Biomass production and phosphorus accumulation of potato as affected by phosphorus nutrition

Potato (Solanum tuberosum) generally requires high amounts of phosphate fer tilizer to reach economically acceptable yields, particularly in soils orig inating from volcanic ash. This is a consequence of the potato plants low s oot density and the slow soil diffusion rate of phosphorus (P) in these soi ls. Our objective was to evaluate the effect of P rates on tuber yield, bio mass production, and distribution, biomass P accumulation and concentration , and P distribution in potato cv. Mexiquense. The experiment was carried o ut in an Andisol (7.8 mu g g(-1) Olsen-P) located at the east of Valle de M exico. Fertilization rates were 0, 18, 41, 46, 69, 78, 90, 106, 113, 135, 1 50, 163, and 207 kg ha(-1) P, from ordinary superphosphate. Top growth and root biomass, tuber yield, P percentage and P accumulation in different pla nt parts were measured at harvest. Minimum and maximum average tuber yields were 8.4 and 18.0 Mg ha(-1); the plants absorbed 5.8 and 11.8 kg ha(-1) P, corresponding to 0 (control) and 207 bg ha(-1) P, respectively. Phosphorus fertilization had little influence on plant P concentration, where average concentrations in tuber and top growth were 0.20 and 0.24% P, respectively . By contrast, P accumulation increased with increasing P rates, but P dist ribution between tuber and top growth was dependent on the amount of P appl ied. The control treatment showed approximately 1:1 distribution of P betwe en top growth and tuber, but as P rate increased, top growth P decreased an d tuber P increased. When applying the highest P rate, 36% of P accumulated in the top growth and 64% in the tuber. The information obtained will perm it decisions on the correct use of phosphate fertilizer for potato in Andis ols of the Valle de Mexico.