LOW-TEMPERATURE SEED GERMINATION TESTS

72 RESEARCH REPORTS

PNL Volume 12 1980

Wehner, T. C. and North Carolina State University, Raleigh, NC, USA

E. T. Gritton University of Wisconsin, Madison, WI, USA

Improvement of the germination ability of peas in cold soil would permit

earlier planting of the crop in the spring, and would allow more uniform stand

establishment under adverse soil conditions. Other researchers have found

genetic differences in emergence speed of pea seedlings from cold soil (Torfason

and Nonnecke, Can. J. Pl. Sci. 39:119-124, 1959). Our objectives were to find

a rapid test to use in screening lines for low-temperature germination ability,

and to determine if selected lines differed genetically for this trait.

Four cultivars were used: 'Alaska' and 'Alsweet', both early-season

cultivars, and 'New Season' and 'New Line Early Perfection' (NLEP), both

mid-season cultivars. In the first tests, only these four cultivars were

used. In a later test, two families (consisting of two parents, their Fi,

reciprocal F1, and F₂) were tested. The two families tested were Alaska

x New Season and NLEP x Alsweet. All seeds used for the cold tests were

produced in the field along one wire trellis in the same growing season. Petri

plates (100 x 15 mm) were filled halfway with sterile silica sand, moisture

was added, and 15 seeds were placed in the sand. The plates were checked

every 12 hours for sprouted seeds. The average number of days for germination

of each plate of 15 seeds was calculated and the data were analyzed as a

completely randomized experimental design. Two replications were employed

in the first tests and six in the tests involving parents, F1's, and F₂.

Three conclusions can be drawn from the data in Table 1. First, there

are differences among cultivars for low-temperature germination ability. Second,

the differences among cultivars become greater as the temperature is dropped

from 20 to 8°C. This is indicated by the greater ranges (number of days between

fastest and slowest germinating cultivars) at the lower temperatures. Third,

there is no correlation between low-temperature germination ability and maturity,

as the fastest and slowest germinators at 8°C are both mid-season cultivars.

PNL Volume 12 1980

RESEARCH REPORTS 73

Distribution of seeds for low-temperature seed germination ability was

similar in the two families tested, so only the Alaska x New Season cross is

presented (Fig. 1). There is a strong maternal effect for this trait since

the Fi tends to be similar to the female parent in mean and range of the distri

bution. The distribution of the Fj ^ls skewed toward the fast-germinating

parent indicating dominance for low-temperature seed germination ability.

Low-temperature germination tests run at 8°C or below should be useful

in screening lines of peas for use in a breeding program to improve cold

tolerance. Maternal effects may complicate the procedure, but the test Is

rapid and genetic variability for the trait exists.