Endophytic bacteria affect sugarcane physiology without changing plant growth

Abstract

The aim of this study was to evaluate if endophyticbacteria inoculants would be beneficial to the sugarcane varietiesIACSP94-2094 and IACSP95-5000, promoting changes inphotosynthesis and plant growth. The plants, obtained frommini stalks with one bud, were treated with two bacteria mixtures(inoculum I or II) or did not receive any inoculum (control plants).The inocula did not affect shoot and root dry matter accumulationas compared to the control condition (plants with native endophyticbacteria). However, photosynthesis and electron transport rate(ETR) increased in IACSP94-2094 treated with the inoculum II,whereas the inoculum I enhanced photosynthesis and stomatalconductance in IACSP95-5000. The inoculum II caused increasein leaf sucrose concentration of IACSP94-2094 and decrease inIACSP95-5000 leaves. Leaf nitrogen concentration was not affectedby treatments, but bacteria inoculation increased nitrate reductaseactivity in IACSP95-5000, and the highest activity was found inplants treated with the inoculum II. We can conclude that bacteriainoculation changed sugarcane physiology, improving photosynthesisand nitrate reduction in a genotype-dependent manner, withoutpromoting plant growth under non-limiting conditions.