Impact Of Hydropriming On Germination And Seedling Establishment Of Sunflower Seeds At Elevated Temperature

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 degrees C (range of 39.3 degrees C to 53.3 degrees 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 seed-ling 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 pri-ming 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.