Phosphorus and carbohydrate metabolism in green bean plants subjected to increasing phosphorus concentration in the nutrient solution

Abstract

Phosphorus (P) is considered an elementary mineral nutrient for plants. Nevertheless, excessive or deficit supply to the crop may cause negative changes at the physiological level. Plants were cultivated in pots in a growth chamber under increasing P concentration (P1 (0.5 mmol/L (con-trol treatment)), P2 (1 mmol/L); P3 (2 mmol/L); P4 (4 mmol/L); P5 (6 mmol/L), and P6 (8 mmol/L)) in the nutrient solution for 40 days. At the end of the experimental period, biomass, carbohydrates concentration, and enzymatic activities related to the synthesis and degradation of sucrose as well as the different fractions of P in different organs of the plant were assessed. The results obtained in this experiment reveal a decrease in biomass under increasing P supply. Fructose, glucose, sucrose, and starch concentrations were higher in the shoots compared to the roots. There were different trends in the roots and shoots in enzymatic activities related to sucrose. The increase in P dose increased the concentration of the different forms assessed for P in all the organs studied. Seed phytate concentration surpassed the threshold established by the Food and Agriculture Organization (FAO) for green bean plants grown under P4, P5, and P6 treatments. Considering the results obtained, we suggest fertigation with a concentration of 2 mmol/L to obtain a higher productivity without excess of phytate in seeds.