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Nodulation, Dinitrogen Fixation, and Yield Improvement in Second‐Crop Soybean Cover‐Inoculated with Bradyrhizobium japonicum
Author(s) -
Ciafardini G.,
Lombardo G. M.
Publication year - 1991
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/agronj1991.00021962008300030024x
Subject(s) - sowing , inoculation , bradyrhizobium japonicum , agronomy , cover crop , biology , bradyrhizobium , horticulture , symbiosis , rhizobiaceae , rhizobium , bacteria , genetics
When soybean [ Glycine max (L.) Merr.) is grown in soil containing few Bradyrhizobium japonicum (Kirch.) Jordon, the limited mobility of the symbiont results in the formation of a small number of nodules distributed mainly on the primary root of the plant near the inoculation point. The authors conducted a 3‐yr study aimed at increasing nodulation and N 2 fixation in ‘Hodgson’ soybean as a second crop, by cover inoculating B. japonicum on the soil with irrigation water at the time of sowing or at the three‐node (V 3 ) stage. Inoculation treatments were: (i) seed inoculation; (ii) cover inoculation at sowing; (iii) seed inoculation plus cover inoculation at sowing; (iv) cover inoculation at the V 3 stage; (v) seed inoculation plus cover inoculation at the V 3 stage; (vi) uninoculated control. The seed plus cover inoculation at sowing or the V 3 stage produced, on the whole, the greatest nodulation, 1.4 to 2.4 times that for seed inoculation alone. The addition of cover inoculation at sowing increased seed yield by 50 g m −2 in 1985 and 90 g m −2 in 1986, regardless of whether the cover inoculation was performed at sowing or the V 3 stage. In 1988, a year in which the soybean was sown about 1 mo later than in the previous years and subjected to higher temperatures, seed and cover inoculation increased N 2 fixation and plant‐N concentration, but not yield.