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Effect of extracts of Persian and Berseem clover on peroxidase activity of field bindweed (Convolvulus arvensis) hypocotyl

Fariba Maighany1, Mahlagha Ghorbanli2 and Morteza Najafpoor3

1Plant Pests and Diseases Research Institute, Tehran, IRAN
2
Faculty of Science, Tarbiat Moallem University, Tehran, IRAN, Email fmaighany@yahoo.com

Abstract

The objective of this study was to determine if Berseem clover (Trifolium alexandrinum L.) and Persian clovers (Trifolium alexandrinum L.) contained water-soluble constituents that affect peroxidase activity in hypocotyls of seedlings of Convolvulus arvensis L. (field bindweed). Because field bindweed is one of the most important weeds in Iran and we have problem for its control. Residues and extracts of several cover crops have been found to cause allelopathic suppression of certain weed species. Many cover crops, such as clover (Trifolium L. spp.), contain secondary plant products that have allelopathic potential, but only a limited number of studies have been conducted to investigate the effect of these chemicals on peroxidase activityAbove ground tissue of Persian and Berseem clover was collected during flowering stage, dried at 50C, and extracted with water for 12 hrs. Three concentrations of aqueous extracts were used: full-strength (33.3 g/L), half-strength (16.7 g/L), and quarter-strength (8.3 g/L). The effects of these extracts on peroxidase activity in hypocotyls of field bindweed seedlings were studied. In general, hypocotyl peroxidase activity increased with increasing concentrations of Berseem clover extracts. In contrast, the effect of Persian clover aqueous extract on the activity of this enzyme was not significant. It is concluded that the presence of clover allelochemicals in the environment cause plant stress, because these chemicals, like other environmental stresses, could induce peroxidase activity in field bindweed. On the other hand, compared with Persian clover, Berseem clover might contain higher amounts of water-soluble allelochemicals, because caused of the significant incerase in peroxidase activity.

Media summary

Persian and Berseem clovers contain water-soluble constituents that affect peroxidase activity of Convolvulus arvensis. Berseem clover extracts caused a more pronounced incerase in peroxidase activity than Persian clover extracts.

Keywords

Allelochemical, clover, field bindweed, peroxidase activity, Trifolium spp.

Introduction

The use of cover crops has become an important part of agricultural practices to reduce soil and water losses and to suppress weeds. Cover crops can suppress weeds in several ways: Allelopathy caused by leaching or exudation of allelochemicals from the cover crop or ots residues; immobilization of nitrogen during decomposition of the cover crop debris; physical barriers and shading associated with debris; changes in physical factors of the soil such as temperature, pH, water holding capacity, and aeration, and competition for resourse, especially light. It appears that no single factor is solely responsible, but rather several or all of these factors interact to produce the observed effects in a cover crop system (White et al. 1989). Numerous authors have considered the role of cover crops as a component of integrated weed management. (Qasem, 1995).

Many cover crops, such as clover (Trifolium L. spp.) contain secondary plant products that have allelopathic potential (Challa and Ravindra, 1995; Lehman and Blum, 1997), but only a limited number of studies have been conducted to investigate the effect of these chemicals on peroxidase activity. When plants are subjected to environmental stresses including allelochemicals, different enzymes of the antioxidant enzymes are involved in response to this stresss. One of the most important of these enzymes is peroxidase. The objective of this study was to determine if Berseem and Persian clovers contained water-soluble constituents that affect peroxidase activity of Convolvulus arvensis L.

Methods

Preparation of aqueous extracts of cover crops

Above ground tissue of Persian and Berseem clover that was irrigated twice a week, from Karaj Field was collected during flowering and dried at 50C for 72 hr. Five gram of dried tissue was added to 150 ml of distilled water and agitated for 12 hrs. Three concentrations of aqueous extracts were used: full-strength (33.3 g/L), half-strength (16.7 g/L), and quarter-strength (8.3 g/L).

Field bindweed seeds were surface sterilized for 1 min in a 50 % sodium hypochlorite solution, rinsed with running tap water for 10 min, and air dried. 25 seeds were placed in Petri dishes that contained 10 ml of the clovers aqueous extract, or distilled water (control). The perti dishes were placed in a non illuminated incubator at 27C (White et al. 1989). The effects of these extracts on peroxidase activity of the hypocotyl of field bindweed seedlings was studied after 3 weeks.

Peroxidase activity measurement

In order to compare changes in peroxidase activity between different concentrations of aqueous extracts of clovers, extraction of foliar protein was done using a Tris-HCl extraction buffer (pH 7.5, 0.05 M) at -4C. The kinetic activity of peroxidase was measured according to Gomori (1955) using a spectrophotometer at 530 nm.

Statistical analysis

The activity of peroxidase was analyzed with 3 replicates by an analysis of variance with Duncan Multiple Range Test (DMRT) at probability level 0.05.

Results

Peroxidase activity of the hypocotyls of field bindweed seedlings increased as the concentration of the aqueous extract of Berseem clover increased (Fig. 1). At full-, half-, and quarter-strength it was increased to by 1.6, 1.2, and 1.1, compared to the untreated water control. However, the difference between half- and quarter- strengthes was not significant. The effect of different concentrations of Persian clover aqueous extracts on peroxidase activity of field bindweed seedlings was not significant (Fig. 2).

Figure 1. Effect of Beerseem clover aqueous extracts on peroxidase activity of field bindweed seedlings hypocotyl.

Figure 2. Effect of Persian clover aqueous extracts on peroxidase activity of field bindweed seedling hypocotyl.

Conclusion

In spite of the fact that plant peroxidase has been studied by many workers, their physiological functions are only partially understood (Abeles et al. 1988). In the present study, the effect of clover aqueous extracts on the activity of hypocotyl peroxidase varied depending on clover species and the concentration of aqueous extract. It is concluded that the presence of clover allelochemicals in the environment is a plant stress factor, because these chemicals, like other environmental stresses, could induce peroxidase activity in field bindweed. On the other hand, it seemed that compared with Persian clover, Berseem clover extracts could have contained more allelochemicals, because its extracts caused a higher increase in peroxidase activity.

References

Abeles FB, Morgens DP, Callahan A, Dinterman RE, Schmidt J (1988) Induction of 33-KD and 60-KD peroxidases during ethylene-induced senescence of Cucumber cotyledons. Plant Physiology 87, 609-615.

Challa P, Ravindra V (1998) Allelopathic effects of major weeds on vegetable crops. Allelopathy Journal 5, 89-92.

Gomori G (1955) Preparation of buffers for use in enzyme studies. Methods in Enzymology 1, 138-146

Lehman ME, Blum U (1997) Cover crop debris effects on weed emergence as modified by environmental factors. Allelopathy Journal 4, 69-88.

Qasem JR (1995) Allelopathic effects of Amaranthus retroflexus and chenopodium murale on vegetable crops. Allelopathy Journal 2, 49-66.

White RH, Worsham AD, Blum U (1989) Allelopathy potential of legume debris and aqueous extracts. Weed Science 37, 674-679.

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