Physiological Quality of Strawberry (Fragaria vesca L.) Seeds Subjected to Water Stress

Abstract

Water availability is a key determinant of seed germination and early seedling establishment, whereas water deficit restricts imbibition and delays the metabolic processes required for successful germination. This study evaluated the physiological quality of strawberry (Fragaria vesca L.) cv. Sensação seeds subjected to polyethylene glycol (PEG 6000)-induced water stress. Seeds were exposed to osmotic potentials of 0.0, −0.1, −0.2, −0.3, and −0.4 MPa under controlled laboratory conditions in a completely randomised design with four replicates of 50 seeds. Germination, first germination count, germination speed index, root length, and shoot length were evaluated. Water stress markedly reduced the first germination count, with a significant decline observed as early as −0.1 MPa, indicating that early seed vigour was impaired even under moderate osmotic restriction. In contrast, final germination, germination speed index, and shoot length were not significantly affected within the tested range. Root length showed a decreasing trend with increasing stress intensity, although this response should be interpreted cautiously because it was not consistently supported by both parametric and non-parametric analyses. Overall, the results indicate that the first germination count was the most sensitive indicator of PEG-induced water stress in strawberry seeds, demonstrating that early vigour is affected before final germination capacity is substantially compromised under the evaluated conditions.