Impacto da nutrição mineral no crescimento do Pinhão Manso (Jatropha curcas L.).

Abstract

Aiming evaluate the effects and mechanisms from the nutrient availability in the plant growth medium, seedlings of pinhão-manso (Jatropha curcas L.) had been watered with different concentrations of Hoagland solutions: 0(T1), 20(T2), 40(T3), 60(T4) and 80%(T5) of its original ionic concentration, for 90 days, under green house conditions. The treatments had five independent replications. The leaf dry mass production was higher at T3 and kept with minor variation in the following treatments. The stem and roots dry mass accumulation increased by increasing nutrient availability up to T3 and decreased back at greater than. The shoot to root ratios in T1 and T5 had been greater than 1.0 while in T3 it neared 1,0. Significant differences for plant height and leaf number were just observed 20 days after experiment starting. The leaf total proteins accumulation increased rapidly up to T3 and slowly in the subsequent treatments. The N concentration in leaves showed a similar pattern that found for total proteins; this way, increasing N concentration in the irrigation solution to 40% and above does not altered N metabolism. The highest leaf P concentration was recorded in plants grown in T5 although its root mass recorded at this treatment become lower, compared to T3. The leaf sodium concentration was never lower than potassium no matter what treatment was. The potassium accumulation in the leaves was not proportional to its increasingly concentration in the irrigation solutions. On the other hand despite its low concentration in the irrigation solution, sodium was accumulated greatly in the leaves in all treatments.