Pinhão-manso: crescimento sob condições diferenciadas de irrigação e de adubação no semiárido nordestino Jatropha: growth under different conditions of irrigation and fertilization in the northeastern semiarid

Uma das alternativas para ocupação do espaço deixado pelo algodão no semiárido cearense é o cultivo do pinhão-manso (Jatropha curcas L.) visando à produção do biodiesel. Face ao exposto, realizou-se este trabalho de campo para avaliar os efeitos de diferentes lâminas aplicadas (735,53; 963,30; 1.191,03; 1.418,82 e 1.646,60 mm) e níveis de adubação nitrogenada (0; 25; 50 e 75 kg ha-1 de N) no crescimento da cultura do pinhão-manso. Os dados referentes ao crescimento da fitomassa fresca epígea foram obtidos em sete diferentes épocas do ciclo da cultura (30; 60; 90; 120; 150; 180 e 210 dias após poda). De acordo com os resultados, a altura caulinar e a taxa de crescimento relativo em altura caulinar obtiveram comportamento linear e crescente com o incremento das lâminas aplicadas. A época de coleta influenciou não apenas os valores de altura, mas também de diâmetro caulinar obtendo-se, em ambas as variáveis, comportamento linear ao decorrer da condução do experimento. Houve um declínio nos valores da taxa de crescimento relativo em altura e no diâmetro caulinar causado pelos fatores climáticos (temperatura, umidade relativa, pluviosidade e evaporação) e pelo início da floração e formação de frutos.One of the viable alternatives for the occupation of the space left by the cotton in the semiarid of Ceará is the cultivation of Jatropha curcas L. aiming the production of biodiesel. Thus, this study aimed to evaluate the effects of different levels of irrigation water (735.53, 963.30, 1191.03, 1418.82 and 1646.60 mm) and nitrogen fertilizer (0, 25, 50 and 75 kg N ha-1) on the growth of the Jatropha curcas L crop. The data regarding the growth of fresh biomass epigeal phytomass were obtained at seven different crop cycle times (30, 60, 90, 120, 150, 180 and 210 days after pruning). According to the results, the stem height and the relative growth rate in stem height had a linear increase with the increase of water depths. The collection time influenced the values of height and stem diameter, resulting in both a linear behavior over the course of the experiment. There was a decline in the values of relative growth rate in height and stem diameter caused by climatic factors (temperature, relative humidity, rainfall and evaporation) and the onset of flowering and fruit formation

Production components of Jatropha under irrigation and nitrogen fertilization in the semiarid region of Ceará

ABSTRACTJatropha curcas L. proves to be a promising species, considering its inclusion in the National Program of Biodiesel Production and Use. However, since it has not been genetically improved, agronomic information is still scarce in the literature, especially under conditions of water and nutritional stress. Thus, this field study aimed to evaluate the effects of irrigation depths (735; 963; 1,191; 1,418 and 1,646 mm) and nitrogen fertilization (0; 25; 50 and 75 kg ha-1) on the production of Jatropha plants. Plants under the highest irrigation depth showed the highest values of number of fruits and productivity of fruits, seeds and albumen. Plants under the irrigation depth of 1,191 mm showed the highest values of mean mass of albumen and the ratios between mass of albumen and mass of seeds and between mass of albumen and mass of fruits. Nitrogen fertilization did not influence the production components of Jatropha