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King Abdulaziz University (2018)

EFFECTIVENESS OF SILICON FOR MITIGATING DROUGHT STRESS IN SORGHUM (SORGHUM BICOLOR L)

Ahmad, Aaftab

Titre : EFFECTIVENESS OF SILICON FOR MITIGATING DROUGHT STRESS IN SORGHUM (SORGHUM BICOLOR L)

فاعلية تطبيق السيليكون على تحمل إجهاد الجفاف في محصول الذرة الرفيعة

Auteur : Ahmad, Aaftab

Université de soutenance : King Abdulaziz University

Grade : Master Thesis 1439 AH 2018 AD

Résumé
Drought stress can be managed by better irrigation scheduling and the use of some nutrients. To investigate this hypothesis a detailed field experiment was conducted at Hada Al-Sham research station of King Abdulaziz University Jeddah Saudi Arabia (from Mar-Sep, 2017) by using multi-cuts sorghum fodder crop. A local cultivar of sorghum Jizani variety (drought resistant) was grown under bubbler irrigation system. The experiment was conducted in a split plot design with three replications. Irrigation was applied as main plot treatments (100% ETc, 80% ETc and 60% of ETc) and the Si (as a nutrient) was applied as foliar spray comprising 0 kg ha-1 as control, 1 kg ha-1 and 2 kg ha-1 as sub-plot treatments. Irrigation and Si treatments were applied at five-leaf stage during all three cuts, before that all experimental units were maintained at full water supply (100% ETc). The experiment continued for three consecutive cuts and at each cut the crop was harvested at 50% heading stage. The results revealed that individually the deficit irrigation (100% to 60% of ETc) (induced drought stress) extensively shortened plant height and reduced the fresh and dry forage yield, during all the cuts, thereby, reducing biomass production of sorghum. The drought stress has non-significant effect on number of tillers m-2 during 1st cutting and increased for 2nd and 3rd cuts (number of tillers), similarly the drought stress significantly increased the root volume and water use efficiency. The Si levels independently improved all the above mentioned parameters. Furthermore, the interaction of Si and irrigation scheduling (deficit irrigation) was significant that enhanced productivity of sorghum. It was clear that using 2 kg ha-1 of Si improved the yield significantly in all irrigation treatments and was more effective than using 1 kg ha-1. The fresh yield and dry yield increased by 25-30% when using the 2 kg ha-1 Si treatment over no Si treatment in control irrigation treatments, while it reached 40% in the 60% ETc irrigation treatments. When it comes to irrigation treatments effects on yield, reducing the irrigation from 100% ETc to 60% ETc (approximately 25% water saving) reduced the yield by almost 22% in all cuts while the decrease was about 15% when using 2 kg ha-1 Si treatments in all cuts as a fresh weight. For the dry weight, the reduction in yield due to the reduction of irrigation from 100% ETc to 60% ETc was around 23% while it was around 13% under 2 kg ha-1 Si treatments. The water balance irrigation scheduling method is a useful option for irrigation management with periodic real field moister contents calibration. The conclusion from this study is that irrigation scheduling and Si application helps to alleviate the detrimental effects of drought stress on sorghum fodder production by increasing the plants’ water uptake efficiency, root depth and root volume. The application of Si at 2 kg ha-1 significantly improved sorghum yield. The yield of the sorghum under deficient irrigation (60% ETc) with the application of 2 kg ha-1 Si was even higher than that of the 100% ETc without Si application. Therefore, the use of deficit irrigation in producing Sorghum with Si application can save water resources in arid regions with economically reasonable yield. These findings would be useful as a reference material to benefit the livestock sector in Saudi Arabia.

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Page publiée le 26 mars 2019