Differences in low-K tolerance， photosynthetic characteristics and antioxidant enzyme system between different sugarcane genotypes

A hydroponic experiment was conducted to investigate the differences of low-K tolerance ability， photosynthetic characteristics， chlorophyll fluorescence parameters and antioxidant indexes between Yuetang 60 （YT60）and BC2-32， a progeny of Erianthus arundinaceus. The results showed that there was decline with 59.39% in dry weight of BC2-32 under low K stress， while only 30.61% for YT60， indicating that YT60 was more tolerant to low K stress than BC2-32. Under low K stress， the decline of leaf chlorophyll content， net photosynthetic rate（Pn）and maximum photochemical efficiency（Fv/Fm）was less and the increase of SOD activity， proline and malondialdehyde （MDA）content was also less for YT60 compared to BC2-32， which demonstrated that the photosynthetic characteristics and related indexes of the antioxidant enzyme system could be used as the indicators for screening sugarcane genotype with low K tolerance.