The initial inhibition of protochlorophyll regeneration in dark-grown leaves of barley after a short light pulse, and in greening leaves subjected to dark periods followed by a short light pulse

The regeneration of protochlorophyll in darkness after a short irradiation of a dark-grown leaf of barley ( Hordeum distichum L. cv. Weibull's Ingrid), in which the protochlorophyll pool has reached its final value, starts only after a period of 2–6 min. On the other hand, the regeneration starts immediately after a repeated irradiation, provided the dark period between the two irradiations has not been long enough for the end value of the pool size to be reached. The same pattern is followed even during the process of greening. During this process the end value of the pool size of protochlorophyll during dark periods becomes smaller the more chlorophyll has been formed.