عنوان مقاله [English]
To evaluate the effects of methanol and drought stress on chlorophyll fluorescence parameters, chlorophyll and relative water content in sugar beet, a study was conducted in 2008 in Maahdasht (Karaj, Iran). Aqueous solutions of 0 (control), 7, 14, 21, 28, 35% (v/v) methanol with each solution containing 0.2% glycine and a second factor, namely drought stress (irrigation after 70% depletion of available water) and normal irrigation (irrigation after 40% depletion of available water) constituted the treatments. The solutions were sprayed overhead, 3 times in two week intervals on foliage parts of the crop sugar beet. Results indicated that there was no significant difference between levels of solution on minimum chlorophyll fluorescence (F0), fluorescence variavle (FV) and maximum chlorophyll fluorescence (FM), but there was a significant difference observed between levels of solutions on photochemical capacity of photosystem 2 (FV/FM) at a 5% probability level. Analysis of variance revealed that before a third foliar application, chlorophyll content did not show any significant difference, whereas there was a significant difference observed among levels of solutions on chlorophyll content after the third application at a 5% probability level. Also results indicated that drought stress significantly decreased photochemical capacity of photosystem 2 (FV/FM), fluorescence variavle (FV) and maximum chlorophyll fluorescence (FM) at 5% probability level. As for minimum chlorophyll fluorescence (F0) no significant difference was observed between the two levels of irrigation. Also drought stress significantly increased chlorophyll content at 5% probability level. Both factors (levels of solution and different irrigation levels) affected relative water content (RWC) at 1% probability level. The highest correlation was observed between white sugar yield and photochemical capacity of photosystem 2 (FV/FM). In this study interactive effect was not found to be significant.