Location: Soybean and Nitrogen Fixation ResearchTitle: Expression of drought-tolerant N2 fixation in heterogeneous inbred families derived from PI 471938 and Hutcheson soybean
|RIAR, MANDEEP - North Carolina State University|
|CEREZINI, PAULA - Londrina State University|
|MANANDHAR, ANJU - North Carolina State University|
|SINCLAIR, THOMAS - North Carolina State University|
|LI, ZENGLU - University Of Georgia|
|Carter Jr, Thomas|
Submitted to: Crop Science Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/15/2017
Publication Date: 1/15/2018
Citation: Riar, M.K., Cerezini, P., Manandhar, A., Sinclair, T.R., Li, Z., Carter Jr, T.E. 2018. Expression of drought-tolerant N2 fixation in heterogeneous inbred families derived from PI 471938 and Hutcheson soybean. Crop Science Society of America. 58:364-369. https://doi.org/10.2135/cropsci2017.02.0089.
Interpretive Summary: Summer drought has always been the most important barrier to profitable soybeans. Few soybeans are irrigated. Thus, drought-tolerant soybean varieties are an economic alternative to irrigation. Drought tolerance is rare or absent in US grown soybean, but has been discovered in a few exotic Asian soybeans. One such exotic type, PI 471938 from Nepal, is unusual in that it can sustain N fixation longer than US types during a drought. US breeders are now working to transfer this trait to commercial cultivars. However, the inheritance of this new trait (ease of manipulating the trait in plant breeding) is not well understood. This paper sheds light on the inheritance of sustained N fixation and helps breeders better understand how to select and use this trait in their research programs.
Technical Abstract: Nitrogen fixation of soybean is particularly vulnerable to drought, since, in most genotypes, N2 fixation activity decreases very early in the soil drying cycle. Although a few soybean genotypes, including ‘PI 471938’, have been identified that express N2 fixation tolerance of drought, it is unknown how readily this trait is transferred to progeny. Unfortunately, the techniques used to pheno¬type for the tolerance trait are either too crude or too labor-intensive to allow the acquisition of data required for a classical inheritance assess¬ment. In this study, a heterogeneous inbred family (HIF) population derived from PI 471938 × ‘Hutcheson’ was studied for its N2 fixation drought tolerance to obtain a preliminary indi¬cation of the expression of this trait in progeny genotypes. An in situ flow-through acetylene reduction assay was used to track the N2 fixation rates of 13 HIFs over dry-down periods lasting about 2 wk. There was a distinct segregation among the HIFs, with nine exhibiting tolerance equivalent to PI 471938 and four exhibiting sensitivity equal to or greater than Hutcheson. These results indicate that N2 fixation drought tolerance might be transferred to progeny lines fairly readily, or at least retained in a selected population such as these HIFs.