Atmospheric plasma overcomes seed dormancy in Pityrocarpa moniliformis (Benth.) Luckow & R. W. Jobson

Abstract

Plasma technology consists of a fast, clean method with great potential for use in agriculture and forestry, especially in modifying the cutaneous surface of dormant seeds. The objective of this study was to evaluate the effect of applying atmospheric cold plasma onto Pityrocarpa moniliformis seeds, verifying its implications on the seed coat permeability, as well as its germination and vigor. The seeds were submitted to atmospheric cold plasma for 1.5; 2.0; 3.0; 4.0; and 5.0 minutes, using seeds without any treatment as the control. After application, the integument’s wettability, imbibition curve and electrical conductivity of the imbibition solution were determined. The seeds were also submitted to the germination test which determined their viability, median, uniformity and asymmetry. The germination speed index, the first germination count and the seedling length were concomitantly evaluated with the germination test. The seeds subjected to plasma for 4.0 and 5.0 minutes had the smallest apparent contact angles of 64 and 61º, respectively, characterizing greater wettability of the integument among the tested treatments. The highest imbibition rate and solute release was observed in seeds treated by 0.5; 1.5 and 4.0 minutes. The plasma provided an increase in germination and seed vigor in all tested treatments when compared with the control. The use of atmospheric plasma applied to Pityrocarpa moniliformis seeds proved to be efficient as a method to overcome integumentary dormancy, increasing the integument’s wettability and improving the germination percentage and vigor.