Effect of low positive temperature on the antioxidant system formation in de-etiolated and etiolated Amaranthus tricolor L. seedlings grown from seeds treated with growth regulators

In the Non-chernozem zone of Russia, the recurrent spring cold up to 1-2 °C can cause damage and death of thermophilic amaranth seedlings. Pre-sowing treatment of seeds with growth regulators is an inexpensive and effective method to reduce the negative effect of hypothermia on seed germination. The aim of the research was to study the effect of low-temperature stress on etiolated and de-etiolated seedlings of amaranth cv. ‘Valentina’ ( A. tricolor L.) grown from seeds treated with growth stimulants. Seeds were pretreated with aqueous solutions of Albit (1 g/L), hydrogen peroxide (H2O2) - 5 mM and succinic acid (ScA) - 500 mg/L. Seeds were germinated in peat pots at 23 ± 2 °C (T23) for 7 days. On the 7th day, peat pots with seedlings grown in the light and in the dark were moved to thermostat at 2.0 ± 0.5 °C (T2) for 8 hours. Determination of the amount of amaranthine, chlorophylls and carotenoids were carried out according to generally accepted methods. Pretreatment of seeds with the growth regulators Albit, H2O2, and ScA increased hypocotyl length, root length, and biomass of light and etiolated seedlings. Low positive temperatures increased the content of amaranthine and carotenoids but reduced the content of chlorophylls. It was shown that all used growth regulators - H2O2, Albit and ScA trigger or at least maintain the system of antioxidant protection in light and etiolated seedlings of amaranth cv. ‘Valentina’ under low positive temperatures.