Nitrogen Metabolism of Stargrass as Affected by Nitrogen and Soil Salinity1
- G. W. Langdale,
- J. R. Thomas and
- T. G. Littleton2
Interactive effects of soil salinity and N fertilizer on stargrass (Cynodon plectostachyus (K. Schum.) Pilger) growth and N metabolism were investigated. Nitrogen contents were partitioned to study the effects of substrate salinities on hydrolysis of protein-N and the accumulation nonprotein-N assimilates. Mixed chloride-sulfate solutions of the same ionic ratios and electrical conductivities (EC) of 4.8, 9.6, and 14.4 mmhos/cm were equilibrated with Brennan fine sandy loam (Typic Haplustalf) soil, after which N was applied in a factorial arrangement at rates of 0, 67, 133, and 200 mg/kg of soil.
Nitrogen fertilizer interacted significantly with soil salinity to stimulate dry matter and protein-N yields at the 4.8-mmhos/cm level. No evidence of a toxic nonprotein-N accumulation in plant tissue was observed even with high N fertilization at this salinity level. The 9.6-mmhos/cm salinity treatment was considerably more deleterious to dry matter than to protein-N production processes. Dry matter production and protein-N synthesis were severely inhibited at the 14.4.mmhos/cm salinity level although NO3-N appeared to be adequately absorbed and reduced.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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