Termografia para detecção de estresse térmico na aclimatização de mudas micropropagadas de bananeira, suplementadas com bactérias promotoras de crescimento em diferentes ambientes

Abstract

The banana tree (Musa spp.) produces one of the most consumed fruits in the world, a banana. The conventional propagation of this fruit is carried out through seedlings formed from rhizome. In order to ensure a more uniform production and meet the demand of the consumer market, we sought to propagate seedlings free of phytosanitary problems, such as seedlings from tissue culture (micropropagated). Acclimatization is one of the stages of micropropagation in which seedlings produced under in vitro conditions are transferred to ex vitro conditions, being necessary to reduce the stresses caused to plants with the change of environment. Thus, the objective of this study was to investigate the influence of thermal stress through thermography on the development of banana cv. Prata Catarina, supplemented with growth promoting bacteria, in the acclimatization phase. Five treatments were performed: T1 - the seedlings remained 14 days in a shade tunnel and then remained 46 days in the greenhouse; T2 - 7 days in the controlled temperature room and then 53 days in the greenhouse; T3 - the seedlings remained in the greenhouse for 60 days; T4 - 14 days in the temperature controlled room and then 46 days in the greenhouse; T5 - 7 days in temperature controlled room, 7 days in sombrite tunnel and 46 days in greenhouse. 108 seedlings were used per treatment, and four applications were made with bacterial isolates, with a 15 day interval. Leaf temperature (Tf) variation was evaluated using the infrared thermometer and the FLIR® thermographic camera. Nine readings were taken during 60 days. The seedlings inoculated with the bacterium Bacillus LPPC 159 did not present significant differences when compared to the fertilized seedlings. The seedlings acclimatized for 7 days in a controlled temperature room, plus 7 days in sombrite tunnel and 46 more days in roof had larger pseudostem diameter (mm), fresh mass (g) and dry mass (g). The seedlings acclimatized for 60 days on a screen, obtained higher leaf temperatures frequently on the evaluation days. Already the seedlings acclimatized for 14 days in temperature controlled room and 46 days in roof, showed lower leaf temperature values. It is concluded that the use of shading in the acclimatization phase combined with the use of BPCPs, provides better survival conditions of micropropagated seedlings in this phase.