Efeito da utilização de microrganismos (azospirillum brasilense e trichoderma harzianum), no desenvolvimento inicial da cultura da alface em ambiente controlado

Abstract

The beneficial action provided by the symbiotic interaction between plant species and soil microorganisms is known and reported in several works, mainly in the case of plant nutrition and rhizosphere conditioning. Among these microorganisms, the genus Azospirillum stands out, with beneficial effects ranging from biological nitrogen fixation (BNF) to the synthesis of hormones such as indoleacetic acid (IAA). Some fungi may also have agricultural benefits. As an example, the fungi of the genus Trichoderma, present positive results in terms of plant growth, positively influencing the germination of seeds and the general development of the culture. Lettuce (Lactuca sativa L.) is an annual herbaceous plant belonging to the Asteraceae family, it represents 50% of all national production and commercialization of the leafy vegetable segment. The quality of germination and emergence in the lettuce crop is the main productive characteristic, since the life cycle of the culture is considered short. Thus, the present work was based on measuring the effects of the use of these microorganisms on the germination and initial development of lettuce seedlings. The research was conducted at the Laboratory of Soil Physics, at the Federal University of Fronteira Sul in Laranjeiras do Sul - Paraná. From June 2022 to August 2022. A completely randomized design (DIC) was used, with 10 treatments and 4 replications, totaling 40 experimental units. The treatments used were the following: T0: Control; T1; Azospirillum brasilense in a 1:100 ratio; T2: Azospirillum brasilense in the proportion 1:133 ; T3: Azospirillum brasilense in the proportion : 1:200 ; T4: Azospirillum brasilense in the proportion 1:400 ; T5: Azospirillum brasilense in the proportion 1:100 + Trichoderma harzianum in the proportion 1:100 ; T6: Azospirillum brasilense in the proportion 1:133 + Trichoderma harzianum in the proportion 1:100 ; T7: Azospirillum brasilense in the proportion 1:200 + Trichoderma harzianum in the proportion 1:100 ; T8 Azospirillum brasilense in the proportion 1:400 + Trichoderma harzianum in the proportion 1:100, T9 Trichoderma harzianum in the proportion 1:100. The seedlings were evaluated in terms of leaf area, diameter, area and root length. In addition, the germination percentage was evaluated and the germination speed index was calculated. The data obtained were submitted to individual analysis of variance, and the means were grouped by the Scott-Knott test, at 5% probability, using the SISVAR® statistical program. The use of Azospirillum brasilense in the initial development of the lettuce crop, promotes positive results for the root system and shoot. With regard to Trichoderma harzianum, the results suggest a deleterious effect on germination and initial development of plants, hindering the establishment and development of lettuce. Regarding the association between Azospirillum and Trichoderma, the results showed little synergistic action between bacteria.