Phosphorus (P) is one of the most critical elements for agriculture, not only by the high P requirement for adequate crop growth and development, but also by the gradual scarcity of its natural sources. The differentiation among genotypes is required for further mechanism investigation, and to combine different mechanisms at the same individual which might allow superior tolerance. This work aimed to differentiate, in hydroponic solution, wheat genotypes with contrasting P deficiency tolerance. Three studies were carried out. In the first one, the effect of endosperm removal on wheat seedling P response was evaluated. In the second one, seedlings from two wheat cultivars contrasting in the response to P starvation, Anahuac (sensitive) and Toropi (tolerant) were evaluated at different P availabilities. In the third study, five recombinant inbred lines were evaluated in hydroponic solution. The wheat endosperm contains enough P to mask the seedling P response. The endosperm removal allows evaluation of P tolerance in 10 days-old seedlings. The ratios between shoot free phosphate (Pi) concentration at 10 and 1.000 µmol L-1 P doses can identify the tolerant genotypes. Tolerant genotypes have a ratio around 1.0 and sensitive ones have around 0.5 ratio. The total amount of Pi in the shoot or in the whole plant can also be used. Toropi and the inbred lines NYW 865-016, NYW 865-081 and NYW 865-086 are more tolerant than Anahuac and the inbred lines NYW 865-034 e NYW 865-073. Toropi tolerance, at the conditions used in this work, is not due to root system volume but might be related to P transport and P internal use.
Triticum aestivum; phosphate; initial growth
