Genotypic variation of sugarcane for salinity tolerance: Morphological and physiological responses

ABSTRACT Sugarcane (Saccharum spp.) is an important crop due to sugar, ethanol and bioenergy production. Its cultivation may occur in tropical regions exposed to high salinity. The aim was to identify cultivars tolerant to salinity to allow the cultivation of sugarcane (Saccharum spp.) in saline soils. To test the hypothesis that sugarcane show natural genotypic variation to salinity tolerance, we tested ten cultivars (SP80-3280, RB855453 RB966928, RB855156, SP80-1842, SP80-1816, RB928064, RB867515, RB92579, RB855536) and two sugarcane species: IM76-228 (S. robustum) and IN84-82 (S. spontaneum) under two concentrations of sodium chloride (NaCl): control (concentration found naturally in the soil used: electrical conductivity of 0.083 dS m-1) and soil enriched with NaCl: EC of 7.2 dS m-1. Biometry and photosynthesis traits were evaluated. The plants were collected and leaf (LDM), stem (SDM), root and total dry matter were used to estimate the tolerance index (TI). A cluster analysis was done to identify phenotypic dissimilarity. Three distinct groups regarding salinity tolerance on biomass-basis were formed. The cultivars RB855156, SP80-1842, SP80-1816 and species IM76-228 showed no reduction in LDM and SDM. Nonetheless, the cultivars SP80-3280, RB928064, RB92579 and species IN84-82 were impaired by salinity. The cultivar SP80-1816 showed the highest biomass accumulation and the highest TI. Therefore, we found a great genotypic variation regarding salinity tolerance in sugarcane, which can be explored by growers to cultivate in saline soils. Also can be used by the Sugarcane Breeding Programs to improve the salinity tolerance.