Wednesday, November 7, 2007
296-19
Nutrient Uptake and Manganese Response in Conventional and Glyphosate-resistant Soybean.
J.L. Loecker, N.O. Nelson, W.B. Gordon, L.D. Maddox, and K.A. Janssen. Agronomy, KSU, 2011B Throckmorton, Manhattan, KS 66506
Glyphosate-resistant (GR) soybean cultivars are widely accepted in the United States . Glyphosate-resistant technology provides many benefits to production agriculture, yet GR soybeans may require some additional management factors in order to obtain maximum yields. The objectives of this research are to determine (i) nutrient uptake in glyphosate-resistant and conventional (CV) soybean isogenetic lines and (ii) response of GR and CV soybean to manganese fertilization. A field study was conducted at 5 locations in Kansas from 2005 to 2007. Manganese soil test levels ranged from 15 to 52 ppm and pH ranged from 5.9 to 8.0. Soybean isolines were planted at each location in a split-block design with 4 replications. Manganese treatments consisted of soil-applied MnSO4 at 0, 2.8, 5.6, and 8.4 kg Mn/ha and foliar applied Mn at 0.22 and 0.45 kg/ha. Leaf tissue and whole plant samples were taken at approximately R1, R3, and R6 growth stages and analyzed for various nutrients such as Mn, N, P, K, Cu, Zn, and Fe. Whole plant samples were analyzed separated by leaves, stems, and pods. There were no significant differences between variety uptake for any of the nutrients. There were no yield differences between GR and CV isogenic lines at low yielding locations (< 3.3 Mg/ha). At high yielding environments, CV soybean yield was 600 kg/ha greater than GR soybean yield for the 0 kg Mn/ha rate. However, Mn additions increased yield of GR soybean by 540 kg/ha but did not affect CV soybean yield. Our results indicate no response to Mn treatments in CV or GR soybean at low yielding environments and in high yielding environments GR soybean respond positively to Mn treatments and CV soybean yields are not affected.