EFFECT OF MINERAL NITROGEN LEVELS AND FOLIAR SPRAY WITH (Spirulina platensis) EXTRACT ON GROWTH, YIELD AND QUALITY OF LETTUCE PLANTS

Hassan, Asem A. S. A.; El Nagy, M.

doi:10.21608/zjar.2025.451783

EFFECT OF MINERAL NITROGEN LEVELS AND FOLIAR SPRAY WITH (Spirulina platensis) EXTRACT ON GROWTH, YIELD AND QUALITY OF LETTUCE PLANTS

Document Type : Original Article

Authors

Asem A. S. A. Hassan ¹
M. El Nagy ²

¹ . Hort. Dept. (Olericulture), Fac. of Agric., Zagazig Univ., Egypt,

² Plant Prod. Dept. (Horticulture – Vegetables), Fac. of Technol. and Develop., Zagazig Univ., Egypt.

10.21608/zjar.2025.451783

Abstract

This study was conducted during the two successive winter seasons of 2022/2023 and 2023/2024 to evaluate the effect of three mineral nitrogen levels (30, 60, and 90 kg N/feddan) and foliar application of Spirulina platensis (SP) at rates of 0, 1, 2, and 4 ml/l on the growth, yield, chemical composition, and nitrate accumulation of lettuce (Lactuca sativa L., cv. Dark Green). The experiment was set up in a two-factorial design: Factor A involved nitrogen levels as main plot, while Factor B included (SP) as foliar spray as sub plots. Results showed that applying 90 kg N/feddan or spraying spirulina at 4 ml/l individually led to the highest values for most tested traits, including plant height, number of leaves, leaf area, head diameter, fresh weight, dry matter percentage, pigment content, total yield, vitamin C, and total sugars% in both seasons. However, 90 kg N/feddan also caused the highest nitrate accumulation and lowest nitrogen use efficiency, conversely spirulina at 4 ml/l reduced nitrate levels and enhanced nitrogen use efficiency. Certainly, the combination of 90 kg N/feddan with 4 ml/l spirulina showed a clear superiority in most of studied traits while significantly reducing nitrate content and improving nitrogen use efficiency compared to 90 kg N/feddan alone. Interestingly, the treatment of 60 kg N/feddan with 4ml/l (SP) showed no significant differences with 90 kg N/feddan without (SP) in most important traits such as (total yield, …. etc.) in both seasons. This suggests the potential to reduce mineral nitrogen fertilizer by 30 kg N/feddan through partial substitution with (SP), contributing to lower environmental pollution, improving nitrogen efficiency and reducing nitrate accumulation in lettuce leaves. The dual N/Spirulina combination is promising for enhanced lettuce production economy.

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