Ecophysiological determinants of tuber yield as affected by potato genotype and phosphorus availability

The aim of this study was to evaluate the sensitivity of eco-physiological determinants of tuber yield in different potato genotypes (Solanum tuberosum L.) in response to phosphorus (P) availability. Two field experiments (Experiments 1 and 2) were carried out in southern Chile. In each experiment treatments were a factorial combination of (i) twenty-two genotypes of potatoes and (ii) two P fertilization rates (0 and 130 kg P ha(-1), -P and +P, respectively). Tuber yields were affected (P< 0.05) by the P rate, genotypes and the P rate x genotype interaction. Depending on the genotype, yield reduction ranged between 20 and 66%. Across experiments, tuber yield responses were highly related (R-2 = 0.93, P< 0.01) to total biomass and not to harvest index. The harvest index was only affected (P< 0.05) by the genotype. In both experiments, radiation intercepted was affected by the P rate, genotype and the P rate x genotype interaction, while radiation use efficiency was only affected by the genotype as well as by P rate x genotype interaction in Experiment 2. Total biomass was better related (P< 0.01) to radiation intercepted than to radiation use efficiency. Therefore, changes in tuber yield were related (P< 0.001) to the changes in intercepted radiation in response to P deficiency. In addition, the results showed that yield, biomass and radiation intercepted responses to P fertilizer varied with genotype. The present study demonstrated in a broad range of genotypes that radiation interception is more important than radiation use efficiency in determining potato yield under P deficiency. Based on genotypic variability in yield response and sensitivity of radiation intercepted to P deficiency, there is potential for improving P use efficiency in potato production systems through breeding and crop management programs. (C) 2015 Elsevier B.V. All rights reserved.