RESPONSE OF ANNUAL MEDICS (MEDICAGO SPP) AND FIELD PEAS (PISUM-SATIVUM) TO HIGH-CONCENTRATION OF BORON - GENETIC-VARIATION AND THE MECHANISM OF TOLERANCE

The genetic range and mechanism of tolerance to high concentrations of B were examined for field peas and annual medic species. Both genera showed a wide range in response to B. The most tolerant Australian varieties of pea included Early Dun, Partridge, Dun, Derrimut, Dundale, Alma and Maitland, while Parraggio, Ghor and Cyprus were the most tolerant of the Australian medics. Accessions more tolerant than the Australian varieties were identified for both species. The highest percentage of tolerant accessions of medics originated from the central and western Mediterranean regions, while the two tolerant peas identified originated from India. The mechanism of tolerance consisted of exclusion of B from the roots and shoots of tolerant lines, and was therefore consistent with previous results for wheat and barley.