Chlorophyll fluorescence and stomatal conductance of ten sugarcane varieties under waterlogging and fluctuation light intensity

Under natural conditions, plants are often subjected to waterlogging due to poor soil drainage and or exessive rainfall. This condition leads to reduced maximum quantum yield of photosystem II (f(v)/f(m)) under suboptimal growing system. Under well-watered conditions (WW), the f(v)/f(m) of ten varieties of sugarcane were maintained at more than 0.78. However, following waterlogging for 4 days and a constant light of 3000 mu molmol(-1) for 60s, the f(v)/f(m), of ten varieties of sugarcene varied from 0.587 in PS882 (V4) to 0.740 in GMP2 (V9). Meanwhile, under fluctuating light intensity from dark to highlight of 1600 mu molmol(-1), the f(v)/f(m), of all varieties decreased to below of 0.1 except in the genotype PSJK922 (V5) at 28 DAT (day after treatment) of waterlogging. This difference was then further examined through measurements of stomatal conductance (g(s)) among the varieties. There was negative correllation between f(v)/f(m) and stomatal conductance, high g(s), was not associated with lower f(v)/f(m). Dendrogam analyses showed the variety of PS881 (V1), PS864 (V3) and Kidang Kencana (KK) were highly sensitive to waterlogging. These results suggest potential screening of plants based on improve f(v)/f(m) under abiotic condition.