Crescimento, pigmentos fotossintéticos e metabolismo antioxidante de plântulas de cevadas sob tratamentos e estresses abióticos

Abstract

The present work aimed to evaluate the physiological attributes of the initial growth and the biochemical performance of barley plants, maintaining different seed treatments, under the influence of soil flooding, at different temperatures. The experimental design was completely randomized, in a 2x6x2 factorial scheme, with two barley cultivars: ABI Rubi and BRS Caue, six seed treatments: Control, Fipronil + pyraclostrobin + methyl thiophanate, Fluazinam + methyl thiophanate, Lambdacyhalothrin + thiamethoxam, Triadimenol and Fipronil; and two soil water conditions, at temperatures of 20 and 30ºC, with four replications per treatment. Underlying variables of growth attributes were emergence, IVE, VE, shoot and root length, shoot and root dry mass, and leaf area. The environmental biochemical variables in the seedlings were chlorophyll a, chlorophyll b, total chlorophyll, carotenoids, peroxide and lipid peroxidation content and the activity of SOD, CAT and APX enzymes. The ABI Rubi and BRS Caue cultivars showed similar performance under the evaluated conditions. Seed treatment with Triadimenol resulted in a decrease in shoot length and leaf area. The effect of other seed treatments on growth attributes varied according to the cultivar, being more pronounced at a temperature of 20ºC. Flooding caused a reduction in seedling growth, mainly in the leaf area. The content of photosynthetic pigments showed a reduction in flooding, mainly at a temperature of 20ºC. The activity of antioxidant enzymes was higher in flooded conditions and at a temperature of 30ºC, while the effects of seed treatments varied according to the cultivar. Higher levels of hydrogen peroxide and lipid peroxidation were observed in flooded conditions, varying their interaction with the other factors. Both cultivars showed similar performance of growth attributes, photosynthetic pigments and antioxidant metabolism under the evaluated conditions.