|Kumar, K - UNIVERSITY OF MINNESOTA|
|Rosen, C - UNIVERSITY OF MINNESOTA|
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 15, 2004
Publication Date: October 1, 2004
Citation: Kumar, K., Rosen, C.J., Russelle, M.P. 2004. Influence of enhanced protease inhibitor activity in plant residues on nitrogen mineralization in soil [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. CD-ROM. Paper No. 3645. Technical Abstract: The role of proteases in breaking down high molecular weight proteinaceous compounds is an important step of the N cycle. These enzymes help in converting organic forms of N into inorganic forms, which plants can then use. Previously, we showed that protease inhibitor chemicals reduced soil N mineralization. We hypothesized that transgenic plant residues containing protease inhibitors may also slow down N mineralization in soil and plant residues compared to isogenic plants without the protease inhibitors. Other groups have produced such transgenic plants to provide defense against insect attack. Transgenic and isogenic plants of Brassica napus were grown in pots in a greenhouse and labeled with 15N. After 6 weeks, plants were harvested and the above ground portions were cut into small pieces and thoroughly mixed. Closed incubation and leaching tube studies were conducted in the laboratory to study N release from transgenic and non-transgenic isogenic plants. Total N mineralization from treatments with transgenic plant residues was significantly less compared to control plant residue treatments. Differences were due to lower inorganic N release from transgenic plants rather than to a reduction in N mineralized from soil organic matter. We conclude that enhancing protease inhibitor concentration in plants may slow the release of N from crop residues, thereby preventing untimely accumulation of nitrate in the soil between successive crops.