Inoculantes formulados com polímeros e bactérias endofíticas para a cultura da cana-de-açúcar

Abstract

Resumo -O objetivo deste trabalho foi avaliar o efeito da utilização, em campo, de inoculantes compostos pela mistura de estirpes de bactérias diazotróficas e pelos polímeros carboximetilcelulose e amido, sobre a fixação de nitrogênio, em cana-de-açucar. O delineamento experimental foi de blocos ao acaso, em esquema fatorial 4x2, com quatro formas de fornecimento de N: controle absoluto, controle nitrogênio (adubação com 120 kg ha -1 de N), inoculante polimérico líquido (IPC 0,8), e inoculante polimérico gel (IPC 2,2); e duas variedades de cana-de-açúcar (RB72454 e RB867515), em parcelas subdivididas (três épocas de avaliação -6, 9 e 11 meses após o plantio), com quatro repetições. Como veículo inoculante foi testada a proporção 60:40 dos polímeros carboximetilcelulose e amido, nas concentrações 0,8 e 2,2 g L -1 (IPC 0,8 e IPC 2,2, respectivamente). Os parâmetros avaliados foram: a produtividade de colmos, a massa de matéria seca total e o acúmulo de nitrogênio. Os tratamentos com os inoculantes com a mistura de bactérias diazotróficas endofíticas e os polímeros promoveram aumento médio da produtividade das variedades RB72454 e RB867515 de 50 e 30 Mg ha -1 , respectivamente, e aumento médio da massa da matéria seca da variedade RB867515 de 18 Mg ha -1 , em comparação ao controle absoluto, aos 11 meses após a inoculação, e não diferiram significativamente do tratamento controle nitrogênio.Termos para indexação: Saccharum officinarum, amido, bactérias diazotróficas, carboximetilcelulose. Inoculants containing polymers and endophytic bacteria for the sugarcane cropAbstract -The objective of this work was to evaluate the effects of field application of inoculants composed of a mixture of diazotrophic bacterial strains and of carboxymethyl cellulose and starch polymers on nitrogen fixation in sugarcane. The experimental design was in randomized blocks in a 4x2 factorial arrangement: four types of nitrogen supply -absolute control, nitrogen control fertilized with 120 kg N (urea) ha -1 , polymeric liquid inoculant -IPC 0.8, and polymeric gel inoculant -IPC 2.2; and two sugarcane varieties (RB72454 and RB867515), with split plots (three harvest times -6, 9 and 11 months after planting), with four replicates. As inoculant vehicles, carboxymethyl cellulose and starch polymers with a 60:40 ratio were tested at 0.8 and 2.2 g L -1 concentrations (IPC 0.8 and IPC 2.2, respectively). The evaluated parameters were stem productivity, total dry matter and nitrogen accumulation. The treatments with the inoculants containing a mixture of diazotrophic bacteria and polymers led to an average increase of 50 and 30 Mg ha -1 in the productivity of the varieties RB72454 and RB867515, respectively, and to an average increase of 18 Mg ha -1 in total dry matter of variety RB867515, in comparison to the absolute control 11 months after inoculation, with no significant difference from the nitrogen control.

Inoculation of sugarcane with diazotrophic bacteria

“…In the first ratoon crop, inoculation caused a significant increase in dry matter production compared to the absolute control, but did not differ from the N-fertilized control. In the second ratoon crop, variety RB867515 showed no response to inoculation, but was responsive to N fertilization in stalk yield, dry matter and total N. The lack of response of this variety (RB867515) to treatments with inoculation and N fertilization in the plant-cane crop may be characteristic of the variety, since it produces high yields on N-poor soils (Silva et al, 2009;Schultz et al, 2012). In the first ratoon crop, due to the reduction in available soil N after the plant-cane harvest, there was no response in the variety to the treatments with inoculation and N fertilization in the accumulation of total dry matter production, which was however not reflected in significant increases in stalk yield and in total N, stocks, probably due to the high use efficiency of available soil N of this variety.…”

“…Govindarajan et al (2006) evaluated the inoculation of Burkholderia vietnamiensis, strain MG43, in the varieties Co 86032 and Co 86027 of micropropagated sugarcane after different evaluation periods up to 12 months after planting, and found that inoculation with strain MG43 promoted increases of 20 and 19 % in dry matter production of Co 86032 and Co 86027, respectively. Testing the same inoculum as in this study in a medium texture Hapludult, Silva et al (2009) found that stalk yield increased by 50 Mg ha -1 in variety RB72454 and 30 Mg ha -1 in variety RB867515, 11 months after planting, compared to the absolute control; these increases were similar to those recorded in the control fertilized with 120 kg ha -1 N. Similar results to those mentioned above were reported by Schultz et al (2012) in studies carried out for two years in a Fluventic Eutrudept in the region of Campos dos Goytacazes, Rio de Janeiro, for variety RB867515. The results obtained to date and reported in the literature show that diazotrophic inoculation in sugarcane increased the crop yield potential, but with great variability in the responses and influence of soilclimatic factors involved in the production process.…”

“…Field studies showed the efficiency of the inoculant in increasing stalk and dry matter yield of different sugarcane varieties (Oliveira et al, 2003;Silva et al, 2009;Schultz et al, 2012). The benefits of inoculation with diazotrophic bacteria for the crop are not yet fully understood , however there are reports that the plantbacteria association may increase the contribution of atmospheric N 2 by biological fixation in plants, according to the cultivar and environmental conditions (Oliveira et al, 2003;Baldani et al, 2009).…”

Bactérias Diazotróficas E Vermicomposto Como Fontes Alternativas De N Para O Arroz Irrigado

“…Bactérias diazotróficas utilizadas na fixação de nitrogênio em gramíneas (ROESCH et al, 2005;MENDONÇA et al, 2006;GUI-MARÃES et al, 2007;MATTOS et al, 2008, SILVA et al, 2009) e outras espécies (WEBER et al, 2000;BAL-DOTTO et al, 2010) têm sido estudadas nos últimos anos. Estes estudos mostram a efetividade deste tipo de associação ao hospedeiro.…”

Tolerância da bactéria diazotrófica Gluconacetobacter diazotrophicus a herbicidas utilizados na cultura da cana-de-açúcar

“…Bactérias diazotróficas podem associar-se à cana-deaçúcar, naturalmente, ou ser inoculadas para promover efeitos benéficos (Silva et al, 2009). Algumas espécies de bactérias endofiticas capazes de fixar N atmosférico como Gluconacetobacter diazotrophicus, Herbaspirillum spp., Azospirillum amazonense, Burkholderia spp.…”