Effect of culture medium nitrogen, phosphorus and potassium on the yield and nutritive value of Lemna gibba L. (Lemnaceae)

Abstract

Lemna gibba was grown in outdoor to determine the effect of three N-NH4 + :N-NO3 - proportions (1:3, 1:1 and 3:1), as well as the phosphorus (1,5; 3,0 and 4,5 mg.L-1) and potassium (3,0; 6,0 and 9,0 mg.L-1) concentrations added to the culture medium, on the yield and nitrogen, phosphorus and potassium content. Both, fresh and dry weight yields decreased as N-NH4 + proportion increased. Increasing culture medium potassium concentration favored the fresh weight yield. Dry matter content decreased with both N-NH4 + proportions higher than N-NO3 - and increasing the potassium concentration in the culture medium. Nitrogen uptake and content enhanced with high N-NH4 + proportions; and, by increasing phosphorus and potassium concentrations in the culture medium. Phosphorus and potassium uptake and content increased as their respective culture medium concentration increased. High proportions of N-NH4 + in the culture medium decreased phosphorus and potassium content in dry matter. L. gibba yields and crude protein content are optimize with culture medium N-NH4 + :N-NO3 - proportion of 1:1 and 3:1 respectively. Potassium and phosphorus concentrations over 9 and 4,5 mg.L-1 respectively are optimal.