Dynamics of absolute and relative growth and net assimilation in potatoes (Solanum tuberosum L.) under the influence of cattle and guinea pig manure, H2Organix levels, and evaluation period

Abstract

The study was conducted in Challajauira, La Paz, Bolivia, with the objective of evaluating the effect of cattle manure versus guinea pig manure and four levels of H2Organix on the absolute growth rate (AGR), relative growth rate (RGR), net assimilation (TAN), and potato (Solanum tuberosum L.) yield over four periods (days) and six replicates, with the goal of improving microbial efficiency in mineralization and increasing yield. The data were analyzed using mixed-effects linear models, Tukey's post hoc tests, and Pearson's correlation analysis in the R Project v4.4.3 software. Guinea pig manure significantly outperformed cattle manure in TCA (1.55 vs. 1.04 g/day) and yield (1075 vs. 794 g/plant), with no differences in TCR or TAN. The period was the determining factor for all variables, with maximum TAN at 32 days (0.00234 g/cm² day), maximum TCR at 63 days (0.0824 g/g day), maximum TCA at 91 days (3.18 g/day), and maximum yield at 152 days (1.728 g/plant). H2Organix levels did not influence growth. The correlation analysis showed that TCA (91 days) was the best predictor of final yield (r = 0.490). The models explained between 46.6 % and 68.5 % of the variability (conditional R²). It is concluded that guinea pig manure improves absolute growth and potato yield; the period is the dominant factor; the addition of H2Organix does not provide additional benefits under the evaluated conditions; and TCA at 91 days is an early indicator of yield.