International Journal of Agriculture and Crop Sciences. Available online at www.ijagcs.com IJACS/2012/4-19/1452-1457 ISSN 2227-670X ©2012 IJACS Journal
Allelopathic Effects of Wheat Seed Extracts on Seed and Seedling Growth of Eight Selected Weed Species Soheila Porheidar Ghafarbi1, Sirous Hassannejad2*, Ramin Lotfi3 1. MS of weed science 2. Assistant professor of weed science, Department of Plant Eco-physiology, University of Tabriz 3. PhD student of crop physiology, Department of Plant Eco-physiology, University of Tabriz Corresponding author email:
[email protected] ABSTRACT: Allelochemicals have the potential to create friendly-eco products for weed management. A factorial experiment (using RCBD design) with 3 replication was conducted in 2011, to evaluation seed germination and seedling growth of some weed soaked in distilled water (control) and aqueous extract of wheat (Triticum aestivum L.) seeds. The first factor included different wheat extract concentrations (0, 2.5, 5, 10 and 20 percent) and the second factor was the eight weed species (Rumex crispus L., Datura stramonium L., Sisiymbrium irio L., Daucus Carota L., Peganum harmala L., Cardaria Draba L., Hordeum spontaneum and Avena ludoviciana).Whereas wheat extract concentration increased, the inhibitory effect of allelopathic material on seeds germination and seedling growth indices also increased. As seed germination and seedling growth factors of R. crispus, P. harmala and D. carota were reduced by increasing wheat extract concentration, while seed germination of D. stramonium, C. draba, and S. riro in 5%, 5%, and 2.5% of wheat extract concentrations was increased. The results showed that S. riro was most sensitive to aqueous extract of wheat seeds and R. crispus was most resistant. Wheat seeds extract concentration of 20% has inhibitory effect on all seeds and seedling indices. As a result the allelopathic properties of wheat seeds extract can inhibitory effects on weed species. Key words: Allelopathy, Seedling Growth, Seed Germination, Wheat Seeds Extract, Weeds Species. INTRODUCTION Seeds of some crops possess allelopathic potential or weed-suppressing activity, including wheat (Wu et al., 1999). Aqueous extracts of wheat seed were allelopathic to the germination and growth of a number of weed species (Liebl and Worsham, 1983). Allelopathy has been defined as the inhibitory or stimulatory effects of a plant or microorganism on other plants through the release of chemical compounds into the environment. Most allelochemicals are classified as secondary metabolites of the plant (Kruse et al., 2000). However, these stimulatory and inhibitory effects depend on the concentration of the compounds (Bhowmik and Inderjiit, 2003). When susceptible plants are exposed to allelochemicals, germination, growth and development may be affected (Xuan et al., 2004). The most frequent reported gross morphological effects on plants are inhibited or retarded seed germination and effects on coleoptile elongation and shoot and root development (Kruse et al., 2000). Haig (2008) classified allelochemicals into several categories, such as glucosinolates, phenolic compounds, terpenoids, alkaloids, hydroxamic acids, and other compounds (flavonoids, quinones, polyacetylenes). Allelopathy in cereals (cultivated and wild plants of the Poaceae family) was attributed mostly to hydroxamic acids (Sanchez-Moreiras et al., 2004). Many of such natural compounds have been shown to be promising prospects for natural pesticides development (Dayan et al., 2009; Ma et al., 2011). Bio-herbicides represent solution to heavy use of synthetic herbicides which it causes serious threats to the environment, consumers and increases costs of crop production (Asghari and Tewari, 2007). Allelochemicals may be used to develop new tools to combat the evolution of herbicide resistance in weeds (Anjum and Bajwa, 2005). An equally promising way to use allelopathy in weed control is using extracts of allelopathic plants as herbicides (Dayan, 2002; Singh et al., 2005). Because biosynthesized herbicides are easily biodegradable, they are believed to be much safer than synthesized herbicides (Duke et al., 2000). Many authors reported employ plants extracts for controlling weeds with variable success (Hussain et al., 2007; Iqbal et al., 2009; Naseem et al., 2009).
Intl J Agri Crop Sci. Vol., 4 (19), 1452-1457, 2012
Understanding the response of weed to allelopathic plants potential for weed control is very important. Therefore, the objective of this study was to determine the effects of wheat extract on seed germination and seedling growth of some its main weeds under lab conditions. MATERIAL AND METHODS In order to determine the effects of wheat seeds extract on seed and seedling growth of its main weeds [Rumex crispus L. (curlydock), Datura stramonium L. (datura), Sisiymbrium irio L. (London rocket), Daucus Carota L. (Carrot), Peganum harmala L. (harmel), Cardaria Draba (L.) Desv. (horay cress), Hordeum spontaneum C. Koch. (Wild barley), and Avena ludoviciana Durieu (oat)], a Factorial experiment (using RCBD design) with three replications was carried out in agronomy laboratory of University of Tabriz. The first factor included different concentrations of the wheat seeds extract (0, 2.5, 5, 10 and 20 percent). The second factor was the eight weed species. Two hundred grams of wheat seeds powder were separately suspended in 1000 ml distilled water and shaken for 24 hours by a horizontal rotary shaker in room temperature to obtain 20 percent concentration of aqueous extract. The solution was diluted appropriately with distilled water to give the other extract concentrations of 2.5, 5 and 10 percent. In this experiment, 16 seeds of each weed species were placed on Whatman filter paper in 9 cm petri dishes. Four ml of distilled water and final wheat seed aqueous extract concentrations were added to each petri dish. Their solutions were applied where required during the course of experiment. Then, their petri dishes were incubated at 20±ºC and germinated seeds (protrusion of radicle by 2 mm) were counted every day up to 7 days. Germination rate (GR) and mean germination time (MGT) were calculated according to Ellis and Roberts (1980): GR= MGT= Where n is the number of seeds germinated on day D, D is the number of days from the beginning of the test and GR is the mean germination rate. Then percentage of germination was also determined. At the end of test, number of root, length and fresh weight of root and shoot were measured. Root and shoot of each sample were then dried in an oven at 80 ºC for 24 hours (Perry 1977) and mean dry weight of root and shoot for each treatment at each replicate was determined. All the data were analyzed on the basis of experimental design, using MSTATC and SPSS-16 software. The means of each trait were compared according to Duncan multiple range test at P 0.05 and standard error values. Excel software was used to draw figures. RESULTS Germination percentage of H. spontaneum, A. ludoviciana, R. crispus, P. harmala and D. carota seeds in control (wheat seeds extract concentration of 0%) were significantly higher than that of wheat seeds extract treatments. While, seed germination of D. stramonium, C. draba, and S. riro were stimulated in 5%, 5%, and 2.5% of wheat seeds extract concentrations. However, highest concentration of this extract (20%) has inhibitory effect on seed germination of all weed species (Tab. 1). Difference of mean germination time at H. spontaneum, A. ludoviciana, P. harmala, and C. draba among control and wheat seeds extract treatments were not significant. However, with increasing these extract concentrations, mean germination time at D. stramonium, R. crispus, and D. carota was significantly increased (Tab. 1). Wheat extract treatments were significantly reduced germination rate of H. spontaneum, A. ludoviciana and C. draba seeds, compared with control. In contrast, difference in germination rate of S. riro, D. stramonium, R. cricpus, P. harmala, and D. carota in control and wheat extract treatments was not statistically significant (Tab. 1).
Table 1. Effects of wheat seeds extract concentrations on weed species seed germination Treatment
Hordeum
Sisiymbrium
Avena
Datura
Rumex
Peganum
Cardaria
Daucus
Intl J Agri Crop Sci. Vol., 4 (19), 1452-1457, 2012
G% 0 2.5 5 10 20 MGT 0 2.5 5 10 20 GR 0 2.5 5 10 20
spontaneum
riro
ludoviciana
stramonium
crispus
harmala
draba
carota
97.92 a 97.92 a 89.58 ab 66.67 def 2.08 o
14.58 mno 31.2 jklm 6.250 o 0.00 o 0.00 o
95.83 a 91.67 a 89.58 ab 72.92 bcde 0.00 o
10.42 no 16.67 lmno 27.08 klmn 8.33 o 6.250 o
50.00 fghi 45.83 ghij 43.75 hijk 8.33 o 6.25 o
70.83 cde 64.58 def 62.50 efg 62.50 efg 10.42 no
87.50 abc 81.25 abcd 89.58 ab 33.33 ijkl 0.00 o
91.67 a 60.42 efgh 45.83 ghij 12.50 no 2.08 o
0.2167 g 0.1733 g 0.3200 g 0.7633 g 0.3333 g
1.777efg 0.9467g 5.000 cd 0.0000 g 0.0000 g
0.2200g 0.2500 g 0.2133 g 0.4033 g 0.0000 g
4.833cde 1.390 fg 1.910 defg 7.000 bc 5.000 cd
1.183 g 1.403 fg 1.450 fg 8.333 ab 10.33 a
0.5267 g 0.5300 g 0.5700 g 0.6433 g 1.667 fg
0.3800 g 0.5000 g 0.4667 g 1.300 fg 0.0000 g
0.5000 g 0.9300 g 0.9600 g 4.500 cdef 3.333 defg
5.250 b 9.000 a 3.347 bcde 2.057 defg 0.3333 fg
0.5833 fg 1.133 efg 0.2067 fg 0.0000 g 0.0000 g
5.333 b 4.057 bcd 4.777 bc 2.58 cdef 0.0000 g
0.2200 fg 0.3333 fg 0.5467 fg 0.1567 fg 0.1000 fg
0.9133 efg 0.7333 fg 0.7000 fg 0.1333 fg 0.1133 fg
1.977 defg 1.923 defg 1.857 defg 1.640 defg 0.2767 fg
2.633 cdef 2.057 defg 2.157 defg 0.7933 fg 0.0000 g
2.110 defg 1.080 efg 1.047 efg 0.2300 fg 0.03333 g
G%: germination percentage, MGT: germination mean time and GR: germination rate. Different letter in each column indicate significant difference at p 0.05
Mean length of root and shoot at H. spontaneum, S. riro, A. ludoviciana, R. crispus, P. harmala, C. draba, and D. carota seedling by increasing of wheat extract concentrations were significantly decreased. However, in seedling of D. stramonium, highest root and shoot length were obtained from wheat extract concentrations of 2.5% (Tab. 2). Table 2. Effect of wheat seeds extract concentrations on MLR and MLS in seedling weeds Treatment MLR 0 2.5 5 10 20 MLS 0 2.5 5 10 20
Hordeum spontaneum
Sisiymbrium riro
Avena ludoviciana
Datura stramonium
Rumex crispus
Peganum harmala
Cardaria draba
Daucus carota
11.41 a 2.193bc
0.5133 defg 0.0000 g
10.50a 1.320 cde
0.04667 g 0.1000 fg
2.267 bc 0.0000 g
0.0000 g 0.0000 g 0.0000 g
0.2800 efg 0.1400 fg 0.0000g
0.0000 g 0.0000 g 0.0000 g
1.160def 0.4267 defg 0.0000g 0.0000g 0.0000g
0.9933 defg 0.0000 g
1.487bcd 0.6867defg 0.0000 g
2.433 b 0.7533 defg 0.0000 g 0.0000 g 0.0000 g
0.0000 g 0.0000 g 0.0000 g
0.0000 g 0.0000 g 0.0000 g
12.24 a 10.95 a 6.887 bc 2.120 def 0.0000 g
0.7867 fg 0.3467 fg 0.0000g 0.0000 g 0.0000 g
7.740b 6.027 c 1.827 efg 1.013 fg 0.0000 g
0.1867 g 0.9333 fg 0.3133 g 0.0000 g 0.0000 g
3.000 de 1.700efg 1.033fg 0.05333 g 0.0000 g
1.567efg 0.7467 fg 0.1533 g 0.1133 g 0.02000 g
3.500 d 1.167 fg 0.7133 fg 0.1933g 0.0000g
3.000 de 0.900 fg 0.1733 g 0.0266 g 0.0000 g
MLR: means length of root and MLS: means length of shoot. Different letter in each column indicate significant difference at p 0.05
Means numbers of root was stimulated with increasing of wheat seeds extract concentrations at H.spontaneum up to 5% and at A. ludoviciana and P. harmala up to 2.5%. In seedling of S. riro, D. stramonium, R. crispus, C. draba, and D. carota, number of root in control were significantly higher than that of wheat extracts treatments. This indicated that H.spontaneum, A. ludoviciana, P. harmala were most resistant species than that of S. riro, D. stramonium, R. crispus, C. draba, and D. carota (Fig. 1).
Intl J Agri Crop Sci. Vol., 4 (19), 1452-1457, 2012
Means number of root
H. spontaneum S. riro A. ludoviciana D. stramonium R. crispus P. harmala C. draba D. carota
Wheat seeds extract concentrations Figure 1. Effect of wheat seeds extracts concentration on means number of root on seedling of weed species; Bar=±SE, P
