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ARS Home » Plains Area » Mandan, North Dakota » Northern Great Plains Research Laboratory » Research » Publications at this Location » Publication #148214
Title: RUSSIAN WILDRYE NUTRITIVE QUALITY AS AFFECTED BY ACCESSION AND ENVIRONMENT.

Author
item Karn, James
item Mayland, Henry
item Berdahl, John
item ASAY, K - RETIRED,ARS,LOGAN,UT
item JEFFERSON, P - AGRIC&AGRI-FOOD,SK,CA

Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2004
Publication Date: 4/15/2005
Citation: Karn, J.F., Mayland, H.F., Berdahl, J.D., Asay, K.H., Jefferson, P.G. 2005. Russian wildrye nutritive quality as affected by accession and environment. Can. J. Plant Sci. 85:125-133.

Interpretive Summary: Russian wildrye has been used to provide needed spring and fall grazing, especially in Canada, but its use has been limited in the USA because of its reputation as a tetany prone forage. A multi-location study was undertaken to determine if breeding and selection could be used to develop Russian wildrye plants that were less likely to cause grass tetany. The objective of the current research was to determine if plants could be developed with lower grass tetany potential and higher nutritive quality. Sixty seven Russian wildrye plant selections from the U.S. National Germplasm System were established in plots at Logan, UT, Mandan, ND, and Swift Current, Saskatchewan, Canada. Plants were sampled at two stages of maturity over 2 yr. Location, year and stage of maturity were significant different for in vitro dry matter digestibility (IVDMD), crude protein, and neutral detergent fiber (NDF). Unfortunately nutritive quality differences for test plants among locations and years were not as consistent as desired, likely due to differences in growing conditions among environments or locations. Relatively high mathematical relationships between potassium and IVDMD, NDF and crude protein suggest that breeding for higher nutritive quality may also produce a more tetany prone forage, because high potassium levels are usually associated with grass tetany. On the other hand magnesium levels were also highly related with IVDMD, crude protein, and NDF and higher magnesium levels would be beneficial in preventing grass tetany. A relatively high positive relationship between IVDMD and crude protein, and a high negative relationship between IVDMD and NDF indicate that selection for plants with higher IVDMD should also result in plants with higher crude protein and lower NDF.

Technical Abstract: Lack of high-quality forage for spring and fall grazing is a continual problem for ranchers in the Northern Great Plains and intermountain-west regions of the USA. Russian wildrye [Psathyrostachys juncea (Fischer) Nevski] has been used to meet this niche grazing need, especially in Canada. However, its use has probably been limited because of high spring concentrations of N and K, which have given it a reputation of being a tetany-prone forage. A multi-location study was undertaken to determine if breeding and selection techniques could be used to develop Russian wildrye plants that were less likely to cause grass tetany. The subject of the current research was a corollary aspect of the grass tetany project to determine if plants could be developed with higher nutritive quality, and most important whether plants could be developed with higher nutritive quality and lower tetany potential. Sixty seven Russian wildrye accessions from the U.S. National Germplasm System were established in space-plant nurseries at Logan, UT, Mandan, ND, and Swift Current, Saskatchewan, Canada. Plants were sampled at two stages of maturity over 2 yr. Location, year and stage of maturity effects were significant (P<0.01) for in vitro dry matter digestibility (IVDMD), crude protein, and neutral detergent fiber (NDF). Location by year and location by stage of maturity interactions for all three nutritive quality components indicate somewhat less continuity between main effects than desired, which was likely a result of differences in growing conditions among environments. Relatively high correlation coefficients between K and IVDMD, NDF, and crude protein suggest that breeding for higher nutritive quality may also produce a more tetany prone forage, because high K levels are usually associated with grass tetany. On the other hand, Mg levels were also highly correlated with IVDMD, crude protein, and NDF and higher Mg levels would be beneficial in preventing grass tetany. Calcium and phosphorus were very poorly related to quality components and the K/(Mg+Ca) ratio which has also been suggested as an indicator of grass tetany. The K/(Mg+Ca) ratio was only moderately related to IVDMD, crude protein, and NDF.