Abstract

This study aimed to investigate the gas exchange, growth and biomass production of Cnidoscolus quecifolius fertilized with potassium and submited to different water conditions. The experiment was conducted in a completely randomized design, with 4 replications and two plants per experimental unit, with treatments arranged in factorial scheme 3 × 4, corresponding to three levels of potassium (0 (control), 97.5 and 195 mg dm^-3 K) and four levels of water (100% (control), 75%, 50% and 25% of pot capacity). Growth (height, shoot diameter, leaf area, and dry mass) and physiogical parameters (water potencial (Ψw), stomatal conductance (gs), transpiration rate (E), net photosynthesis (A), CO₂ intercelular concentration (Ci), carboxylation efficiency (A/Ci), and intrinsic water use efficiency (A/E). Increase in potassium promoted rise in Ψw, gs, E, and A. However, it not influenced the growth parameters, except roots dry mass. Reduction in water levels reduced Ψw, gs, E and A, growth and dry matter production of plants. It is recommended that the substrate moisture level of 75% of the pot capacity in the early growth stages of faveleira seedlings.

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