Soil-based cycling and differential uptake of amino acids by three species of strawberry (Fragaria spp.) plants

Authors: REEVE, J. - UTAH STATE UNIVERSITY; Smith, Jeffrey; CARPENTER-BOGGS, LYNNE - WASHINGTON STATE UNIV; REGANOLD, JOHN - WASHINGTON STATE UNIV

Submitted to: Soil Biology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2008
Publication Date: 7/14/2008
Citation: Reeve, J.R., Smith, J.L., Carpenter-Boggs, L., Reganold, J.P. 2008. Soil-based cycling and differential uptake of amino acids by three species of strawberry (Fragaria spp.) plants. Soil Biology and Biochemistry. Volume 40, Issue 10, October 2008, p. 2547-2552.

Interpretive Summary: Evidence is growing that amino acids can be an important source of plant nitrogen in nutrient limited natural ecosystems, but relatively little is known about the effect of agricultural management on soil amino acid pools which may provide this nitrogen. Organic management in particular relies on slow release organic nitrogen inputs which could result in greater pools of soil amino acid nitrogen available for plant uptake. Moreover, we know little about potential differences in amino acid uptake ability within plant families and whether this ability may have been lost during domestication. In order to determine the relative effects of soil type and management on amino acid turnover, we measured the effect of fine- versus coarse-textured soil and organic versus conventional management on free amino acid uptake by strawberry. Fine-textured and organically managed soils contained significantly higher total C and N than coarse-textured and conventionally managed soils but there were no significant differences in free amino acid uptake by texture or management. Two wild species of strawberry, Fragaria virginiana and F. chiloensis, took up significantly more of the amino acid glycine than the domesticated species, F. fragaria. These findings are important to scientists and producers because if strawberry cultivars could be selected or bred for their ability to capture amino acid nitrogen, it could improve nitrogen use efficiency in farming systems that rely on the breakdown of organic matter as N source. This could also greatly improve profitability of organic strawberry production.

Technical Abstract: Evidence is growing that amino acids can be an important source of plant N in nutrient limited natural ecosystems, but relatively little is known about the effect of agricultural management on soil amino acid pools and turnover. In order to determine the relative effects of soil type and management on amino acid turnover, we measured the effect of fine- versus coarse-textured soil and organic versus conventional management on free amino acids and proteolytic activity in the field. Secondly, we conducted greenhouse experiments to determine the ability of domestic and wild strawberry to utilize amino acid-N. Fine-textured and organically managed soils contained significantly higher total C and N than coarse-textured and conventionally managed soils. There were no significant differences in free amino acids or protease activity by texture or management. Amino acid turnover was calculated at 0.7 to 1.5 h. Turnover time was significantly greater in fine-textured soils. Turnover time as a result of substrate additions was significantly shorter in coarse-textured soils; in fine-textured soils turnover time was shorter under conventional management. This suggests less competition for amino acids in soils with greater C, N and/or cation exchange capacity (CEC), such as fine-textured and organically managed soils. Two wild species of strawberry, Fragaria virginiana and F. chiloensis, took up significantly more 14C labeled glycine than the domesticated species, F. fragaria. More research is needed to determine whether strawberry cultivars could be selected or bred for their ability to capture amino acid N, thus improving N-use efficiency in farming systems relying on the breakdown of organic matter as N source.