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Influence of Bradyrhizobium japonicum Strain and Far‐Red/Red Canopy Light Ratios on Nodulation of Soybean
Author(s) -
Hunt P. G.,
Kasperbauer M. J.,
Matheny T. A.
Publication year - 1990
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1990.0011183x003000060030x
Subject(s) - bradyrhizobium japonicum , canopy , biology , seedling , microbial inoculant , inoculation , phytotron , shoot , loam , horticulture , botany , agronomy , rhizobiaceae , symbiosis , soil water , bacteria , ecology , genetics
Dinitrogen fixation, an important aspect of soybean [ Glycine max (L.) Merr.] production, is affected by many environmental factors. Nodulation can be altered, for example, by changes in the ratio of far‐red to red (FR/R) canopy light. The influence of canopy light spectral balance on the nodulation of ‘Coker 368’ soybean when inoculated with different strains of Bradyrhizobium japonicum was evaluated in field and growth chamber studies. Soybean seedlings were inoculated with USDA 110 (110) or Brazil 587 (587) and grown in 10‐cm diameter pipes that were filled with vermiculite and inserted at 1.0‐m intervals in seedling soybean rows that were oriented north‐south (N/S) or east‐west (E/W) on a Norfolk loamy (fine‐loamy, siliceous, thermic Typic Kandiudult). The FR/R ratios of canopy light (relative to the ratio in incoming sunlight, which was assigned a value of 1.00), were 1.38 for N/S‐ and 1.26 for E/Woriented rows. Row orientation significantly affected nodulation when 110 was the inoculum but not when 587 was the inoculum. Nodule biomass of ll0‐inoculated seedlings was 48% higher with E/W than with N/S row orientation. In the growth chamber study, soybean seedlings were inoculated with 110 or 587, and their shoots received high or low FR/R ratios at the end of each day. Nodulation was significantly affected by the FR/R ratio of canopy light when the inoculant was 110 but not when the inoculant was 587. Soybean seedlings that received the low FR/R ratio and were inoculated with 110 had 53% greater nodulation; the FR/R effects on nodulation were not statistically significant when the seedlings were inoculated with 587. These results show that even small changes in the FR/R ratio of canopy light can affect soybean nodulation in both field and controlled environments. They also show that this effect can be enhanced or diminished by B. japonicum strain.