Desenvolvimento floral e estaminal no clone CP76 de Anacardium occidentale L.: cajueiro-anão precoce (Anacardiaceae)

Foram estudados o desenvolvimento floral inicial bem como a ontogênese estaminal em Anacardium occidentale L. As flores apresentam cinco sépalas e cinco pétalas com desenvolvimento helicoidal e unidirecional, respectivamente, androceu com um estame com desenvolvimento heterocrônico e heteromórfico marcante em relação aos nove estames restantes, e um carpelo unilocular terminal. O processo histogênico é idêntico em ambos os tipos de estames. Ao final da ontogênese estaminal, as anteras possuem quatro esporângios, sendo que cada esporângio apresenta epiderme, endotécio, duas camadas médias, tapete e tecido esporogênico. A porção interna do tapete não se origina do conectivo.

Efeito da temperatura na germina̧ão de sementes de Sebastiania commersoniana (Baillon) Smith & Downs separadas pela colora̧ão do tegumento

Sebastiania commersoniana (Euphorbiaceae) is a tree species of riparian forests in Brazil. Seeds of this species released from mature fruits have heteromorphy in coat colour: dark (dark-brown to black), striated (dark with light-grey stria) and clear (light-grey to whitish). In this work two experiments were carried out in order to study the effect of temperature on seed germination in interaction with coat colour. Germination final percentage and speed index were evaluated. In the first experiment seeds of the three colours were submitted to constant (30°C) and alternating (20-35°C) temperatures. For all the seed colours, best results were obtained at alternating temperature. Physiological quality of striated seeds was greater than those clear seeds and dark seeds were intermediate. In the second experiment striated and clear seeds were submitted to three amplitudes of alternating temperature: 5°C (20-25°C and 25-30°C), 10°C (20-30°C and 25-35°C) and 15°C (20-35°C). Both germination percentage and speed were higher in striated seeds and for the two seed colours, best results were obtained at 20-30°C and 20-35°C. These temperatures are recommended for the germination test.