BACTÉRIAS PROMOTORAS DE CRESCIMENTO NA EMERGÊNCIA DE PLÂNTULAS DE ALGODÃO SOB ESTRESSE HÍDRICO

Abstract

The present study aimed to evaluate the use and effect of growth-promoting bacteria in conditions of low water availability on the emergence of cotton seedlings, considering seedling emergence speed indices in the field. The study was conducted in a protected environment at the State University of Goiás, Campus Sudoeste University Unit of Santa Helena de Goiás, a region with a climate classified as Aw and precipitation distributed in two well-defined seasons: dry season or winter (May-October) and rainy season or summer (November-April), with an average temperature of 25 C°, so that total precipitation reaches approximately 1500 mm annually. The soil used will be the Dystrophic Red Oxisol with a clay texture, typical of the region. The experimental design used was a randomized block design (DBC) in a 4x4 factorial scheme (4 inoculations/doses and 4 levels of water availability) and four replications with 50 seeds each, in a total of 64 experimental units. Each plot was composed of pots with a capacity of 15L, filled with soil with corrected acidity. The inoculations were made with bacteria of the genus Bacillus and Azospirillum applied, as recommended by the manufacturer, in isolation and in combination (coinoculation), added to the control treatment, that is, without the application of inoculants. And water availability will be proposed based on reference evaporation (ETo), which corresponded to 40, 60, 80 and 100% of ETo, measured by a mini evaporimeter tank installed inside the greenhouse, and calibrated with the class tank The standard, according to the equation presented by Santos et al., (2017). However, it should be noted that the 40% sample did not evolve. The cotton cultivar used was the conventional FM 944 faber Max GL, with an average cycle of 160 to 180 days, with an average ideal daily growth of 1 cm day-1. The cultivar has the advantages of high structure retention and exceptional fiber quality, presents aggressive root development and strong initial start with productivity of 391.4 @/ha, yield 37.3%. It is concluded that the use of the bacteria analyzed in the cotton culture showed significant differences through conoculation, with both bacteria standing out individually in isolated cases, however, there was no difference in the volume of aerial and root parts, there was a difference in the diameter of thatch. It was observed that the water deficit was of paramount importance for its germination and its development in the seedling phase. However, the 40% layer did not show normal seedlings and some buckets did not germinate.