Differential tolerance to Fe and Zn deficiencies in wheat germplasm

Tolerance to Fe deficiency of wheat genotypes exhibiting differential toler ance to Zn deficiency is not known, even though the relationship between Fe nutrition and differential tolerance of wheat genotypes to Zn deficiency h as been hypothesised frequently. In the present experiment, eight Triticum aestivum and two T. turigidum L. conv. durum cultivars were grown in nutrie nt solution deficient in either Zn or Fe. Three indices of tolerance to nut rient deficiency were compared: relative [(-nutrient/+nutrient) x 100] shoo t growth, shoot dry weight under nutrient deficiency and relative shoot/roo t dry weight ratio. Genotypes Aroona, Excalibur, Stilleto and Trident were classified as tolerant to both Zn and Fe deficiency, while durum wheats Dur ati and Yallaroi were sensitive to Zn deficiency and moderate to sensitive to Fe deficiency. Genotypes Excalibur, Stilleto and Trident come from the s ame breeding programme and have the common parent (line MEC3 = Sonora64//TZ PP/YAQUI54) that could have been the donor of the genes for tolerance to Zn deficiency. When Fe-deficient, all wheat genotypes were severely chlorotic but kept producing shoot and root dry matter at a relatively high rate, ma king the relationship between the relative shoot growth and the relative le af chlorophyll content poor. This is the first report of wheat genotypes ex hibiting multiple tolerance to Zn and Fe deficiencies.