| Genetic variability in aluminum tolerance of Triticinae
V.T. SAPRA, M.A. CHOUDRY and L.M. MUGWIRA Albama A&M University, Normal, AL., U.S.A. Differential tolerances of species and cultivars to aluminum have been reported (FOY, 1974). CAMPBELL and LAFEVER (1976) and FOY et al. (1974) found varying degrees of aluminum tolerance between wheat cultivars. SLOOTMAKER (1974) studied the tolerance to high soil acidity in wheat and related species, and concluded that the A-genome of Triticum species contributes to tolerance. SAPRA et al (1978) reported that some triticale cultivars are tolerant to aluminium while others are highly sensitive. In another study Sapra et al (unpublished) found that rye homoelogous chromosomes 3R and 4R/7R contribute to aluminum tolerance. The present study was undertaken to determine the degrees of Aluminum tolerance in wheat, rye and triticale species. Materials and Methods Several diploid and tetraploid species of wheat were acquired from germplasm laboratory, USDA, Beltsville, MD. Rye species were supplied by Dr. J.C. CRADDOCK, USDA, Beltsville, MD. Additional diploid species of wheat were supplied by Drs. B.L. JOHNSON and J. WAINES, University of California, Riverside, California. Several accessions of both diploid and tetraploid species were included in the study. Four uniform seedlings of each accesion were planted in 32 litre plastic tanks (53 x 27 x 27 cm) containing 1/5 Steinberg nutrient solution as modified by FOY et al. (1967). Four replications of each accession were used. Each accession was randomized within each replication. Two levels of aluminum (0 and 8 ppm) were used to differentiate the response of roots to aluminum. The solutions were adjusted twice daily to pH 4.5 + or - 0.2. After ten days of growth in nturient solution, the mean root lengths were recorded and the relative root lengths (8/0 ppm) were calculated. Results and Discussions The mean root lengths, range and relative root lengths of different diploid and tetraploid id species are presented in Tables 1 and 2, respectively. The relative root length of diploid species T. monococcum (AA) and Agropyron (EE) were 47 and 27 percent, respectively. A elongatum was found to be highly sensitive to aluminum. Slootmaker (1974) reported similar results. for T. monococcum and T. boeticum. However, he did not study A. elongatum. In our study T. boeticum was intermediate in tolerance, similar to those reults found by SLOOTMAKER (1974) in barley medium. We found that greater diversity exists between and vithin diploid species (Fig. 1). |
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