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Early Maturing Soybean Nodulation and Performance with Selected Bradyrhizobium japonicum Strains
Author(s) -
Wiersma J. V.,
Orf J. H.
Publication year - 1992
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1992.00021962008400030019x
Subject(s) - bradyrhizobium japonicum , sowing , inoculation , cultivar , bradyrhizobium , agronomy , biology , nitrogen fixation , grain yield , fertilizer , dry weight , horticulture , zoology , symbiosis , rhizobiaceae , rhizobium , bacteria , genetics
Seed inoculation with Bradyrhizobium japonicum (Kirchner) Jordan is a common production practice for most soybean [ Glycine max (L.) Merr.] growers in northwest Minnesota; however, plants seldom are well‐nodulated. Our objectives were to (i) identify strains of B. japonicum that enhance nodulation and agronomic performance of Maturity Group 00 soybean cultivars grown on soils having a range of NO 3 − −N concentrations; and (ii) assess cultivar‐by‐strain specificity. Six cultivars and five B. japonicum strains were evaluated in six field trials during 1988 to 1990. Nonfertilized (1988–1990) and N fertilized (1990), uninoculated controls were included. Soil NO 3 − −N concentrations (0–60 cm) at planting ranged from 52 to 175 kg N ha −1 . Residual soil NO 3 − −N values were low and substantially less than initial values in only three environments. Nonetheless, significant increases in response to inoculation were observed for grain yield, seed weight, and grain N concentration in 17 of 18 comparisons. In 1990 trials, fertilizer N (168 kg ha −1 ) increased seed weight and grain N concentration significantly more than inoculation. Nodule number ( r = −0.89; significant at P = 0.05) and dry weight ( r = −0.97; significant at P = 0.01) were inversely correlated with soil NO 3 − −N (0–60 cm) at planting. Estimated (difference method) N 2 fixation ( r = ‐0.93; significant at P = 0.05) and relative increases in grain yield ( r = −0.93; significant at P = 0.05), seed weight ( r = ‐0.97; significant at P = 0.01) and grain N concentration ( r = −0.95; significant at P = 0.05) were inversely correlated with soil NO 3 − −N (0–60 cm) at harvest. Although similar responses were observed among all cultivars, B. japonicum strains 61A152 and 61A212 generally outperformed other strains. Cultivar‐by‐strain specificity could not be detected. Soybean producers in northwest Minnesota should realize significant increases (10% or greater) in grain yield in response to inoculation of rhizobia‐free soils, provided initial soil NO 3 − −N concentrations (0–60 cm) are less than 110 kg N ha −1 and N mineralization during the growing season is minimal.