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Inhibitory effects of Sorghum halepens root and leaf extracts on germination and early seedling growth of widely used medicinal plants.

Introduction

Allelopathy is a topic of great interest in the field of chemical ecology [21]. Allelopathy is defined as interactions between plants which might lead to either simulation or inhibition of growth [27]. Evidence for allelopathic interactions in nature caused by plants containing chemicals with allelopathic activity (phenols, terpens, flavonoids, polyacetylene, fatty acids, steroids, etc.) and their ability to inhibit seed germination or plant growth have been described through several experiments [5]. Allelopathic substances may be released by a variety of mechanisms from various plants structure [30,2,24,6,15,18].

A variety of plants, such as Oriza sativa, Triticum aestivum, Glycine max, Ambrosia artimisiifolia, Populus Spp. and Malus pumila, exude allele-chemicals through their living roots, or upon their death and decay under natural conditions [5].

Most studies on Allelopathy have focused on the effects of extract from plant organs on seed germination and seedling growth, for it is difficult to identify the allelochemicals from the effects of competition among plants [4].

Many weed species have been studied in vitro for their allelopathic potential on various field crop species such as Chenopodium album L. [28], Nepeta meyeri [22], Brassica nigra [32],and Lantana camara [28].

Sorghum halepens (L.) Pers. (Johnsongrass) is a large, perennial grass that propagates by seeds and rhizomes. A native of the Mediterranean region, Sorghum halepens has become well established in warm regions of all major agricultural areas of the world [20]. It has been reported as one of the world's ten worst weeds [17]. The success of this weed is attributed to its growth rate, reproductive potential, efficient utilization of resources and allelopathy. Among these the allelopathic nature of the weed has been helpful in its fast spread.

Several works have demonstrated the harmful effect of some sorghum species to many crops and weeds including reduced seed germination and germination of subsequent small grain crops when grown in rotation [1,12]. Water extract from Sorghum bicolar residues inhibited germination and decreased root and shoot growth of corn and wheat [16]. Residues of sorghum-sudangrass (Sorghum bicolar (L.) Var. sudanense) cover crops preceding no till establishment of alfa alfa significantly reduced weed populations compared with no residue or foxtail millet residue [14]. Machado [19] reported that aqueous extracts of Sorghum halepens retarded growth of shoot and root of Downy brome.

The purpose of the present research was (a) to elucidate the inhibitory effects of aqueous extracts obtained from root and leaves of Sorghum halepens through Petri dish on germination and early seedling growth of six popular medicinal plants in Iran under laboratory conditions and (b) to determine any allelopathic interference of residues of Sorghum halepens with the growth and development of Plantago ovata and Nigella sativa in pot test.

Materials and methods

I. Aqueous extracts

Sorghum halepens plants were collected during the flowering stage from agricultural research station of University of Zabol, (36[degrees] 380 N and 59[degrees] 70 E), Iran. To evaluate the phytotoxicity of allelochemicals produced by Sorghum halepens, the effects of water soluble compounds on germination was analyzed using a methodological design similar to the one previously used by Romel, et al., [28] and Mutlu and Okkes, [22]. The plant material was separated into leaves and stems after being washed thoroughly with distilled water and was dried in an oven at 70[degrees]C for 24 hours. The dried samples were grounded in a blender after being cut into 1-cm pieces and. The aqueous leaf extract was prepared by soaking 5 gram of this powdered leaf material in 100 ml distilled water for 24 hours. Then, this extract was filtered (using Whatman filter paper No. 42). The filtered solutions (stock solutions) were held in a refrigerator for a short time until they got bioassay. Stock solution (5% w/v) was diluted appropriately with distilled water to give the final concentrations of 5, 10, 20, 30, 40 and 50 g [L.sup.-1]. Distilled water was the control.

11. Plant materials

Seeds of six medicinal plants, including Ocimum basilicum (basil), Nigella sativa L. (black seed), Cuminum cyminum (cumin), Foeniculum vulgare Mill. (fennel), Plantago ovata Forsk. (isabgol),and Plantago psyllium (psyllium) were obtained locally, and before being used for bioassays, their germination potentials was examined at 25 [+ or -] 1[degrees]C in darkness and germination over 85% also guaranteed the viability of the seeds [25]. The plant seeds were sterilized with 10:1 water/bleach (commercial NaOCl) solution for 5 minutes and subsequently washed with diluted water.

III. Seed germination tests

Six tests corresponding to the treatments mentioned above were performed on each species in this study; watering with concentrations of 5, 10, 20, 30, 40 and 50 g [L.sup.-1] along with a control in a germination test consisting of seeds incubated on filter paper with solely distilled water. For each treatment, four different replications were tested. Each replicate was composed of 25 seeds placed in a 10-cm diameter plastic Petri dish on a filter paper, kept saturated by regular watering. The Petri dishes were placed in a germinator (25[degrees]C, 70% humidity and constantly dark) and a period of 7 days was allocated to their growth. The Petri dishes were watered once in every 2-3 days with either different concentrations of aqueous solution of root and leaf extract or distilled water for the controls if necessary.

After these 7 days, the length of root and shoot, as well as the weight of the dry matter of the plants were measured. During the experiment, germinated seeds (root emergence [greater than or equal to] 1 mm) were counted each day. Seed germ inability was assessed by the final cumulative percentage of germination at the end of the tests.

Seedling performance was assessed through relative seed germination (RSG), relative elongation of root (RER) and relative elongation of shoot (RES) tests [31] as follows:

RSG = number of seeds ger min ated in extract/number of seeds ger min ated in control x 100

RER = mean root length in extract/mean root length in control x 100

RES = mean shoot length in extract/mean shoot length in control x 100

IV. Water Uptake

Several two-gram samples of each plant's seeds were soaked for 8 hours in Sorghum halepens leaf and root aqueous extracts of 0, 5, 10, 20, 30, 40 and 50 g [l.sup.-1] water. The seeds were then taken from the solutions, blotted between two folds of filter paper for 2 hours, and weighed. The water uptake was calculated by subtracting the original seed weight from the final seed weight. Distilled water was used as the control [32].

V. Phytotoxic effect of residue incorporation

In order to test the short-term allelopathy of Sorghum halepens, effect of plant residues incorporated with soil was studied. For incorporation treatments, residues of dried Sorghum halepens were mixed with a garden soil per 200 [cm.sup.3] pot. The amount of plant residues incorporated in a soil medium was 0, 5, 10, 20 and 30 g [kg.sup.-1]. In each pot 10 seeds from Plantago ovata or Nigella sativa were sown at a depth of 1 cm. The pots were saturated with water by surface irrigation. During plant growth pots were irrigated daily by spraying with water until water drained from the bottom of the pot. Germination was measured daily for 20 days. All plants were harvested to determine shoot height, root length and dry weight of roots and shoots of seedlings. The tests were performed in a green house in four replicates.

Statistics Design:

Germination and seedling growth bioassays were conducted in a complete randomized design (CRD) with four replications. The experiments were repeated twice and the pooled mean values were separated on the basis of Duncan Multiple Range Test (DMRT) at a probability level of 0.05.

Results and discussion

Germination

The root and leaf extracts of Sorghum halepens significantly inhibited seed germination of Plantago ovata, Plantago psyllium, Foeniculum vulgare and Ocimum basilicum seeds compared to corresponding controls. In contrast, the germination of Nigella sativa seeds was increased by both leaf and root extracts of Sorghum halepens at low concentration while that of Cuminum cyminum seeds was not affected even at the highest extract concentration level.

Among the survivors, the highest inhibitory effect (98.33%) was recorded in Plantago ovata seeds at concentration of 50 g [L.sup.-1] aqueous leaf extract. The determined inhibitions were higher for leaf extracts than for root extracts and were more pronounced at increasing concentrations of the leaf extract (Table 1).

The relative seed germination (RSG) of the 6 medicinal plants is represented in Fig. 1 the maximum relative seed germination (84.27%) was found in Cuminum cyminum at leaf concentration of 20 g [L.sup.-1] followed by (71.93%) in Nigella sativa seeds at the same treatment. Among the plants, Cuminum cyminum and Nigella sativa was less sensitive to the exposure of different concentrated extracts.

Effect of root and leaf aqueous extracts of Sorghum halepens on seedling growth

Root Elongation

Table 2 shows the average of root length of tested medicinal plants. The extract from roots and leaves of Sorghum halepens significantly inhibited the root length of germinated Plantago psyllium, Plantago ovata and Foeniculum vulgare seedlings, compared to related controls. The inhibitions were relatively enhanced with the increasing amount of both extract concentrations. The leaf extracts proved to have more effective allelopathic effect in comparison to the root extracts. On the contrary, the root length of Cuminum cyminum, Nigella sativa and Ocimum basilicum seedlings were promoted by concentrations of 5, 10, 20 g [L.sup.-1] of both extracts while demonstrating a slight inhibition at 30, 40 and 50 g [L.sup.-1] concentrations. In addition to inhibiting root elongation, some other morphological abnormalities occurred too; (such as twisted root growth caused by many extracts). The most severely twisted roots were observed in seedling treated with leaf and root extracts of Foeniculum vulgare. In all concentrations, the leaf extracts of Sorghum halepens caused the greater reduction in root length when compared with the root extracts of Sorghum halepens. Among the medicinal plant receptors, root elongation of Cuminum cyminum was less sensitive to the exposure of different concentrated extracts.

Maximum relative root growth (RER) was found in Cuminum cyminum (118%) at leaf concentration of 10 g [L.sup.-1] while the minimum (0.39%) was found in Plantago psyllium at root concentration of 50 g [L.sup.-1] (Fig. 2).

Shoot Elongation

Stem length was relatively more resistance to allelochemicals compared to the root elongation. Table 3 shows the mean stem lengths of the assayed medicinal plants when using different extract concentrations. All extracts caused a marked influence on the shoot length of test plants seedlings. A remarkably high degree of inhibition occurred with leaf extracts at the highest concentrations. The extracts inhibited stem length of Plantago psyllium, Plantago ovata and Ocimum basilicum seedling but the same extracts generally stimulated stem growth of Foeniculum vulgare, Nigella sativa and Cuminum cyminum seedlings at low concentrations. Regarding the overall treatment among the six bioassay species, the Cuminum cyminum was the least sensitive to the aqueous extract, followed by Nigella sativa and Ocimum basilicum, while Plantago psyllium and Plantago ovata were the most sensitive.

Maximum (136%) relative shoot growth (RES) was observed in Cuminum cyminum at leaf concentration of 50 g [L.sup.-1] (Fig. 3).

Seedling Dry Matter

The average dry matter weight of the germinated seedling of all the plants are shown in table 4. The leaf and root extracts from Sorghum halepens reduced the dry weight of seedling in Plantago psyllium, Plantago ovata, Foeniculum vulgare, Ocimum basilicum, and Nigella sativa significantly while increasing the dry weight of Cuminum cyminum at low concentrations. In this study at all extract concentrations, the dry matter of test plants seedling was significantly reduced more by the leaf extracts than by the root extracts.

Water Uptake

Many enzymatic functions important to plants are inhibited by the presence of allelochemicals (Turk and Tawaha, 2002; Rice, 1984). To a large extent, the activity of these enzymes is primarily related to water imbibition by the seeds.

Different concentrations of root and leaf aqueous extracts had little effect on water uptake by germination plant seeds in this experiment. Moreover, increasing the concentration of aqueous root and leaf extracts did not significantly inhibited water imbibition (Table 5).

Phytotoxic effect of residue incorporation

Seed germination of Plantago ovata and Nigella sativa was significantly reduced by residue incorporation treatment compared to control (Table 6). Percent germination varied among plants from 2.7% (for Plantago ovatato in 30 g [kg.sup.-1] residue added to the soil) to 58.5% (for Plantago ovatato in 5 g [kg.sup.-1] residue added to the soil). The species also varied in their sensitivity to the different amounts of residue incorporated to the soil. While increasing the amount of residue incorporated to the soil reduced Nigella sativa germination with fixed rate, the germination of Plantago ovata in the control was slightly lower than germination with low residues incorporation.

Plant height of both species was negatively correlated with the quantity of residues (Table 6). The highest Plant height in both plants occurred in the control, which was significantly greater than the residue incorporation treatment. Significant inhibitory effects were found in pot containing 5 g [kg.sup.-1] residue added to the soil or above as compared to the untreated control. The inhibitory effect on plant height increased with increasing plant residue incorporated with soil. Residues from Sorghum halepens plants at the highest amount of 30 g [kg.sup.-1] reduced shoot elongation of Plantago ovata and Nigella sativa by 47 and 56%, respectively.

Soil amended with residues inhibited the accumulation of dry weight in roots of Plantago ovata and Nigella sativa seedlings by 40 to 62% (Table 6). 30 g [kg.sup.-1] residue added to the soil had most effective influence on root dry weight of seedling of both species, which was significantly lower than all other treatments.

Also, shoot dry weight of seedlings was affected by the amount of Sorghum halepens residues added to the soil. The dry weight of shoots in both species declined sharply as the concentration of residues increased, reached 62 and 53% inhibition in Plantago ovata and Nigella sativa respectively, at the highest residue concentration.

Accumulation of dry weight in roots was relatively more sensitive to allelochemicals compared to the shoot dry weight. Taken together, germination, plant growth and development of Plantago ovata seedling was more sensitive than Nigella sativa seedling.

Discussion

Previous researches have reported phenolic acids to be of decomposing residue, the root was supposed to be responsible for growth and yield reduction was associated with allelopathy of some sorghum species [11]. Guenzi and McCalla [16] quantified five phenolic acids in sorghum residue; ferulic, p-comedic, syringic, vanillic, and p-hydroxybenzoic. Cherney, et al. [7] also found vanillic acid, phydroxy-benzaldehyde, p-coumaric acid, and ferulic acid in four sorghum species including Sorghum halepens; again the concentration of p-coumaric was highest followed by ferulic acid. Two other compounds, dhurrin and sorgoleone, were associated with allelopathy by sorghum species. Allelopathy in sorghum genus (cultivated and wild plant of sorghum genus) was attributed mostly to sorgoleone [34].

The process of seed germination is a crucial stage in plant growth. Allelochemicals can affect the establishment or regeneration of population by affecting seed germination [5]. Increasing germination can enhance the competitive ability of plant for both above-ground and underground resources.

In the present study, however, interest has been primarily focused on the allelopathic potentials of the aqueous extract or residues from Sorghum halepens. The effect of aqueous extracts from the roots and the leaves or application of varying amounts of residues of Sorghum halepens were determined on seed germination and early seedling growth during germination of several popular medicinal plants of Iran.

The experiment revealed that different concentration levels of leaf and root extracts can inhibit the germination seeds of medicinal plant studied to a certain extent while having an amelioration effect on the others. These findings coincided with the report of Daniel [10], who has formerly stated that allelopathy includes both promoting and inhibitory activities and is a concentration-dependence phenomenon.

The results also showed that allelochemicals in extracts of root and leaf can have both beneficial and harmful effects on growth of the seedlings. Overall growth rate of seedlings was also reduced in most treatments compared to control, while Cuminum cyminum and Nigella sativa seedling showed a slight promotion at low concentrations. Allelochemicals promoted the seed germination and seedling growth as a result of the stimulation for cell division and elongation [5].

In most cases, Leaf extracts had more allelopathic effect (either negative or positive) than did the root extracts. The results of this study are also congruent with the data by Turk and Tawaha [32] who reported that most inhibitory effect of allelopathic plants was produced by leaf extracts. Differences in leaf and root extract effects may indicate the presence of different (concentrations of) allelochemicals in roots and leaves. For example, sorgoleone, an allelochemical of sorghum genus [12] constituted more than 80% of root exudates composition (Nimbal, et al., 1996; Czarnota, et al., 2003), while none was found in immature and mature leaves and stems of sorghum [36]. Sorghum shoots, in contrast, produce higher amounts of cynogenic glucosides the phenolic breakdown products of which inhibit considerable plant growth [12,35,29]. The relative effectiveness of shoot and root extracts is of utmost importance in adoption of an appropriate tillage method.

The effects (either inhibitor or stimulus) of these extracts were apparently greater on the roots of test plants than on the shoots of the same. In other words, the results indicated that these extracts were more effective on the roots than on the shoots of the test plants. These results are in agreement with previous studies which report allelochemicals to have more pronounced effects on root growth than on hypocotyl growth or shoot growth [32]. The reason behind such a result is that root is evidently the first to absorb the allelochemicals or autotoxic compounds from the environment [32].

Sorghum halepens allelochemicals did not affect imbibition, the first phase of germination. It indicates that the observed alterations in seeds germination are due to not only water stress but also the toxicity of Sorghum halepens allelopathic compounds. It is also in agreement with data presented by Bernat, et al. [4] who suggested that lack of water available for seed germination due to binding water by compounds present in extract of Sorghum halepens also play a minimal role in reduction of seed germination, so that the mode of action of Sorghum halepens allelochemicals would be mainly according to their toxic nature.

Seed germination and growth characteristics of Plantago ovata and Nigella sativa were lower with dry residue incorporation than in the control. The residue incorporation with dry materials significantly affected both seed germination and plants growth. Any inhibition of plant growth should be due primarily to the presence of toxic compounds or excessive solutes within the ground plant samples. Cochran et al. [8] and Elliott et al. eported that crop or weed residue toxicity to plant seedling was likely caused by an allelopathic substance released from residues and accumulate in the soil, and also residue inhibition on seedling growth was enhanced if plant residue was incorporated before sowing.

Based on the relative reaction of germination and early seedling growth to different concentrations of root and leaf extracts, the sensitivity may be classified in the following order of decreasing inhibition:

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

Plantago psyllium, Plantago ovata, Foeniculum vulgare, Ocimum basilicum, Nigella sativa and Cuminum cyminum.

Prati and Bossdorf [26] reported that the degree of allelopathic interference is species-specific and can even vary within species. Einhelling [13] observed that the inhibition threshold varies with the plant process involved as well as the sensitivity of the receiving species.

Conclusion

This test shows that root and leaf extracts or residues from Sorghum halepens indicate variable allelopathic activity on seed germination and early seedling growth of the medicinal plants studied. Such allelopathic activities depend on both the concentration levels of the extracts and the parts of allelopathic plant from which the extract has been derived. Allelochemicals may directly prevent or promote germination and seedling growth, consequently influencing the number of plants of each species in a crop community. The varying degree of inhibition observed in different crops used in this experiment highlights their differential responses and the need to evaluate the allelopathic compatibility of such underutilized crops as medicinal plants with allelopathic weeds before their introduction into agricultural system.

References

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(1) Mohammad R. Asgharipour, (2) Mohammad Armin

(2) Department of Agriculture, University of Zabol, Zabol, I.R. Iran Tel: +989153167234, Fax No: +985422235478

(2) Islamic Azad University, Branch of Sabzevar

Mohammad R. Asgharipour, Mohammad Armin: Inhibitory Effects of Sorghum Halepens Root and Leaf Extracts on Germination and Early Seedling Growth of Widely Used Medicinal Plants: Adv. Environ. Biol., C(C): CC-CC, 2010

Corresponding Author

Mohammad R. Asgharipour, Department of Agriculture, University of Zabol, Zabol, I.R. Iran Tel: +989153167234, Fax No: +985422235478

E-mail: m_asgharipour@yahoo.com
Table 1: Influence of various concentrations of leaf and root aqueous
extracts made from Johnson grass on the germination of receptor
medicinal plant seeds.

Concentration    N. Sativa         O. basilicum      C. cyminum
(g kg-1)
                 LE       RE       LE       RE       LE       RE

0                89a *    89a      90a      90a      95a      95a
5                93a      93a      82a      85a      94a      95a
10               91a      95a      80ab     85a      95a      95a
20               84a      88ab     76b      82a      92a      92a
30               75b      77b      77b      80a      91a      90a
40               58c      58c      62c      78ab     89a      91a
50               54c      63c      61c      76b      90a      90a

Concentration    F. vulgare        P. Ovata          P. psyllium
(g kg-1)
                 LE       RE       LE       RE       LE       RE

0                87a      87a      86a      86a      88a      88a
5                80a      81a      62b      72a      78a      84a
10               78a      80a      62b      70a      72a      80a
20               73a      77a      58b      68ab     68b      80a
30               73a      76a      44c      54b      45c      62b
40               69b      72a      32d      52b      31d      54bc
50               66b      71a      26d      52b      23e      41c

* Values followed by the same letter within the same columns do not
differ significantly at P = 5% according to DMRT.

Table 2: Influence of various concentrations of leaf and root aqueous
extracts made from Johnson grass on root elongation of receptor
medicinal plat seedlings.

Concentration    N. sativa           O. basilicum      C. cyminum
(g kg-1)
                 LE         RE       LE       RE       LE       17.1b

0                20.1a *    20.1a    8.2a     8.2a     17.1b    19.2a
5                20.4a      21.4a    7.3a     7.2a     19.1a    20.2a
10               21.8a      20.8a    6.8ab    7.7a     19.0a    16.5b
20               18.2b      18.2b    6.2b     6.2ab    17.3b    12.7c
30               16.3c      17.0b    4.9c     5.8ab    12.8c    10.9d
40               14.7d      14.2c    4.3c     5.3b     10.4d    10.2d
50               12.1e      15.7c    3.1d     4.0c     10.9d    10.2d

Concentration    F. vulgare        P. ovata          P. psyllium
(g kg-1)
                 LE       RE       LE       RE       LE       RE

0                9.4a     9.4a     11.6a    11.6a    10.1a    10.1a
5                7.3b     8.2b     10.4b    9.2b     8.3b     9.2ab
10               7.1b     8.6ab    9.2c     8.3b     8.5b     8.8b
20               7.5b     6.7c     7.2d     8.4b     6.7c     6.5c
30               5.9c     6.5c     6.1e     4.1c     3.9d     4.7d
40               4.0d     4.7d     3.5f     2.3d     2.4e     1.8e
50               3.3e     5.4d     2.2g     1.0e     1.1f     1.3e

50 * Values followed by the same letter within the same columns do not
differ significantly at P = 5% according to DMRT.

Table 3: Influence of various concentrations of leaf and root aqueous
extracts made from Johnson shoot elongation of receptor grass on
medicinal plant seedlings.

Concentration    N. Sativa          O. basilicum      C. cyminum
(g kg-1)
                 LE        RE       LE       RE       LE       RE

0                18.7b *   18.7b    12.5b    12.5b    21.1     21.1b
5                21.1a     19.9a    13.6a    13.1b    22.1b    23.2a
10               19.4ab    20.1a    14.8a    15.4a    26.6a    24.6a
20               20.5ab    19.5a    12.9b    12.4b    22.8b    23.8a
30               14.1c     15.3c    10.2c    11.2bc   18.4c    19.3c
40               10.0d     12.6d    8.5d     10.2c    19.5c    18.8c
50               10.2d     9.4e     8.2d     10.8c    16.5d    15.7d

Concentration    F. vulgare        P. ovata          P. psyllium
(g kg-1)
                 LE       RE       LE       RE       LE       RE

0                12.7a    12.7a    11.3a    11.3a    12.1a    12.1a
5                11.4b    11.2b    10.0a    10a      10.2b    10.4b
10               9.3c     10.5b    8.2b     9.2ab    10.2b    9.3b
20               8.9c     10.6b    7.6b     9.7ab    8.3c     8.8c
30               6.1d     9.8c     5.3c     8.4b     6.8d     7.4d
40               4.2d     7.1d     2.1d     6.2c     2.1e     5.2e
50               2.7e     6.2e     1.2e     3.1d     2.0e     4.1e

* Values followed by the same letter within the same columns do not
differ significantly at P = 5% according to DMRT.

Table 4: Influence of various concentrations of leaf and root aqueous
extracts made from Johnson grass on dry weight of receptor medicinal
plant seedlings.

Concentration    N. sativa          O. basilicum      C. cyminum
(g kg-1)
                 LE        RE       LE       RE       LE       RE
0                30.3a *   30.3a    18.9a    18.9a    24.8b    24.8b
5                30.0a     29.9a    15.1b    14.7b    29.8a    30.7a
10               29.8a     29.6a    15.6b    16.7ab   33.0a    32.4a
20               28.0a     27.3a    13.8b    13.5b    29.0a    29.2a
30               22.0b     23.4b    10.9c    12.3bc   22.6b    23.2b
40               17.9c     19.4b    9.3d     11.2c    21.6bc   21.5b
50               16.1c     18.2b    8.2d     10.7c    19.8c    18.7c

Concentration    F. vulgare        P. ovata          P. psyllium
(g kg-1)
                 LE       RE       LE       RE       LE       RE
0                18.1a    18.1a    19.9a    19.9a    20.2a    20.2a
5                13.5b    14.0b    14.8b    13.9b    13.4b    14.2b
10               11.9c    13.8b    12.6b    12.7b    13.5b    13.1b
20               11.9c    12.5c    10.7c    13.1b    10.9c    11.1c
30               8.7d     11.8c    8.3d     9.1c     7.7d     8.8d
40               5.9de    8.5d     4.1e     6.2d     3.3e     5.1e
50               4.4e     8.4d     2.5f     3.0e     2.3e     3.9f

* Values followed by the same letter within the same columns do not
differ significantly at P = 5% according to DMRT.

Table 5: Influence of various concentrations of leaf and root aqueous
extracts made from Johnson grass on water uptake of receptor medicinal
plant seeds at different soaking periods.

Concentration    N. sativa           O. basilicum      C. cyminum
(g kg-1)
                 LE        RE        LE       RE       LE       RE

0                0.75a *   0.78a     0.78a    0.76a    0.64a    0.66a
5                0.69a     0.77a     0.68ab   0.72a    0.62a    0.62a
10               0.73a     0.68ab    0.71a    0.74a    0.55b    0.63a
20               0.78a     0.73a     0.72a    0.68ab   0.60a    0.62a
30               0.58b     0.61b     0.66ab   0.56b    0.57ab   0.64a
40               0.67ab    0.71a     0.62b    0.61b    0.60a    0.54b
50               0.66ab    0.72a     0.68ab   0.65b    0.55b    0.55b

Concentration    F. vulgare        P. ovata           P. Psyllium
(g kg-1)
                 LE       RE       LE        RE       LE       RE

0                0.72a    0.70a    1.81a     1.78a    1.78a    1.81a
5                0.68a    0.72a    1.72a     1.76a    1.68a    1.76a
10               0.66a    0.66a    1.70a     1.68a    1.66a    1.77a
20               0.68a    0.64a    1.62ab    1.71a    1.57b    1.69a
30               0.62b    0.64a    1.66a     1.66a    1.58b    1.67a
40               0.58b    0.59b    1.58b     1.55b    1.47b    1.61b
50               0.56b    0.58b    1.60ab    1.57b    1.52b    1.51b

* Values followed by the same letter within the same columns do not
differ significantly at P = 5% according to DMRT.

Table 6: Influence of Johnson grass residue incorporation on
germination, plant height, shoot dry weight and root dry weight of
Plantago ovata and Nigella sativa 20 day after sowing.

Residue          Emergence (%)           Shoot length (mm)
(g kg-1 soil)
                 P. ovata    N. sativa   P. ovata    N. sativa

0                0 52.8a     41.2a       21.2a       25.0a
5                5 58.5a     38.5b       16.4b       18.7b
10               10 21.0b    19.3c       14.8b       16.9b
20               20 7.8c     9.2d        12.2b       17.2b
30               30 2.7d     7.8d        9.9c        14.1c

Residue          Shoot dry weight        Root dry weight
(g kg-1 soil)    (g per plant)           (g per plant)
                 P. ovata    N. sativa   P. ovata    N. sativa

0                0.21a       0.34a       0.15a       0.29a
5                0.20a       0.28b       0.14a       0.26a
10               0.16b       0.22c       0.10b       0.22b
20               0.10c       0.23c       0.09b       0.22b
30               0.08c       0.16d       0.06c       0.18c

* Values followed by the same letter within the same columns do not
differ significantly at P = 5% according to DMRT.
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Title Annotation:Original Article
Author:Asgharipour, Mohammad R.; Armin, Mohammad
Publication:Advances in Environmental Biology
Article Type:Report
Geographic Code:1USA
Date:May 1, 2010
Words:5918
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