Abstract
The present study aimed to evaluate the productive performance of maize crop when seed inoculated with A. brasilense, associated with different foliar doses of magnesium in the crop vegetative stages. For this, two essays were conducted in field conditions, one located in Laranjeiras do Sul-PR and the other in Entre Rios do Oeste-PR. A randomized blocks scheme was used, with a 3 × 2 factorial, being the treatments with magnesium (Mg): magnesium sulphate; magnesium oxide and without magnesium, and the presence or absence of seed inoculation with A. brasilense. The magnesium sources were supplied via foliar at the V4 stage of the crop, using doses of 6 kg ha-1. Evaluations were carried at R1 determining the SPAD index and stem diameter and, at the end of the productive cycle, were evaluated production components and yield. In both sites no significant effects of foliar application with Mg were observed over the evaluated parameters. The A. brasilense inoculation provided an increase of 9.66% and 6.32% in stem diameter and of 6.8% and 6.24% in the SPAD index in Laranjeiras do Sul and Entre Rios do Oeste respectively, however, they did not increase production components and yield. It is concluded that the inoculation with A. brasilense increases of stem diameter values and SPAD index, in turn the foliar fertilization with different sources of magnesium do not interfere in the development and productivity of corn crop.
Highlights
Seeking an increase in the crop yield it is considered the seed inoculation with growth promoting bacteria (GPB), among them stands out the Azospirillum brasilense (Novakowiski et al, 2011; Dartora et al, 2013; Costa et al, 2015) which have many beneficial effects, for example, stimulus to plants development from the provision of vegetal hormones such as auxins, gibberellins and cytokinin (Kuss et al, 2007), providing in many cases more vigorous and productive plants (Cassán & Diaz-zorita, 2016), promoting higher nutrients absorption such as nitrogen, potassium and phosphorus (Hungria et al, 2010), besides reducing adverse effects caused by environmental conditions such as hydric deficit, by stimulus in the antioxidative vegetal system (Bulegon et al, 2016) and the crops gas exchanges (Bulegon et al, 2017)
For the parameter inoculation with A. brasilense, there was a significant effect on stem diameter and SPAD index for plants cultivated in both locations (Table 2)
In research of Altarugio et al (2017), it is reported that even in soil with adequate levels of Mg, its foliar application increases the SPAD index and the maize production components when applied at V4 and R2
Summary
Maize is the main cereal cultivated worldwide with a total production in 1.07 billion tons (USDA, 2018), with Brazil having a representability of about 7.62% of its global production with 82 million tons (CONAB, 2018), filling the third place in the global scenario of maize production. In study with the foliar supply of Mg doses in soybean and maize was evidenced the potential of its use (Altarugio et al, 2017), these authors found for the maize crop that the supply in the reproductive stages increases crop yield, even though its application in vegetative stages did not show the same responses. The A. brasilense inoculation associated to magnesium fertilization may assist the plants development with lower chlorophyll relative content and higher development, providing higher yield, given that both of them have an influence in important biochemical and physiological reactions on plants. The present study aimed to evaluate the productive performance of maize crop when seed inoculated with A. brasilense, associated with different foliar doses of magnesium in the crop vegetative stages
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