Impact of hydropriming on germination and seedling establishment of sunflower seeds at elevated temperature

Abstract

High temperature is a limiting factor in the seed germination of most crops. This study evaluated the effects of hydropriming at 6, 12 and 18 h on germination performance and seedling establishment of sunflower seeds under high air temperature. Results showed that germination of unprimed seeds was suppressed at an average elevated temperature of 44.3 °C (range of 39.3 °C to 53.3 °C) for eighteen days indicated by an increased lag time to onset of germination and decreased germination percentage. Conversely, priming seeds for 12 h to 18 h increased the germination percentage, time to 50% seedling emergence (T₅₀), germination index and vigour index. Seedlings emerging from primed seeds exhibited uniform 16-day old seedlings (18 days after sowing), leading to greater seedling dry weight and shoot length as compared to unprimed seeds. Conversely, the total chlorophyll content remain unchanged for all seeds. The significant increase in the shoot parameters suggested a positive association with priming and stress tolerance. The priming duration of 12 h to 18 h showed improvement at elevated air temperature through the reduction of ungerminated seeds and increase in seedling growth characteristics.