Seed mass modulates tolerance to water deficit in Luetzelburgia auriculata (Allemão) Ducke seedling

Abstract

In semi-arid regions, water deficit occurs for long periods, but the adaptation mechanisms developed by endemic species are little known. The objective of this study was to determine the tolerance of Luetzelburguia auriculata (Allemão) Ducke seedlings to water stress regarding germination and seedling establishment related to seeds’ mass. The experiment was conducted in a completely randomized design in a 2 x 5 factorial scheme, with two classes of seeds (ligh t < 0.35 g and heavy ≥ 0.35 g) and five osmotic potential levels (-0.2; -0.4; -0.6; -0.8 and -1.0 MPa), distributed in four replications of 25 seeds per plot. The following parameters were evaluated: germination rate (GR), first germination count (FGC), germination speed index (GSI), mean germination time (MGT), root length (RL), fresh and cotyledon dry mass (CFM/CDM) and fresh and dry root mass (RFM/RDM). As the osmotic potential became more negative, there was a reduction in physiological variables. The h eavy seeds (≥ 0.35 g) showed increases when compared to light seeds (<0.35 g), of 15.73, 22.94, 15.02, 23.33, 31.43, 21.43% for the variables GR, FGC, RL, CFM, CDM and RFM, respectively. Therefore, heavy seeds are more tolerant to water stress and should be prioritized for the recovery of degraded areas, especially in places with low rainfall.