TISSUE DAMAGE AND PHYSIOLOGICAL QUALITY ON CORN SEEDS SUBJECTED TO RUPTURE COMPRESSION

Abstract

Rupture in seeds reduces germination, even if the damage does not occur on metabolic tissue, and causes an increase in attack of microorganisms. Understanding the mechanics of tissue failure will allow developing more appropriate management conditions to reduce mechanical damage or its effects; thus, the objective of this study was to know the nature of the maize (Zea mays L.) seed tissue failure subjected to axial compression depending on the type of endosperm and moisture content. The physiological quality and cell damage of corn seeds of three varieties with floury endosperm (Cacahuacintle), semi-dent (HS-2) and flint (Palomero) were evaluated with 12 and 20 % moisture contents and compressed at a speed of 1 mm min^-1 between polished plates until just the moment the break ocurred. In the rupture zone, the endosperm showed a proportion of 92.20 % with cell wall rupture, larger than the area of 7.8 % without cell wall rupture; the aleurone layer also showed a proportion of cells with cell wall rupture of 87.8 %, higher than that of cells without cell wall rupture (12.3 %). There were no fractures on embryo tissue nor scutellum; however, germination in seeds subjected to breakage was lower (55.0 %) than that of the control (85.2 %). The proportion of cell rupture was significantly different between the two moisture levels studied. There were no significant differences in the proportion of cell rupture between varieties. The standard germination of compressed Cacahuacintle and HS-2 seeds was higher for 12 % moisture content compared to those compressed with 20 % moisture content.