Physic nut plants present high mycorrhizal dependency under conditions of low phosphate availability

Abstract

The physic nut (Jatropha curcas L.) is a perennial tree that occurs naturally in the tropical and subtropical regions of Brazil. Fruits of physic nut present an oil content of 28% on a dry weight basis. Although the plant has adapted to diverse soil conditions such as low fertility, the correction of soil acidity and the addition of fertilizer are essential for highly productive plants. Thus, the response of the physic nut to different soil phosphorus levels (P) and arbuscular mycorrhizal fungi (AMF) inoculation must be characterized. Hence, the objective of the present study was to evaluate the response of physic nut seedlings to arbuscular mycorrhizal fungi (AMF) inoculation at different levels of soil P. Experiment was carried out in a greenhouse encompassing AMF treatments (inoculation with Gigaspora margarita or Glomus clarum, and the non inoculated controls), and phosphorus treatments (0, 25, 50, 100, 200 and 400 mg kg -1 added to soil). At low soil P levels, arbuscular mycorrhizal fungi inoculation had a significant positive effect on plant growth, shoot and root dry matter content, plant height, number of leaves, total leaf area, leaf area per leaf and the Dickson quality index. The root:shoot ratio and the leaf area ratio were also affected by mycorrhizal inoculation and the level of P addition. Physic nut plants exhibited high mycorrhizal dependency at soil P additions up to 50 mg kg -1 . Key words: mycorrhizal inoculation, plant growth, leaf area, biomass dry matter. resuMoO pinhão manso (Jatropha curcas L.) é uma planta perene que pode ser encontrada naturalmente em regiões tropicais e subtropicais do Brasil. Seus frutos apresentam 28% de óleo com base no peso seco. Apesar de o pinhão manso apresentar alta adaptabilidade às diversas condições do solo como baixa fertilidade, a correção da acidez do solo e a adição de fertilizantes são fundamentais para a alta produtividade das plantas. Por isto é essencial avaliar o comportamento do pinhão manso em diferentes níveis de P e sua resposta a inoculação dos fungos micorrízicos arbusculares (FMA). O objetivo do trabalho foi o de avaliar o efeito dos fungos micorrízicos arbusculares em mudas de pinhão manso em diferentes doses de P no solo. Foi conduzido um experimento em casa de vegetação, com tratamentos de fungos micorrízicos (Controle, Gigaspora margarita e Glomus clarum) e de adição de P (0, 25, 50, 100, 200 e 400 mg kg solo vegetativo como: peso da matéria seca da parte aérea e das raízes, altura, diâmetro do caule, número de folhas, área foliar, área foliar por folha e índice de qualidade Dickson, principalmente nas doses menores de P. A relação raiz:parte aérea e relação da área foliar foram influenciadas pela micorrização e pelos teores de P no solo. O pinhão manso apresentou alta dependência micorrízica até a dose de 50 mg kg -1 de P.palavras-chaves: inoculação de micorrizas, desenvolvimento da planta, área foliar, matéria seca da biomassa.

Rendimiento de Jatropha curcas L. inoculada con micorriza y aplicación de composta de caña

“…Symbiosis increases, over time, the growth of the hyphae towards non-rhizospheric depths from more distant soil profiles, as has been demonstrated in coffee plantations (Cardoso et al, 2003), improving nutrition and transport to the root of the plant (Schweiger and Jakobsen, 2000), thus favoring not only nutrition but also the transport of water (Auge, 2004), compared to a non-mycorrhizal plant. Nutrition and the supply of water to the Jatropha plant by mycorrhization induced a 30% increase in the photosynthetic rate, with phosphorus levels of 200 and 400 mg kg soil -1 compared to non-mycorrhizal plants (Balota et al, 2011). In tomatillo inoculated with Glomus intraradices and Azospirillum Figura 2.…”

“…The diameter of the stem is important to the survival and growth of Jatropha in the field; overall, it was 10% larger in inoculated plants compared to the control plants. In greenhouse conditions, Balota et al (2011) found that mycorrhizal Jatropha plants have greater height and stem diameter compared with non-mycorrhizal plants at low levels of phosphorus. This suggests that the increase in the development of the host plant can be due to an increase in the intake of nutrients (Balota et al, 2011).…”

“…El diámetro del tallo tiene importancia con la sobrevivencia y el crecimiento de Jatropha en el campo y en general, en las plantas inoculadas fue 10 % mayor en comparación con las plantas testigo. En condiciones de vivero, Balota et al (2011) encontró, que las plantas de Jatropha micorrizadas presentan mayor altura y diámetro de tallo, en cotejo con las plantas no micorrizadas a bajos niveles de fósforo. Este hecho sugiere, que el incremento en el desarrollo de la planta hospedera, puede deberse a un incremento en la toma de nutrientes (Balota et al, 2011).…”

“…la nutrición, sino también el transporte da agua (Augé, 2004), en comparación con una planta sin micorrizar. La nutrición y el abastecimiento de agua a la planta de Jatropha mediante la micorrización induce aumento de 30% en la tasa fotosintética con niveles de fósforo de 200 y 400 mg kg -1 de suelo, en comparación con las plantas no micorrizadas (Balota et al, 2011). En tomate de cáscara, inoculado con Glomus intraradices y Azospirillum brasilense más vermicomposta, Velasco et al (2001) citan el incremento en la actividad fotosintética en la etapa de floración en comparación con el testigo, y esta condición la refieren a la ventaja de la nutrición de la planta.…”

“…Jatropha is known for its ability to survive in soils too poor for agriculture (Brittaine and Lutaladio, 2010;Balota et al, 2011), but the correction of acidity in tropical soils and the addition of fertilizers are essential steps for obtaining highly productive plants (Balota y Lutaladio, 2010;Balota et al, 2011), pero la corrección de la acidez en los suelos tropicales y la adición de fertilizantes son esenciales para lograr plantas altamente productivas (Balota et al, 2011). La capacidad de supervivencia Jatropha en suelos de baja fertilidad no significa alta productividad.…”