Abstract

The objective of this study was to quantify the nutritional efficiency and responsiveness in relation to nitrogen of twelve genotypes of physic nut (Jatropha curcas L.) grown in soil without nitrogen supply and also with three levels of fertilization in a controlled environment. The experiment was conducted in factorial scheme 12 × 4 with four replications, the factors being: 12 genotypes of physic nut and four levels of nitrogen fertilization, studied in a randomized design. The plants were grown in pots, without restrictions, for 100 days and their dry matter and N contents were evaluated (for roots, leaves and total). Subsequently, the efficiency ratios for absorption, translocation, use and responsiveness in relation to the N supply were calculated. Overall, the nutritional efficiencies for nitrogen increase linearly with the increase of nitrogen supply in the soil. The genotypes CNPAE 161-II, CNPAE 167-II, CNPAE 180-I, CNPAE 255-I and CNPAE 300-I were classified as efficient and responsive to nitrogen fertilization being highlighted for plant breeding programs aiming to improve this agronomic trait.

Key words: Physic nut, mineral nutrition, alpha parameter.