Using upper-bound slope through origin to estimate genetic harvest index.

(...) We propose that the slope of an upper-bound in the grain yield vs. dry matter plot passing through the origin approximates the genetic harvest index (HI) because the highest grain yields against given dry matter represent the least-stressed and/or stress-adapted plants and passage of the line through the origin is necessary to satisfy the definition of HI. This HI also provides a useful reference for interpreting agronomic data with respect to stress effects associated with management practices (...)