Phosphate availability in combination with nitrate availability affects root yield and chicon yield and quality of Belgian endive (Cichorium intybus).

摘要

Chicory cv. Flash plants were grown on sand in tanks in the open at Versailles, France, and were given nutrient solutions containing 0.6 or 3.0 mM NO3- and 0.05 or 1.00 mM PO43-. The results suggested that N limitation had the greatest impact on theshoot:root dry weight ratio; only small changes in the ratio could be attributed to P limitation alone. In the first half of the growing season, N limitation caused significant increases in the activity in the roots of sucrose sucrose fructosyl transferase, responsible for fructan synthesis, and sucrose synthase, responsible for sucrose catalysis; the effect of P limitation on their activity was less pronounced. With N limitation, P uptake was decreased by 40-60% over the experimental period. P limitation decreased N uptake by 60% during the tuberization period (107 days after sowing (DAS)). With N limitation, P concentrations in roots were decreased by 20-25%. With P limitation, total N concentration in roots was decreased by 50%, while nitrate concentration was increased more than 8 times. These effects were detected only at 107 DAS. The total amino acid content of roots was not affected by P limitation, but was reduced by N limitation. P limitation did altered the relative amino acid composition of roots early in the vegetative period. Roots harvested at the end of the vegetative period were forced in the dark to produce an etiolated bud, the edible chicon. High N and P availability were associated with poor chicon yield and quality. Low P duringthe vegetative period moderated the adverse effects of high nitrate and greatly improved chicon yield and quality.