Abstract
The development of cultivars with an improved nitrogen use efficiency (NUE) together with the application of plant growth-promoting bacteria is considered one of the main strategies for reduction of fertilizers use. In this sense, this study: i) evaluated the effect of Azospirillum brasilense on the initial development of maize genotypes; ii) investigated the influence of A. brasilense inoculation on NUE under nitrogen deficit; and iii) sought for more NUE genotypes with higher responsiveness to A. brasilense inoculation. Twenty-seven maize genotypes were evaluated in three independent experiments. The first evaluated the initial development of maize genotypes with and without A. brasilense (strain Ab-V5) inoculation of seeds on germination paper in a growth chamber. The second and third experiments were carried out in a greenhouse using Leonard pots and pots with substrate, respectively, and the genotypes were evaluated at high nitrogen, low nitrogen and low nitrogen plus A. brasilense Ab-V5 inoculation. The inoculation of seeds with A. brasilense Ab-V5 intensified plant growth, improved biochemical traits and raised NUE under nitrogen deficit. The inoculation of seeds with A. brasilense can be considered an economically viable and environmentally sustainable strategy for maize cultivation.
Highlights
The world yield and productivity of maize (Zea mays L.) doubled in the last three decades, resulting in an output of 1,034.8 million tons of grain in 2017/2018 [1]
The objectives of this study were to i) evaluate the effect of A. brasilense on the initial development of maize genotypes to identify those most responsive this plant growth-promoting bacteria (PGPB); ii) determine the influence of A. brasilense inoculation on nitrogen use efficiency (NUE) of maize grown under N deficit; and iii) identify maize inbred lines with higher NUE that are more responsive to A. brasilense inoculation
Apart from phenylalanine ammonia-lyase (PAL) (-5.87%), the mean inoculation efficiency indices (IEI) values were positive for all evaluated traits, ranging from 1.82 (RSA) to 23.56% (PPO)
Summary
The world yield and productivity of maize (Zea mays L.) doubled in the last three decades, resulting in an output of 1,034.8 million tons of grain in 2017/2018 [1]. This significant yield increase is attributed mainly to chemical fertilizers, breeding and crop management [2]. The dependence of modern agriculture on chemical fertilizers is alarming, since the indiscriminate use of these inputs has been causing serious environmental problems, e.g., water eutrophication, soil acidification and air pollution [3,4,5]. Without N fertilizers, the global food production would be sufficient for less than half the current population of 7.6 billion people [9]
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