AIR PLASMA TREATMENT EFFECTS ON SEEDS PHYSIOLOGY, GERMINATION AND SEEDLING.

The need of environment-friendly strategies for food production and plant protection makes the use of plasma-assisted technologies in agriculture as an innovative practice [1]. The non-equilibrium character of low temperature plasmas enables the production of reactive oxygen and nitrogen species (ROS and RNS) efficient in the decontamination, sterilization and chemical modification of surfaces. On seeds, the plasma treatment affects the basic physiological processes improving germinability and biometric parameters of plantlets [2]. We focused on the effect of plasma treatment on the morphology of seeds, germination and radicle development, either by using imaging techniques such as high-resolution computed X-ray microtomography (µXCT) or by following the development of seeds germination in vitro and in an artificial soil-like substrate. Since seeds germination relies mainly on the accumulation of mineral macronutrients (such as N, K, Ca, Mg, P, and S) and micronutrients (such as Cl, Fe, B, Mn, Zn, Cu, Mo, and Ni, generally in the range of ppm) in certain seed tissues [3], X-ray micro-fluorescence (m-XRF) was used to investigate the localization of mineral elements in seeds before and after plasma treatment [4]. Our results show that plasma treatment changed neither seed structure nor morphology. The increase of the germination rate was observed together with better developed root apparatus and improved biometric parameters. Moreover, we observed that macro- and micro-nutrients concentrated in the radicle, moving from the endosperm and the cotyledons. Redistribution of these elements could explain the faster germination of the plasma-treated seeds, being a similar process as generally observed in seed tissues during germination. The plasma treatment is therefore somehow anticipating and implementing the mobilization of key-nutrients towards the radicle, resulting in faster and higher germination of the seeds as well as improved characteristics of the plantlet, especially at the root level.