اثر تنش كم آبي بر پارامترهاي فلورسانس كلروفيل در گوجه فرنگي گلخانه اي پيوندي و غير پيوندي

The Effect of Water Stress on Chlorophyll Fluorescence Parameters of Grafted and Non-grafted Greenhouse Tomatoes

In this research using three types of greenhouse tomato (lycopersicum esculentum Mill.) including: 1-cultivar Trust as non grafted plants(T), 2-Trust grafted onto Eldorado (TE) and 3-Trust grafted onto Maxifort (TM) along with Three media: rockwool (RW), sawdust (SAW) and sawdust containers equipped with a capillary system (CA) were employed to study the effect of water stress on chlorophyll fluorescence parameters. Results of the experiment indicated that, when medium water potential reduces (becomes more negative), water stress can occur and cause some changes in chlorophyll fluorescence indices as measured through dark adapted method. Increasing water stress resulted an increase in F0 and a reduction of Fm in all plants and media, consequently, a reduction of Fv and Fv/Fm ratio as well. Different media showed significant differences in rate of loosing water (change in water potential with time). Capillary systems helped sawdust media loose water at a slower rate, keeping the medium moist for a longer period. So, plants cultured in this medium showed less fluctuation of Fv/Fm index than those cultured in other media. Plant types also showed significant differences especially under severe water stress. The least Fv/Fm ratio was measured in "T" plants. Results of this experiment showed that, Fv/Fm can vary due to water stress, but itʹs changes are small and hardly detectable, and just if used together with other indices, can possibly be a usefull tool for evaluating a plantʹs stress status.