Cultivar-specific adaptation of growth and photosynthetic activity in developing apricot dense canopies

Light is the most important environmental factor for plants, which are not able to modify the surrounding habitat. Many distinct features, such as light intensity and light quality, change in shade habitats, because of neighbouring vegetation, increased far-red (FR) light, reduced blue (B) and red light (R) and decreasing photosynthetic photon flux density (PPFD), and these have a direct effect on photosynthesis and photomorphogenesis. In apricot cultivar populations, a wide range of growth habit ideotypes are revised: from upright, standard, to open and spreading. To ascertain if the modified light quality surrounding the plant affects photosynthetic activity and habit development of four cultivars, potted plants were grown in dense-community canopies and in an open-clearing habitat. The assimilation rate differed between genotypes and was also influenced strongly by the proximity signal generated by neighbouring plants inside the canopies. Based on the observed results, all genotypes showed a strong plasticity adaptation to the open-clearing and dense-community growth habitats. Individual genotypes differ from each other in their capacity to adapt their photosynthetic system and morphological growth traits under community-canopy conditions, in relation to their intrinsic fitness strategy in shade habitats.