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Comparison of survival percentage of three varieties of pistachio under drought and salinity stress showed there is a significant different among pistachio varieties tolerance to drought and salinity condition. In drought stress, Sarakhs and Akbari showed the highest and lowest tolerance respectively (Figure1 A), while the results of salinity stress On the contrary and demonstrate that Akbari and Sarakhs showed the lowest and highest tolerance, respectively (Figure1 B).
Effect of drought and salinity in Proline content
Free proline content was analyzed in leaves of stressed and control pistachio varieties seedlings. Under drought and salinity stress conditions, proline content increased significantly in comparison with control plants. Under stress conditions, variety of Sarakhs exhibited lower contents of proline than that of the two another varieties. Proline content increased, significantly in Akbary veriety exposed to drought and salinity stress from 3 and 9 days after beginning of stress. Surprisingly, proline content of the Badami and Sarakhs varieties increased alone 9th day after stress. When compared with controls meanwhile, both drought and salinity stress increased proline content in Badami and Akbari varieties relative to controls (Figure- 2).
The effects of salinity and drought stresses on total phenolic content shown in Fig. 3. Of the three varieties, the highest phenolic content was recorded in Sarakhs and Badami varieties under drought stress in 9th day after start stress. However, in salinity alone Sarakhs and Akbari varieties significantly higher at 9 days after treatment (Figure 3).
Changes in H2O2 content and lipid peroxidation of pistachio seedlings
To investigate the differential oxidative damage brought about salt and drought stresses in three pistachio varieties, we measured the contents of H2O2 and lipid peroxidation in pistachio leaves (Figure. 4&5).
Under salinity stress conditions, H2O2 contents increased from 3rd day after stress and in 9th day Badami and Sarakhs verities have highest amount of H2O2. However, except Sarakhs, the level of H2O2 was significantly increased from 3rd day after stress in Badami and Akbari varieties under drought stress conditions. In addition, the level of H2O2 in salt stress was higher than to drought stress (Figure. 4).
Similarly, lipid peroxidation assessed by MDA content in pistachio varieties leaves significantly increased 3 days after salt and 6 days after drought stress in all varieties except Badami (Figure 5). The level of lipid peroxidation was higher in 9th day than to other days in all stress conditions.
Changes in activities of antioxidant enzymes
We measured the enzymatic activity of SOD, PPO and CAT in leaves of seedlings of three varieties expose with salinity and drought stress. As shown in Table 1. salinity and drought stress increased the activity of SOD, PPO and CAT in leaves of three varieties. More precisely, the SOD activity of Badami in salinity stress and Akbari in drought stress were higher than that of control. All varieties exhibited a similar increasing in SOD activity in drought conditions after start stress. However, in salinity stress Sarakhs variety has highest SOD activity in 3rd day after stress and in Badami and Akbari varieties the highest SOD activity observed in 6th day. In addition, the SOD activity level was equal to drought and salinity stress, except Badami in salinity stress (Table. 1).
Similarly, the activity of PPO in leaves of three varieties increased upon treatment with Drought and salinity. Furthermore, Akbari also showed higher PPO activity in drought and salinity stress, when compared with other varieties. PPO activity in all of varieties in drought stress increased from 3rd day to 9th and in salinity stress highest activity for this enzyme recorded in 3rd day after stress and then decreased it. The results showed that PPO activity levels in drought stress were higher than salinity stress (Table. 1).
The activity of CAT showed that varieties of Badami and Akbari have highest CAT activity under drought stress in 6th and 3rd respectively. Varieties of Sarakhs and Badami showed highest CAT activity in 6th day and Akbari demonstrate in 3rd day and then decreased. In salinity stress all of varieties showed highest CAT activity in 6th day. Also, CAT activity level to drought and salinity stress (Table. 1).
Under Drought and Salinity stress conditions, varieties of Badami in drought and Akbari in drought and salinity stress exhibited higher contents of soluble sugar at 9th day. Increasing in soluble sugar in drought and salinity stress started from 6th day and amount that significantly increased in Badami and Akbary than to Sarakhs variety. Except Badami, in other varieties were soluble sugars content in salinity stress higher than drought stress (Fig. 6).
Glycine-betaine content was significantly increased in salinity and drought than control. The highest content of Glycine-betaine resulted in Badami in dought stress to 6th day and Akbari in salinity and drought stress at 9th day. In salinity start of Glycine-betaine increasing was from 3rd day for Sarakhs and Badami and 9th day for Akbari. But, in drought stress start of Glycine-betaine increasing was from 3rd day for Badami and 6th day for Akbari and Sarakhs. According to the results, amount of Glycine-betaine in Sarakhs is significantly lower than Akbari and Badami (Fig. 7).
Anthocyanin pigments were extracted from the Pistachio leaves seedlings and roughly measured spectrophotometrically. Anthocyanin content was significantly increased in salinity and drought stress than control condition. The highest content of Anthocyanin in drought stress showed in 9th day in all tested varieties, while in salinity stress there was this increasing in 3rd day for Sarakhs and in 6th day for Akbari and Badami. Compare of three varieties at control condition showed that Akbari and Sarakhs have highest and lowest anthocyanin content (Fig. 8).
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