Inducing autotetraploids in cassava using oryzalin and colchicine and their in vitro morphophysiological effects.

Polyploid induction has been used for plant breeding to produce bigger and more robust plants than diploid types. The present study aimed to develop a methodology for in vitro induction of polyploidy in cassava. Apical and lateral microcuttings from the BRS Formosa variety were treated with six oryzalin concentrations for 24 and 48 h.

Analyses of several seed viability markers in individual recalcitrant seeds of Eugenia stipitata McVaugh with totipotent germination.

The use of biochemical seed viability markers is often compromised by the unknown partitioning of analytes in bulk seed lots consisting of inseparable populations of viable and nonviable seeds. We took advantage of an unusual morphological syndrome found in the recalcitrant, undifferentiated seeds of Eugenia stipitata: one seed can be cut into several parts, each of which can germinate and develop into seedlings. We used four seed parts from one individual seed to analyse seed moisture content (MC), seed viability and the antioxidant glutathione (γ-glutamyl-cysteinyl-glycine; GSH), glutathione disulphide (GSSG) and intermediates of glutathione synthesis and breakdown.

Seed size influence on germination responses to light and temperature of seven pioneer tree species from the Central Amazon.

In Amazon secondary forests are dominated by pioneer species that typically produce large amounts of small and dormant seeds that are able to form a persistent soil seed bank. Seed dormancy in this group of species is overcome by environmental conditions found in open areas, such as high irradiation or alternating temperatures. Nevertheless, a variety of germination responses to environmental factors is known among pioneers; some of them may germinate in diffuse light or in darkness condition at constant temperature.