Simplified Methods for Screening Cowpea Cultivars for Manganese Leaf-Tissue Tolerance
- A. H. Wissemeier * and
- W. J. Horst
In cowpea [Vigna unguiculata (L.) Walp.) dark brown speckles on old leaves are typical symptoms of Mn toxicity and indicate Mn sensitivity of leaf tissue. Induction and subsequent quantification of brown Mn speckles in leaf tissues were used to screen cowpea cultivars for Mn leaf-tissue tolerance using three different techniques: (i) leaf cuttings cultured for 22 d in solution culture with 20 μM MnSO4, (ii) leaf rings mounted on leaves of intact plants and filled with 500 μM MnSO4 for 5 d, and (iii) leaf disks floated for 3 d on 500 μM MnSO4. Density of brown speckles differed considerably among the six cultivars tested, and was not related to the Mn concentrations of the leaf tissues. There were close relationships between genotypic Mn-toxicity symptom expression and depression of dry matter production of the cultivars at high Mn supply in a long-term sand culture experiment. The floating leaf-disk method is particularly suited for screening large numbers of cowpea cultivars for Mn leaf-tissue tolerance because it requires only 3 d. The ranking of the cultivars for Mn tolerance was highly correlated (r2 = 0.95) to Mn tolerance of intact plants.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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