Previous PageTable Of ContentsNext Page

Allelopathic effects of saffron corms on germination of several important crops

Forugh Abbassi

Department of Biology, Islamic Azad University of Mashad, Iran. Email: forugh_abbassi@yahoo.com

Abstract

Saffron is an important cash crop in south Khorasan province of Iran. This is a perennial crop with longevity up to 12 years but the plantations start to thin out after 5-6 years, therefore the economic yield reduces. The aim of present study was to evaluate the allelopathic effects of saffron corm on seed germination of several important crops. For this purpose water extracts of dried powder of corm (corms from 4- and 14- year-old plantations) were used towards different seeds. Treatments were 0 (distilled water), 0.5, 1 and 3% water extracts of corms. These extracts were used on seeds of important crop species such as barley (Hordeum vulgaris), wheat (Triticum sativus), corn (Zea mays), canola (Brassica napus), cotton (Gossypium hirsutum), and soybean (Glycine max). Results indicated allelopathic effects but the magnitude for each species and the various germination indices were different. Radicle length was more affected than other parameters.

Media Summary

The allelopathic effects of saffron corm on several crop plants was investigated. There were allelopathic effects with radicle length being most affected.

Key words

Allelopathy, saffron, germination, crops.

Introduction

The germination of seeds under field conditions is often influenced by the presence of other plants. This interference arises from allelopathy (Rice, 1984). Allelopathy is an important mechanism of plant mediated by the release of plant produced phytotoxins to the plant environment. Soil sickness problem in crop growing could also be attributed to the allelopathic effects or even the autotoxicity (Singh et al. 2002). The toxicity of allelochemicals released in the environment is the function of their concentration as well as age and metabolic stage of the donor-plant (Rice 1984; Wardle et al. 1993). Saffron (Crocus sativus L.) is a perennial plant with succulent corm, belonging to Iridaceae family. Saffron is considered to be the most expensive spice in the world. The flower of saffron is a light purple, with thread-like reddish coloured stigma that is valued both as a spice and as a natural dye. Saffron is a perennial crop with longevity more than 12 years, but farmers have actually understood that after several years of growing saffron in same field, the plantations start to thin out after 5-6 years, therefore after about 7 years the economic yields start to reduce. Furthermore in dry areas such as Iran which water is the most limiting factor for crop production, the main challenge is to increase production by operating proper method of irrigation and efficient use of water and other resources. Mix cropping is one of the methods used to increase efficiency of resource use. This is only possible if there are no allelopathic interactions between crops. Saffron could be intercropped with many crops provided possible allelopathic effect would be considered (Beheshti and Faravani 2003). Thus the purpose of the present study was to check the allelopathic activity of saffron corms on germination of some species which could be used as intercrops or in crop rotation system.

Methods

Study of the allelopathic effects of water extracts from saffron corms from 4- and 14-year-old plantations on germination of barley (Hordeum vulgare), wheat (Triticum sativum), canola (Brassica napus), cotton (Gossypium hirsutum), corn (Zea mays) and soybean (Glycine max) was conducted under lab conditions in a completely randomized design with factorial arrangement and in four replications. The corms were thoroughly washed, dried at 75C and grounded (0.5 mm). Water extracts of grounded corms were prepared according to Narwal (1996). Treatments containing corm extracts in different concentrations: 0 (distilled water - control), 0.5, 1 and 3%. The extracts were deposited on Petri dishes with 25 seeds of six different species. After ten days the percentage and rate of germination, and plumule and radicle length as well as dry and fresh weight of seedlings were measured. Statistical analysis of the results was carried out by MSTATC software. Duncan Multiple Range Test (DMRT) for comparison of means was used.

Results and discussion

Table 1 shows that water extract of corms from both plantations did not significantly affect dry weight, percentage and rate of germination of barley, but significantly reduced plumule length at 3% concentration for corms from 14-year-old plantation. The results also showed that with increasing extract concentration, radicle length and fresh weight of seedlings were decreased.

Note the following pertains to the 6 tables below %G: % Germination; GR: Germination Rate; PL: Plumule Length; Rl: Radicle Length; DW: Dry Weight; FW: Fresh Weight.

*Values with same letters in every column there are not significantly different.

Table 1. Allelopathic effects of saffron corms on seed germination of barley.

year

Concentration
(%)

%G

GR

PL
(cm)

RL
(cm)

DW
(g)

FW
(g)

               
 

0

61a*

36.08a

3.2 a

8.46a

0.030a

0.245 a

 

0.5

52a

29.78a

2.53ab

3.28bc

0.029a

0.115 b

4

1

57a

26.00a

2.73ab

3.10bc

0.030a

0.147 b

 

3

57a

31.03a

2.53ab

2.27 c

0.033a

0.180 ab

               
 

0

61a

36.08a

3.20 a

8.46 a

0.03oa

0.245 a

 

0.5

57a

29.23a

3.23a

4.54 b

0.032a

0.180 ab

14

1

59 a

32.41a

2.41ab

2.85bc

0.034a

0.150 b

 

3

43a

25.87a

2.33 b

2.88bc

0.030a

0.110 b

Percentage of germination and dry weight of wheat seedlings was not suppressed by any of the extracts (Table 2). Germination rate, plumule and radicle length and fresh weight of wheat seedlings were affected by extract at different concentrations of corms from both plantations. At 1% concentration, germination rate and seedling growth were stimulated, whereas their fresh weight at 3% extract of corms from 4-year-old plantation was reduced, while at 1% concentration of extract of corms from 14-year-old plantation was stimulated.

Table 2. Allelopathic effects of saffron corms on seed germination of wheat.

year

Concentration
(%)

%G

GR

PL
(cm)

RL
(cm)

DW
(g)

FW
(g)

 

0

99.00a*

89.00bc

2.88 b

5.06ab

0.037a

0.145 bc

4

0.5

96.00a

94.08ab

4.02 a

6.47 a

0.034a

0.185abc

 

1

99.00a

96.50 a

3.24ab

4.86ab

0.035a

0.193 ab

 

3

90.00a

84.83ab

3.20ab

2.68 b

0.034a

0.134 c

               
 

0

99.00a

89.00bc

2.88 b

5.11ab

0.036a

0.145 bc

14

0.5

97.00a

95.00ab

3.38ab

6.61 a

0.035a

0.185abc

 

1

97.00a

94.00ab

3.38ab

5.98ab

0.037a

0.197 a

 

3

100.0a

92.53a

2.88ab

2.88 b

0.038a

0.164abc

Table 3 shows that except for dry weight, other germination indices of corn were affected by water extracts of saffron corms.

Table 4 indicates that there was no significant effect of different concentrations of extracts of corms from both plantations on germination rate, radicle length, dry and fresh weight of soybean, whereas germination and plumule length were stimulated.

Table 5 shows that extracts at different concentrations of corms from both plantations reduced radicle length of canola only slightly. However, different extracts did not significantly affect other indices of canola germination.

Table 6 shows that there was no significant reduction in dry and fresh weight and plumule and radicle length of cotton. Whereas 0.5% extract of corm from 4-year plantation and 1% extract from 14-year plantation reduced percentage of germination. As well the rate of germination was significantly reduced by 0.5% extracts of corms from both plantations.

Table 3. Allelopathic effects of saffron corms on seed germination of corn.

year

Concentration (%)

%G

GR

PL
(cm)

RL
(cm)

DW
(g)

FW
(g)

 

0

65.00 a*

20.85a

3.27 a

5.08a

0.367a

0.597ab

4

0.5

59.00 ab

16.79ab

2.25ab

4.67a

0.197a

0.557ab

 

1

42.00 bc

11.59 c

2.05 b

2.93 b

0.405a

0.445 b

 

3

48.00abc

12.58bc

2.42ab

2.37 b

0.545a

1.368 a

               
 

0

65.00 a

20.86 a

3.27 a

5.08 a

0.367a

0.597 ab

14

0.5

53.00abc

14.82bc

2.30ab

2.21 b

0.282a

1.140 ab

 

1

37.00 c

10.01 c

3.02ab

2.56b

0.365a

0.462 b

 

3

49.00abc

13.28bc

2.39ab

2.24 b

0.232a

0.442 b

Table 4. Allelopathic effects of saffron corms on seed germination of soybean.

year

Concentration
(%)

%G

GR

PL
(cm)

RL
(cm)

DW
(g)

FW
(g)

 

0

9.00 b*

5.74 a

2.06 b

3.42a

0.088a

0.109a

4

0.5

15.00ab

5.31 a

2.27 b

3.14a

0.091a

0.093a

 

1

18.00ab

6.99 a

3.22ab

2.48a

0.094a

0.061a

 

3

15.00ab

5.08 a

4.12 a

1.87a

0.071a

0.074a

               
 

0

9.00 b

5.74 a

2.06 b

3.49a

0.088a

0.109a

14

0.5

22.00ab

9.21 a

1.95b

2.58a

0.088a

0.159a

 

1

25.00 a

6.21 a

3.34ab

2.96a

0.090a

0.058a

 

3

18.00ab

6.66 a

2.28 b

2.87a

0.074a

0.110a

Table 5. Allelopathic effects of saffron corms on seed germination of canola.

year

Concentration
(%)

%G

GR

PL
(cm)

RL
(cm)

DW
(g)

FW
(g)

               
 

0

88.00a*

31.41a

3.10 a

3.94 a

0.005 a

0.280 a

4

0.5

86.00a

28.25ab

3.13 a

2.50 ab

0.003 a

0.028 a

 

1

80.00a

29.24a

2.49ab

2.80ab

0.003a

0.030 a

 

3

88.00a

31.00a

3.007a

2.11 b

0.003 a

0.021 a

               
 

0

88.00a

31.41a

3.10 a

3.94 a

0.005 a

0.280 a

14

0.5

83.00a

29.38a

2.45ab

2.24 b

0.003 a

0.039 a

 

1

73.00a

22.59b

1.92 b

2.20 b

0.005 a

0.027 a

 

3

75.00a

30.21a

3.18 a

2.05 b

0.003 a

0.021 a

Table 6. Allelopathic effects of saffron corms on seed germination of cotton.

year

Concentration
(%)

%G

GR

PL
(cm)

RL
(cm)

DW
(g)

FW
(g)

               
 

0

63.00a*

16.88 a

1.80 b

2.74a

0.226ab

0.489ab

4

0.5

14.00 b

3.307 c

2.35ab

1.51 b

0.075 b

0.448ab

 

1

14.00 b

4.148 c

3.83 a

2.08 ab

0.178ab

0.382ab

 

3

18.00 b

4.345 c

1.83 b

2.58 a

0.248ab

0.645 a

               
 

0

63.00 a

16.88a

1.80 b

2.74 a

0.226ab

0.489ab

14

0.5

47.00 a

11.23 b

2.35ab

2.26 ab

0.177ab

0.328ab

 

1

27.00 b

7.707bc

1.86 b

2.53 a

0.088 b

0.299ab

 

3

26.00 b

7.380bc

1.90 b

2.29 ab

0.448a

0.220 b

In this experiment, the water extracts of saffron corms induced allelopathic effects on germination of tested species. Previous reports indicate the ability of some plants to affect the germination and growth of other plants (Putnam 1994). In agricultural crop production the main concern has usually been the effect of toxins from one crop on the yield of next crop (Francis 1986). But in the literature there is are detailed reports on allelopathic effects of saffron corm on germination or growth of next crops (Farhoodi et al. 2003).

In this study, no significant effect of extracts at different concentrations for corms from 4- and 14-year plantations on percentage and rate of germination of barley, wheat, soybean and canola were observed, but these indices in corn and cotton were reduced.

Mostly in all tested species with increasing concentrations of extracts (from 4- and 14-year plantations), radicle length was reduced more than other germination indices. Moreover all germination indices of cotton were reduced more than other species especially in extracts of corms from 4-year plantation. Whereas, certain of germination indices of wheat were slightly increased in comparison with others crops, particularly at low extract concentrations. However, Hosseini and Rizvi (2003) reported that at higher concentration of water extract from saffron corms (20%) the percentage and rate of germination of wheat as well as its dry weight of radicle and plumule were strongly reduced.

Conclusion

There were some allelopathic effects of saffron corms on germination of all tested species except wheat, but this effect was more pronounced for cotton and soybean. Although there is strong evidence for allelopathic effects of some plants on others (Rice 1984, Putnam 1994, Moyer and Huang 1997), these effects have not, until now, been investigated for bulb plants such as saffron or other similar crops.

References

Beheshti, S.A. and M. Faravani (2003) The effect of different plant density and plant rates on yield of saffron (Crocus sativus) and black zira (Bunium persicam) in intercropping system. Third National Symposium on Saffron, Iran. P: 29-33.

Farhoodi, R; A. Rahnema and H. Esmail Zade (2003) The situation of saffron in mix cropping Third National Symposium on Saffron, Iran. P: 173-178.

Francis, C.A. (1986) Biological efficiencies in multiple cropping systems. Advances in Agronomy. 42: 1-41.

Hosseini, M. and S.J.H. Rizvi (2003) A preliminary investigation on possible role of allelopathy in saffron (Crocus sativus L.) Third National Symposium on Saffron, Iran. P: 133-138.

Moyer, J.R. and H.C. Haung (1997) Effects of aqueous extracts of crop residues on germination and seedling growth of ten weed species. Botanical Bulletin Academe. Sinica 38: 131-139.

Narwal S.S. (1996) Suggested methodology for allelopathy field observations and methodology (Eds) S.S Narwal and P. Tauro. Scientific Publishers. Jodhpur. P: 255-266.

Putnam, A.R. (1994) Phytotoxicity of plant residues. In P.W. Unger (Ed). Managing Agricultural Residues. Lewis Publishers, Boca Raton. PP: 285-314.

Rice, E.L. (1984) Allelopathy. 2nd edition. Orlando, Florida: Academic Press In. P: 422.

Singh, H.P; D.R. Batish, and R.K. Kohli (1999) Autotoxicity: Concept, organisms and ecological significance. Critical Reviews in Plant Sciences. 18: 757-772.

Wardle, D.A; K.S. Nicholson and A. Rahman (1993) Influence of plant age on the allelopathic potential of nodding thistle (Cardus nutans L.) against pasture grasses and legumes. Weed Research. 33: 69-78.

Previous PageTop Of PageNext Page