The initial vigor of seeds under cold stress influences the performance of rice seedling

Rice is a summer crop of great importance in Brazil and is subject to abiotic cold stress at sowing. With the use of high vigor seeds, it is possible for seedlings to have a capacity to recover from this type of stress, tolerating the stress and ensuring initial establishment, uniformity and consequently greater productivity. Therefore, the objective was to evaluate the recovery capacity of rice seedlings from seeds with contrasting vigor, after periods of cold stress. The study was carried out at the Seed Analysis Laboratory of the State University of Santa Catarina. The batches used were from the cultivar SCS122 Miura, from the 2018/2019 harvest and physiological characterization was carried out. Then, two batches were selected (low and high vigor) that were subjected to two, three, four and five days of cold at 10 °C followed by periods of post-stress recovery (exit and five days) at 25 °C. Control was maintained in the germinator at a constant 25 °C. After each period, normal and abnormal seedlings and dead seeds, shoot and root length and seedling dry mass were evaluated. A completely randomized design was used with four replications under a three-factorial scheme. It was observed that when subjected to two days of stress, the batch with greater vigor showed recovery capacity. The lower vigor batch had its performance drastically reduced after stress. It is concluded that the performance of rice seedlings under cold stress is favored by the initial vigor of the seed.