Date of Graduation
12-2015
Document Type
Dissertation
Degree Name
Doctor of Philosophy in Crop, Soil & Environmental Sciences (PhD)
Degree Level
Graduate
Department
Crop, Soil & Environmental Sciences
Advisor/Mentor
Nathan A. Slaton
Committee Member
Larry C. Purcell
Second Committee Member
Trenton L. Roberts
Third Committee Member
Andy Mauromoustakos
Fourth Committee Member
Steve Phillips
Keywords
Biological sciences, Nutrient management, Plant analysis, Plant nutrition, Potassium, Soil fertility, Soybean
Abstract
The potassium (K) requirement of soybean [Glycine max (L.) Merr.] was investigated to determine whether cultivar sensitivity to K deficiency was affected by growth habit (determinate or indeterminate) and how cultivars from each growth habit accumulate and distribute K among plant structures. We also diagnosed K deficiency across reproductive growth stages (R2-6) using trifoliolate leaf- and petiole-K concentrations and at harvest (R8) using seed-K concentration. Soybean responded similarly to K deficiency in terms of yield, selected yield components, and seed-K concentration, regardless of growth habit. The yield loss from K deficiency was greatest on the middle to upper nodes of the indeterminate cultivar and bottom and upper-middle nodes of the determinate cultivar. Seed-K concentration decreased from the bottom to the top nodes of K-deficient plants compared to K-sufficient plants, suggesting K concentration of seeds collected from the upper nodes would be of value for diagnosing K deficiency. We found that both growth habits accumulated maximal K at the R5.5-6.0 stage with the peak accumulation rate at the R3-4 stage. Soybean accumulated 35-45% of the maximum K by the R2 stage and 65-70% by the R4 stage, suggesting that K deficiency of soybean could possibly be corrected by timely fertilization during the early reproductive stages. Trifoliolate leaf- and petiole-K concentrations from the R2 to R5.5 stages were highly correlated with relative soybean yield. The K concentrations in both tissues peaked near the R2 stage and declined linearly at a constant rate with increasing plant age regardless of cultivar, site-year, and K fertility level, indicating that the critical K concentration at each stage beyond the R2 is a negative linear function of time. Mature seed-K concentration across 100 site-years in North America was strongly correlated with relative soybean yield and may seed analysis be an effective post-season tool for diagnosing K deficiency. The threshold of deficient seed-K concentration (
Citation
Parvej, M. (2015). Defining the Potassium Nutritional Requirements and Distribution among Plant Parts of Representative Soybean Cultivars from Different Maturity Groups. Graduate Theses and Dissertations Retrieved from https://scholarworks.uark.edu/etd/1341