Chromosome numbers were determined in 52 individuals of 14 taxa of'&ucaena Benth. from 22 populations. For I,. cu.rpidata and L. lempirana these are the first published chromosome counts. Intraspecific variability was found for L. lmpirana, L. macrophylla and L. shanonii, and one diploid population of the tetraploid species L. pallida was identified. Comparison of our data with those in the literature showed that for L. collinsii and L. macroptylla thrre is a relationship between chromosome number and subspecies delimitation. The variability detected in chromosome numbers shows the complexity of the diploid and trtraploid species evolution, and suggests multiple origins for some of the polyploid taxa. 0 2000 Tlir Linnran Sucirt) of 1,ondon
Anthers obtained from flowers buds of soybean cultivar IAS -5 were cultured in two basal culture media (B5 and B5 long). Cytological examinations of the in vitro anthers were performed during the first 20 days of culture to assay the viability (by propionic-carmine and fluorescein diacetate tests) and the stage of development of pollen grains. The frequencies of viable pollen grains varied significantly between bud sizes on the propionic-carmine analysis.The basal culture media and bud size had no clear effect on the frequencies of binucleate symmetrical and multinucleate pollen grains. Chromosome counts of metaphasic microspores throughout the culture period showed microspores with higher ploidy level in addition to normal chromosome number (n=20).
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