Early changes in arbuscular mycorrhiza development in sugarcane under two harvest management systems

Abstract

Sugarcane (Saccharum spp.) is grown on over 8 million ha in Brazil and is used to produce ethanol and sugar. Some sugarcane fields are burned to facilitate harvesting, which can affect the soil microbial community. However, whether sugarcane pre-harvest burning affects the community of arbuscular mycorrhizal fungi (AMF) and symbioses development is not known. In this study, we investigated the early impacts of harvest management on AMF spore communities and root colonization in three sugarcane varieties, under two harvest management systems (no-burning and pre-harvest burning). Soil and root samples were collected in the field after the first harvest of sugarcane varieties SP813250, SP801842, and RB72454, and AMF species were identified based on spore morphology. Diversity indices were determined based on spore populations and root colonization determined as an indicator of symbioses development. Based on the diversity indices, spore number and species occurrence in soil, no significant differences were observed among the AMF communities, regardless of harvest management type, sugarcane variety or interactions between harvest management type and sugarcane variety. However, mycorrhiza development was stimulated in sugarcane under the no-burning management system. Our data suggest that the sugarcane harvest management system may cause early changes in arbuscular mycorrhiza development.

Presence and diversity of arbuscular mycorrhizal fungi in soil regularly irrigated with vinasses

“…Among the species reported by Azevedo et al (2014) as the most frequent species (> 50%) in soil from sugarcane crops without vinasses irrigation, Acaulospora scrobiculata coincides with the present work, while other species are different (A. morrowiae, Glomus macrocarpum, and Scutellospora pellucida) to found in our study.…”

“…The colonization percentage agreed with that reported by Azevedo et al (2014) for AMF colonization in sugarcane roots (31-36%) in perturbed (burning) and not perturbed soil (not burned) (49-51%).…”

“…Some of the genus found in CS and VS soil have been reported in soil from sugarcane crops in Brazil without vinasses irrigation such as Acaulospora, Glomus, Funneliformis, Paraglomus, Gigaspora, Scutellospora, and Racocetra (Azevedo et al, 2014). This could suggest certain preference of AMF by sugarcane plants regardless of environment conditions and resistance of AMF species to vinasses irrigation found in this study.…”

“…However, in sugarcane crops with different management systems (burning and unburning) the AMF spore abundance was reported from 31 to 40 spores per 50 g of soil (Azevedo et al, 2014).…”

“…This could explain why the application of highly acidic vinasses (as de- It has been reported that soils cultivated with sugarcane crop have an organic matter high content (59 g kg -1 to 6.9 g kg -1 ) and high total nitrogen content (1.8 g kg -1 to 2.4 g kg -1 ) (Mthimkhulu et al, 2016), which are concordant with values and the classification found in this study. Also a phaeozem soil is characterized by a pH ranging from 5 to 7 (FAO, 2014) and the pH of sugarcane soils is reported on a wide range from 4.5 to 6.0 depending on fertilizer application rates and soil type (Azevedo et al, 2014;Mthimkhulu et al, 2016).…”