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Use of allelopathy in field crops in pakistan

Zahid Ata Cheema1, Abdul Khaliq2 and Nadeem Iqbal3

1 Professor, Weed Science Allelopathy Lab., Department of Agronomy, University of Agriculture, Faisalabad 38040, Pakistan. zacheema@pakwatan.com; cheemaza@yahoo.com
2
Assistant Professor, Department of Agronomy, University of Agriculture, Faisalabad 38040, Pakistan khaliquaf@yahoo.com
3
Research Officer, Weed Science Allelopathy Lab., Department of Agronomy, University of Agriculture, Faisalabad 38040, Pakistan pk_nadeem@pakwatan.com

Abstract

Field studies were carried out (2002-2003) to enhance the efficacy of tank-mixed allelopathic crop water extracts and reduced rates of herbicides. Results revealed that sorghum water extracts used in combination with and of the recommended doses each of fenoxaprop-p-ethyl (463.3 and 231.65 g a.i. ha-1), clodinafop proprargyl (18.5 and 9.26 g a.i. ha-1) and carfentrazone+isoproturon (370.65 and 185.00 g a.i. ha-1) reduced weed dry weight by 76-85%, 92-95% and 86-90%, respectively, which were equal to their full doses. Reduced rates of atrazine in combination with sorghum and sunflower water extract at 10 L ha-1 suppressed weed dry weight by 86-100%, which was similar to full dose. Combination of sorgaab (sorghum water extract) with reduced rate of pendimethalin (500 and 667 g a.i. ha-1) and S. metolachlor (667 and 1000 g a.i. ha-1) as pre emergent herbicide gave weed control in cotton equal to their label doses. Sorghum water extract with and 1/3 dose of pendimethalin reduced weed dry weight by 73 and 82% and its full dose (1.25 kg a.i. ha-1) suppressed weed dry weight by 81%. Sorgaab at 12 L ha-1 combined with ethoxy sulfuron at 15 g a.i. ha-1 and butachlor at 600 g a.i. ha-1 reduced weeds by 77 and 68% which was equal to the full dose of these herbicides. In conclusion, this two year study has shown that allelopathy can be utilized for reducing the dose of herbicide by 40-67% in combination with allelopathic crop water extracts and still obtain the same weed control.

Media summary

Pakistani scientists working at the University of Agriculture, Faisalabad has developed a new use of allelopathy for reducing herbicide(s) usage. The water extracts obtained from mature sorghum and sunflower herbage mixed in spray tank with low herbicide rates gave effective weed control in field crops.

Key Words

Allelopathic water extracts, herbicide, weed control, field crops

Introduction

Allelopathic potentiality under field conditions can be utilized in different ways i.e. crop rotation and intercropping, crop residues as mulch or water extracts as foliar sprays and tank mixing of the extracts with low herbicide rates. Intercropping of dwarf sorghum (Srghum bicolour L. Moench) in maize (Zea mays L.) culture suppressed the Cyperus rotundus population by 30% (Mehmood, 2003). The intercrop system was economical than sole maize (Mahmood, 2003) and the intercropping of sorghum, sesame (Sesamum indicum L.), soybean (Glysine max Merrill) in cotton (Gossypium hirsutum L.) controlled the population of Cyperus rotundus in the range of 62-94% (unpublished data). The sorghum mulch used at 6 t ha-1 gave 50% weed control in wheat (Triticum aestivum L.) (Cheema and Khaliq, 2000) and sorghum mulch at 15 t ha-1 suppressed the Cyperus rotundus density by 53% (Mahmood and Cheema, 2004). However, the use of mulches was uneconomical due to higher cost. Foliar spray of allelopathic crop water extracts provided weed inhibition ranging from 18 to 46% and this inhibition depended upon the number of sprays, concentration and rate and type of crop used for extraction (Cheema et al., 2000; Khaliq et al., 1999). The inhibition was also species specific, some weeds showed more response, while others were least affected. Complementarity of allelochemicals and herbicides can be exploited as means of weed control. Kebede (1994) postulated that a herbicide applied along with allelopathic conditions could have supportive action thus herbicide rate can be reduced by using allelopathic products in mixture with herbicides. This will decrease environmental contamination and herbicide carry over adverse effects on next crop. Cheema et al (2003d) reported 50% decrease in the rate of isoproturon when sorgaab (sorghum water extract) was tank mixed at 12 L ha-1 and sprayed at 30 days after spraying (DAS). These results encouraged to investigate further on these lines. This present paper is focused mainly on the possible reduction in herbicide rates by combining different allelopathic water extracts in field crops as wheat, maize, cotton, rice and mungbean (Vigna mungo) in Punjab, Pakistan.

Methods

Field experiments regarding utilization of allelopathy for weed management in field crops such as wheat, cotton, rice, maize and mungbean were carried out at the Agronomic Research Area, university of Agriculture, Faisalabad, Pakistan. The soil belongs to the Lyallpur soil series (Aridisol-fine-silty, mixed, hyperthermic ustalfic, haplargid in USDA classification and Haplic Yermosols in FAO classification scheme). The pH of the saturated soil paste (pHs) and electrical conductivity (EC) of the saturated extract (ECe) were 7.9 and 0.41 dSm-1, respectively. Sorghum and sunflower plant herbage was harvested at maturity, dried, chaffed with fodder cutter into 2 cm pieces and kept under cover to avoid possible leaching by rain. Chaffed plant herbage was soaked in water in a ratio of 1:10 w/v for 24 h at room temperature (302C) and filtered to collect the extract. The same was boiled at 100C to reduce its volume by 20 times. The concentrated extracts were combined with reduced rates of different herbicides. Volume of spray was determined by calibration. Important weeds of experimental sites were Phalaris minor Retz., Avena fatua L., Chenopodium album L., Convolvulus arvensis L., Trianthema portulacastrum L., Cyperus rotundus L. and Echinochloa crus-galli L. P. Beauv. Experimental details for individual crops are given as under:

Wheat

Sorgaab at 12 L ha-1 was combined with and of the reduced doses of fenoxaprop-p-ethyl (46.33 and 23.17 g a.i. ha-1), clodinafop propargyl (18.5 and 9.26 g a.i. ha-1) and carfentrazone+isoproturon (370.65 and 185.3 g a.i. ha-1), respectively. Recommended rates of these herbicides (fenoxaprop-p-ethyl at 92.66 g a.i. ha-1, clodinafop propargyl at 37.1 g a.i. ha-1 and carfentrazone+isoproturon g a.i. ha-1) were kept as standard . In addition, a weedy check was maintained for comparison. Spraying was done at 25 DAS.

Cotton

In this experiment, reduced rates of two pre-emergence herbicides (1/2 and 2/3) as pendimethalin (500 and 667 g a.i. ha-1) and s-metolachlor (1000 and 1330 g a.i. ha-1) were combined with sorgaab at 10 L ha-1 and sprayed as pre-emergence. Recommended dose of pendimethalin and s-metolachlor (1 kg a.i. ha-1 and 2 kg a.i. ha-1, respectively) were kept as standard. Weedy check was also maintained.

Rice

The treatments included combination of sorgaab with 1/2 dose each of ethoxysulfuron (15 g a.i. ha-1) and butachlor (600 g a.i. ha-1) where full dose of ethoxysulfuron at 30 g a.i. ha-1 and butachlor at 1200 g a.i. ha-1 as standard and weedy check was maintained for comparison between the treatments. All the treatments except weedy check were sprayed at pre-emergence stage.

Maize

Atrazine reduced by 50% and 66% (500 and 750 g a.i. ha-1, respectively) were applied with sorghum and sunflower water extracts each at 10 L ha-1. Recommended dose of atrazine (1.5 kg a.i. ha-1) was included as standard. All the treatments were sprayed at 15 DAS. Weedy check was also included in the experiment for comparison.

Mungbean

Pendimethalin (500 and 750 g a.i. ha-1) were combined with sorgaab at 10 L ha-1. Full dose of pendimethalin at 1.5 kg a.i. ha-1 was kept as standard. Weedy check was also maintained. All the treatments except weedy check were sprayed as pre-emergence.

In all the treatments weeds were harvested at ground level from a quadrat of 50 cm x 50 cm and oven dried for recording dry weight. The yield of the respective crop was recorded after harvesting at maturity. Data were statistically analysed using standard procedures.

Results

Results revealed that sorghum water extract (sorgaab) used in combination with and of the recommended doses of each of fenoxaprop-p-ethyl (46.33 and 23.17 g a.i. ha-1), clodinafop propargyl (18.5 and 9.26 g a.i. ha-1) and carfentrazone+isoproturon (370.65 and 185.3 g a.i. ha-1) reduced weed dry weight by 76-85%, 91-95% and 86-90%, respectively over control which were statistically equal to the reduction in weed dry weight realized with the full dose of respective herbicides used alone (Table-1). The respective increase in wheat grain yield recorded with the combined spray of sorgaab with reduced rates of herbicides was 13-14, 14-15 and 19 % over control while the comparable increase in grain yield with the recommended doses of these herbicides used alone was 16, 17 and 21 %, respectively, over control. The reduction in weed dry weight in these studies can be attributed to the combined action of the sorghum water extract with reduced rates of herbicide. Cheema et al (2003a) reported that combined spray of fenoxaprop-p-ethyl (375 g a.i. ha-1) reduced weed dry weight by 87% and that what we observed as well in our study. .

Combined application of sorghum water extract (10 L ha-1) with reduced rates of pendimethalin (667 and 500 g a.i.ha-1) and s-metolachlor (1330 and 1000 g a.i.ha-1) as pre-emergence decreased total weed dry weight by 78-82% and 72-75%, respectively over control that was quite higher than the reduction in weed dry weight (80and73%, respectively) achieved with recommended dose of three herbicides used alone (Table-1). Reduced rates of pendimethalin with sorgaab increased seed cotton yield by 7-18% over control while the same herbicide used alone increased the yield by 17% over control. However the reduced rates of s-metolachlor failed to achieve dose of their herbicide used alone. Cheema et al (2002) in a previous study reported that pendimethalin (500 g a.i. ha-1) in combination with sorgaab (12 L ha-1) reduced the Trianthema portulacastrum dry weight by 76% over control.

Table-1: Effect of combined application of allelopathic crop water extracts with reduced rates of herbicides on weed dry weight and yield of some field crops

Treatments

Weed dry weight
(g per 0.25 m2)

Yiel
(Mg ha-1)

Wheat

   

Fenoxaprop-p-ethyl at 46.33 g a.i. ha-1+sorgaabat 12 L ha-1

1.234 (-76)1

4.23 (13)

Fenoxaprop-p-ethyl at 23.17 g a.i. ha-1+sorgaabat 12 L ha-1

0.831 (-85)

4.27 (14)

Clodinafop propargyl at 18.5 g a.i. ha-1+sorgaabat 12 L ha-1

0.479(-91)

4.30 (15)

Clodinafop propargyl at 9.26 g a.i. ha-1+sorgaabat 12 L ha-1

0.251 (-95)

4.28 (14)

Carfentrazone+isoproturon at 370.65 g a.i. ha-1+sorgaabat 12 L ha-1

0.771 (-86)

4.45 (19)

Carfentrazone+isoproturon at 185.3 g a.i. ha-1+sorgaabat 12 L ha-1

0.540 (-90)

4.48 (19)

Control (weedy check)

5.50 (-)

3.75 (-)

LSD(P=0.05)

0.209

0.125

Cotton

   

Pendimethalin at 667 g a.i. ha-1+sorgaab at 10 L ha-1

13.38 (-82)

1.04 (18)

Pendimethalin at 500 g a.i. ha-1+sorgaab at 10 L ha-1

16.08 (-78)

0.93 (7)

s-metolachlor at 1330 g a.i. ha-1+sorgaab at 10 L ha-1

20.75 (-72)

0.89 (3)

s-metolachlor at 1000 g a.i. ha-1+sorgaab at 10 L ha-1

18.45 (-75)

0.88 (3)

Control (weedy check)

73.25 (-)

0.85 (-)

LSD(P=0.05)

3.13

0.280

Rice

   

Ethoxysulfuron at 15 g a.i. ha-1+sorgaab at 12 L ha-1

7.80 (-77)

5.79 (10)

Butachlor at 600 g a.i. ha-1+sorgaab at 12 L ha-1

10.85 (-68)

5.91 (13)

Control (weedy check)

33.83 (-)

5.25 (-)

LSD(P=0.05)

0.348

0.103

Maize

   

Atrazine at 500 g a.i. ha-1+sorghum and
sunflower water extracts each at 10 L ha-1

6.04 (-85)

4.25 (52)

Atrazine at 750 g a.i. ha-1+sorghum and
sunflower water extracts each at 10 L ha-1

0.28 (-99)

4.27 (53)

Control (weedy check)

40.00 (-)

2.80 (-)

Mungbean

   

Pendimethalin at 500 g a.i. ha-1+sorgaab at 10 L ha-1

13.61 (-67)

0.869 (13)

Pendimethalin at 750 g a.i. ha-1+sorgaab at 10 L ha-1

8.76 (-79)

0.934 (22)

Control (weedy check)

40.90 (-)

0.77 (-)

LSD(P=0.05)

3.22

0.096

1Figures given in parenthesis show % over control; Recommended dose of herbicides for a) wheat fenoxaprop-p-ethyl at 92.66 g a.i. ha-1, clodinafop propargyl at 37.1 g a.i. ha-1; carfentrazone+isoproturon at 741.3 g a.i. ha-1; b) cotton pendimethalin at 1.0 kg a.i. ha-1; s-metolachlor at 2.0 kg a.i. ha-1; c) rice ethoxysulfuron at 30 g a.i. ha-1, butachlor at 1200 g a.i. ha-1; d) maize atrazine at 1.5 kg a.i. ha-1; e) mungbean pendimethalin at 1.5 kg a.i. ha-1.

In rice, combined application of sorgaab (12 L ha-1) with each of ethoxysulfuron (15 g a.i. ha-1) and butachlor (600 g a.i.ha-1) decreased total weed dry weight by 77 and 68% respectively, while the respective reduction in weed dry weight achieved with full dose of these herbicides used alone amounted to be 66 and 64%, respectively (Table-1). The respective increase in paddy yield with combined spray of sorgaab and both the herbicides was also higher than that achieved with recommended doses of herbicides used alone.

In maize, reduced rates of atrazine (500 and 750 g a.i.ha-1) in combination with 10 L ha-1 of each of sorghum and sunflower water extracts reduced weed dry weight by 85 and 99%, respectively while the full dose of atrazine used alone gave 100% reduction in weed dry weight over control (Table-1). These treatments enhanced grain yield by 52-53% while the full dose of atrazine used alone increased maize yield by 50% over control. Cheema et al (2003b) revealed that atrazine (150 g a.i. ha-1) in combination with sorgaab (12 L ha-1) gave 39% maize grain yield increase over control while atrazine alone (300 g a.i. ha-1) gave 41% higher yield than control.

Application of sorgaab (10 L ha-1) in combination with pendimethalin (500 and 700 g a.i.ha-1) reduced weed dry weight by 67 and 79%, respectively over control as compared with 87% reduction in total weed dry weight recorded with the full dose of pendimethalin used alone (Table-1). Combined spray of sorgaab with 500 g a.i.ha-1 gave 13% increase in Mungbean grain yield that was 22% higher over control with 750 g a.i.ha-1 pendimethalin. Pendimethalin used alone at recommended rate gave a yield advantage of 14%, over control. Cheema et al (2003c) reported that mungbean grain yield with pendimethalin(500 g a.i. ha-1) in combination with sorgaab (10 L ha-1) gave 53-95% reduction in weed dry weight and was at par with that recorded with pendimethalin (1500 g a.i. ha-1) alone. Mungbean grain yield was also comparable in both of these treatments.

Conclusion

These studies have revealed that herbicide dose can be effectively reduced in combination with allelopathic crop water extracts on one hand and the efficacy of these allelopathic extracts can be enhanced in combination with reduced rates of herbicides for managing weeds in field crops.

References

Cheema ZA and Khaliq A (2000). Use of sorghum allelopathic properties to control weeds in irrigated wheat in a semi arid region of Punjab. Agriculture, Ecosystems and Environment. 79, 105-112.

Cheema ZA, Jaffer I and Khaliq A (2003d). Reducing isoproturon dose in combination with sorgaab for weed control in wheat. Pakistan Journal of Weed Science Research 9, 153-160.

Cheema ZA, Sadiq HMI and Khaliq A (2000). Efficacy of sorgaab (sorghum water extract) as a natural weed inhibitor in wheat. International Journal of Agriculture and Biology 2, 144-146. www.ijab.org

Cheema, ZA, Khaliq A and Farooq R (2003a). Effect of concentrated sorgaab alone and in combination with herbicides and a surfactant in wheat. Journal of Animal and Plant Science 13, 10-13

Cheema, ZA, Khaliq A and Tariq M (2002). Evaluation of concentrated sorgaab alone and in combination with three pre-emergence herbicides for weed control in cotton (Gossypium hirsutum L.). International Journal of Agriculture and Biology 4, 549-552.

Cheema, ZA, Farid MS and Khaliq A (2003b). Efficacy of concentrated sorgaab in combination with low rates of atrazine for weed control in maize. Journal of Animal and Plant Science 13, 48-52.

Cheema, ZA, Hussain S and Khaliq A (2003c). Efficacy of sorgaab in combination with allelopathic water extracts and reduced rates of pendimethalin for weed control in Mungbean. Indus Journal of Plant Science 2, 21-25.

Kebede, Z. (1994). Allelopathic chemicals: their potential uses for weed control in Agroecosystem.www.colostate.edu/Depts/Entomology/courses/en570/papers1994/kebede.html.

Khaliq A, Cheema ZA, Mukhta MA and Basra SMA (1999). Evaluation of sorghum (Sorghum bicolor) water extract for weed control in soybean. International Journal of Agriculture and Biology 1, 23-26.

Mahmood A (2003). Utilization of allelopathic properties of sorghum for controlling purple nutsedge (Cyperus rotundus L.) in maize. Ph.D Dissertation, University of Agriculture, Faisalabad, Pakistan.

Mahmood A and Cheema ZA (2004). Influence of sorghum mulch on purple nutsedge (Cyperus rotundus L.). International Journal of Agriculture and Biology 6, 86-88.

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