INFLUENCE OF RED LASER RADIATION ON THE VIGOR OF TOMATO SEEDS AFFECTED BY AGING

The loss of vigour in tomato seeds (Solanum lycopersicum L.) due to aging is a normal condition. This study provides a future reference in regard to the possible applications pre-sowing of red laser radiation treatments on tomato seeds to improve the vigour of the aged seeds. The objective of the study was to analyse the effects of laser radiation on aged tomato seeds, on the rate of germination and growth. It is hypothesized that at least one treatment of red laser radiation could improve the seed vigour. Two groups of seeds were used, one with 11 years of aging and another with seeds aged 11 years plus 24 h of artificial aging. For the radiation, a red laser diode of 660 nm was used with a potency of 100 mW, at a radiation density of 0.2 mW cm^-2, eight exposure times to the laser radiation and a control. The data were subjected to an analysis of variance and the means were compared with the Tukey test (HSD; p ≤ 0.05). In seeds with 11 years of aging, the laser treatment at 120 s improved seed vigour by 125 %, resulting from an increase in the growth of the radicle (167 %, p ≤ 0.05) compared to the control (100 %). On the other hand, the laser treatment at 60 s improved the tolerance to stress from artificial aging, the vigour index increased 143 % compared to the control (100 %), as a result of an improvement in germination of 162 % and in the hypocotyl growth (130 %, p ≤ 0.05), compared to the control (100 %). Red laser radiation on tomato seeds affected by natural or artificial aging can influence the processes of photo morphogenesis and increase seed vigour.