Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2005
Publication Date: 2/24/2006
Citation: Hooks, T., Pedersen, J.F., Marx, D.B. 2006. Variation in the u.s. photoperiod insensitive sorghum collection for chemical and nutritional traits. Crop Science. Crop Sci. 46:751-757
Interpretive Summary: Approximately 4000 photoperiod insensitive sorghum lines (lines that will flower and set seed in temperate climatic zones) are held by the National Germplasm System. New technologies including Near Infrared Spectroscopy and application of geostatistical models make screening of those lines for chemical (starch, fat, crude protein, acid detergent fiber, phosphorous) and nutritional (total digestible nutrients, metabolizable energy, net energy gain, net energy maintenance, and net energy lactation) content efficient. We used these technologies to: 1) generate chemical and nutritional values for lines in the U.S. photoperiod insensitive sorghum collection, 2) describe variability for those traits, 3) select accessions in the highest 1% and lowest 1% for each trait, and 4) describe relationships among the accessions. Lines with the best nutritional value or chemical value were identified using advanced statistical techniques for use in developing improved parental lines and hybrids. The observed values for all lines evaluated were entered onto the USDA, ARS, GRIN database (http://www.ars-grin.gov/cgi-bin/npgs/html/desclist.pl?69) to permit free access to these data. Availability of these data will enhance utilization of this biological resource by industry.
Technical Abstract: Screening germplasm for chemical and nutritional content can be expensive and time consuming. Near Infrared Spectroscopy (NIRS) and application of geostatistical models can make screening more efficient. The objectives of this study were to utilize these two technologies to: 1) generate chemical and nutritional values for the U.S. photoperiod insensitive sorghum [Sorghum bicolor (L.) Moench] collection, 2) describe variability for those traits, 3) select accessions in the highest 1% and lowest 1% for each trait, and 4) describe relationships among the accessions. Accessions from the U.S. photoperiod insensitive sorghum collection were grown and seed were produced at Ithaca, NE, during 2001 and 2002 in non-replicated single-row plots. Samples were scanned on a NIRS spectrometer, and equations were developed for starch, fat, crude protein, acid detergent fiber, phosphorous, total digestible nutrients, metabolizable energy, net energy gain, net energy maintenance, and net energy lactation. The NIRS generated values for each accession can be accessed on GRIN at http://www.ars-grin.gov/cgi-bin/npgs/html/desclist.pl?69. The highest and lowest 1% of accessions were identified for each trait using best linear unbiased predictors (BLUPs). Means and standard deviations for observed values and variances due to accessions were calculated. Rank correlations between BLUPs and observed values ranged from r=0.77 to r=0.98. Principal component analysis showed that much of the total variation among the accessions is attributable to a contrast of starch with a weighted average of fat, crude protein, acid detergent fiber, and phosphorus. Cluster analyses showed clear separation of clusters based on canonical values, but no geographical or sociological interpretation of the clusters was apparent.