Andréa Bicca Noguez Martins

Antioxidant activity of corn seeds after thermal stress

The aim of this research was to analyze the effect of different temperatures on physiological quality and relate the responses with the antioxidant activity of three lots of corn seeds. The seeds from three lots were exposed for 24h at temperatures of 15, 25, 35 and 40°C and then evaluated for percentage, speed index and first germination count, as well as early growth and activity of antioxidant enzymes in the seedlings. The experimental design was completely randomized with four replications, with subsequent polynomial regression analysis. The results showed that the seeds from the three lots of corn exposed to temperatures of 15 and 40°C, were of better high physiological quality (vigor), which explains the low activity of enzymes of the antioxidant defense system in these same temperatures. The antioxidant defense system is related to the physiological quality of corn seeds exposed to thermal stress.

Accelerated aging test in amaranth (Amaranthus cruentus L.) seeds.

The use of vigor tests for assessing seed lot quality is an important tool for production and commercialization. However, research on evaluating the quality of amaranth seeds is still scarce. The objective of this work was to evaluate procedures for conducting the accelerated aging test, aiming at the identification of different levels of vigour among lots of amaranth (Amaranthus cruentus L.) seeds cultivar BRS Alegria. Five seed lots were used and submitted to tests of germination, first count of germination, seedling emergence and accelerated aging, using the aging periods of 24, 48 and 72 hours and adopting the traditional methodology with water and the use of saturated (40g NaCl in 100mL of water) and unsaturated (11g NaCl in 100mL of water) sodium chloride (NaCl) solution. The accelerated aging test at 41oC and periods of 24, 48 and 72 hours of conditioning saturated NaCl solution allowed the stratification of the lots at vigour levels, similar to the results obtained by the seedling emergence test and the first count of germination. The accelerated aging test, using saturated saline solution (40g NaCl in 100mL of water) for 24 hours at 41°C, is therefore suitable for evaluating the physiological potential of amaranth seeds.