The physiology of various antistress-antioxidants, plant growth regulators and mineral salts in promoting seed germination and seedling emergence under low soil temperature and soil moisture conditions in processing carrots

Optimizing root grades is critical for maximizing profits in processing carrots. However, cold and dry weather conditions challenge carrot production and often limit germination and seedling emergence, reducing seedling emergence. Experiments were conducted to develop an integrated approach using gel seeding technology and seed preconditioning using compounds that belong to both natural and synthetic antistress-antioxidants, plant growth regulators and mineral salts to promote early and uniform emergence under limiting temperature (5°C) and soil moisture (20% FC) conditions. Carrot seeds of cv. Oranza were used in this study. Germination and emergence was delayed and inhibited at 5°C. Seedling emergence and vigor was also delayed and inhibited at 5°C and 20% FC, in combination. However, seed preconditioning using KNO3 at 1.5%, lutein at 1 mg·L -1, citric acid at 10 mg·L-1, ascorbic acid at 100 mg·L-1 and spermidine at 10 mg·L-1 all hastened and promoted emergence at 5°C and at 20% FC compared to the untreated control and acted as Germination and Emergence Promoters (GEPs). Among the GEPs, spermidine and KNO3-preconditioned seeds sown directly into the soil enhanced seedling emergence in the field trial conducted in Avonport, NS. GEPs did not replace the GA requirement; rather, they may have protected GA synthesis under limiting conditions. GEPs may have enhanced seed germination and seedling vigor through protecting proteins involved in the germination process and also through the induction of new proteins.