One of the obstacles of agriculture practiced in soil of low fertility is soil acidity and generally involves manganese toxicity in plants. The development of cultivars tolerant to Mn would be beneficial to farmers due to reduction in use of liming and consequently reduction in the cost of production. With this objective a preliminary experiment was conducted in nutrient solution which showed that the breeding line was highly tolerant to Mn. This breeding line originated from the cultivar IAC-Foscarin 31. Both the genotypes were planted in a pot experiment conducted in the greenhouse, in a Red Dusky Latosol soil with high Mn concentration. The results showed that the genotype tolerant had a vigorous vegetative growth attaining a height three times that of the normal genotype and without symptoms of Mn toxicity in the leaves and with roots showing normal colour with nodules. The normal genotype (IAC-Foscarin 31) showed dwarf plants with thick stems and crinkled leaves, typical of Mn toxicity symptoms. The taproot and some secundary roots showed dark coloration showing necroses of the tissue due to Mn toxicity. The concentration of Mn in the above ground parts and roots contained 33 and 15% more concentration than the normal genotype and the quantity of Mn absorbed was also 60 and 46% more than IAC-Foscarin 31 showing that the soybean breeding line is extremely tolerant to high Mn content in the plants.
soybeans; breedingline; manganese; tolerance; toxicity