: 共有3条查询结果,搜索用时 6 毫秒
1
1.
Soybean response to nodulation by rhizobitoxine-producing bradyrhizobia as influenced by nitrate application 总被引:1,自引:0,他引:1
Foliar chlorosis of soybean (Glycine max [L.] Merr.) resulting from nodulation by rhizobitoxine-producing (RT+) strains of Bradyrhizobium japonicum is commonly less severe in the field than under greenhouse conditions. Differences in nutritional conditions between the field and greenhouse may contribute to this phenomenon. In particular, field-grown plants obtain some N from soil sources, whereas in the greenhouse soybean is often grown in low-N rooting media to emphasize symbiotic responses. Therefore, we examined the effect of NO3
- on the expression of RT-induced symptoms. Soybean plants inoculated with RT+ bradyrhizobia were grown for 42 days in horticultural vermiculite receiving nutrient solution amended with 0.0, 2.5, or 7.5 mM KNO3. Foliar chlorosis decreased with increasing NO3
- application whereas nodule mass per plant was generally increased by NO3
- application. Total amounts of nodular RT remained constant or increased with NO3
- application, but nodular concentrations of RT decreased. Chlorosis severity was negatively correlated with shoot dry weight, chlorophyll concentration, and total shoot N content. It was concluded that application of NO3
- can reduce the negative effects of RT production on the host plant. This suggests that any NO3
- present in field soils may serve to limit chlorosis development in soybeans.Abbreviations RT
rhizobitoxine
- RT+
rhizobitoxine-producing
- Lb
leghemoglobin
Published as Miscellaneous Paper No. 1429 of the Delaware Agricultural Experiment Station. 相似文献
2.
Rhizobitoxine-producing (RT+) strains of Bradyrhizobium japonicum, differing in their abilities to induce foliar chlorosis with ‘Forrest’ soybean (Glycine max [L.] Merr.), were evaluated for effects on short term shoot productivity, nodulation, N2 fixation, and nodule protein production under greenhouse conditions. Soybeans were singly inoculated with washed suspensions
of (Group II) USDA strains 31, 46, 76, 94, 110, 123 or 130. Strains USDA 110 and USDA 123 (Group I/Ia) were included as RT-controls.
The plants were cultured in the absence of combined N in horticultural-grade vermiculite for 49 days. Beginning 21 days after
planting, plants were evaluated weekly for chlorophyll, leaf protein and biomass accumulation, nodular contents of leghemoglobin,
soluble protein and RT, and total shoot N content. Rhizobitoxine was detected in nodules of all RT+ strains with the exception of USDA 31. However, only USDA 76 and USDA 94 produced both quantifiable concentrations of RT
and symptoms of RT-induced chlorosis. Coincident with moderate to severe chlorosis were reductions in chlorophyll concentrations,
shoot and nodule dry weight, leaf protein and total N2 fixation. During extended periods of severe chlorosis, reductions in Lb and soluble nodular protein were observed. Based
on carbon accumulation, all non-chlorotic treatments were statistically more productive than the chlorotic treatments. Similarly,
non-chlorotic Group II treatments tended to fix less carbon relative to the RT-Group I/Ia controls, although these differences
were not statistically significant. The results of this study suggest that, in the absence of discernable foliar chlorosis,
the effect of RT+ (Group II) nodulation on short term soybean productivity is minimal.
Published as Miscellaneous Paper No. 1439 of the Delaware Agricultural Experiment Station.
Published as Miscellaneous Paper No. 1439 of the Delaware Agricultural Experiment Station. 相似文献
3.
Isopropylmalate dehydrogenase (IPMDH) is the third enzyme specific to leucine biosynthesis. It catalyzes the oxidative decarboxylation of 3-isopropylmalate (3-IPM) to 2-ketoisocaproic acid. The partially purified enzyme from pea (Pisum sativum L.) shows a broad pH optimum of 7.8 to 9.1 and has Km values for 3-IPM and NAD of 18 and 40 [mu]M, respectively. O-Isobutenyl oxalylhydroxamate (O-IbOHA) has been discovered to be an excellent inhibitor of the pea IPMDH, with an apparent inhibitor constant of 5 nM. As an herbicide, O-IbOHA showed only moderate activity on a variety of broadleaf and grass species. We characterized the herbicidal activity of O-IbOHA on corn (Zea mays L.), a sensitive species; giant foxtail (Setaria faberi) and morning glory (Ipomoea purpurea [L.] Roth), moderately tolerant species; and soybean [Glycine max L. Merr.), a tolerant species. Differences in tolerance among the species were not due to differences in the sensitivity of IPMDH. Studies with [14C]O-IbOHA suggested that uptake and translocation were not major limitations for herbicidal activity, nor were they determinants of tolerance. Moreover, metabolism could not account for the difference in tolerance of corn, foxtail, and morning glory, although it might account for the tolerance of soybean. Herbicidal activity on all four species was correlated with the accumulation of 3-IPM in the plants. 相似文献
1