Characterization of Differential Aluminum Tolerance among Varieties of Wheat and Barley

Abstract

Aluminum‐sensitive ‘Monon’ wheat (Triticum aestivum, spp vulgare (Vill. Host) Mac Key and ‘Kearney barley (Hordeum vulgare) (L. emend. Lam) varieties had higher root cation exchange capacities and induced lower pH levels in nutrient solutions than did Al‐tolerant ‘Atlas 66’ wheat and ‘Dayton’ barley varieties. Sensitive varieties contained higher concentrations of Al (and usually P) in their roots and lower concentrations of Ca in their tops than tolerant varieties, when grown in solutions containing Al. Furthermore, roots of Al‐sensitive varieties made less growth and contained higher concentrations of Al than those of tolerant varieties, even when the two were grown in the same container of vigorously aerated nutrient solution. This suggests either that zones of differential pH still exist around the roots of different varieties or that sensitive varieties absorb more Al at the same pH or both. Whether the lower Al tolerance of certain varieties is simply the result of greater accumulation of Al by roots, greater sensitivity to the same concentration of Al already absorbed, or both, cannot be determined from the present study. Differential Al tolerance of varieties was not closely related to differences in the Al or P contents of plant tops.

Mechanism of Aluminum Tolerance in Snapbeans

“…The nutrient solution was a modified Steinberg solution (10) The experimental design was a randomized complete block with five replicates. The treatments were a complete factorial of two cultivars x two Al levels.…”

“…The nutrient solution contained both NH4' and NO3-, which resulted in an initial decline in pH, followed by a subsequent increase in pH as plants grew (10,11). Aluminum at 148 uM resulted in significantly lower final solution pH levels compared to treatments with no Al (Table I) Sonication of roots in distilled water for 1 min was used to remove loosely adhering soution from near the root surface, along with organic acids external to the roots.…”

Induction of Aluminum Tolerance in Wheat Seedlings by Low Doses of Aluminum in the Nutrient Solution

“…The modified 'pulse' method was used for screening varieties and hybrid populations of wheat (2). The Al concentration in nutrient solution that caused irreversible damage of root apical meristem in 4-d-old seedlings during 24 were added at concentrations of 2.5 uCi/ml (4 ,ug/ml) and 10 ,uCi/ml (10 The distribution of Al in root subcellular fractions from induced and control Atlas 66 seedlings was studied using the methods described earlier (20). Significantly more Al was found in all fractions from pretreated roots than in controls (Table IV), but the relative distribution of Al between subcellular fractions was unchanged.…”

“…In fact, Al tolerance in wheat was found to be determined by several genes (16) and can explain the existence of different degrees of Al tolerance in wheat (1,10).…”

“…Plants differ in their reaction to Al toxicity, and variability was found between plant species as well as between cultivars of cultivated plants (1,7,10). The plant reaction to Al was found to be genetically controlled (5, 23).…”