CHANGES IN APICAL MORPHOLOGY DURING FLORAL INITIATION AND REPRODUCTIVE DEVELOPMENT IN QUINOA (CHENOPODIUM-QUINOA WILLD)

A numerical scale for identifying main apex morphological development stages from vegetative to open flower in quinoa (Chenopodium quinoa Wi lld.) has been developed, using SEM photographs and stereomicroscope o bservations. The scale accounts for the different patterns of developm ent found in the two inflorescence types known in the species (glomeru late and amaranthiform). Eight stages are described for the glomerulat e inflorescence, and seven for the amaranthiform inflorescence. Develo pment of the apical meristem ends with the formation of an apical flow er in the glomerulate type, and is interrupted by the appearance of a cap-like structure in the amaranthiform type inflorescence. This struc ture has not been observed in other Chenopodium species. A terminal fl ower is formed in all flower-bearing second-order axes in the glomerul ate inflorescence; and the formation of a cap is repeated for the apic al meristems of second-order axes in the amaranthiform inflorenscence. Differentiation of axillary meristems progresses basipetally at a con stant rate of 0 . 21 nodes degrees Cd-1 (base temperature 64 degrees C ) for the glomerulate inflorescence (variety Baer I) and in two stages for the amaranthiform inflorescence (variety Amarilla de Marangani): an initial Faster period with a rate of 0 . 28 nodes degrees Cd-1 (bas e temperature 3 . 7 degrees C) in the upper nodes and a second, slower one, with a progression rate of 0 . 7 nodes degrees Cd-1 in lower nod es. A description of the distribution of the grain-bearing glomeruli o n the mature inflorescence is given. (C) 1996 Annals of Botany Company .