Screening of wheat Landraces from Madeira Island for iron tolerance

Since the fifteen century, the rainfed-cultivation of wheat for grain is traditionally performed on the Island of Madeira. Under several microclimatic conditions and along very sloppy mountains, the landraces are grown on isolated terraces of Andosols with high amounts of iron. Iron oxides are the main inorganic binding agent contributing to the stability of aggregates and to soil fertility in long-term sustainable agriculture in acid and iron-rich soils. After a two day period of seedling initial growth, a screening test of sixty traditional wheat (Triticum spp.) landraces from the ISOPlexis Genebank at the University of Madeira, Funchal, was performed using nutrient solutions containing 10 or 600 mM Fe, during five days, under controlled laboratory conditions. The elongation of the longest primary root was measured for each genotype and the mean root increment relative to control (as, % relative root increment or RRI; n=28) calculated. This parameter appeared to be a sensitive indicator of Fe tolerance in wheat. Over 85% of wheat germplasm showed the RRI higher than 50%, while the RRI of seven accessions exceeded 70%. This indicates that those landraces are Fe tolerant and might be of particular interest for cultivation under acid rich iron soils of tropical and subtropical areas.