VERAPAMIL INFLUENCE ON CALCIUM AND ALUMINUM ABSORPTION BY ROOTS OF 3 SORGHUM CULTIVARS

Verapamil [a-isopropyl-a[(n-methyl-N-homoveratryl)-y-amino-propyl]-3,4-dimethoxyphenylacetonitril] (400-mu-M) inhibited membrane calcium (Ca++) transport, but not aluminum influx, in sorghum [Sorghum bicolor (L) Moench] roots of the acid stress sensitive cultivar, Funk G522DR. In an acid stress tolerant cultivar, SC283, neither Ca++ nor aluminum (Al) transport through the plasmalemma were influenced by verapamil. In a second acid stress tolerant cultivar, SC574, verapamil influenced aluminum but not calcium membrane transport. Differences in modes of ion transport through root membranes may partially explain cultivar variation in response to acid soil stress.