Abstract Salt stress causes several physiological and biochemical disorders and impairs plant growth. However, adequate fertilization can improve the nutritional status and may reduce significantly the harmful effects caused by salt stress. From this perspective, this study aimed to evaluate the impact of different combinations of nitrogen, phosphorus and potassium fertilization on the antioxidant activity and accumulation of organic and inorganic solutes in West Indian cherry leaves, in the second year of production. The experimental design was in randomized blocks, with treatments distributed in a 10 × 2 factorial arrangement corresponding to ten fertilization combinations (FC) of NPK (FC1: 80-100-100%, FC2:100-100-100%, FC3:120-100-100%, FC4:140-100-100%, FC5:100-80-100%, FC6:100-120-100%, FC7:100-140-100%, FC8:100-100-80%, FC9:100-100-120%, and FC10:100-100-140% of the recommendation) and two levels of electrical conductivity of irrigation water (ECw) (0.6 and 4.0 dS m-1), with three replications. The multivariate analysis showed that irrigation with water of different electrical conductivities (0.6 and 4.0 dS m-1) resulted in different responses concerning the enzyme activity, production of organic compounds, and accumulation of inorganic solutes in the leaves. Under irrigation with low salinity water, there was greater accumulation of K+, soluble carbohydrates, and proline, and lower activity of antioxidative enzymes, especially SOD and APX. Under high salinity water, greater enzyme activity and higher concentrations of Na+ and Cl- were observed. The results indicate that the response of West Indian cherry to salinity was more towards redox homeostasis than osmotic homeostasis through the accumulation of compatible solutes. Fertilization combination FC5 (100-80-100% corresponding to 200, 24 and 80 g plant-1 of NPK) modulates the enzyme activity of SOD and APX attenuating the impacts of salinity, being an efficient combination to preserve redox homeostasis in West Indian cherry plants grown under salt stress. growth However perspective nitrogen leaves blocks 1 FC (FC FC1 (FC1 80100100%, 80100100 100 100%, 80-100-100% FC2100100100%, FC2100100100 FC2 FC2:100-100-100% FC3120100100%, FC3120100100 FC3 120 FC3:120-100-100% FC4140100100%, FC4140100100 FC4 140 FC4:140-100-100% FC510080100%, FC510080100 FC5:100-80-100% FC6100120100%, FC6100120100 FC6 FC6:100-120-100% FC7100140100%, FC7100140100 FC7 FC7:100-140-100% FC810010080%, FC810010080 FC8 80%, FC8:100-100-80% FC9100100120%, FC9100100120 FC9 120%, FC9:100-100-120% FC10100100140% FC10100100140 FC10 140% FC10:100-100-140 recommendation ECw (ECw 0.6 06 0 6 (0. 40 4 4. m1, m1 m , replications m-1 compounds K K+ carbohydrates proline enzymes Na Cl observed 10080100% 10080100 100% (100-80-100 200 8 plant1 plant- 80100100% 8010010 80-100-100 FC2100100100% FC210010010 FC2:100-100-100 FC3120100100% FC312010010 12 FC3:120-100-100 FC4140100100% FC414010010 14 FC4:140-100-100 FC510080100% FC51008010 FC5:100-80-100 FC6100120100% FC610012010 FC6:100-120-100 FC7100140100% FC710014010 FC7:100-140-100 FC810010080% FC81001008 80% FC8:100-100-80 FC9100100120% FC910010012 120% FC9:100-100-120 FC1010010014 FC10:100-100-14 0. (0 m- 1008010 (100-80-10 20 801001 80-100-10 FC21001001 FC2:100-100-10 FC31201001 FC3:120-100-10 FC41401001 FC4:140-100-10 FC5100801 FC5:100-80-10 FC61001201 FC6:100-120-10 FC71001401 FC7:100-140-10 FC8100100 FC8:100-100-8 FC91001001 FC9:100-100-12 FC101001001 FC10:100-100-1 ( 100801 (100-80-1 80100 80-100-1 FC2100100 FC2:100-100-1 FC3120100 FC3:120-100-1 FC4140100 FC4:140-100-1 FC510080 FC5:100-80-1 FC6100120 FC6:100-120-1 FC7100140 FC7:100-140-1 FC810010 FC8:100-100- FC9100100 FC9:100-100-1 FC10100100 FC10:100-100- 10080 (100-80- 8010 80-100- FC210010 FC2:100-100- FC312010 FC3:120-100- FC414010 FC4:140-100- FC51008 FC5:100-80- FC610012 FC6:100-120- FC710014 FC7:100-140- FC81001 FC8:100-100 FC910010 FC9:100-100- FC1010010 FC10:100-100 1008 (100-80 801 80-100 FC21001 FC2:100-100 FC31201 FC3:120-100 FC41401 FC4:140-100 FC5100 FC5:100-80 FC61001 FC6:100-120 FC71001 FC7:100-140 FC8100 FC8:100-10 FC91001 FC9:100-100 FC101001 FC10:100-10 (100-8 80-10 FC2100 FC2:100-10 FC3120 FC3:120-10 FC4140 FC4:140-10 FC510 FC5:100-8 FC6100 FC6:100-12 FC7100 FC7:100-14 FC810 FC8:100-1 FC9100 FC9:100-10 FC10100 FC10:100-1 (100- 80-1 FC210 FC2:100-1 FC312 FC3:120-1 FC414 FC4:140-1 FC51 FC5:100- FC610 FC6:100-1 FC710 FC7:100-1 FC81 FC8:100- FC910 FC9:100-1 FC1010 FC10:100- (100 80- FC21 FC2:100- FC31 FC3:120- FC41 FC4:140- FC5:100 FC61 FC6:100- FC71 FC7:100- FC8:100 FC91 FC9:100- FC101 FC10:100 (10 FC2:100 FC3:120 FC4:140 FC5:10 FC6:100 FC7:100 FC8:10 FC9:100 FC10:10 (1 FC2:10 FC3:12 FC4:14 FC5:1 FC6:10 FC7:10 FC8:1 FC9:10 FC10:1 FC2:1 FC3:1 FC4:1 FC5: FC6:1 FC7:1 FC8: FC9:1 FC10: FC2: FC3: FC4: FC6: FC7: FC9:
Resumo O estresse salino causa distúrbios fisiológicos e bioquímicos que prejudicam o crescimento vegetal. Entretanto, acredita-se que a fertilização mineral adequada pode melhorar o estado nutricional e reduzir os danos causados pelo estresse salino. Dessa forma, o objetivo deste estudo foi avaliar os impactos de diferentes combinações de fertilização com nitrogênio, fosforo e potássio sobre o acúmulo de solutos (orgânicos e inorgânicos) e atividade antioxidante em folhas de aceroleira cultivada sob estresse salino no segundo ano de produção. O delineamento experimental foi em blocos casualizados com os tratamentos distribuídos em esquema fatorial 10 × 2, correspondendo a 10 combinações de adubação (FC) com nitrogênio, fósforo e potássio (FC1: 80-100-100%; FC2:100-100-100%; FC3:120-100-100%; FC4:140-100-100%; FC5:100-80-100%; FC6:100-120-100%; FC7:100-140-100%; FC8:100-100-80%; FC9:100-100-120% e FC10:100-100-140% da recomendação, referente ao segundo ano de cultivo) e dois níveis de condutividade elétrica da água (ECw) utilizada na irrigação (0,6 e 4,0 dS m-1), com três repetições. A análise multivariada mostrou que irrigação com água de diferentes condutividades elétricas (0,6 e 4,0 dS m-1) apresentou processos distintos em relação à atividade enzimática, produção de compostos orgânicos e acúmulo de solutos inorgânicos nas folhas. Sob irrigação com água de baixa salinidade houve maior acúmulo de K+, carboidratos solúveis e prolina, e menor atividade de enzimas antioxidativas, especialmente SOD e APX. Sob alta salinidade se observou maior atividade enzimática e maiores concentrações de Na+ e Cl-. Os resultados indicam que a resposta da acerola à salinidade foi mais no sentido da homeostase redox do que da homeostase osmótica por meio do acúmulo de solutos compatíveis com o metabolismo. A combinação de adubação FC5 (100-80-100% da recomendação correspondente a 200, 24 e 80 g planta-1 de NPK) modula a atividade enzimática da SOD e APX, atenuando os impactos da salinidade, sendo uma combinação eficiente para preservar a sua homeostase redox nas aceroleiras sob estresse salino. vegetal Entretanto acreditase acredita forma nitrogênio 1 2 FC (FC FC1 (FC1 80100100% 80100100 100 100% 80-100-100% FC2100100100% FC2100100100 FC2 FC2:100-100-100% FC3120100100% FC3120100100 FC3 120 FC3:120-100-100% FC4140100100% FC4140100100 FC4 140 FC4:140-100-100% FC510080100% FC510080100 FC5:100-80-100% FC6100120100% FC6100120100 FC6 FC6:100-120-100% FC7100140100% FC7100140100 FC7 FC7:100-140-100% FC810010080% FC810010080 FC8 80% FC8:100-100-80% FC9100100120% FC9100100120 FC9 120% FC9:100-100-120 FC10100100140% FC10100100140 FC10 140% FC10:100-100-140 cultivo ECw (ECw 0,6 06 0 6 (0, 40 4 4, m1, m1 m , repetições m-1 K K+ prolina antioxidativas APX Na Cl. Cl . Cl- metabolismo 10080100% 10080100 (100-80-100 200 8 planta1 planta planta- NPK 8010010 80-100-100 FC210010010 FC2:100-100-100 FC312010010 12 FC3:120-100-100 FC414010010 14 FC4:140-100-100 FC51008010 FC5:100-80-100 FC610012010 FC6:100-120-100 FC710014010 FC7:100-140-100 FC81001008 FC8:100-100-80 FC910010012 FC9:100-100-12 FC1010010014 FC10:100-100-14 0, (0 m- 1008010 (100-80-10 20 801001 80-100-10 FC21001001 FC2:100-100-10 FC31201001 FC3:120-100-10 FC41401001 FC4:140-100-10 FC5100801 FC5:100-80-10 FC61001201 FC6:100-120-10 FC71001401 FC7:100-140-10 FC8100100 FC8:100-100-8 FC91001001 FC9:100-100-1 FC101001001 FC10:100-100-1 ( 100801 (100-80-1 80100 80-100-1 FC2100100 FC2:100-100-1 FC3120100 FC3:120-100-1 FC4140100 FC4:140-100-1 FC510080 FC5:100-80-1 FC6100120 FC6:100-120-1 FC7100140 FC7:100-140-1 FC810010 FC8:100-100- FC9100100 FC9:100-100- FC10100100 FC10:100-100- 10080 (100-80- 8010 80-100- FC210010 FC2:100-100- FC312010 FC3:120-100- FC414010 FC4:140-100- FC51008 FC5:100-80- FC610012 FC6:100-120- FC710014 FC7:100-140- FC81001 FC8:100-100 FC910010 FC9:100-100 FC1010010 FC10:100-100 1008 (100-80 801 80-100 FC21001 FC2:100-100 FC31201 FC3:120-100 FC41401 FC4:140-100 FC5100 FC5:100-80 FC61001 FC6:100-120 FC71001 FC7:100-140 FC8100 FC8:100-10 FC91001 FC9:100-10 FC101001 FC10:100-10 (100-8 80-10 FC2100 FC2:100-10 FC3120 FC3:120-10 FC4140 FC4:140-10 FC510 FC5:100-8 FC6100 FC6:100-12 FC7100 FC7:100-14 FC810 FC8:100-1 FC9100 FC9:100-1 FC10100 FC10:100-1 (100- 80-1 FC210 FC2:100-1 FC312 FC3:120-1 FC414 FC4:140-1 FC51 FC5:100- FC610 FC6:100-1 FC710 FC7:100-1 FC81 FC8:100- FC910 FC9:100- FC1010 FC10:100- (100 80- FC21 FC2:100- FC31 FC3:120- FC41 FC4:140- FC5:100 FC61 FC6:100- FC71 FC7:100- FC8:100 FC91 FC9:100 FC101 FC10:100 (10 FC2:100 FC3:120 FC4:140 FC5:10 FC6:100 FC7:100 FC8:10 FC9:10 FC10:10 (1 FC2:10 FC3:12 FC4:14 FC5:1 FC6:10 FC7:10 FC8:1 FC9:1 FC10:1 FC2:1 FC3:1 FC4:1 FC5: FC6:1 FC7:1 FC8: FC9: FC10: FC2: FC3: FC4: FC6: FC7: