Stomatal response to water stress in leaves of different sugarcane cultivars.

Drought is one of the main environmental stresses for sugarcane. In order to understand the stomatal response of drought stress in different sugarcane cultivars, the present research was conducted using differently drought-resistant sugarcane cultivars F172, GT21, YT93 / 159 and YL6 as plant materials, which were grown in pots in the greenhouse at Guangxi University in 2012. At elongation stage, the plants were treated with varied degrees of drought stress: 1 mild drought, 65%-70% of the soil water capacity; 2 moderate drought, 45%-50% of the soil water content; 3 severe drought with 25%-30% of soil water capacity and; 4 control with 75% of soil water capacity The relative water content in plant leaf was detected, and the. stomatal characteristics in lower epidermis of the plant leaf were observed with scanning electron microscopy. The results showed that the stomatal conductance under water stress declined sharply in 4cultivars. The stomatal conductance in the drought-tolerant F172 and GT21 was lower than that in the drought- susceptible YT93 / 159 and YL6 under severe drought stress. After re-watering in 3 days, the stomatal conductance in F172 and GT21 were increased to 82. 07 and 88. 85 mmol . m^-2 . s^-1, while that in YT93 / 159 and YL6 was only 18.88 and 33.08mmol . m^-2 . s^-1, respectively. The water stress resulted in sunken and closed stomata, and reduction in stomata length and width, which showed significant differences in different cultivars. The density of stomata was increased significantly in most drought-tolerant F172 under severe drought stress. The ratio of stomata closure was nearly 3-4 times in F172 and GT21 as much as that in YT93 / 159 and YL6. Under drought stress, the leaf relative water content was reduced. However, the drought-tolerant cultivars F172 and GT21 maintained higher leaf relative water content under severe drought stress than the other two, and YT93 / 159 showed the lowest, and the water content could be restored after re-watering. The results indicated that the drought-resistance of sugarcane cultivars was closely related to the stomatal characteristics and water content in leaf. [ABSTRACT FROM AUTHOR]