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2071163 
Journal Article 
Tolerances of 20 rice (Oryza sativa) cultivars to excess aluminum and manganese 
Nelson, LE 
1983 
Yes 
Agronomy Journal
ISSN: 0002-1962
EISSN: 1435-0645 
HEEP/83/10508 
75 
1 
134-138 
HEEP COPYRIGHT: BIOL ABS. Mg toxicity is a rare occurrence in flooded or paddy rice (O. sativa L.); this is not the case for upland rice grown on aerobic soils. Although acid upland soils may contain toxic levels Al and Mn, cultivar tolerances to excess Al and Mn do not necessarily coincide. A procedure for rapid screening of rice cultivars for tolerances to excess Mn and to correlate tolerances between excess Al and Mn was developed. Nine rice cultivars were grown in a greenhouse for 4 wk in nutrient solutions containing 1 mug cm-3 and 80 mug cm-3 Mn. The relative tolerance was expressed as a ratio of the excess Mn treatment to the optimum or control treatment using weights of plant parts, height, root length and tiller number. These expressions of relative tolerance to excess Mn were used to rank the 9 cultivars. These rankings were then compared to a ranking based on previous results obtained at IRRI (International Rice Research Institute) when the cultivars were grown on an acid soil. Significant Spearman's rank correlation coefficients were observed between rankings for tolerance to acid soil toxicity and relative root weight and relative tiller number. Other rank correlations with acid soil toxicity were not significant. Subsequently, 20 cultivars were screened for tolerance to excess Mn by growing them in a greenhouse for 4 wk in solutions containing 0.5 and 80 mug cm-3 Mn. These cultivars were also screened for tolerance to excess Al by growing them for 3 wk at 3 and 30 mug cm-3 Al. The correlation between tolerances to excess Al and Mn was tested using relative root length for Al and relative shoot weight for Mn. The correlations were not significant. Large differences in tolerance to excess Mn were observed among rice cultivars; screening trials using soils containing excess amounts of available Mn can not be replaced by short-term screening in nutrient solutions. Apparently, tolerance to excess Al is not necessarily correlated with tolerance to excess Mn.