Screening sugarcane (Saccharum sp.) genotypes for salt tolerance using multivariate cluster analysis

Disease-free sugarcane plantlets of 11 cultivars derived from meristem cuttings were photoautotrophically grown on the MS medium and subsequently exposed to 0 (control) or 200 mM NaCl (salt stress) for 14 days. Sodium ion (Na+) in all sugarcane varieties was enriched when plantlets were subjected to 200 mM NaCl, except K88-1. Chlorophyll a (Chl(a)), chlorophyll b (Chl(b)) and total carotenoids (Cx+c), in the salt stressed leaves of all genotypes decreased significantly, but the extent of decrease was variable among different genotypes. In contrast, proline content in salt stressed plantlets of all sugarcane genotypes increased markedly, except in genotypes K95, K92-2 and LK92-4. Maximum quantum yield of PSII (F-v/F-m), photon yield of PSII (I broken vertical bar(PSII)), quantum efficiency of PSII (qP) and net photosynthetic rate (P-n) in salt stressed plantlets of all genotypes were significantly dropped, whereas I broken vertical bar(PSII) and qP in cv. KK88-1 were alleviated, resulting in improved P-n. Moreover, growth parameters including shoot height, root length, fresh weight, dry weight and leaf area in salt stressed plantlets of all genotypes were significantly inhibited. The Na+ accumulation, pigment degradation, proline accumulation, photosynthetic abilities and growth inhibition in saline regimes were subjected to Hierarchical cluster analysis. Salt tolerant, K88-1 and UT94-7 and salt susceptible, K92-2 and LK92-4 classes of sugarcane genotypes were classified. The salt tolerant cultivars may be further studied including yield, sugar content and ratoon recovery rate in saline field trials.