Previous PageTable Of ContentsNext Page

Screening of allelopathic wheat varieties from Chinese germplasm collection

Xiaoke Zhang1,2, Wenju Liang1, Chuihua Kong1, Yong Jiang1, Peng Wang1

1 Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China, www.iae.ac.cn Email: liangwj@iae.ac.cn
2
Graduate School of the Chinese Academy of Sciences, Beijing 100039, China

Abstract

Twenty-seven local wheat (Triticum aestivum L.) varieties with different origins and agronomic traits from a Chinese wheat germplasm collection were selected to evaluate their allelopathic potential against lambsquarters (Chenopodium album L.) and redroot amaranth (Amaranthus retroflexus L.) that cause damage to wheat production in China. Six varieties were found to demonstrate obvious allelopathic potential using pot culture and equal-compartment-agar methods. Root growth of test weeds C. album and A. retroflexus were significantly inhibited by these allelopathic wheat varieties. Results suggested that allelopathic potential of wheat germplasm might be evaluated by a combination of multiple methods. RI (response index) could be an effective parameter to evaluate allelopathic potential of different wheat varieties.

Media summary

The allelopathic potential of twenty-seven local wheat varieties from a Chinese germplasm collection was evaluated by a combination of multiple methods.

Key Words

Allelopathic wheat variety, Chinese wheat germplasm, weed control

Introduction

Weeds impose an important biological constraint to wheat production worldwide. In China, lambsquarters (Chenopodium album L.) and redroot amaranth (Amaranthus retroflexus L.) are widespread weeds in wheat field and substantially reduce wheat yield. Their control has been characterized by hand and high dose of herbicides. It is desirable to have alternative weed control method in wheat fields. Application of allelopathy to control weeds can avoid environmental contamination and improve crop yield. Allelopathic control refers to the eco-friendly method that exploits allelochemicals from volatile, leachate, exudates or residues of certain plant to control weeds (Weston 1996).

In recent years, it has been found that some wheat varieties have allelopathic traits and can suppress weed growth through the allelochemicals synthesized and released from wheat varieties themselves. Alleopathic wheat varieties have been evaluated from different wheat germplasm collections (Blum et al. 1992; Oueslati 2003; Weston 1996; Wu et al. 2001; Wu et al. 2002). Wu et al. (1998) showed that radical elongation of ryegrass was inhibited over a range from 19.2% to 98.7% and for seed germination from 4.2% to 73.2% among thirty-eight wheat (Triticum aestivum L.) and one durum wheat (Triticum durum Desf.) cultivars. This indicates that allelopathic potential of wheat varieties was correlated with their heredity and allelochemicals released into the environment under natural conditions (Kong et al. 2002; Wu et al. 2003). Thus, wheat allelopathy has a potential to improve weed management in wheat production.

The objective of this study is to evaluate allelopathic potential of 27 wheat varieties from a Chinese germplasm collection with different origins and agronomic traits against C. album and A. retroflexus.

Methods

Plant material

Seeds of 27 Chinese wheat varieties with different origins and agronomic traits were provided by the Crop Breeding Institute, Academy of Agricultural Sciences in Liaoning (LNAA), Jilin (JLAAS) and Heilongjiang (HLJAAS) provinces, Academy of Agricultural Sciences in Jinzhou (JZAAS), Baicheng (BCAAS) and Tieling (TLAAS) cities, Northeast Normal University (NNU) and Shenyang Agricultural University (SYAU). The origin of 27 wheat varieties is described in Table 1. Seeds of lambsquarters (C. album L.) and redroot amaranth (A. retroflexus L.) were collected at the Shenyang Experimental Station of Ecology (4131' N, 12322' E), Chinese Academy of Sciences.

Table 1. The origin of wheat varieties

No.

Variety

Origin

No.

Variety

Origin

No.

Variety

Origin

1

Liaochun 10

LNAA

10

Jin 2003

JZAAS

19

Fengqiang 5

JLAAS

2

Liaochun 11

LNAA

11

Liaochun 9

LNAA

20

Fengqiang 7

JLAAS

3

Longfu 970227

HLJAAS

12

Liaochun 13

LNAA

21

Fengqiang 9

JLAAS

4

Longfu 9

HLJAAS

13

Tiechun 1

TLAAS

22

Fengqiang 10

JLAAS

5

Longfu10

HLJAAS

14

Tiechun 3

TLAAS

23

Jichun 9806

JLAAS

6

Longfu12

HLJAAS

15

Shenmian 85

SYAU

24

White spring 5

BCAAS

7

Longfu13

HLJAAS

16

Jin 2004

JZAAS

25

Fengqiang 6

JLAAS

8

Jin 2001

JZAAS

17

Fengqiang 3

JLAAS

26

Fengqiang 8

JLAAS

Pot culture

The pot culture experiment was conducted in a greenhouse. Soil used for pot culture was obtained from Shenyang Experimental Station of Ecology. Soil characteristics are: pH 6.46, total organic carbon 1.03 %, alkali N 97.70 mg/kg, and total N 0.07 %. The experiment design was a complete randomized design with four replications. The 27 wheat varieties tested were divided into three groups. The soil was sieved with 5mm mesh screen and thoroughly mixed. A plastic pot (18 cm diameter, 14 cm high) was filled with 2.5 kg soil. Seeds of C. album and A. retroflexus were soaked with 1 mol/l KNO3 for 45 min to break dormancy, and then rinsed several times with distilled water. The seeds of test weeds and wheat were pre-germinated in Petri dishes covered with filter papers. After germination, the 0.045-0.05 g seeds (about 100 seeds) of C. album and A. retroflexus were sown in the center of each pot and 20 seeds of wheat were sown around weeds, and then covered with soil. Seedlings were thinned to 12 plants per pot after emergence. During the growth period, the plants were irrigated with tap water regularly, and urea fertilizer was applied before jointing stage. At wheat heading stage, the root length of test weeds was measured. The growth of test weeds alone without wheat was selected as control. Every group had its own control.

ECAM (Equal-compartment-agar method)

The ECAM described by Wu et al. (Wu et al. 2000) was slightly modified. All seeds were stirred with a magnetic stirrer with 2.5% (v/v) sodium hypochlorite solution for 10 min to surface sterilize, then washed with sterilized water for three times (3 min per time). The surface-sterilized seeds of test weeds were soaked in sterilized water for 12h then incubated in Petri dish covered with filter paper. A quantity of 1.5% agar and Petri dishes (15 cm diameter) were autoclaved. Each Petri dish was filled with 200 ml of 1.5% agar. Each Petri dish was irrigated with 10 ml sterilised water every day. The root length of weeds was measured after 8 days of growth of wheat and test weeds in the same dish.

Data analysis

All experiment data were subjected to statistical analysis of variance (ANOVA) in the SPSS statistical package. The inhibitory activities of all wheat varieties were evaluated using the following Response Index (RI) (Williamson and Richardson 1988). RI= 1-C/T (T≥C) or =T/C-1 (T<C). C (Control) is the root length of C. album or A. retroflexus growing alone without wheat. T (Treatment) is the root length of C. album or A. retroflexus growing with different wheat varieties.

Results

The inhibitory effects of wheat varieties on root length of C. album and A. retroflexus

In the first group, the inhibitory effects of wheat varieties (from No. 1 to 10) on the root length of C. album and A. retroflexus are shown in Figure 1A. Root length of C. album and A. retroflexus differed significantly among 10 wheat varieties in pot culture and laboratory condition. It also showed that there was a larger variation in root length of C. album in pot culture than in laboratory condition. Root length of test weeds ranged from 2.53cm to 6.66cm in pot culture, and in ECAM from 0.88 cm to 1.59 cm. Among these test wheat varieties, No. 2, 3 and 9 exhibited stronger inhibitory effect than other wheat varieties. Compared with other varieties, inhibitory effects of these three varieties had significant differences (P < 0.01). According to the results, these wheat varieties could be screened as candidates with allelopathic traits.

The results of the second group (Figure1B) indicated that there are differences among varieties (from No. 11 to 18). Root length of C. album and A. retroflexus varied from 0.96 cm to 2.34 cm in laboratory and from 5.53 cm to 8.02 cm in pot culture. Significant differences were observed in root length of C. album in pot culture (P < 0.05) and A. retroflexus with ECAM (P < 0.01). Wheat varieties of No. 16, 17 and 18 had a greater inhibitory effect than others.

A

B

C

Figure 1. The inhibitory effect of wheat varieties on root length of C. album and A. retroflexus ( A-the first group; B- the second group; C- the third group).

RE-Root length of A. retroflexus with ECAM;RP- Root length of A. retroflexus in pot culture;LE- Root length of C. album with ECAM;LP- Root length of C. album in pot culture; 0-control.

The results of the third group (Figure1C.) suggested that root length of C. album and A. retroflexus differed significantly among different wheat varieties. Larger variation existed in root length of C. album and A. retroflexus cultured in pot culture experiment. The root length of C. album and A. retroflexus varied from 0.8cm to 1.98cm in laboratory and from 0.45 cm to 5.48 cm in pot culture. In these test wheat varieties, No. 20, 21 and 23 exhibited strong allelopathic traits and were selected as candidates with allelopathic traits, No. 19 and 25 had the least inhibitory activity among the third group of wheat varieties.

Table 2. Response Index (RI) of different wheat varieties on the growth of C. album and A. retroflexus

 

ECAM

Pot culture

Average RI

NO.

C. album

A. retroflexus

C. album

A. retroflexus

 

1

-0.21

bcdefg

-0.10

bcdefgh

-0.69

gh

-0.73

i

-0.43

cde

2

-0.37

efg

-0.21

cdefghi

-0.78

gh

-0.75

i

-0.53

e

3

-0.41

fg

-0.25

defghi

-0.66

gh

-0.72

i

-0.51

de

4

-0.40

fg

-0.15

bcdefgh

-0.70

gh

-0.65

ghi

-0.48

cde

5

-0.04

abc

-0.20

cdefghi

-0.59

g

-0.69

hi

-0.38

bcde

6

-0.22

bcdefg

-0.05

bcdef

-0.61

gh

-0.59

defghi

-0.37

bcde

7

-0.11

bcde

-0.03

bcdef

-0.76

gh

-0.62

efghi

-0.38

bcde

8

-0.15

bcdef

-0.06

bcdefg

-0.69

gh

-0.75

i

-0.41

bcde

9

-0.30

cdefg

-0.15

cdefgh

-0.82

h

-0.75

i

-0.51

de

10

-0.34

defg

-0.29

efghi

-0.63

gh

-0.66

ghi

-0.48

de

11

0.01

cdefg

0.21

b

-0.28

f

-0.50

cdefg

-0.14

abcd

12

0.23

a

0.59

a

-0.12

def

-0.45

bcde

0.06

a

13

-0.10

bcde

0.13

bc

-0.18

def

-0.54

cdefgh

-0.17

abcde

14

-0.21

bcdefg

0.11

bcd

-0.18

def

-0.44

bcd

-0.18

abcde

15

-0.32

cdefg

0.08

bcd

-0.05

cde

-0.45

bcde

-0.19

abcde

16

-0.23

cdefg

-0.46

hi

-0.12

def

-0.46

bcde

-0.32

abcde

17

-0.30

cdefg

-0.36

fghi

-0.05

bcde

-0.41

bc

-0.28

abcde

18

-0.34

defg

-0.39

fghi

-0.04

bcd

-0.46

bcdef

-0.31

abcde

19

0.06

ab

-0.05

bcdef

-0.29

f

-0.09

a

-0.09

abc

20

-0.15

bcdef

-0.41

ghi

-0.31

f

-0.63

fghi

-0.38

bcde

21

-0.08

bcd

-0.52

i

0.12

abc

-0.32

b

-0.20

abcde

22

-0.33

defg

-0.07

bcdefg

-0.66

gh

-0.15

a

-0.30

abcde

23

-0.20

bcdefg

-0.13

bcdefgh

-0.23

def

-0.32

b

-0.22

abcde

24

-0.31

cdefg

-0.20

cdefghi

-0.27

ef

-0.07

a

-0.21

abcde

25

-0.22

bcdefg

0.58

a

0.19

a

-0.45

bcd

0.03

a

26

-0.45

g

0.06

bcde

0.30

a

-0.02

a

-0.03

ab

27

-0.16

bcdef

-0.37

fghi

0.17

ab

-0.14

a

-0.13

abcd

All values in a row not followed by the same letter are significantly different. Small letter represent significant level at 5%.

Through the RI calculation, 27 different varieties could be compared under a uniform criterion (Table 2). Positive values indicate stimulation and negative values inhibition. The absolute value of RI varied directly with the strength of the effect. From the Table 2, we observed that the RI of all seedlings ranged from –0.78 to 0.58. Significant differences (P < 0.01) were found in inhibitory effects among wheat varieties tested in these studies. Through the analysis of the average value of RI, we selected several strongly allelopathic wheat varieties that included No.2, 3, 4, 9, 10, and 20 and their average RI values were between–0.53 and–0.38, and the average RI values of wheat No.12, 19, 25, 26 and 27 were between–0.13 and 0.06. They showed no allelopathic potential and should be considered as non-allelopathic varieties. These results were similar with that of Fig.1.

Conclusion

Several allelopathic wheat varieties were screened using ECAM and pot culture methods. Root length was the most reliable response parameter because it had high sensitivity to allelochemicals and easy to measure (Belz and Hurle 2004). Therefore, root length may be a key parameter to verify allelopathic strength of different wheat varieties. The results suggested that several wheat varieties, such as No. 2, 3, 9, 16, 17 and 18, are allelopathic to lambsquarters and redroot amaranth. The use of these allelopathic wheat varieties is likely to reduce high dose herbicide application to control weeds in wheat fields. Further research is necessary to confirm these allelopathic wheat varieties using chemical finger-printing and to evaluate their weed-suppressive effect under natural conditions.

Acknowledgements

This work was financially supported by Hundreds-Talent Program of Chinese Academy of Sciences (BR0401) and the Natural Science Foundation of Liaoning Provice (20042008).

References

Blum U, Gerig TM, Worsham AD, et al (1992). Allelopathic activity in wheat-conventional and wheat-no-till soils: Development of soil extract bioassays. Journal of Chemical Ecology 18, 2191-2221.

Belz RG and Hurle K (2004). A novel laboratory screening bioassay for crop seedling allelopathy. Journal of Chemical Ecology 30, 175-198.

Kong CH, Hu F, Chen XH, et al (2002). Assessment and utilization of allelopathic crop varietal resources. Scientia Agricultura Sinica 35, 1159-1164.

Oueslati O (2003). Allelopathy in two durum wheat (Triticum durum L.) varieries. Agronomy Ecosystem Evironment 96, 161-163.

Weston LA (1996). Utilization of allelopathy for weed management in Agroecosystems. Agronomy Journal 88, 860-866.

Williamson GB and Richardson D (1988). Bioassay for allelopathy: measuring treatment response with independent controls. Journal of Chemical Ecology 14, 181-188.

Wu H, Pratley J, Lemerle D, et al (1998). Differential allelopathic potential among wheat accessions to annual ryegrass. Proceedings of the 9th Australian Agronomy Conference, Wagga Wagga, Australia. 567-571.

Wu H, Haig T, Pratley J, et al (2000). Distribution and exudation of allelochemicals in wheat Triticum aestivum. Journal of Chemical Ecology 26, 2141-2154.

Wu H, Haig T, Pratley J, et al (2001). Allelochemicals in wheat (Triticum aestivum L.): Variation of phenolic acids in shoot tissues. Journal of Chemical Ecology 27, 125-135.

Wu H, Pratley J, Haig T, et al (2002). Biochemical basis for wheat seedling allelopathy on the suppression of annual ryegrass (Lolium rigidum). Journal of Agricultural and Food Chemistry 50, 4567-4571.

Wu H, Pratley J, Ma W, et al (2003). Wheat allelopathy: quantitative trait loci and molecular markers Theoretical and Applied Genetics 107, 1477-1481.

Previous PageTop Of PageNext Page