Comparison of techniques for determining the effect of aluminium on the growth of,and the inheritance of aluminium tolerance in wheat

The effect of Al on the growth of plants derived from the F3 generation of a cross between Al tolerant (Waalt) and Al sensitive (Warigal) wheat cultivars, grown in low ionic strength nutrient solutions, were assessed by a number of methods viz; root length and haematoxylin stain after 3 days exposure to Al and plant top and root yields, and root length and visual assessment for Al damage after 4 weeks growth.Of these methods haematoxylin stain (3 days) and visual assessment at 4 weeks identified the same plants as being sensitive or tolerant to Al and clearly segregated the 2 populations. Consequently these 2 methods were used as standard techniques to determine the ability of the other methods to distinguish between tolerant and sensitive plants.The ratio of plant top: root yields clearly segregated the 2 populations. The 2 populations could not be clearly distinguished based on plant top or root yields, or on root length either after 3 days or 4 weeks exposure to Al.Within the population of tolerant plants, root length was significantly correlated with root weight (r²=0.86) and top weight (r²=0.71). None of these relationships were significant for the population of sensitive plants.These techniques were applied in a number of separate experiments on the F2 and F3 populations from a Waalt × Warigal cross. The results indicate that Al tolerance in wheat is inherited by a single gene and that this gene has incomplete dominance.