Efeito de exsudatos de sorgo (Sorghum bicolor L.) sobre a divisão celular e anatomia de plântulas de feijão (Phaseolus vulgaris L.)

Abstract

One experiment was established at Lavras Federal University (UFLA) greenhouse and laboraty, in 1994, to test the allelopathic effects of sorghum, BR 601 variety, root exudates on bean seedlings. Sorgoleone (SGL) was extracted by dipping the sorghum roots in methylenum chloride and acetic acid. Hoagland and Johanson solutions of 0.00,0.01,0.05, 0.10 and 0.15 mM of SGL were used as substracts to growth 7day-old bean plants. The beans did not show visual symptons of phytotoxicity during the trial period; however, cytogenetic observations showed that concentrations of 0.01 mM and above, reduced the number of ce.ls in the prophase, metaphase and anaphase stages in relation to the control without SGL. Among the cells in metaphase, it was noticed colchicinic effects at the third and fifth days after treatments with sorgoleone concentration dependent. On the seventh day, these results had inverse proportion to the SGL concentration varying from 34.3% with 0.01 mM and 6.6% with 0.15 mM. Within the cells in anaphase state it could be still noticed that the chromossomes bridged, laggard ones and polyploid cells. It was not observed any alterations in bean anatomy caused by the treatments of 0.01 and 0.05 mM of SGL on the seventh day. However, some changes in the level of chollenchyma, corticol parenchyma, vascular bundle and amyliferous sheath, have been noticed caused by the treatments of 0.10 and 0.15 mM of SGL.