Relationship Between Productivity and Phosphate Requirement as a Parameter of Selection inMedicago rigidula(L.) Allioni

摘要

AbstractAmong one hundred lines ofMedicago rigidula(L.) Allioni, fifteen (5 high‐producing, HP, 5 intermediate‐producing, IP, and 5 low‐producing, LP) were chosen as experimental material because of their different dry‐matter production when grown at 0.5 mg L‐1of P2O5in hydroponic solution (critical level). The aim of this work was to evaluate the response to selection with respect to dry‐matter yield (DMY), made at 0.5 mg L‐1of P2O5and to check if superior lines could also be isolated when plants were grown at 20 and 200 mg L‐1of P2O5. Results show that HP lines were also superior with respect to DMY (g/plant) at the higher phosphorus concentrations. Highly‐productive line selection inM. rigidulacan also be achieved when plants are grown at a critical level of phosphorus in the nutrient solution. Phosphate content in the dry matter produced and phosphatase activity were also analysed. Plants of the more‐productive lines were characterized by lower phosphate content per unit dry matter and by a higher p