1a.Objectives (from AD-416):
To develop high yielding drought tolerant cultivars adapted to Missouri and other drought-prone U.S. environments
1b.Approach (from AD-416):
Soybean germplasm will be screened to identify drought tolerance. Putative tolerant types will be verified. Genetics of the tolerance will be investigated. Drought tolerance genes, as found, will be transferred to adapted cultivars. This work will be pursued in lab, greenhouse, and field studies.
This project is related to Objective 3 of this in-house project: to discover novel genes/alleles in soybean for ‘tolerance to drought and related stress’, determine their inheritance, determine genomic location, transfer to adapted germplasm, and release. The Drought Tolerance project seeks to unlock the rich store of drought tolerance genes that exist in the USDA’s preserve of soybean germplasm. This preserve was formed by scientists through decades of work, combing the globe to find exotic soybean. This reservoir of exotic diversity, although collected by scientists, was produced originally by over 3000 years of ‘on-farm breeding’ in Asia, in which farmers adapted the soybean to a range of climate conditions. Special genes for drought tolerance, bred into soybean so long ago by these ancient farmers, are key to coping with the problem of drought in the USA today. The drought problem is so severe for our farmers in the USA because U.S. varieties do not presently contain these special drought genes from Asia. The central theme of our drought tolerance work is that we can ‘turn the tables’ on drought in the USA by putting the world’s genetic resources in soybean to work on U.S. farms. To that end, the United Soybean Board's drought tolerance project coordinates the research activities of 8 scientists and 7 research institutions in the Midwest and South. This effort is aimed at transferring drought genes from exotic Asian material into adapted genetic materials which will protect agriculture from damaging droughts.
An important and under researched aspect of drought tolerance is soybean rooting. As a first step in elucidating the importance of rooting, we described genetic diversity regarding rooting depth. More than 100 soybean genotypes were screened in the field. Rooting depth was assessed using herbicide placement approximately 3 feet deep in the soil, resulting in shoot symptoms as the roots reached and took up herbicide. This system worked effectively and genetic differences were noted. Field variability for this trait is high and tests were repeated to validate genotypic comparisons. Results suggest that a very few breeding lines and cultivars possess a deep rooting trait that may be valuable to soybean production. Hybridization of soybean genotypes to genetically test this hypothesis was completed, F1 plants grown in winter nurseries, and F2 populations were grown in 2012. F3 plants were grown in the USDA winter nursery in 2012-13 and F4 plants are being increased in 2014.