CARROT SEED GERMINATION AT HIGH TEMPERATURE CONDITIONS
Carrot seed germination and consequently stand establishment may be reduced under 35ºC. Studies on carrot germination at high temperature in response to genotype, umbel order, seed maturation and priming were performed to determine some conditions that led to improved germination at 35°C. Seeds from 34 cultivars and 125 accessions were germinated at 25 and 35°C. In other studies, seeds from primary, secondary and tertiary umbels were harvested separately and tested for germination at 20 and 35°C. Seeds harvested at different maturation periods (20, 30 and 40 days after anthesis - DAA) and primed in a PEG solution were also evaluated in both germination temperatures. In all studies, high temperatures decreased germination. Many of the commercial cultivars had reduced germination at 35°C; XPC-3617, Alvorada, Brasilia and Esplanada had the greatest germination at 35°C. The accession PI 319858 germinated 95% in both temperatures and was considered as thermotolerant. Seeds from primary and secondary umbels had greater vigor and germination at high temperature than seeds from tertiary umbels. At 20°C, unprimed seeds from umbels harvested after 20, 30 and 40 DAA germinated 88, 95 and 95%, respectively, while at 35°C, seeds germinated only 4, 13 and 28%, respectively. Seeds from umbels harvested after 40 DAA and primed for 9 days germinated 98 and 89% at 20 and 35°C, respectively. Selection of superior thermo¬tolerant genotypes, as well as the use of seed priming and/or other cultural practices during seed production may help circumvent carrot thermoinhibition problems.
Nascimento, W.M., Pereira , R.S., Vieira, J.V. and Cantliffe , D.J. (2012). CARROT SEED GERMINATION AT HIGH TEMPERATURE CONDITIONS. Acta Hortic. 936, 133-138
Daucus carota L., thermoinhibition, seed priming, maturation