Stand establishment in processing carrots – Effects of various temperature regimes on germination and the role of salicylates in promoting germination at low temperatures

Abstract

The effects of various temperature regimes on carrot seed germination and the possibility of hastening germination at a low temperature using salicylates were studied. Seeds were incubated at various temperatures viz., 25, 20, 15, 10, 5 and 2°C. Salicylates such as, 2,6-dihydoxybenzoic acid (DHBA), acetylsalicylic acid (ASA), salicylic acid (SA) were supplied at 0, 1, 10, 100 and 1000 mg L-1 continually to the seeds incubated at 25 and 5°C until germination. Data on germination percentage were collected, and vigor value was calculated. Incubating seeds at various low temperature regimes significantly and proportionately reduced germination percentage and vigor value. The highest cumulative germination and vigor value was observed at 25°C. Critical threshold temperature for germination (GT50) was 5°C. Seed treatment using salicylates hastened germination at 5°C. 2,6-dihydoxybenzoic acid 1, ASA 100 and SA 1 mg L-1 all were effective in hastening germination at 5°C. Among all the salicylates, ASA 100 mg L-1 was the most effective in advancing germination at 5°C. Salicylates at the highest concentration of 1000 mg L-1 inhibited germination significantly both at 25 and 5°C. Key words: Acetylsalicylic acid, carrot, 2,6-dihydoxybenzoic acid, germination percentage, rate of germination, salicylates, SA, temperature, thermogenesis, vigor value