IOA Conference and Exhibition Valencia, Spain - October 29 – 31, 2007 3.4 - 1 Increase of corn seeds germination by oxygen and ozone treatment Frédéric Violleau 1 , Kheira Hadjeba 1 , Joël Albet 2 , Roland Cazalis 1 and Olivier Surel 1 1. EI-Purpan, 75 voie du TOEC, 31076 Toulouse Cedex 03, France 2. ENSIACET, 118 route de Narbonne, 31077 Toulouse Cedex 4, France Abstract Corn seed were treated with pure oxygen ([O 3 ] = 0 g/m 3 ) and oxygen charged with ozone ([O 3 ] = 20 g/m 3 ) during 6.8 or 20.5 minutes. Germination tests were started immediately or 48h after treatment. Effects of oxidative treatments on germination were determinate by measuring seedlings and roots (>3 and >20mm) rate at 3, 4 and 5 days after imbibition. Results obtained for treated seeds samples were higher than untreated one. A faster start of germination for treated samples than untreated was observed. This early germination start led to have more germinated seeds with large root in treated samples than untreated at 4 and 5 days. Nevertheless a too long ozone treatment seemed to be penalizing on germination rate whereas a short one seemed to be most beneficial. Key-words: Ozone; oxygen; seeds; germination; seedling; root; corn. Introduction Exogenous oxidative treatment of seeds for breaking the seed dormancy has been well studied. Main studies focussed on breaking seed dormancy by H 2 O 2 treatment. Authors [1] discussed the effect of H 2 O 2 on subsequent growth of young seedling and observed the promotion of seedling growth by H 2 O 2 treatment of seed in barley, corn, haricot, vegetable marrow, melon, radish and carrot. Ozone, reactive oxygen specie of interest as H 2 O 2 for seed oxidative stress [2], has also been used for grain and plant treatment. Ozone has been often used for mycotoxins [3-7] or fungus [8-9] degradation present on seed grain surface. Positive effect of ozone on plant growing, feeding gas near plant roots, has been also described [10]. Seed germination rate has been enhanced after treatment in an aqueous ozone and microwave bath [11]. Germination and growth properties of corn, haricot, barley and sunflowers seeds have been increased after humidification and treatment with ozone gas [12]. In another hand, negative effect of ozone on seed germination has been described. Germination of wheat seeds has been significantly reduced after a too long exposure to ozone gas [13]. Ozone has been used in process to ensure that seeds do not germinate [14]. View to these studies, a positive effect of a soft ozone treatment on germination has been described. Nevertheless, effect on germination of oxygen, main component of gas charged with ozone, has not been studied. Moreover, in all these works, germination experimental conditions and kinetics are not often described. The aims of this work are twofold: i) to evaluate the positive effect of oxygen and ozone treatment on germination rate of corn ii) to study oxygenation and ozonation influence on germination kinetics. Material and methods Materials Corn seed were purchased and selected for there low germination quality. Equipment Ozone was generated by Ozat CFS-1 ozonator (Ozonia) supplied with pure oxygen bottles. A 0.05 m diameter and 1 m height glass column was used for ozonation and pure oxygen treatments. Seeds were disposed as a fixed bed on a support grid located above a ceramic porous distributor to gas introduction. Gas was introduced at the bottom of the column and pass through seeds with a 0.55 m 3 /h flow rate. At the top of the column, effluent gases from the reactor were vented to a thermal destruction system (θ = 350°C). Ozone concentration in the gas introduced at the bottom