Abstract
The use of inoculants containing growth-promoting diazotrophic bacteria can stimulate mass and nutrient accumulation in sugarcane. The purpose of this study was to evaluate plant growth and accumulation of macroelements in sugarcane, variety RB92579, under bacterial inoculation with or without N fertilization. The field experiment was carried out in a Red-Yellow Podzolic soil in Seropédica, RJ, in a randomized block design with four replications. The treatments consisted of 50 kg N ha-1; 50 kg N ha-1 + inoculation; inoculation; and an absolute control. The following bacteria were inoculated: Gluconacetobacter diazotrophicus, Herbaspirillum seropedicae, Herbaspirillum rubrisubalbicans, Azospirillum amazonense, and Burkholderia tropica. The plants were sampled at 100, 130, 168, 212, 261, and 295 days after planting (DAP), and growth and nutrient accumulation rates were estimated by functional analysis of plant growth. Nutrient accumulation rates were highest around 180 DAP for N and P, and around 160 DAP for K, in the different treatments, preceding the maximal crop growth rate (between 210 and 220 DAP). The accumulation of biomass, N, P and K was greater and crop growth rates were higher in the treatments with bacterial inoculation fertilized or not with 50 kg N ha-1, compared with the control. Key words: Saccharum species, inoculum, growth promotion.
Highlights
The release of new sugarcane varieties contributed to this increase in cultivated area and productivity
Nutrient accumulation rates were highest around 180 days after planting (DAP) for N and P, and around 160 DAP for K, in the different treatments, preceding the maximal crop growth rate
The accumulation of biomass, N, P and K was greater and crop growth rates were higher in the treatments with bacterial inoculation fertilized or not with 50 kg N ha-1, compared with the control
Summary
The release of new sugarcane varieties contributed to this increase in cultivated area and productivity. The selection of varieties was based on various parameters related to growth patterns, e.g., shoot dry matter accumulation throughout the cycle. In the case of sugarcane, this pattern is represented by a sigmoid curve which shows an initial phase of slow growth followed by an exponential growth phase and maturation, when growth becomes slow and eventually stagnant (Oliveira et al, 2010). Nitrogen is one of the most required nutrients for sugarcane growth, along with potassium. The low use efficiency of N fertilizer in commercial sugarcane crops (Trivelin et al, 2002), calling for an increase in the efficiency of these fertilizers is a challenge to improve the profitability and sustainability of this crop
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