Abstract
ABSTRACT This work aimed to evaluate the physiological and biochemical changes resulting from controlled deterioration in different lots of sunflower seeds. Two sunflower seed lots of the cultivar Hélio 253 were subjected to simulated deterioration, using the accelerated aging test methodology (41 °C and 100% RH) for 0, 48, 72, and 96 h. Then, the seeds were subjected to the tests of germination, first germination count, seedling length and dry matter, emergence, accelerated aging, electrical conductivity, and total seedling length. The antioxidant activity was evaluated through the enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), and peroxidase (POX) at 0, 2, 4, and 6 days after sowing. Deterioration caused a reduction in the germination and vigor of the seeds, mainly in the lot with lower initial vigor and for the longest exposure times (72 and 96 h). For both lots, reductions in SOD activity and increases in POX and APX were observed during seed germination, mainly after 48 h of exposure to aging deterioration. Peroxidase enzymes are activated in deteriorated and non-deteriorated sunflower seeds, mainly after two days of germination.
Highlights
The world production of sunflower (Helianthus annuus L.) exceeds 50 million tons per year, making it one of the most important oilseed crops produced at the global level (FAOSTAT, 2020)
There were no differences between the lots regarding seedling growth, the superiority of lot 1was noted by the tests of first germination count, accelerated aging, emergence, emergence speed index (ESI), and electrical conductivity (Table 1)
The results indicate faster germination of seeds in lot 1, besides a greater tolerance to stress conditions, guaranteed by a greater organization of cell membranes
Summary
The world production of sunflower (Helianthus annuus L.) exceeds 50 million tons per year, making it one of the most important oilseed crops produced at the global level (FAOSTAT, 2020) Given this scenario, the demand for highquality seeds is increasing and involves a series of genetic, physical, physiological, and sanitary attributes that influence germination capacity and the development of vigorous plants in the field (MARCOS-FILHO, 2016). The low capacity of protection against excess ROS leads to physiological imbalances and increased respiration, favoring the loss of vigor and viability of seeds (EBONE; CAVERZAN; CHAVARRIA, 2019) In this context, the action of antioxidant enzymes (especially in orthodox species), such as superoxide dismutase (SOD), peroxidases (POX), and ascorbate peroxidase (APX), and non-enzymatic mechanisms play important roles in controlling oxidative stress and assist in the normal functioning of plant cells even under stress conditions (EBONE; CAVERZAN; CHAVARRIA, 2019; KAPOOR et al, 2019)
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