Effect of water deficit on stomatal characteristics and ultrastructure of chloroplast in tomato leaves.

The variety of 'Liaoyuanduoli' was cultivated in the plastic tunnel,and five treatments of different irrigation levels were conducted.The amount of irrigation per bucket was 2 000 mL as control(CK),1 500 mL(T1),1 000 mL(T2),500 mL(T3) and 300 mL(T4),respectively.Stomatal characteristics and ultrastructure of chloroplast in tomato leaves were investigated by using scanning and transmission electron microscopes at the end of water deficit and 10 d after water recovering.Total stomatal density,the closed stomatal number and the ratio of the two in tomato leaves increased with water deficit levels intensified;while,the stomata length,width and its open status decreased.After 10 d recovering water,the total stomatal density and the closed stomatal number decreased among treatments,and the open status of stomata increased.These parameters of T1 and T2 treatment were almost recovered to the level of control;however,there still existed a big difference among treatment T3,T4 and control.The chloroplast shape became slender under water deficit,and the membrane integrity of chloroplast declined,even the membrane disjointed with T3 and T4 treatment.The grana number per chloroplast declined and the oil body and starch grain numbers per chloroplast increased.The chloroplast lamellae structure of treatment T3 presented loose and flexual phenomena,while there was not integrated lamellae structure of treatment T4 at all.The ultrastructure of tomato leaves could be recovered to normal level under mild water deficit level,while photosynthesis organs were damaged irreversibly under severe water deficit.Furthermore,photosynthesis would be affected seriously.