Aluminium tolerance and calcium efficiency of cowpea genotypes

Abstract

Cowpea (Vigna unguiculata) seedlings were grown in solution culture for 4 days in a growth chamber at different levels of Ca and Al. Increasing the Ca supply completely eliminated inhibition of root elongation by Al. This was mainly due to decreasing Al concentrations especially in the root tips. Increasing Al supply depressed Ca concentrations in all root tissue uniformly. Inhibition of root elongation by Al could be explained by induction of Ca deficiency as indicated by the Ca concentrations of the root tips compared to plants with limited Ca supply. Fifty‐five cowpea genotypes differed considerably in response of root elongation to Al. When 10 genotypes were cultivated with high and low Ca supply, important genotypical differences in Ca requirements for dry matter production were observed. A positive relationship between Al tolerance and Ca efficiency of the genotypes was generally noted. Even though Ca efficiency appeared to be a prerequisite for Al tolerance, Ca efficiency did not guarantee Al tolerance. The results indicated that genotypes selected for Al tolerance will also be adapted to soils with low Ca supply.

Key words:

• Aluminium screening
• root growth
• Vigna unguiculata