The standard procedure for determining nitrogen (N) status in small grains is to sample lower stem tissue for nitrate (NO₃) analysis. The tissues are then submitted to a laboratory for analysis. Sap nitrate (NO₃) can be analyzed in the field, immediately after collecting the sample, using a Cardy meter. Guidelines for sap analysis have not yet been determined. The objectives of this study were to: (i) correlate NO₃-N in dried stem tissue with sap NO₃-N , and (ii) develop sap NO₃ test guidelines for N management in durum and feed barley. In November 1998 one variety of durum (Kronos) and one variety of feed barley (Gustoe) were planted at the Maricopa Agricultural Center. Three N rates (80, 200, and 400 lbs N/acre) were applied in four split applications. Each treatment was replicated five times in a randomized complete block design. Samples were collected from lower stems at the 3-4 leaf 2 node, flag leaf visible, and heading growth stages. Grain yields ranged from 4330 lbs/A to 6794 lbs/A for Kronos and 3220 lbs/A to 4533 lbs/A for Gustoe. Correlation coefficients between stem NO₃-N and sap NO₃-N were 0.76 for Kronos and 0.60 for Gustoe. Sap NO₃-N analysis can be used to determine N status during the season for Kronos. Results for the barley suggest at low concentrations of NO₃ in the lower stem, the Cardy meter may underestimate NO₃ concentrations. This may be due to changes in moisture content in the stem as the season progresses.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/205172 |
| Date | 05 1900 |
| Creators | Riley, E. A., Thompson, T. L., White, S. A., Ottman, M. J. |
| Contributors | Ottman, Michael J. |
| Publisher | College of Agriculture, University of Arizona (Tucson, AZ) |
| Source Sets | University of Arizona |
| Language | en_US |
| Detected Language | English |
| Type | text, Article |
| Relation | AZ1147, Series P-119 |
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