Effects of plant density, mineral fertilization and effective microorganisms on the development and essential oil yield of Ocimum basilicum L.

Document Type : Research article

Authors

1 Department of Horticulture, Faculty of Agriculture, Al-Azhar University, Assiut, Egypt

2 Central Laboratory of Organic Farming, Agricultural Research Center, Giza, Egypt

10.21608/aasj.2025.457748

Abstract

This study examined the impacts of plant density, mineral fertilizers (NPK), biological fertilizers (effective microorganisms, EM), and their interactions on the growth, essential oil content, and chemical composition of sweet basil (Ocimum basilicum L.) using a split-plot design with three replicates. The main factor consisted of three plant density levels: high, medium, and low (90, 60, and 42 plants/10.8 m², equivalent to 33333, 22222 and 15555 plants/feddan, respectively). The secondary factor included five fertilizer treatments: the full NPK recommended dose (100%), EM alone, and combinations of 75%, 50%, and 25% NPK with EM. Results showed that lower plant density enhanced per-plant traits, including branch number, herb and leaf dry weights per cut, seasonal yield per plant, and NPK percentages in dried leaves, but reduced plant height. Conversely, the highest density maximized herb and leaf dry weight yields per feddan = (4200 m2). Essential oil yield per plant per season increased at lower density, while oil yield per fed decreased. The 75% NPK + EM and 100% NPK treatments produced the highest plant height, branch number, dry weights, seasonal yield per plant, and essential oil content across all three cuts during both seasons. The optimal combination for growth parameters, essential oil percentage, oil yield per plant, and NPK percentages in dried leaves was the lowest density (42 plants/10.8 m²) with 75% NPK + EM, while the highest essential oil yield per feddan was achieved with the highest density (90 plants/10.8 m²) combined with 75% NPK + EM.

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