Plastic responses to clipping in two species of Amaranthus from the SierraNorte de Puebla, Mexico

This study investigates the plastic responses after shoot removal of Amaran thus cruentus L. and A. hypochondriacus L. This practice is common in the S ierra Norte de Puebla, Mexico, where both species are cultivated and used a s a food source during the vegetative stage. Empirical observations indicat e that biomass increases in clipped plants. The experimental study carried out on both species of Amaranthus imitated local farm management. Three lev els of shoot removal were applied to plants of both species: Control, 10% a nd 40%. In A. cruentus plants with 10% of the shoot removed produced more s talk biomass, more leaves, greater leaf area, greater length of primary bra nches and a larger number of secondary branches than the control plants. In A. hypochondriacus, there were no differences among levels of shoot remova l in stem biomass; in general, the number of primary and secondary branches in control plants was greater than that in clipped plants. Patterns of bio mass allocation revealed important differences between species, as clipped plants allocated more biomass to seeds in A. cruentus, while control plants allocated more to leaves in A. hypochondriacus. Furthermore, changes in re sponse at the primary branch (secondary branches, leaf biomass, and area) l evel were observed between species. In general, clipped plants of A. cruent us overcompensate for the damage, while this response was not evident in cl ipped plants of A. hypochondriacus. Instead, this species showed high toler ance to damage. The phenotypically plastic responses expressed for both spe cies can be used as a guide to improve management of these plants by local farmers from the Sierra.