INVOLVEMENT OF A HIGH IRRADIANCE RESPONSE IN PHOTOINHIBITION OF WHITE CLOVER SEED-GERMINATION AT LOW WATER POTENTIAL

Seeds of white clover (Trifolium repens L., cv. Podkowa) were germinated at water potential psi = -0.3 MPa in darkness, at 25-degrees-C. A short exposure to blue light (B) inhibited germination in a manner similar to that described earlier for red (R) and far-red (FR) light (Niedzwiedz-Siegien and Lewak 1989). No reversibility of B, R and FR effects was observed. Saturation irradiance and energy was the lowest for R and the highest for B. The reciprocity of irradiance versus time of exposure was observed only for non-saturating irradiances of B, R and FR.