Potencial de acessos de Coffea arabica L. do Banco Ativo de Germoplasma da EPAMIG para a tolerância à seca

Abstract

The objective of this study was to identify Coffea arabica L. genotypes from the Epamig Germplasm Bank with potential for tolerance to water deficit in the initial growth phase and under field conditions. The experiment was set in a greenhouse at the EPAMIG Experimental Station in Lavras-MG. Sixteen accessions of Coffea arabica L. from the Germplasm Bank of EPAMIG in Patrocínio-MG were used, in addition to two cultivars, one considered tolerant (IPR 100) and the other sensitive (Rubi MG1192) to water deficit. Two treatments were carried out in relation to water availability, the first maintaining soil moisture at 100% available water and the second with total suspension of irrigation. Morphological and vegetative growth characteristics were evaluated, as well as physiological characteristics in 4 different periods. Subsequently, 7 contrasting accessions were selected, in addition to the two cultivars considered as a standard (one tolerant and sensitive) to water deficit for leaf biochemical and anatomical evaluations. The selected accessions were also evaluated in the field for yield, beverage quality and adaptations to the dry period. There was a variation among genotypes regarding the evaluated characteristics, demonstrating different adaptation mechanisms in the face of water stress. There was growth limitation in most of the genotypes evaluated due to water deficit, besides a reduction in gas exchange and leaf water potential. The maintenance in gas exchange was observed under low water potential in accession ‘Híbrido de Timor UFV 377-21’, in addition to an increase in ascorbic acid content, under induced water deficit and in the dry period in the field. Greater growth in the root system and maintenance of gas exchange were observed in accession ‘Híbrido de Timor UFV 376-12’. After the return of irrigation, recovery in gas exchange and predawn water potential was observed in most of the evaluated accessions. In cultivar IPR100, there was an increase in the activity of catalase and ascorbate peroxidase during stress. The main leaf anatomical adaptations, both in the initial developmental phase and in adult plants, were a greater relationship between polar and equatorial stomatal diameter, greater thickness of adaxial cuticles, greater frequency of xylem vessels and relative hydraulic conductivity, when submitted to water deficit. ‘Híbrido de Timor UFV 376-12’ stood out in terms of anatomical and physiological adaptations. Regarding yield and beverage quality, the accessions ‘Híbrido de Timor UFV 377-21’, ‘UFV 442-42’ and ‘UFV 376-31’ stood out. In general, the accessions showed adaptations to water stress in the initial development and in the field. ‘Híbrido de Timor UFV 376-12’, ‘UFV 377-21’ and ‘UFV 376-31’ stood out, with potential for drought tolerance.