Comparison of potato (Solanum tuberosum L.) tuber size distribution fitting methods and evaluation of the relationship between soil properties and estimated distribution parameters

Abstract Accurate estimation of tuber size distribution (TSD) parameters in discretely categorized potato ( Solanum tuberosum L ) yield samples is desirable for estimating modal sizes, which fundamental to prediction. In the current work, systematic digs were conducted on five commercial fields N = 119) compare Weibull, Gamma and Gaussian functions relative-likelihood-based goodness-of-fit observed discrete distributions. Parameters estimated using maximum likelihood (MLE) three distributions but also derived percentiles approach Weibull accuracy against MLE approaches. The relationship between TSD soil nutrient variability was examined best-fitting model's parameters. had lower overall relative than approaches across locations, consistently Root Mean Square Error marketable range. Negative relationships percentile-based shape parameter concentrations Phosphorus Nitrogen, with significant (non-zero-overlapping 95% confidence interval) regression coefficients P (−0.74 ± 0.33 proportional numbers −1.3 0.62 weights). Stem density negatively associated scale mode number (regression −0.98 0.63 −1.08 0.78 respectively) weight −0.99 −1.04 0.69 related tuber-number-based while positively associating distribution. results suggest that excess application increase small tubers did not contribute final yield.