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Relationships of N, P, and K with the chlorophyll fluorescence, leaf nutrient accumulation, and soluble carbohydrate concentration in the stem of Caesalpinia echinata Lam

ABSTRACT

The aim of this study was to evaluate the effect of N, P, and K in the accumulation of these elements in the leaf and their relations with the chlorophyll a fluorescence parameters and with the concentration of soluble carbohydrates in stems of young plants of Caesalpinia echinata.Eight-month-old plants were grown in polyethylene pots. which received N, P, and K in isolated form ((NH4)2SO4, P2O5, KCl) and the combined form NPK in the ratio 10:10:10 and 04:14:08. The pots were arranged in randomized blocks. The applications were repeated each 90 days during 450 days. The results demonstrated that C. echinata is more responsive to N. Plants showed higher leaf N concentrations and positive correlation with the concentration of chlorophyll a and b. However, the treatments did not influence the potential quantum yield of PSII (FV/FM) and the performance index (PITOTAL). The concentration of sucrose in the stem bark was higher than that of secondary xylem and superior in fertilizers rich in P (P and NPK 04:14:08) suggesting increased demand of substrate for forming the wood in these treatments, which could result in more resistant stems and higher survival of the plants under field conditions.

Keywords:
Brazilwood; fluorescence; nutrients; soluble carbohydrates

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