|May Iii, Oscar|
Submitted to: Journal of Sustainable Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/1998
Publication Date: N/A
Interpretive Summary: Cotton production costs are among the highest of all row crops. A significant production cost is amelioration of compacted subsoil layers by tillage operations. Most cotton is produced on soils that have hard subsurface layers which restrict root growth and limit yields. Producers have little choice but to mechanically disrupt the compacted subsoil layer to realize economically viable yields. Cotton varieties with roots able to penetrate the hard subsoil layer could allow growers to skip subsurface tillage operations and thereby reduce production costs and soil erosion. The objective of this study was to screen a wide array of cotton varieties to determine if any had the genetic ability to root through the hard subsurface soil. We did not find any variety that could root unimpeded through the hard soil layer. We did find some varieties with better rooting potential than others. Those varieties with better rooting ability can be used as parents of new varieties in the cotton breeding program, while those with poor rooting ability can be eliminated from consideration. We plan to screen more exotic germplasm in an attempt to identify germplasm with superior ability to root through hard soil layers.
Technical Abstract: Cotton production has increased dramatically on the Coastal Plain of southeastern USA since eradication of the boll weevil (Anthonomus grandis Boh.). 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. 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 at 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. Combined analysis of variance over years revealed significant genotypic variation and a genotype x yr interaction for root penetration of the pan. Despite the genotype x 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.