THE USEFULNESS OF CHLOROPHYLL FLUORESCENCE IN SCREENING FOR DISEASE RESISTANCE, WATER STRESS TOLERANCE, ALUMINIUM TOXICITY TOLERANCE, AND N USE EFFICIENCY IN MAIZE

Plant breeders need to know which traits are the most highly associated with grain yield in order to concentrate breeding efforts. Plant production, driven by photosynthesis, is sensitive to abiotic (environmental) and biotic (diseases) stresses. Among all photosynthetic functions, Photosystem II (PSII) is believed to be the most stress sensitive. The in vivo chlorophyll fluorescence (CF) technique is a powerful nondestructive and fast method to detect changes in the photosynthetic activity in leaves influenced by changes in the environment or by natural and anthropogenic stress. The ratio Fv/Fm has been shown to be a reliable indicator of stress. We compared CF assessments and conventional approaches, for constraints such as drought stress, N deficiency and aluminum toxicity which have induced damage to the PSII apparatus, and these changes have permitted us to distinguish genotypes tolerant and sensitive for each mentioned stress. Also, the CF parameters have indicated that maize inbred lines L4, L1, and L2 were resistant and line L3 was susceptible to the two southern rust pathogen (Puccinia polysora) isolates. Finally, the results found in this study have shown that in vivo CF measurements can be a useful tool to help in the screening of maize germplasm for abiotic and biotic stress tolerance.