Abstract:
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Adverse environmental conditions limit crop yield and better understanding of plant response to stress will assist the
development of more tolerant cultivars. Maize and common bean plantlets were evaluated under salinity, ...[+]
Adverse environmental conditions limit crop yield and better understanding of plant response to stress will assist the
development of more tolerant cultivars. Maize and common bean plantlets were evaluated under salinity, high temperature,
drought and waterlogged conditions to identify biochemical markers which could be useful for rapid identification of putative
stress tolerant plants. The levels of phenolics (free, cell wall-linked, total), aldehydes including malondialdehyde and
chlorophylls (a, b, total) were measured on stressed plantlets. Only two indicators were statistically non-significant:
chlorophyll b in maize plantlets stressed with sodium chloride and malondialdehyde content in drought stressed maize. The
most remarkable effects of abiotic stresses can be summarized as follows: (i) salinity increased levels of free phenolics in maize
plantlets and chlorophylls (a, b, total) in common bean; (ii) high temperature (40 °C) elevated levels of chlorophylls (a, b,
total) in maize but decreased chlorophylls (a, b, total) and free phenolics in common bean; (iii) drought increased phenolics
and decreased chlorophylls (a, b, total) in maize and increased chlorophyll pigments (a, b, total) in common bean; (iv)
waterlogging increased free phenolics and decreased chlorophylls (a, b, total) in maize and increased chlorophyll (a, total) in
common bean. Free phenolics and chlorophylls, especially a, were the most responsive indicators to stress and can, therefore, be
considered putative biochemical markers for abiotic stress tolerance in maize and common bean. The use of Fisher s linear
discriminant analysis to differentiate non-stressed and stressed plants in breeding programs is also a novel aspect of this report.
Fisher s linear discriminant functions classified correctly 100% of non-stressed or stressed originally grouped plants.
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