RESUMO A ocorrência de fontes hídricas com elevadas concentrações de sais é um problema frequente na região semiárida do Nordeste do Brasil. Assim, a busca por estratégias de manejo capazes de minimizar o efeito do estresse salino nas culturas é de extrema importância. Neste contexto, objetivou-se com este trabalho avaliar as trocas gasosas e a produção do maracujazeiro amarelo ‘BRS GA1’ em função das estratégias de irrigação com águas salobras e doses de potássio. A pesquisa foi desenvolvida sob condições de campo em São Domingos, PB, Brasil, utilizando-se o delineamento de blocos casualizados em esquema fatorial 6 × 2, sendo os tratamentos constituídos de seis estratégias de irrigação com águas salinas (SE - irrigação com água de baixa salinidade durante todo ciclo; irrigação com água de alta salinidade na fase vegetativa - VE; floração - FL; frutificação - FR; nas fases sucessivas vegetativa/floração - VE/FL; vegetativa/frutificação - VE/FR) e duas doses de potássio (60 e 100% (345 g de K2O por planta por ano) da recomendação, com quatro repetições e três plantas por parcela. Utilizaram-se dois níveis de salinidade da água (1,3 e 4,0 dS m−1), em diferentes fases fenológicas da cultura. A irrigação com água de 4,0 dS m−1 reduziu o potencial hídrico e osmótico foliar, a condutância estomática, a transpiração e a taxa de assimilação de CO2 do maracujazeiro-azedo, independente da estratégia de irrigação. O estresse salino nas fases vegetativa e de floração de forma contínua comprometeu a produção do maracujazeiro-azedo.
ABSTRACT The occurrence of water sources with high concentrations of salts is a common problem in the semi-arid region of north-eastern Brazil. The search for management strategies that can minimize the effect of salt stress on crops is therefore extremely important. As such, this study aimed to evaluate gas exchange and production in the yellow passion fruit ‘BRS GA1’as a function of irrigation strategies using brackish water and doses of potassium. The research was carried out under field conditions in São Domingos, in the state of Paraíba, Brazil, using a randomized block design in a 6 × 2 factorial scheme, with treatments comprising six irrigation strategies using water (irrigation with low-salinity water throughout the cycle – WS; irrigation with high-salinity water during the vegetative stage – VE; during the flowering stage – FL; the fruiting stage – FR; during successive vegetative/flowering stages - VE/FL; successive vegetative/fruiting stages - VE/FR) and two doses of potassium (60% and 100% of the recommended dose of 345 g K2O per plant per year), with four replications and three plants per plot. Two levels of water salinity (1.3 and 4.0 dS m−1) were used during different phenological stages of the crop. Irrigation with water at 4.0 dS m−1 reduced the leaf water potential, leaf osmotic potential, stomatal conductance, transpiration, and rate of CO2 assimilation of the yellow passion fruit, regardless of the irrigation strategy. The continuous salt stress during the vegetative and flowering stages compromised production in the yellow passion fruit.low-salinity water throughout the cycle – WS; irrigation with high-salinity water during the vegetative stage – VE; during the flowering stage – FL; the fruiting stage – FR; during successive vegetative/flowering stages - VE/FL; successive vegetative/fruiting stages - VE/FR) and two doses of potassium (60% and 100% of the recommended dose of 345 g K2O per plant per year), with four replications and three plants per plot. Two levels of water salinity (1.3 and 4.0 dS m−1) were used during different phenological stages of the crop. Irrigation with water at 4.0 dS m−1 reduced the leaf water potential, leaf osmotic potential, stomatal conductance, transpiration, and rate of CO2 assimilation of the yellow passion fruit, regardless of the irrigation strategy. The continuous salt stress during the vegetative and flowering stages compromised production in the yellow passion fruit.
