الفهرس 
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Abstract
Objectives: The aim of this study was to examine the response of Sukkary and Gahrawy mango cultivars to saline water irrigation. Determine the suitable anti-salinity agents for root-stocks under study and detect either salicylic acid or Nano silicon is effective for mitigating salinity stress. Horizontally expanding mango cultivation with the use of low-quality (saline) water irrigation by using mango rootstocks in the production of grafted seedlings for establishing new farms.
Methods & Results: The present investigation was carried out at the nursery of Pomology Department of Agriculture Faculty, Damietta University, Egypt during two successive seasons 2017/18 and 2018/19. One year old seedlings of two poly embryonic mango cultivars were used for this research namely Sukkary (the certified salt tolerant rootstock in Egypt, according to (Galán-Saúco, 2016), and Gahrawy planted in Damietta governorate especially at Om EL-Reda village (Doaa and Shalan, 2020). Mango fruits of Sukkary and Gahrawy were brought from a private orchard in Om EL- Reda village at Damietta governorate. Seeds were freshly extracted from ripen fruits and washed twice in tap water and sown at the end of August and September for Sukkary and Gahrawy cultivars, respectively. The collected seeds were sown in perforated black polyethylene bags (40*20 cm) filled with peat moss and sand at ratio of 1:2v/v, respectively (one seed for each). The bags were watered regularly. Two months later the sexual seedlings were removed and nucellar seedlings were transplanted. Six months after sowing, the nucellar seedlings of uniform growth vigor were selected and transplanted singly into perforated 20 cm pots filled with prescribed medium. Two months after the transplantation the healthy seedlings were classified into nine similar groups (9 seedlings for each). Each group was arranged into three replicates (3 seedlings for each) and then subjected to one of the following treatments during both two seasons. Tap water irrigation (TWI) as control (T1), TWI and spraying Salicylic acid (SSA) at 1.0g/L (T2), TWI and spraying Nano silicon (SNSi) at 1.0g/L (T3), Sea water irrigation (SWI) at 1750ppm (T4), SWI at 1750ppm and SSA at 1.0g/L (T5), SWI at 1750ppm and SNSi at 1.0g/L (T6), SWI at 3500ppm (T7), SWI at 3500ppm and SSA at 1.0g/L (T8) and SWI at 3500ppm and SNSi at 1.0g/L (T9).
The obtained results showed that the most prominent results were as follows, a reduction in most parameters was noticed except sodium and proline content and salinity symptoms parameters were increase due to increasing salinity levels. Positive effects were including enhancement in leaf pigments, soluble carbohydrate and total phenols content, magnesium, nitrogen, phosphorus, potassium and decreasing of salinity symptoms parameters due to irrigation with salty water at 1750ppm together with foliar spraying Nano-silicon and salicylic acid at 1 g/L.. The results confirmed that the effects of Nano-silicon and salicylic acid on the behavior of treated seedlings differ according to the variety.
Conclusion: saline water irrigation at 1750 ppm increase the percentage of seedlings height increase, photosynthetic pigments, total phenols, proline, soluble carbohydrates and increase absorption of the elements. The values of IC50 and salinity symptoms are reduced. It is possible to use low quality water which reached its concentration up to 3500 ppm, and spraying with anti-salinity, such as salicylic acid or Nano-silicon at 1g /L. The cultivars showed a differences under the influence of used anti-salinity agents, where it was noticed that salicylic acid was more effective to overcome the effects of salinity in Sukkary cultivar and the same trend was with Nano-silicon for Gahrawy cultivar.