Mycorrhizal effectiveness on physic nut as influenced by phosphate fertilization levels

Elcio Liborio Balota,Alexandra Scherer,Oswaldo Machineski

doi:10.1590/s0100-06832012000100003

Elcio Liborio Balota, Alexandra Scherer + Show 1 more

Open Access

https://doi.org/10.1590/s0100-06832012000100003

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Abstract

In recent years, physic nut (Jatropha curcas L.) has attracted attention because of its potential for biofuel production. Although it is adapted to low-fertility soils, physic nut requires soil acidity corrections and addition of a considerable amount of fertilizer for high productivity. The objective of this research was to evaluate the effectiveness of arbuscular mycorrhizal fungi (AMF) (control without AMF inoculation, Gigaspora margarita inoculation or Glomus clarum inoculation) on increasing growth and yield of physic nut seedlings under different rates of P fertilization (0, 25, 50, 100, 200, and 400 mg kg-1 P soil) in greenhouse. The experiment was arranged in a completely randomized, block in a factorial scheme design with four replications. The physic nut plants were harvested 180 days after the beginning of the experiment. Mycorrhizal inoculation increased physic nut growth, plant P concentration and root P uptake efficiency at low soil P concentrations. The P use quotient of the plants decreased as the amount of P applied increased, and the P use efficiency index increased at low P levels and decreased at high P levels. Mycorrhizal root colonization and AMF sporulation were negatively affected by P addition. The highest mycorrhizal efficiency was observed when the soil contained between 7.8 and 25 mgkg-1 of P. The physic nut plants responded strongly to P application, independent of mycorrhizal inoculation.

Highlights

In recent years, physic nut (Jatropha curcas L.) has attracted attention because of its potential to be used for biofuel production
arbuscular mycorrhizal fungi (AMF) inoculation significantly increased total dry matter (TDM); increases of 522, 213 and 210 % were recorded in the treatments P0, P25 and P50, respectively
The results show that mycorrhizal physic nut plants were less sensitive to P levels than these other plant species, as little more than 100 mg kg-1 P was required to induce significant changes in its development

Summary

Introduction

Physic nut (Jatropha curcas L.) has attracted attention because of its potential to be used for biofuel production. The physic nut plant is found in the tropical and subtropical regions of Brazil, and is considered a rustic crop that can grow under diverse soil and climate conditions and thrive in low-fertility soils (Saturino et al, 2005; Dias et al, 2007). The plants depend on the neutralization of soil acidity and fertilization to achieve high yield levels. Phosphorus is one of the major limiting nutrients for crop production, in the tropics, and is found at extremely low levels in the soil solution. Low P levels in acidic soils are caused by the reactivity of the element with Fe and Al, leading to P precipitation and reducing the nutrient content (Novais et al, 2007). It has been estimated that if the current P fertilizer application rates are maintained worldwide, the available supply of P rocks could be depleted by the end of the 21st century

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