Effect of drought stress on proline, soluble sugars, malondialdehyde and pigments content in northern commercial Citrus rootstocks

Citrus often were encountered with periodic droughts. For this reason, drought effect on six-month-old seedlings of Poncirus (PT) (Poncirus trifoliata Raf.),Troyer citrange (TC) (Citrus sinensis Osbec. × Poncirus trifoliata Raf.),Citrumello (CR) (Citrus paradisi M. × Citrus sinensis Osbec.),Sour orange (SO) (Citrus aurantium L.),andCleopatra mandarin (CM) (Citrus reshni L.) were tested on 2014 in Ramsar Citrus Research Institute. This research was conducted as factorial experiment based on completely randomized design with three replications. The factors included commercial Citrus rootstocks and two level of irrigation. The results showed that maximum quantities of proline, total soluble sugars, malondialdehyde and carotenoid and minimum quantities of total, b and a chlorophyll were observed in drought stress. Maximum accumulation of proline (ordered 306.41 and 281.65 µmol/gdw) and total soluble sugars (ordered 233.79 and 137.9 mg/gdw) and minimum accumulation of malondialdehyde (ordered 179.21 and 204.1 µmol/gdw) were observed in SO and CM rootstocks under drought stress. Decreasing amount of total and chlorophyll a in CM and chl b in SO rootstock was more than other rootstocks and decreasing amount of total and b, a chlorophyll in CR was least. Furthermore, increasing amount of carotenoid in SO and CM was most and the least amounts in PT was observed. On the basis of the study, trifoliate rootstocks as Poncirus, Troyer citrange and Citrumello tolerate as much as drought.