Date of Award
Master of Science
Antonio P. Mallarino
Interest in re-evaluating the value of tissue testing to assess P and K status in corn (Zea mays L.) and soybean (Glycine max L. Merr.) is increasing. The objective of this research was to study relationships between grain yield response to P and K and the concentration of these nutrients in plant tissue. Single-year and multi-year response trials were conducted in Iowa at 30 sites for P (32 sites-years with corn and 34 with soybean) and at 53 for K (67 sites years with corn and 52 with soybean) that encompassed 17 soil series. We sampled above-ground plant parts at the V5-V6 growth stage, corn ear-leaf blades at the R1 stage, and uppermost trifoliolate soybean leaves at R2-R3 stage. Critical concentration ranges were defined using linear-plateau and quadratic-plateau models. All models fit significantly (P ≤ 0.01) and R2 values were 0.31-0.45 for corn plants P, soybean plants and leaf P, and soybean plant K; 0.51-0.53 for K in corn plants and leaves and soybean leaves K; and 0.62-64 for corn leaf P. Critical concentration ranges were 4.8-5.5 and 2.5-3.1 g P kg-1 and 18.8-25.4 and 10.6-14.2 g K kg-1 for corn plants and leaves; and 3.3-4.1 and 3.5-4.7 g P kg-1 and 18.9-22.7 and 15.6-19.9 g K kg-1 for soybean plants and leaves. We conclude that P testing of corn ear-leaves at R1 was better than of young plants at V5-V6 but either tissue provided similar K assessments. Testing soybean plants for P at V5-V6 was better than testing leaves at the R2-R3 stage but K testing of leaves was better than K testing of plants.
Andrew John Stammer
Stammer, Andrew John, "Plant tissue analysis to assess phosphorus and potassium nutritional status of corn and soybean in Iowa" (2015). Graduate Theses and Dissertations. 14709.