Seedling emergence and early growth of jatropha plants exposed to aluminum Emergência de plantulas e crescimento inicial do pinh o manso exposto a alumínio

Jatropha curcas L. is a potential oilseed crop for biodiesel production with scarce information about the aluminum effect on the emergence and early growth. This work aimed to evaluate the seed germination and early plant growth of Jatropha plants subjected to aluminum in the irrigation water. Seedlings emergence was evaluated in the presence of five concentrations of aluminum chloride hexahydrated (AlCl3.6H2O) in irrigation water: 0, 5, 10, 15 and 20 mmol L-1. Data was taken on percentage of seedling emergence, speed index, average time for emergence, height, root lengths and shoot and root dry weights. In another experiment, the plants were raised in absence of aluminum up to 25 days after sowing (DAS) and then subjected to the same aluminum concentration in the first experiment. Data was taken on survival rate, chlorophyll content, leaf area, height, root length and shoot and root dry weights. The emergence and speed index of Jatropha seedlings was reduced by the increased aluminum concentrations in irrigation water, with a decrease in seedling emergence of 98% at concentration of 20 mmol L-1. The plants exposed to aluminum at 25 DAS had leaf edge rolling, leaf chlorosis and necrosis, and reduced survival rate, leaf area, chlorophyll content, and shoot and root lengths and dry weights. Therefore, the aluminum in solution affect the seedlings emergence and early growtht of Jatropha plants, observing its toxic effect from the concentration of 5 mmol L-1. O pinh o manso (Jatropha curcas L.) é uma oleaginosa com potencial para a produ o de biodiesel com poucas informa es a respeito do efeito do alumínio sobre a germina o e crescimento inicial. Objetivou-se avaliar a germina o de sementes e o crescimento inicial do pinh o manso exposto a solu es de alumínio na água de irriga o. No primeiro experimento avaliou-se a emergência das plantulas na presen a de cinco concentra es da solu o de alumínio hexahidratado (AlCl3.6H2O) na água de irriga o: 0, 5, 10, 15 e 20 mmol L-1. Avaliou-se a porcentagem, o índice de velocidade e o tempo médio de emergência, altura, comprimento das raízes e massas secas da parte aérea e das raízes das plantulas. No segundo experimento as plantas foram mantidas livres de alumínio até os 25 dias após a semeadura (DAS) e foram ent o expostas às mesmas concentra es de alumínio do primeiro experimento. Avaliou-se a porcentagem de sobrevivência, índice de clorofila, área foliar, altura, comprimento das raízes e massas secas da parte aérea e das raízes. A emergência e a velocidade de emergência das plantulas de pinh o manso foram