Reliability of nitrate accumulation among a set of sorghum A-lines and sudangrasses

Authors: Boerman, Nicholas

Submitted to: National Association of Plant Breeders
Publication Type: Abstract Only
Publication Acceptance Date: 7/15/2022
Publication Date: 8/8/2022
Citation: Boerman, N.A. 2022. Reliability of nitrate accumulation among a set of sorghum A-lines and sudangrasses [abstract]. National Association of Plant Breeders. P. 88.

Interpretive Summary:

Technical Abstract: Sorghum is an important component of forage cropping systems in semi-arid environments. Accumulation of nitrate at levels toxic to livestock is a critical issue that often arises during times of drought stress or when high rates of nitrogen fertilizer is applied. Reducing nitrate accumulation through selection of improved germplasm could have a profound economic impact for producers. The objective of this study was to determine the reliability of nitrate accumulation for stem and leaf tissue of plants grown under high nitrate conditions. A sudangrass population selected for reduced nitrate accumulation and its base population, in addition to 20 sorghum A-lines were evaluated in a greenhouse over two growing seasons. 0.25 g ammonium nitrate was applied once every two weeks and approximately 100 ml of water was supplied daily through drip irrigation. Five to six weeks after planting, stem and leaf tissue were harvested, dried, and ground separately. A wet chemistry spectrophotometric method was used to quantify nitrate concentration. The reliability due to genotypes, defined as the genotypic variance divided by the phenotypic variance was 15% in leaf and 6% in stem tissues, respectively. Thus indicating 85-94% of the study’s variance was due to non-genetic effects. The large non-genetic effect makes selecting specifically for low nitrate accumulation challenging. Therefore, evaluation of advanced generation lines during multi-environment trials could be the most efficient manner to determine the line’s ability to accumulate nitrate. Additionally, four lines had less than 700 ppm change between growing seasons, indicating it may be possible to improve the stability of nitrate accumulation across diverse growing environments. Improving the stability of nitrate accumulation could lower the economic impact to producers by reducing the likelihood of dangerous nitrate accumulation in response to unexpected climatic events, such as drought.