Vol 8, Issue 2, 2015 ISSN - 0974-2441 EFFECT OF PLANT GROWTH REGULATORS ON GROWTH AND ESSENTIAL OIL CONTENT IN PALMAROSA (CYMBOPOGON MARTINII) AHAMAD FAIZ KHAN 1* , FARINA MUJEEB 2 , FAROOQI AHA 3 , ALVINA FAROOQUI 1 1 Department of Bioengineering, Integral University, Lucknow, Uttar Pradesh, India. 2 Department of Biosciences, Integral University, Lucknow, Uttar Pradesh, India. 3 Ex-Scientist, Department of Plant Physiology, Central Institute of Medicinal and Aromatic Plants (CIMAP), Lucknow, Uttar Pradesh, India. Email: erfaizkhan_6@yahoo.com Received: 18 December 2014, Revised and Accepted: 30 January 2015 ABSTRACT Objective: The aim was to examine the responses viz., herbage yield, essential oil content and oil composition to varying levels of gibberellic acid (GA 3 ), kinetin and indole acetic acid (IAA) in Palmarosa (Cymbopogon martinii). Methods: Essential oils were obtained by hydro-distillation using a Clevenger-type apparatus and oils composition was analyzed by gas chromatography-mass spectrometry. Nitrate reductase (NR) activity was evaluated by in-vivo assay. Protein content was evaluated by Lowry method. Chlorophyll was estimated by Arnon method. Results: Plant growth was improved by GA 3 significantly, and the increase was maximum at 100 ppm concentration in plant height, leaf area, tiller number and herbage yield. Chlorophyll content, protein content, NR activity and oil content increased in the plants due to GA 3 treatment compared to untreated plants, and the increase was maximum at 100 ppm concentration. Effect of IAA and kinetin was similar to GA 3 but maximum effect was observed at 50 ppm concentration. Geraniol content of the essential oil of Palmarosa increased due to GA 3 and kinetin treatment while percentage of geranyl acetate decreased. Conclusion: On a comparative basis, among the three promotional hormones, GA 3 was most effective in stimulating growth, essential oil content, leaf area, tiller number and metabolic parameters (protein content, chlorophyll content and NR activity). Keywords: Cymbopogon martinii, Essential oils, Plant growth regulators, Oil compositon. INTRODUCTION Palmarosa (Cymbopogon martinii [Roxb.] Wats. Var. motia) is a perennial grass, widely distributed in tropical and subtropical regions. It contains essential oil, whose main components are geraniol and geranyl acetate [1]. The essential oil from C. martinii is widely used as a valuable component for perfumes, cosmetic and pharmaceutical products [2,3] and against the action of various bacteria, fungi and microorganisms [4,5]. The essential oil also has some of the important properties such as insect repellent and is also used in aromatherapy [6-9]. Due to these applications, essential oil demand in the domestic and international market has increased, which has stimulated its cultivation. Many factors including age, seasonal variation, nutrition, temperature and phytohormones have an influence on accumulation and metabolism of secondary metabolites [10]. There are numerous reports in the literature concerning the effects of growth regulators on growth and development of various aromatic plants [10]. Most of these growth substances have exhibited influences by modifying the growth characters. Gibberellins are endogenous plant hormones, which improve the growth of plants. In aromatic plants, where active principle is generally present in the leaves or flowers, gibberellins have been used to improve growth and herb yield of aerial parts of the plants. Gibberellic acid (GA 3 ) also significantly enhanced the foliage yield of Cymbopogon jwarancusa [11]. Auxins and cytokinins constitute other major groups of plant hormones. Auxins are well known for their role in cell elongation and differentiation in the plants. Similarly, role of cytokinins in cell division and differentiation in the plants is well established. Both these hormones have been used for improvement of growth and development of aromatic plants. Indole acetic acid (IAA) also stimulated leaf growth in C. jwarancusa [11]. Effect of kinetin on herbage and oil yield has been reported earlier in Mentha specie [12,13]. The present study was under-taken to examine the effect of plant growth regulators on the essential oil biosynthesis in Palmarosa and plant growth. Biosynthesis of terpenoids is dependent on primary metabolism, e.g. photosynthesis and oxidative pathways for carbon and energy supply [10]. Therefore in this study, effect of plant growth regulators on primary metabolic parameters like nitrate reductase (NR) activity, chlorophyll content and protein content was also determined. METHODS Chemicals and reagents Sodium nitrite, potassium dihydrogen phosphate, potassium nitrate, sulfanilamide, N-(1-naphthyl) ethylene dihydrochloride (NED-HCL), anhydrous sodium sulfate, trichloroacetic acid, anthrone, Tween 80, sodium potassium tartrate, cupric sulfate, acetone, sodium sulfate, bovine serum albumin etc., were purchased from Hi-media. Plant material Seedlings of Palmarosa (C. martinii [Roxb. Wats. var. motia Burk] cv. Trishna) were purchased from Central Institute of Medicinal and Aromatic Plants, Lucknow, India and cultivated in pots at herbal garden of Integral University, Kursi road, Lucknow, India. Plant growth regulators treatment The study was conducted during April-July 2013 in a randomized block design with three replications. One seedling was transplanted in each pot. There were three pots for each treatment in one replication. The effect of plant growth regulators on herbage yield was evaluated by spraying plant foliage with solutions of GA 3 , kinetin and IAA each at 25, 50 and 100 ppm. Three foliar sprays of these hormones were given at 15 days intervals starting from 45 days after transplanting. Tween 80 (0.01%) was used as wetting agent. In addition, untreated Research Article