Abstract
Growth responses to different light conditions of the plants from the genus Brassica L. characterized by storage root formation, namely tuberous rooted mustard Brassica napiformis Bailey and field mustard B. rapa L. subsp. japonica Scheb. were studied. In treatments with equal daily light integral of 13.9 mol/m2, storage root formation by both genotypes started earlier under long-day conditions. A sensitivity to photoperiodic signals was firstly manifested by lateral meristems ensuring storage root formation and only later, by the shoot apical meristem. Primary manifestations of the shade-avoidance response in the cenosis was also related to the earlier formation of the storage root along with more active growth of other organs. Plant adaptation to low light involved structural and functional rearrangements providing first of all a relative increase in the lightharvesting leaf surface at more economical consumption of assimilates for their growth due to both a decrease in the specific leaf weight and an increase in the photosynthetic pigment content. For normal photosynthesis and growth occurrence, both species require a relatively low light amount. In B. rapa, daily requirement in incident radiation did not exceed 10 mol/m2. For B. napiformis, it was somewhat higher: storage root formation did not occur at a relatively low daily light integral (9.3 mol/m2), and this is one of the examples of multifaceted morphology during plant development.
Published Version
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