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Allelopathic effect of almond on cress and fenugreek

Ali Reza Astaraei

Department of Soil Science - Collage of Agriculture Ferdowsi University of Mashhad, http://www.ferdowsi.um.ac.ir
Email astaraei@ferdowsi.um.ac.ir

Abstract

Two laboratory and pot experiments were conducted to study the allelopathic effect of almond plant components on cress and fenugreek. For laboratory study, three different concentrations of 0.5, 1.0 and 2.0%(V/V) each with three replications were prepared from the original water-extracts of leaf, bark and leaf-bark mixture and germination bioassays of tested garden vegetables were conducted in petri dish. For pot study, three different levels of 0, l.0 and 2.0% (W/W) from each almond leaf and bark were incorporated into soil, each with three replications. Results of bioassays showed that lowest germination of cress and fenugreek seeds were observed in leaf-bark mixture. In case of radicle length barks were the most phytotoxic for both cress and fenugreek. Significant reductions in germination and radicle length of cress and fenugreek were observed with increasing concentration of extracts. In pot study, the lowest germination observed in almond barks. Dry matter production (DMP) of cress and fenugreek were found minimum in almond barks. Significant reduction in germination, crop length and DMP were observed with increasing concentration of extracts.

Media summery

The results suggest that almond barks and leaves are phytotoxic components and 0.5% and 1.0% concentrations are the threshold concentrations, exhibiting significant inhibitory impacts on cress and fenugreek.

Key Words

Prunus dulcis, aqueous extracts, Lepidium sativum, Trigonella foenum

Introduction

Almond production in Iran is about 100000t, being second after Syria in Asia and with sharing 8% ranks fourth in the world. It is grown in 25 provinces, at a 28-39 latitude, and 400-2500 m above sea levels (Rahemi2002). In Khorasan province, almond plantations under irrigated and non-irrigated are estimated as 1575 and 17212 ha of adult yielding trees and 1345 and 4786 ha of young trees respectively. Plants belonging to Rosaceae species. including almond, peach, apricot, etc. contain up to 3% amygdaline in flowers, leaves and barks that on hydrolysis produce glucose, benzaldehyde and hydrogen cyanide as toxins. Proebsting concluded that benzaldehyde had a little effect, but potassium cyanide caused severe injury to the peach seedlings (Proebsting 1950). Patrick (1971) found that micro-organisms are responsible for hydrolyzing amygdaline and concluded that the inhibition increased with increasing amounts of residue and with increasing time of incubation up to 3 to 4 days. Experiments on the effects of benzaldehyde and cyanide on respiration showed that combination of amygdaline and emulsion markedly inhibited roots’ respiration and calcium cyanide added proved very inhibitory to respiration. Benzaldehyde in water greatly reduced respiration in roots. Ward and Durkee (1956) found that the amygdalin concentration in roots and leaves were highest, whereas, the stems had the lowest concentration. They concluded that, the peach roots had their maximum concentration in the spring, whereas, the tops has their highest concentration in the fall. Hydrolyzable tannins are sugar esters of gallic acid or of gallic and hexaoxydiphenic acid (Robinson 1983) that inhibit the growth and germination of several dry fruits, reduces seedling growth of Carpinus betulus (Mitin 1970). Plant residues having hydrolyzable tannins often contain gallic or ellagic acid, or both and sometimes digallic acid, all of them are phytotoxins and have inhibitory effects (Rice 1983., Rice and Pancholy 1973). Zamani et al. (2002) found that the proline content of almond seedling increased with increasing the water stress. Since organic acids are important as organic osmoregulatory solutes in cells of some Rosaceae, Chenopodaceae and many other species of salt and water stress resistant, they are producing the various allelopathic agents (Rice and Pancholy 1973).

Methods

Laboratory study

Leaf, bark and leaf-bark mixture (50:50w/w) were ground in a grinder and sieved through a 2mm sieve. For extracts preparation, 20g ground leaves, barks and leaf-bark mixture were soaked in 100 ml distilled water at room temperature (30C) for 36 hr. the extracts were filtered through muslin cloth, Whatman filter paper No. 1 and then centrifuged at 3000 rpm for 20 min. Extracts of 0.5, 1.0, and 2.0%(V/V) were prepared by diluting of each original solutions. Germination bioassays were conducted in 10100 mm petri dish (PD) following the techniques proposed by Li et al.(1992). In each PD, 25 seeds of any tested garden vegetables (cress and fenugreek) were placed between 2 filter papers, 3 ml each of extracts or distilled water as control was added per PD on the first day. Thereafter, extract or distilled water was applied as needed. Petri dishes were incubated at 20C for 10 days, seed germination (%), radicle and plumule lengths were recorded at the end of experiment. Seeds with the radicles of at least 2mm were counted as germinated. Germination bioassays were conducted in completely randomized design (factorial) where each treatment was replicated three times.

Pot study

A loamy soil (0-15cm) collected from field was used in pot study. Soil of each pot were thoroughly mixed with each levels of 0, 1.0, 2.0 %(w/w) of ground leaves and barks, each treatment with three replications. All pots were irrigated to have just optimum moisture and kept for 10 days at 25C and watering was done as needed. On the 11th day, 20 seeds of each test crops (cress and fenugreek) were sown in each pot as per the treatment schedule and watering was done during the experiment. 10 days after sowing (DAS) germination (%) and 30 DAS, crop length and dry matter production (DMP) of 10 remaining plants after thinning per pot were recorded.

The data obtained were analyzed as a completely randomized design (factorial) by using MStatC, and treatment means were compared, using Duncans Multiple Range Test at p=0.05.

Results

Extract bioassay

Water-extracts of leaf-bark mixture and bark exhibited maximum inhibitory effects on of seed germination cress (-85%) and fenugreek (-82%) respectively, compared to their controls (Table1 and Table 2). Leaf, bark and leaf-bark mixture extracts did not significantly reduced seed germination of cress when compared to each other, whereas, in case of fenugreek, no significant difference observed between bark and leaf-bark mixture extracts.

Radicle length of cress and fenugreek decreased significantly with water-extract of bark with 87 % and 55% reductions respectively, when compared to their controls. Lowest radicle length of cress and fenugreek was noted in water-extract of bark when compared to the other treatments (Table1 and Table 2).

All water-extracts of leaf, bark and leaf +bark exhibited maximum inhibitory effects on both cress and fenugreek plumule lengths, therefore, no results obtained.

All water-extract concentrations significantly reduced germination and radicle length of both cress and fenugreek test crops. Maximum inhibitory effect of water-extract concentration on germination and radicle length of cress noted at 2% level with 94.5 % and 95% reductions when compared to their controls, whereas, in case of fenugreek, at the same concentration level the reductions were 83% and 66.8% respectively (data not shown).

The interaction effect of different treatments having different concentrations on cress and fenugreek indicated highest reduction in germination of cress at 0.5% concentration in water-extracts of bark (-72.0%) and leaf + bark (-78%), whereas, water-extract of bark at 0.5% concentration resulted in 79% reduction of radicle length, when compared to their controls (Table1). Water-extracts of bark and leaf + bark at 0.5% concentration level exhibited highest reductions in germination (-75%, -67.0%) and radicle length (-42%,-36%) of fenugreek when compared to their controls (Table2).

Residue bioassay

In pot study the lowest seed germination observed in bark residue treatment with 34% (cress) and 68% (fenugreek) reductions, when compared to their controls (Table3 and Table 4). Maximum reduction in crop length also noted with this treatment too. Maximum inhibitory effect of decomposing bark residues in soil noted for dry matter production (DMP) of cress (-85%) and fenugreek (-72%) when compared to their controls (Table 3 and Table 4).

All test concentrations of incorporated residues into soil significantly inhibited germination, crop length and DMP of both cress and fenugreek. The maximum inhibition noted at 2 % concentration level on germination (-36%), crop length (-38.5 %), DMP (-41%) of cress, whereas, for fenugreek at the same concentration level the reductions were 77%, 59% and 87% respectively when compared to their controls (data not shown).

The interaction effect of different treatments with different concentrations on cress showed that the inhibition of incorporated bark residues into soil was more stronger at 1% concentration level for germination (-43%), but for crop length and DMP proved to be at 0.5% level with 57% and 90% reductions respectively (Table 3). Whereas, in case of fenugreek the strongest inhibitory effect of bark residue treatment noted at 0.5% concentration level for germination (-58%), crop length (-32%) and DMP (-61%) when compared to their controls respectively (Table 4). The inhibitory activity of water-extracts of almond residues clearly indicates that the extracts contain water soluble phytotoxins that may release easily during decomposition of almond residues in soil even at relatively small amounts in soil, causing a significant reduction in germination and seedling growth of test crops indicating obvious evidences of allelopathic effects that have been reported and well documented (Proebsting 1950, Ward and Durkee 1956, Patrick 1971, Rice and Pancholy 1973, Rice 1983, Robinson 1983). There are reports that the phytotoxic activities of decomposing residues of many species appear during the early decomposition periods (Narval et al. 1997, Sivagurunathan et al. 1997,Alsaadawi et al. 1998). Several researches indicated the phytotoxic activities of different parts of woody plants on cress and fenugreek (Elakovich and Wooten 1995).

Table1: Interaction effect of different plant water extracts with various concentrations on cress crop

Treatment

Conc.(%)

Germination (%)

Mean (%)

Radicle length (mm)

Mean (mm)

leaf

0.5

26.7

b

13.3 b

6.3

bc

3.8 c

1

10

cd

5

d

2

3.3

d

0

f

Bark

0.5

16.7

c

11.1 b

5.5

d

3.3 d

1

13.3

c

4.3

e

2

3.3

d

0

f

Leaf + Bark

0.5

13

c

8.9 b

6.8

b

5.7 b

1

10

cd

6.1

c

2

3.3

d

4.2

e

Control

 

60

a

60 a

26

a

26 a

Values in the same column followed by the same letters are not significantly different according to DMRT (at p= 0.05)

Table2: Interaction effect of different plant water extracts with various concentrations on fenugreek crop

Treatment

Conc. (%)

Germination (%)

Mean (%)

Radicle length (mm)

Mean (mm)

leaf

0.5

46.7

b

35.6b

23.7

a

17.5b

1

36.7

c

18.3

b

2

23.3

d

10.6

e

Bark

0.5

20

de

14.4c

14.4

cd

11.3c

1

13.3

ef

12.2

de

2

10

f

7.3

f

Leaf + Bark

0.5

26.7

d

17.8c

16.1

bc

12.1c

1

20

de

13.1

de

2

6.7

f

7

f

Control

 

80

a

80a

25

a

25a

Values in the same column followed by the same letters are not significantly different according to DMRT (at p= 0.05)

Table3: Interaction effect of different plant residues with various concentrations in soil on cress crop

Treatment

Conc. (%)

Germination (%)

Mean (%)

Crop length

Mean (cm)

Dry matter (mg)

Mean (mg)

leaf

0.5

70

a

65.3a

43.1

a

36.0a

149.8

a

142.5a

1

70

a

35.8

b

153.2

a

2

56

a

30.3

c

124.5

b

Bark

0.5

66.7

a

46.6b

21.9

d

16.0b

29.5

c

17.5b

1

40

b

14.9

e

11.5

c

2

33.3

b

12.2

e

11.5

c

Control

 

70

a

70a

34.6

b

35.0a

114.6

b

114.6a

Values in the same column followed by the same letters are not significantly different according to DMRT (at p= 0.05)

Table4: Interaction effect of different plant residues with various concentrations in soil on fenugreek crop

Treatment

Conc. (%)

Germination (%)

Mean (%)

Crop length

Mean (cm)

Dry matter (mg)

Mean (mg)

leaf

0.5

46.7

b

35.6b

35.9

b

31.1b

118.1

b

83.7b

1

36.7

bc

34.5

b

98.3

c

2

23.3

de

22.8

c

34.6

e

Bark

0.5

33.3

cd

25.5c

36

b

30.7b

97

c

68.5c

1

30

cd

35.5

b

81.2

d

2

13.3

e

20.7

c

27.3

e

Control

 

80

a

80.0a

53.2

a

53.2a

246

a

246a

Values in the same column followed by the same letters are not significantly different according to DMRT (at p= 0.05)

Conclusion

The results clearly demonstrated that decomposing almond residues in soil release phytotoxins and the amount of these phytotoxins reach maximum at 10 days after decomposition to be high enough to cause inhibitory effects on test crops germination and continued to cause a significant reductions on DMP of tested crops.

References

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Elakovich SD and Wooten JW (1995). Allelopathic woody plants, part I: Abies alba through lyonia Lucida. Allelopathy Journal 2, 117-146.

Li HH, Nishimura H, Hassegawa K and Mizutani J (1992). Allelopathy of Sasa cernua. Journal of Chemical Ecology 18, 1785-1796.

Mitin VV(1970). On study of chemical nature of growth inhibitors in the dead leaves of horn bean and beech. In ‘Physiological – Biochemical Basis of Plant Interactions in Phytocenoses’. (Ed. AM. Grodzinsky), vol2. pp. 177-181. Naukova Dumka, Kiev.

Narval SS, Sarmah MK and Nandal DPS(1997). Allelopathic effects of wheat residues on growth and yield of fodder crops. Allelopathy Journal 4,111-120.

Patrick ZA(1971). Phytotoxic substances associated with the decomposition in soil of plant residues. Soil Science 111,13-18.

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Rahemi AR (2002). The development of almond orchards in Iran. Acta Horticulturae 591, 177-181.

Rice EL (1983). Allelopathy 2nd Ed. Academic Press. New York.

Rice EL and Pancholy SK (1973). Inhibition of nitrification by climax ecosystem. II. Additional evidence and possible role of tannins. American Journal of Botany. 60, 691-702.

Robinson T (1983). The organic constituents of higher plants, 5th Ed. Cordus Press. North Amberst, Massachusetts.

Ward GM and Durkee AB (1956). The peach replant problem in Ontario. III. Amygdaline content of peach tree tissues. Canadian Journal of Botany. 34, 419-422.

Sivagurunathan M, Sumithra Devi G and Ramasamy K (1997). Allelopathic compounds in eucalyptus spp- Allelopathy Journal 4,313-320.

Zammani Z, Taheri A and Vezvaei A (2002). Proline content and stomata resistance of almond seedlings as affected by irrigation intervals. Acta Horticulturae 591, 411-417.

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