Peanut Genotypic Root Architecture in Response to Irrigation.

The Southeastern United States accounts for approximately 75% of the entire peanut (Arachis hypogaea L.) production in the United States (NASS, 2015). Florida is the second largest peanut producing state where the predominant peanut production occurs on sandy soil textures that are characterized as well drained soils. The high permeability of these soils can results in the depletion of plant available water (PAW) to occur relatively quickly, providing the need for supplemental water application to avoid reductions in peanut yields and economic losses. The overall objective of this research are to quantify peanut genotypic responses to irrigation during phenological development for identifying periods of crop development where water savings can occur without reducing production, providing a possibility to reduce water consumption and variable cost associated with crop production. A field study was initiated in 2015 at the University of Florida’s Plant Science Research and Education Unit in North Central Florida (29° 24' 38" N, 82° 10' 12" W). Irrigation and peanut genotype treatments were randomized in split plot arrangement with irrigation as the whole plot and peanut genotype as the sub-plot. Rainout shelters were used to shed rainfall on plots until first bloom and irrigation treatments included: 1) 1.9 cm (100%) for the entire season; 2) 1.1 cm until mid-bloom and 1.9 cm following mid-bloom (60% of optimum treatment). Following first bloom, both irrigation treatments were irrigated similarly. In 2015, the genotype COC 041 responded to the 60% irrigation treatment by producing a greater amount of root area at deeper soil depths of 45-60 and 60-75 cm, while no differences in root area were observed between the two irrigation treatments with the peanut genotype TUFRunner^TM ‘511’. These results indicate that root growth plasticity exist among peanut genotypes in their response to varying amounts of soil water. This study is being repeated in 2016 to further assess the consistency of these genotypic root responses across environmental variation, and to assess soil water fluctuations which may result from different genotypic root architectures.