Genotypic Variation for Root Penetration of a Soil Pan

Abstract

ABSTRACT Cotton production has increased dramatically on the Coastal Plain of the southeastern USA since eradication of the boll weevil (Anthonomus grandis [Boh.]) in the late 1980s. Most of the cotton production in this area occurs on soils possessing subsoil pans. Soil pans limit root growth, requiring mechanical disruption to increase the root zone and facilitate cotton growth. Mechanical amelioration of a soil pan has several disadvantages including expenses for equipment and energy, equipment to break up the pan may not be available, and the effects of mechanical disruption are temporary and contribute to soil erosion. The need for soil pan disruption might be eliminated or reduced with cotton germplasm capable of rooting through high strength soil. Our objective was to identify germplasm with superior rooting ability and thereby initiate breeding efforts incorporating this trait into cultivars. Cultivars and Pee Dee germplasm lines were evaluated at Florence, SC for 2-yr without irrigation for root penetration of a naturally occurring soil pan. Roots were excavated at maturity and rated on a 1–5 scale based on magnitude of the root penetration of the pan. Combined analysis of variance over years revealed significant genotypic variation and a genotype yr interaction for root penetration of the pan. Despite the genotype yr interaction, we identified germplasm that could partially root through the pan. Additionally, we were able to eliminate those genotypes with poor rooting characteristics from further consideration as parents in the breeding program. Cultivars with ability to penetrate a soil pan would make a valuable contribution to sustainable cotton production systems for the USA and developing countries.