Abstract
The objective of this study was to evaluate the effect of irrigation water salinity on gas exchange and antioxidative system responses of grain sorghum varieties. An experiment was conducted in a greenhouse located at the headquarters of Embrapa Semiarid Agriculture, Petrolina-PE, Brazil. The experimental design was randomized blocks, in a 6 x 5 factorial scheme. Six varieties of grain sorghum irrigated with saline water with five levels of salinity were evaluated. Photosynthesis and transpiration rate, stomatal conductance, leaf temperature, intrinsic and instantaneous water use efficiency, relative water content and leaf turgor potential were evaluated, as well as the activity of the enzymes catalase, ascorbate peroxidase and superoxide dismutase, and shoot biomass production. It was observed that irrigation with saline water causes reduction in the gas exchange and water status of grain sorghum varieties. The antioxidative system was activated in the six sorghum varieties to avoid the accumulation of reactive oxygen species, and the synchronism between the enzymes led to a better response of shoot dry mass production of the Ponta Negra variety.
Highlights
Resumo - O objetivo do trabalho foi avaliar o efeito da salinidade da água de irrigação nas trocas gasosas e nas respostas do sistema antioxidativo de variedades de sorgo granífero
Changes in metabolism often cause a secondary stress, oxidative stress, which results from increased production and accumulation of reactive oxygen species (ROS) in cellular metabolism
Among the various enzymes that act in this system, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) stand out
Summary
Resumo - O objetivo do trabalho foi avaliar o efeito da salinidade da água de irrigação nas trocas gasosas e nas respostas do sistema antioxidativo de variedades de sorgo granífero. O sistema antioxidativo foi ativado nas seis variedades de sorgo para evitar o acúmulo de espécies reativas de oxigênio, sendo que o sincronismo entre as enzimas refletiu numa melhor resposta de produção de massa seca da parte aérea da variedade Ponta Negra. Salt stress is one of the environmental factors that most limit the production of plant species in the most diverse environments. In this context, the use of production strategies that reduce the effects of salinity on agricultural crops is imperative for a successful production. CAT and APX, in turn, catalyze the conversion from H2O2 to water
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