Handbook of Plant and Crop Physiology

DORMANCY: MANIFESTATIONS AND CAUSES 167

TABLE 5 Reversible Effects of Brief Exposures

to Red (R 
580 to 680 nm) and Far-Red

(FR700 nm) Radiation on Germination of

Lettuce Seed, cv. ‘Grand Rapids’, in Darkness

Sequence Germination (%)

Darkness 8.5

R (640–680 nm) 98

R-FR 54

R-FR-R 100

R-FR-R-FR 43

R-FR-R-FR-R 99

R-FR-R-FR-R-FR 54

R-FR-R-FR-R-FR-R 98

Source: Ref. 40.

TABLE 6 Time at Room Temperature for Dry After-Ripening of Seeds of Selected Species

Time required (months) Species Alternative method

1 Brome grass (Bromus secalinus) Chilling
2–3 Rice (Oryza sativa)—
12–18 Lettuce (Lactuca sativa) Light, chilling
60 Curled dock (Rumex crispusL.) Light, chilling, alternating tempeature
Source: Adapted from Ref. 10.

Figure 4 Effect of storage temperature on mean dormancy period in rice. Each line represents a different cul-
tivar. (Adapted from Ref. 43.)