INDETERMINATE AND DETERMINATE GROWTH HABIT IN Amaranthus hypochondriacus: ONTOGENY OF SHOOT APICAL MERISTEM AND ITS EFFECT ON SEED WEIGHT

Abstract

Amaranth (Amaranthus hypochondriacus L.) is important for its high protein content, as the nutritional value of its grain is due partly to the amount of protein higher than that of other cereals. Grains form in the inflorescences and their architecture depend on whether growth is determinate or indeterminate. By means of scanning electron microscopy and thinning techniques, we obtained images of the morphological changes of the apical meristem during the life cycle of the plant. That tissue remained undifferentiated in the indeterminate phenotype and the inflorescence was spiked, the apical meristem stopped its activity with the formation of each terminal flower, originating a synchronized development. The development of the inflorescence in determinate growth did not present phenological overlap. The branches of this last phenotype were shorter. The seeds of plants with determinate growth were heavier than those of indeterminate growth. The study of apical meristem morphology could be the basis for the analysis of morphogenetic aspects of development, which at the same time are support for the genetic improvement and agronomic management of A. hypochondriacus.