Growth promotion of pineapple 'vitória' by humic acids and burkholderia spp. during acclimatization

Abstract

SUMMARYIn vitro propagation of pineapple produces uniform and disease-free plantlets, but requires a long period of acclimatization before transplanting to the field. Quicker adaptation to the ex vitro environment and growth acceleration of pineapple plantlets are prerequisites for the production of a greater amount of vigorous, well-rooted planting material. The combination of humic acids and endophytic bacteria could be a useful technological approach to reduce the critical period of acclimatization. The aim of this study was to evaluate the initial performance of tissue-cultured pineapple variety Vitória in response to application of humic acids isolated from vermicompost and plant growth-promoting bacteria (Burkholderia spp.) during greenhouse acclimatization. The basal leaf axils were treated with humic acids while roots were immersed in bacterial medium. Humic acids and bacteria application improved shoot growth (14 and 102 %, respectively), compared with the control; the effect of the combined treatment was most pronounced (147 %). Likewise, humic acids increased root growth by 50 %, bacteria by 81 % and the combined treatment by 105 %. Inoculation was found to significantly increase the accumulation of N (115 %), P (112 %) and K (69 %) in pineapple leaves. Pineapple growth was influenced by inoculation with Burkholderia spp., and further improved in combination with humic acids, resulting in higher shoot and root biomass as well as nutrient contents (N 132 %, P 131 %, K 80 %) than in uninoculated plantlets. The stability and increased consistency of the host plant response to bacterization in the presence of humic substances indicate a promising biotechnological tool to improve growth and adaptation of pineapple plantlets to the ex vitro environment.Index terms: Ananas comosus, plant growth-promoting bacteria, diazotrophic bacteria, humic substances, inoculant, biofertilizer.(

Plant growth promoting bacteria and humic substances: crop promotion and mechanisms of action

“…UENF 114111 and Burkholderia silvatlantica strain UENF 117111) during greenhouse acclimatization was studied by Baldotto and colleagues [33]. The period of pineapple acclimatization is critical due to the low growth rate of roots and shoots.…”

Gladiolus development in response to bulb treatment with different concentrations of humic acids

“…Application of HA, the bioactive fraction of the humified organic matter, to produce spikes and commercial corms, is another technological option. Studies indicate a concentration-dependent response to the action of HA in promoting growth and development of plants (Baldotto et al, 2009(Baldotto et al, , 2010(Baldotto et al, , 2011(Baldotto et al, and 2012. Therefore, studies that confirm the action of HA on the growth and development of ornamental plants and determine the maximum efficiency concentration can promote the diffusion of this new technology.…”

“…The Brazilian floriculture industry occupies an area of approximately 4,500 hectares (ha), including 700 ha under protected cultivation. The sector involves 5000 growers, largely concentrated in São Paulo, Rio de Janeiro and Minas Gerais, and 4000 retail shops (Faria, 2005;Baldotto et al, 2010;Barbosa, 2011).…”

“…Humic acids (HA) induce rooting in many plants of agronomic interest (Canellas et al, 2006;Baldotto et al, 2009Baldotto et al, , 2010Baldotto et al, , 2011Baldotto et al, and 2012. They also have stimulating effects on shoots, such as increases in leaf nutrient accumulation (Chen et al, 2004) and chlorophyll synthesis (Baldotto et al, 2009).…”

Initial growth of maize in response to application of rock phosphate, vermicompost and endophytic bacteria

“…In this study, the increase in the initial growth of maize promoted by Herbaspirillum and Burkholderia were also associated with higher nutrient contents, of N and P, because of their capacity for diazotrophy and phosphate solubilization. Baldotto et al (2010a) used this same strain of Burkholderia, in combination or not with humified organic matter, and noted an increase in its population in pineapple, which showed greater development of roots and shoots, as well as higher contents of macronutrients.…”