Field Crop 2024, Vol.7, No.3, 171-181 http://cropscipublisher.com/index.php/fc 175 involving enhanced nutrient uptake, improved root development, and increased biomass and plant vigor. These benefits underscore the potential of using diazotrophic bacteria as a sustainable agricultural practice to boost sugarcane productivity. Figure 2 Water deficit assay of sugarcane cv. SP70-1143 colonized with the beneficial endophytic diazotrophic bacteria G. diazotrophicus strain PAL5 (Adopted from Vargas et al., 2014) Image caption: (a) Simplified pipeline for water deficit assay. (b) left panel shows qRT-PCR quantification of sugarcane colonization by G. diazotrophicus 7 days after inoculation in hydroponic solution. Bacterial 23S rRNA levels are presented relative to rice 28 S rRNA levels. Right panel shows root and shoot fresh weight measurements 14 days after inoculation and 1 day before treatments. (c) Phenotype of sugarcane cv. SP70-1143 inoculated or not with G. diazotropicus, 3 days after withholding water. Senescent edges are indicated by arrows and are shown in the amplified image from a WD+GD plant. (d) qRT-PCR quantification of sugarcane colonization by G. diazotropicus after 3 days under water deficit assay. Bacterial 23S rRNA levels are presented relative to rice 28 S rRNA levels. (e) Phenotype of sugarcane cv. SP70-1143 inoculated or not with G. diazotropicus, after 40 days withholding water. Bar55 cm. Error bars indicate standard error of the mean. Asterisk mark statistical significance between GD-R vs CT-R (*p＜0.05) and WD+GD-R vs GD-R (**p＜0.01), performed by statistical t-test (unpaired) (Adopted from Vargas et al., 2014) 5 Impact on Sugarcane Yield 5.1 Yield increase statistics The inoculation of sugarcane with diazotrophic bacteria has shown significant improvements in yield across various studies. For instance, inoculation with a consortium of five diazotrophic strains resulted in an increase of stem yield by 22.3 to 38.0 Mg/ha in different sugarcane varieties compared to control treatments (Schultz et al., 2017). Another study demonstrated that inoculation with GluconAcetobacter diazotrophicus and other diazotrophs led to higher biomass accumulation and nutrient uptake, which in turn enhanced the growth rates of sugarcane (Renan et al., 2016). Additionally, the use of mixed inocula in micropropagated sugarcane plantlets showed a synergistic effect, significantly increasing colonization and growth (Oliveira et al., 2009). 5.2 Quality of sugarcane juice The quality of sugarcane juice, an important parameter for both sugar and bioethanol production, is also positively influenced by diazotrophic bacteria. Inoculation with diazotrophic bacteria not only increased the stem yield but also improved the total recoverable sugar yield (Schultz et al., 2017).. Furthermore, the industrial characteristics of sugarcane, such as juice quality, were enhanced by the presence of plant growth-promoting bacteria (PGPB) (Antunes et al., 2019). These improvements are attributed to the better nutrient assimilation and stress tolerance conferred by the bacteria.
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