Influence of Exogenous Tryptophan Application on Production and Carotenoids of Calendula officinalis Under Drip Irrigation Treatments

Aug 26, 2026

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Calendula officinalis is cultivated as cut flowers and valued as a medicinal plant, while irrigation strategies can reduce water use and improve stress management. This study assessed how drip irrigation frequency (once, twice, three times per week) and foliar tryptophan dosing (0, 15, 30, 45 mg/L) affected growth, flowering, photosynthetic pigments, carotenoids, and proline across two consecutive seasons. Results showed higher growth with increased irrigation up to twice per week, while flower production declined as irrigation frequency increased. Tryptophan increased growth up to 45 mg/L, but reduced flowers and proline. Combining twice-weekly irrigation with 45 mg/L yielded maximum pigments and carotenoids and the lowest proline.

LanguageEnglish

CategoryHealthcare

FormatPDF

Pages13

Reading Time33 min

AccessFree to download

Abstract

Introduction

Irrigation management and plant stress tolerance

Tryptophan as a plant amino acid and regulator

Role of tryptophan biosynthesis and abiotic stress responses

Influence of exogenous tryptophan application on production and carotenoids of Calendula officinalis under drip irrigation treatments Hend Fouad Medicinal and Aromatic Plants Research Department, National Research Centre, 33 Elbouhouth St. , Dokki, Giza, Egypt *Corresponding author email: [hendfouad12@yahoo.com](hendfouad12@yahoo.com) [Shaimaa I. M. Elsayed](Shaimaa I. M. Elsayed) Horticultural Crops Technology Department, National Research Centre, 33 Elbouhouth St. , Dokki, Giza, Egypt Rasha Fouad Medicinal and Aromatic Plants Research Department, National Research Centre, 33 Elbouhouth St. , Dokki, Giza, Egypt Saber F. Hendawy Medicinal and Aromatic Plants Research Department, National Research Centre, 33 Elbouhouth St. , Dokki, Giza, Egypt Elsayed A. Omer Medicinal and Aromatic Plants Research Department, National Research Centre, 33 Elbouhouth St. , Dokki, Giza, Egypt Abstract---Calendula officinalis L. is primarily cultivated as cut flowers plant and also regarded as a medicinal plant with a variety of therapeutic uses. Irrigation management results in reduction in irrigation requirements, water saving and conservation. Tryptophan has a major role in improving plant stress tolerance to environmental stresses such as water deficiency. This study investigated the response of C. officinalis cultivated under drip irrigation system to the number of irrigation times week-1 and tryptophan foliar application in two successive seasons. Three irrigation treatments (once, twice and three times week-1 ) were used as the main plots and four tryptophan treatments (0, 15, 30 and 45 mg l-1 ) were applied as subplots with three replicates. Increasing the number of irrigation times from once to twice showed the highest values of investigated growth parameters, while three times a week decreased them to lower values than those of once a week. The opposite was true for flowers production in which increasing number of irrigation decreased the flower production. Increasing tryptophan concentration gradually up to 45 mg l-1 increased growth parameters. On the other hand, increasing tryptophan concentration decreased flowers production and proline under all used irrigation treatments. Irrigation of C. officinalis twice a week combined with application of tryptophan at 45 mg l-1 resulted in the highest values of photosynthetic pigments and carotenoids in petals and the lowest value of proline. Keywords---calendula officinalis, irrigation, tryptophan, photosynthetic pigments, carotenoids. Introduction Calendula officinalis belongs family Asteraceae, is a well-known ornamental plant and therapeutic herb that was used for millennia. English marigold, pot marigold, bride of the sun, bull flower and butterwort are some of its common names (Ashwlayan et al. , 2018) . It is widely grown in sunny areas and in a variety of soils. C. officinalis is a tall plant with sparsely branching erect stems, rectangular lance leaflets with tubular disc florets and thorns curving achene that is yellow or orange in color. Carotenoids, flavonoids, saponins, sterols, phenolic acids, lipids and other biological active constituents found in numerous organs of the plant such as leaves and flowers. It is believed to have medicinal properties and is widely used as an anti-inflammatory, diaphoretic, analgesic and antiseptic activities. It has some therapeutic properties and is used to treat gastrointestinal problems, gynaecological issues, oral disorders, eye diseases, skin injuries and certain burns (Chaparzadeh et al. , 2004 and Karthikeya et al., 2022) . The yellow pigment extracted from its flowers is used as food coloring additive. Flower decoction is utilized to treat cold, digestive system, kidneys and contains antioxidants that stimulate the immune system (Edwards et al. , 2015) . Amino acids are organic compounds that are synthesized by plants, but this process involves energy expenditure and takes time. Amino acids fulfill a wid

FAQs

How do different drip irrigation frequencies affect growth and flower production in Calendula officinalis?

Increasing irrigation from once to twice per week increased growth parameters. Increasing to three times per week reduced growth, while flower production decreased as irrigation frequency increased.

What is the effect of foliar tryptophan concentration on growth, flowers, and proline?

Raising tryptophan concentration gradually up to 45 mg/L increased growth parameters. In contrast, higher tryptophan decreased flowers production and proline under all irrigation treatments.

Which treatment combination produced the best results for photosynthetic pigments and carotenoids?

Drip irrigation twice per week combined with tryptophan at 45 mg/L produced the highest photosynthetic pigments and carotenoids in petals, along with the lowest proline value.

Aug 26, 2026

Upload by Maeve