Physiological Characteristics Of Eucalyptus spp Seedlings Submitted To Saline Stress

Abstract

The objective of this study was to evaluate the effects of increasing sodium chloride (NaCl) concentrations on quantum potential efficiency of the photosystem II (Fv/Fm), index of the intensity of the green color in leaves (SPAD value), dry leaf biomass, leaf area and potassium (K) and sodium (Na) concentrations in Eucalyptus seedlings leaves. The experiment was carried out in a green house, using 11.5 L pots filled with sand and irrigated with nutrient solution, in Campos dos Goytacazes (RJ). The experiment was set up according to a completely randomized factorial design, with four species ( Eucalyptus camaldulensis , Eucalyptus tereticornis , Eucalyptus pellita and Eucalyptus robusta ) and five saline levels (1.41; 2.50; 4.50; 6.45 and 8.33 dS m-1), with five replicates. Up to the maximum applied saline level, seedlings of Eucalyptus camaldulensis , Eucalyptus tereticornis and Eucalyptus robusta showed positive responses regarding SPAD values and quantum potential efficiency of the photosystem II, dry leaf biomass and leaf area. These evaluations suggest tolerance of these species to saline conditions. Seedlings of Eucalyptus pellita showed sensitivity to saline stress. The reductions of dry leaf biomass and leaf area may be related to seedling resistance to saline conditions.Este trabalho objetivou avaliar como o aumento da concentra\ue7\ue3o de cloreto de s\uf3dio (NaCl) influencia o rendimento qu\ue2ntico potencial do fotossistema II (Fv/Fm), \uedndice da intensidade da cor verde nas folhas (valor SPAD), \ue1rea foliar, biomassa seca foliar e concentra\ue7\ue3o de pot\ue1ssio (K) e s\uf3dio (Na) nas folhas de mudas de esp\ue9cies de Eucalyptus. O experimento foi conduzido em casa de vegeta\ue7\ue3o, em vasos de 11,5 L, preenchidos com areia e irrigados com solu\ue7\ue3o salinizada, em Campos dos Goytacazes, RJ. O delineamento experimental foi inteiramente casualizado em esquema fatorial com quatro esp\ue9cies ( Eucalyptus camaldulensis , Eucalyptus tereticornis , Eucalyptus pellita e Eucalyptus robusta ) e cinco n\uedveis de salinidade (1,4; 2,50; 4,50; 6,45 e 8,33 dS m-1), com cinco repeti\ue7\uf5es. At\ue9 o n\uedvel m\ue1ximo de salinidade aplicado, as mudas de Eucalyptus camaldulensis , Eucalyptus tereticornis e Eucalyptus robusta responderam positivamente com rela\ue7\ue3o \ue0s caracter\uedsticas valor SPAD, rendimento qu\ue2ntico potencial do fotossistema II, biomassa seca foliar e \ue1rea foliar. Essas avalia\ue7\uf5es sugerem toler\ue2ncia dessas esp\ue9cies \ue0s condi\ue7\uf5es de salinidade impostas. Mudas de Eucalyptus pellita mostraram sensibilidade ao estresse salino. As redu\ue7\uf5es da biomassa seca e \ue1rea foliar podem estar relacionadas a estrat\ue9gias de resist\ueancia das plantas ao estresse salino