Effect of low temperatures on the germination of different field pea genotypes

Germination, emergence in sand and seedling development of ten field pea (Pisum sativum L.) accessions differing in leaf type, flower and seed color, cold hardiness and growing habit were assessed at three low temperatures of 2degreesC, 5degreesC and 10degreesC and a control temperature of 20degreesC. Seeds germinated and emerged in temperatures ranging from 5 to 20degreesC. Germination and emergence were highest for all accessions at 10degreesC followed by 20degreesC. Germination and emergence occurred earliest at 20degreesC and were delayed as temperature decreased. The GT(50) and ET50 values (days for 50% germination or emergence) were shortest at 20degreesC and longest at 5degreesC. Cold temperatures, particularly 5degreesC, caused a clear reduction in both top growth and root development and yield and individual seedling weight. Seeds failed to germinate or emerge at 2degreesC when left for 216 days: however seeds of some accessions emerged successfully when transferred to 20degreesC after this period. Germination and emergence were not associated with seed or flower color, cold hardiness and leaf type of the pea accessions at either 20degreesC and or l0degreesC. However, red flowered and cold hardy accessions showed better germination and emergence at 5degreesC and their seeds also remained viable for approximately 8 months at 2degreesC. Cold hardy, purple flowered and small seeded accessions produced smaller seedlings and grew slowly. Seed weight was positively and significantly correlated with top and root development of seedlings, total fresh yield and daily growth rate at all temperatures.