Document Type : Research Paper
Authors
1
Researcher, Soil and Water Research Department, Isfahan Agricultural and Natural Resources Research and Education Center, AREEO, Isfahan, Iran.
2
Member of scientific board, Soil and water research division, Esfahan agricultural and natural resources research center, AREEO, Esfahan, Iran
3
Soil and Water Research Department, Isfahan Agricultural and Natural Resources Research and Education Center. Agricultural Research, Education and Extension organization (AREEO), Isfahan, Iran.
Abstract
The application of organic fertilizers can improve the physical and chemical properties of the soil, playing a significant role in enhancing plant drought tolerance. This study investigated the effects of organic fertilizers on the yield and physiological traits of onions under drought stress conditions in the region of Isfahan. The experiment was conducted as a split-plot design within a randomized complete block design (RCBD) with three replications. The main treatments included different levels of allowable soil moisture depletion (35%, 45%, 55%, and 65%), and the sub-treatments consisted of vermicompost (7 tons/ha), municipal solid waste compost (15 tons/ha), farmyard manure (50 tons/ha), and a control (no fertilizer). The results showed that drought stress reduced onion yield, yield components, and leaf chlorophyll content. The highest yield was observed in the vermicompost treatment under no drought stress conditions. The combination of vermicompost and irrigation at 65% allowable soil moisture depletion (30% water savings) resulted in a yield comparable to the no-stress condition without fertilizer application. The highest chlorophyll index was recorded in the no-stress treatment combined with vermicompost (3.81) and compost (3.79). Additionally, the highest proline content was observed under 55% allowable moisture depletion with vermicompost (5.18 mg/g) and compost (3.18 mg/g). These results suggest that the use of organic fertilizers, particularly vermicompost, can mitigate the adverse effects of drought and support crop performance under water-limited conditions
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