Response of cotton cultivars to aluminum in solutions with varying silicon concentrations

Abstract

Cotton (Gossypium hirsutum L.) is extremely sensitive to Al toxicity. Increasing Si concentration in solution has been reported to alleviate AI toxicity. In this investigation the effects of varying Si concentrations (700, 1400, and 2800 μM Si) on reactive Al (defined as Al reactive with aluminon during 10‐s reaction time, without acidification and heating) was studied in solutions containing either 50, 100 or 200 μM Al during 50 d of aging. An increase in Si concentration had negligible effects on the reactive Al in solutions with 50 or 100 μM Al. However, in solutions with 200 μM Al the reactive Al decreased by 6 to 15% with an increase in Si concentration from 0 to 2800 μM.

The effects of either 700, 1400 or 2800 μM Si on root growth of Coker 208, Coker 315, DPL 90, McNair 235, Stoneville 506 and Tifcot 56 cotton cultivars were investigated in solutions containing either 0, 10, 20 or 40 μM Al with 500 μM Ca at pH 4.5. In solutions containing no Al, addition of 700 μM Si improved root growth by 69–87% in Coker 315, DPL 90 and McNair 235 cultivars but not in the other cultivars. In solutions containing 10 μM Al, an increase in Si concentration from 0 to 2800 μM improved the root growth by 15–17% in DPL 90 and McNair 235 cultivars only. An increase in Si additions failed to improve root growth of any of the cultivars in solutions with 20 or 40 μM Al.