Evaluation of Three Commercial Varieties of Sugarcane in Terms of Waterlogging Stress Tolerance in the Early Stages of Growth in Greenhouse Condition

Waterlogging is a global phenomenon that drastically reduces the growth and survival of sugarcane, which leads to 15-45 % reduction in yield.

Three commercial varieties of sugarcane were evaluated to identify the most tolerant varieties to waterlogging stress. Factorial experiment in the basis of completely randomized design with two factors (the first factor related to waterlogging stress at three levels without stress, 7 days and 14 days of waterlogging and the second factor of commercial sugarcane varieties including three varieties CP48-103, CP69-1062 and CP73 21) was carried out in three replications under controlled greenhouse condition.

The results of mean comparison showed that waterlogging reduce the height of plants. the height of plants in different varieties decreased by 5.6% (CP73-21) to 16% (CP48-103). According to the comparison results, the most shoots weight decrease was related to CP48-103 variety. Fresh root weight was increased in stressed plants compared to the control. The interaction of stress and variety showed changes in fresh root weight under different levels of stress (at 5% probability level). Aerial roots were not formed in control plants, but in stressed plants by increasing duration of stress, growth and weight of aerial roots increased. The range of weight changes of aerial roots under stress for 7 days were between 2.3  to 5.7 g and under 14 days treatment, the range of changes was observed between 3.8 to 8.7 g. Leaf mortality were significantly affected by waterlogging stress and variety (at 1% probability level). 7 days stress caused 20% and 14 days stress caused 27% leaf mortality. Increase duration of stress caused the relative moisture content of leaves decreased and the highest decrease seen in 14 days. In 7 days and in 14 days stress, the RWC decreased by 3.2% and 3.5% respectively. The highest amount of chlorophyll a, b and carotenoids was observed in the control treatment and the lowest in the 14 days treatment. The stomatal conductance showed a decrease by increase duration of stress. At 7 days stress, the highest reduction in stomatal conductance was 27.7% and the lowest reduction was 18.4%. In 14 days stress condition, stomatal conductance decreased by 41% to 52%.

The response of the three varieties to duration of waterlogging stress was different. CP69-1062 and CP73-21 varieties showed better adaptation to waterlogging stress compared to CP48-103.