Relationship Between Soybean Yields and Leaf Levels of 10 Elements Determined with Different Regression Models1
- W. M. Walker,
- T. R. Peck and
- S. G. Carmer2
Soybean leaf samples and yields were obtained from experimental plots receiving varying levels of P and K. Yields were regressed on a quadratic polynomial with leaf levels of P and K as variables. This regression had an R2 of 0.495. Yields were regressed on a second quadratic polynomial with leaf levels of N, P, K, Ca, Mg, B, Cu, Fe, Mn, and Zn as variables. With the stepwise regression procedure used for fitting the model, 22 linear and second order terms were fitted to the data. This regression had an R2 of 0.813. The additional variation accounted for by the second regression was statistically significant.
Other polynomial regressions were fitted to the data using ratios of elements as independent variables, but none were superior to the quadratic polynomial in terms of R2 values.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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