NARDI FUNDULEA, ROMANIA ROMANIAN AGRICULTURAL RESEARCH, NO. 30, 2013 www.incda-fundulea.ro Print ISSN 1222-4227; Online ISSN 2067-5720 EVALUATION OF THE ALLELOPATHIC POTENTIAL OF QUINOA (CHENOPODIUM QUINOA WILLD.) Dimitrios J. Bilalis1,*, Ilias S. Travlos1, Anestis Karkanis2, Maria Gournaki1, Giannis Katsenios1, Dimitra Hela3 & Ioanna Kakabouki3 1Laboratory of Agronomy, Faculty of Crop Science, Agricultural University of Athens, 75 Iera Odos str., 11855, Athens, Greece. 2Department of Agriculture Crop Production and Rural Environment, University of Thessaly, Fytokou str., 38446, N. Ionia, Magnisia, Greece. 3University of Ioannina, Dep. of Business Administration of Food & Agricultural Products, 20 Seferi str., 30100 Agrinio, Greece. *Corresponding author. E-mail: [email protected] ABSTRACT The allelopathic effects of three plant tissues of Chenopodium quinoa (leaves, roots and inflorescences) on oat growth were investigated using in vivo tests. Oat growth (fresh and dry weights of above and underground parts) was significantly inhibited from phytotoxic activity of inflorescence tissues, leaves and roots of C. quinoa in pot experiments. The inhibiting actions of aqueous crude extracts of the several plant parts were examined using three bioassay methods: (a) seed germination and radicle growth of oat, (b) fresh and dry weight of bean and (b) fresh weight of duckweed plants. All three in vitro tested species exhibited greater phytotoxic response from the inflorescence tissues, than from the other parts of quinoa, confirming the results of in vivo studies on the potential allelopathic activity of this promising crop. Key words: Quinoa; allelopathy, oat; bioassay, duckweed, bean. INTRODUCTION between all types of plants including microorganisms. Nowadays, allelopathy is not uinoa (Chenopodium quinoa Willd.) is a only considered as a common ability acquired Q highly nutritious plant traditionally grown by the plant kingdom through the course of in the Andean highlands of Bolivia, Peru and evolution (Putnam and Tang, 1986), but is Ecuador. Recently it has acquired an additional among the predominant forces in the interest as an export crop generating resources development of plant communities and spatial for the poor regions where it is usually grown patterns therein (Rice, 1984; Travlos and (Hellin and Higman, 2003). It belongs to the Paspatis, 2008). group of crops known as pseudocereals An early sowing would enable quinoa to (Cusack, 1984; Koziol, 1993) that includes have a head start over weeds as the plant can other domesticated chenopods, amaranths and attain good growth during this period. This is buckwheat. Its grain has a high-protein content more important, since there is an absence of with abundance of essential amino acids, and a any recommendation or use of herbicides to wide range of vitamins, minerals and saponin control weed populations in quinoa and (Bilalis et al., 2012; Repo-Carrasco et al., generally hand weeding is done. A number of 2003). Recently, there has been growing crop plants have been reported to acquire interest in a number of countries (especially in allelopathic potential that affects the growth Europe), initiating introduction and research of other species (Karkanis et al., 2010). work on quinoa (Galwey, 1992; Jacobsen, Weed control has a major impact on grain 1997). yield of quinoa. The crop has a relatively slow Molisch (1937) coined the term first growth, which could result to an allelopathy to refer to biochemical interactions insufficient weed competition (Bhargava et Received 16 August 2012; accepted 12 March 2013. First online: 30 March 2013. DII 2067-5720 RAR-226 360 Number 30/2013 ROMANIAN AGRICULTURAL RESEARCH al., 2006). Therefore, an eventual allelopathic test compounds released by a donor plant. Oat activity of species like that could offer some seeds germinate evenly, resulting in a uniform alternatives through of integration of several and rapid plant growth that enables weed management practices and may help qualification of biological response in plants. reduce herbicide dependency in agriculture. In addition, oat biotest is considered as a Unfortunately, very few studies reported to sensitive and easily facilitated method (Rice, date have assessed in vitro the allelopathic 1984). Eight seeds of oat were placed and potential of C. quinoa, even if there is consi- grown in 10 cm diametric plastic pots derable evidence that several Chenopodium containing 5 g freeze tissues per pot filled species may impose interference through with perlite, in a growth chamber (GRW allelopathic mechanisms -LPpQH]-Osornio et 1000T CMP, E. Chrisagis, Athens, Greece). al., 1996; El-Khatib et al., 2004; Batish et al., The seeds were placed 2 cm deep in 16 test 2006). pots. The pots were watered daily with equal This study reports a preliminary volumes of deionised water. All pots were investigation into the allelochemical watered to maintain adequate moisture. characteristics of quinoa. The objective of this Day/night length, air temperature and RH paper was to detect and evaluate the potential were: 12/12 h, 26/17oC and 50/70% allelopathic activity: (a) of different quinoa respectively. Lighting was provided by four tissues on oat seedling growth and (b) of plant high pressure sodium lamps (Vialox NAV-T extracts on oat radicle growth, bean seedling 400 4Y, Osram, Gmbh, Munich, Germany) growth and duckweed fresh weight and The above- and below-ground growth of oat estimate their dose-response to aqueous were measured after two weeks and used as an extracts of varying concentrations. index of allelochemical activity. Seedlings were collected two weeks after planting and MATERIAL AND METHODS the average shoot fresh and dry weight per pot was determined. The experimental design was Pot experiment a randomised block with four replicates for Plant material was collected at the each treatment and control. reproductive stage of a quinoa crop established in Agricultural University of Plant extracts bioassay Athens (AUA), Greece (latitude 37o ǯ 1 The phytotoxicity of plant extracts was longitude 23o ( LQ -XQH 7KH VRLO quantified with an Avena sativa seed bioassay. was clay loam (CL 0-25 cm; 34.1% clay, The several plant parts (leaves and stems, 28.8% silt and 37.1% sand), calcareous roots, inflorescences) were cut into small o (15.9% CaCO3), with a pH value of 7.29 and pieces, stored for a week at 0 C in the dark relatively moderate organic matter and extracted successively with deionised (determined according to Wakley and Black, water. Aqueous dilutions of the initial crude 1934) and nitrogen content (1.47 and 13.4%, extracts were bioassayed on filter paper in respectively), with sufficient levels of nitrate, plastic Petri plates. Ten oat seeds were placed moderate in available phosphorus and rich in onto two layers of 9-cm filter paper in Petri available potassium and sodium (104.3, 9.95, plates treated with 3 ml of test solution, 590 and 110 ppm, respectively). For the covered, and incubated at 24o C in the dark. purposes of allelopathic experiments three The experimental design was a randomi- tissue types were used: (i) inflorescences, (ii) sed block with four replicate Petri dishes for leaves and stems, and (iii) roots. Bioassay each treatment, while in the control solutions experiments were used to determine the only deionised water was added. Inhibitory inhibitory potential of each of these tissues on concentrations were calculated after 7 days oat above- and below- ground growth in pot and used as an index of allelochemical experiments. Oat (Avena sativa) was included activity. An analysis was conducted according in this study since it has been used extensively to Finney (1962). A 5-mm radicle length was in allelopathy research as the receiver plant to considered germinated, while seeds that did 361 DIMITRIOS J. BILALIS ET AL.: EVALUATION OF THE ALLELOPATHIC POTENTIAL OF QUINOA (CHENOPODIUM QUINOA WILLD.) not germinate were considered to have a growth of beans were measured after 7 days radicle length at 0 mm. Growth was quantified and used as an index of allelochemical by measuring the radicle length of germinated activity. There the same data analysis like in oat and was also expressed as a percentage of oat was conducted, and the I50 value for bean radicle elongation in control dishes. The dose root dry weight was also determined. needed to inhibit oat radicle growth to 50% of Furthermore, the same dilutions of the control radicle growth (hereafter called the I50 initial inflorescence extracts of quinoa were value) was determined from dose-response tested via another bioassay using as test plant bioassays (Finney, 1978). All statistical a species of duckweed (Spirodella polyrhiza analyses were conducted using the Statistica 9 L.) and measuring the decrease of its fresh software package (StatSoft, Inc. 2300 East weight. This plant indicator has been used in 14th Street, Tulsa, OK 74104, USA). several allelopathic studies, since the bioassay Moreover, the phytotoxicity of C. quinoa is sensitive and reliable especially at the first extracts was also quantified by means of a steps of a screening procedure. Moreover, bioassay using common bean plants duckweed species are highly sensitive to (Phaseolus vulgaris) and measuring some of chemicals that inhibit the function of the main features of their first growth. Photosystem II, and their response by Phaseolus species are also often included in chlorosis is readily measurable through the VLPLODUVWXGLHV -LPpQH]-Osornio et al., 1996; drastic