Biodiesel is an alternative to petroleum diesel fuel. It is a renewable, biodegradable, and nontoxic biofuel. Interest in the production of biodiesel from Jatropha curcas L. seeds has increased in recent years, but the ability of J. curcas to grow in salt-prone areas, such as the Caatinga semiarid region, has received considerably meager attention. The aim of this study was to identify the main physiological processes that can elucidate the pattern of responses of J. curcas irrigated with saline water, which commonly occurs in the semiarid Caatinga region. This study measured the activity of the antioxidant enzymes involved in the scavenging of reactive oxygen species, which include catalase (CAT) and ascorbate peroxidase (APX), as well as malondialdehyde (MDA) levels. The levels of chlorophyll (Chl), carotenoids, amino acids, proline, and soluble proteins were also analyzed. The net carbon assimilation rate (P N), stomata conductance (g s), and transpiration rate (E) decreased with salt stress. The activities of CAT and APX were decreased, while H2O2 and MDA levels as well as electrolyte leakage were significantly increased in salt-stressed plants compared to the untreated ones. These observations suggest that the ability of J. curcas plants resist to salt stress is associated with the activities of protective enzymes and their defensive functions. However, our results indicate that the reactive oxygen species scavenging system is not sufficient to protect J. curcas leaves against oxidative damage caused by salt stress, and, therefore, it cannot be treated as a salt tolerant plant species.

Experiências conduzidas em Campinas (solo Latosol Roxo) e Pindorama (solo Podzolizado de Lins e Marília, variação Marília), para estudar os efeitos de diversos tipos de matéria orgânica não decomposta, na presença de adubações minerais com P, PK, NP ou NPK, mostraram que, dos adubos minerais, sòmente o nitrogênio aumentou substancialmente a produção do feijoeiro. Dos adubos orgânicos comparados - ramas de soja perene, capim-gordura, fôlhas de café e serapilheira - o primeiro foi o mais eficiente. Em Campinas, as ramas de soja aumentaram a produção, tanto na ausência como na presença do nitrogênio mineral, quer aplicadas em sulcos laterais aos destinados às sementes de feijão, quer em cobertura, após a emergência das plantas. Em Pindorama, porém, só atuaram favoravelmente quando empregadas em sulcos laterais, na ausência do nitrogênio mineral.

Experiments were conducted at Campinas and Pindorama, State of São Paulo, to study the effects of the indicated treatments on dry beans (Phaseolus vulgarisL.) Of the mineral fertilizers, only nitrogen increased the yields in both localities. Of the organic materials - Glycine javanica, Melinis minutiflora, coffee tree leaves and forest litter - the first mentioned was the most effective. In the Campinas experiment, G. javanica induced considerable yield increases, either when side placed or top dressed in the absence or in the presence of mineral nitrogen. At Pindorama, however, it was effective only when side placed in the absence of mineral nitrogen.