Grober, K.
Besides those mutants of Lycopersicon esculentum described by Stubbe "(Die Kulturpflanze" Vol. 5,6 u. 7), X-ray induced chlorophyll-mutants are existing that become lethal under normal grawth conditions when they have formed cotyledons. For the present these mutants have been classified as xantha- and albina-types. Both homozygous recessive types are viable after being grafted on green stocks and become vigorous and fertile plants. In several combinations the scions produced in contrast to the usual conception--some chlorophill during mid-summer with highest light intensity but not in late autumn, when the days are shortening and light intensity drops.
In consequence of this observation, seeds of homozygous recessive genotypes of ten different mutants were sown in normal garden soil and daylight was excluded. When germinating, the seedlings were illuminated from a short distance (15 cm) by HNI-Fluorescent Tube. Though the measured light intensity (7500 lux) was only that of a cloudy sumer day two of the xantha-mutants showed intense chlorophyll-formation and growth and a third growth only without detectable chlorophyll production. By the same means one albina mutant was induced to form green pigment and secondary leaves. It is tempting to explain these effects of illumination with the spectral energy-distribution characterizing the utilized light-source.