Interactive effect of organic and mineral phosphorus on volatile compounds, morphology, and physiology of garlic (Allium sativum L.)

Abstract

Background: Phosphorus (P) is a macronutrient required by the plants for their normal growth and development. However, the impacts of different forms of P have been rarely tested on the morphology, physiology, and biochemical attributes of garlic (Allium sativum L.) Methods: This study examined interactive effect of mineral-P (mP) as single super phosphate (SSP), and organic-P (oP) as farmyard manure (FYM) on morphological, physiological traits and volatile sulfur containing compounds of garlic. The treatments included T0 = control, T1 = 50 kg ha−1 mP, T2 = 70 kg ha−1 mP, T3 = 90 kg ha−1 mP, T4 = 50 kg ha−1 mP + oP ≈ 50 kg ha−1, T5 = 70 kg ha−1 mP + oP ≈ 60 kg ha−1, T6 = 90 kg ha−1 mP + oP ≈ 30 kg ha−1, and T7 = 50 kg ha−1 mP + oP ≈ 90 kg ha−1. Results: The plant morphological and physiological traits as well as contents of the volatile sulfur containing compounds were significantly altered by the interactive effect of mP and oP. The garlic plants that were treated with T7 generated the maximum bulb output (4382.96 kg ha−1), followed by those fertilized with T5, T6, T2, and T4 which produced 4205.43, 4164.10, 3992.73, and 3916.30 kg ha−1, respectively. The harvest was brought down to 3722.80 kg ha−1 in T3, and it was just 3509.95 kg ha−1 in T1. The response of volatile sulfur containing compounds in garlic leaves (detected by GC–MS and HPLC analysis) indicated that in T7 enormously higher count of constituents in garlic leaves were determined which include aldehydes (3.254 µg/g), hydrocarbons(1.245 µg/g), esters (0.547 µg/g), acids (1.658 µg/g), sulfides (4.985 µg/g), ketones (1.254 µg/g), ethers (8.888 µg/g), alkaloids (0.357 µg/g), heterocyclic polymers (2.684 µg/g), cyclomethycaines (1.854 µg/g), polyolefins (0.214 µg/g), furfuryl and furan derivatives (0.987 µg/g), phenols (0.666 µg/g) and diterpenes(1.256 µg/g). Conclusions: It is noticeable that in absence of oP, the highest level of mP could not improve the volatile compounds, but higher rate of oP even under lower portion of mP recorded higher concentration of the volatile compounds in garlic leaves. Therefore, combined application of organic and mineral P is recommended for better yield and quality of garlic.

Keywords

• Chlorophyll content
• Morphology
• Physiology
• Organic and mineral phosphorus
• Volatile compounds