Salt Tolerance Screening in Six Maize (Zea mays L.) Genotypes using Multivariate Cluster Analysis

The effective indices for salt tolerant classification of maize genotypes were investigated. Six maize cultivars were treated with either 0 (control) or 200 mM NaCl (salt stress). Chlorophyll a (Chl(a)), chlorophyll b (Chl(b)), total chlorophyll (TC) and total carotenoid (Cx+c) concentrations in the salt-stressed leaves dropped significantly. Chl(a) degradation in maize genotypes was correlated with maximum quantum yield of PSII (F-v/F-m). TC content was positively related to photon yield of PSII (Phi(PSII)). F-v/F-m, Phi(PSII) and photochemical quenching (qP) in the salt-stressed leaves decreased dramatically, related to the reduced net photosynthetic rate (P-n), leading to growth reduction. The chlorophyll a fluorescence parameters, F-v/F-m, Phi(PSII) and qP, in the leaf tissues decreased, while non-photochemical quenching (NPQ) increased. Data relating to pigment degradation, chlorophyll a fluorescence diminution, photosynthesis reduction and growth inhibition in salt-stressed maize cultivars were subjected to hierarchical cluster analysis using SPSS software. Two classes of genotypes were identified: salt-tolerant (Waxy 1, Waxy 2 and Waxy 3) and salt-sensitive (Honey, Sweet 1 and Sweet 2).