Développement floral chez <i>Eragrotis tef</i> : dynamique des gamétophytogenèses

A calendar of reproductive events is established in Eragrostis tef (Zucc.) Trotter, a sexual tetraploid Ethiopian cereal, using the microsporogenesis and microgametogenesis as reference scales to which the female gametophytogenesis is related. The absolute frequency is noted for each correlation brought out (microgametogenesis–megagametogenesis). The frequencies of all the female stages found at a same level of anther development are also specified. This preliminary work is done within the scope of an interspecific hybridization program which aims at transferring, to E. tef, genes responsible for the apomictic character present in the genus. </jats:p

Micro- and megagametogenesis in Cichorium intybus L.: succes sive stages and some symptoms of apospory

In &lt;em&gt;Cichorium intybus&lt;/em&gt; L., the mode of reproduction could be at the same time sexual and apomicbic. This could explain the contradictions existing in the interpretation of the heritaibidity of the characters in this species. In this particular case, the only way of describing facultative apospory, functional or not, is to proceed to a cytom-orphological study of the megagametogenesis. In the present study, symptoms of apospory have been observed and described.</jats:p

Apomixie, sexualité et amélioration des graminées tropicales

Apomixis, sexuality and improvement of tropical grasses. Gametophytic apomixis together with sexuality can be used for the improvement of tropical grasses. Apomixis is researched for providing an easy spreading of cultivars. Apomictic and sexual species are found in the genus Brachiaria ; hybridizations are carried out between a tetraploid, colchicine induced form of the sexual species B. ruziziensis Germain et Evrard, and natural tetraploid apomicts, B. brizantha Stapf. and B. decumbens (Hochst) Stapf