The effect of light on cotyledon and primary leaf growth in white light grown <i>Sinapis alba</i>

Abstract

The growth of cotyledons and primary leaves of I‐day‐old Sinapis alba L. plants were studied under various light conditions and action spectra produced. For both responses blue and red light are most effective and a strong fluence rate dependency can be observed. The red light effect appears to be mediated through phytochrome, that of blue light being due to a separate blue light receptor, although this receptor requires the presence of far‐red absorbing phytochrome (P fr ) in order to be effective.