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African Crop Science Journal
African Crop Science Society
ISSN: 1021-9730 EISSN: 2072-6589
Vol. 8, Num. 3, 2000, pp. 295-300
African Crop Science Journal, Vol. 8. No. 3, pp. 295-300

African Crop Science Journal, Vol. 8. No. 3, pp. 295-300

ON-STATION VERIFICATION OF THE USE OF SOYBEAN TRAP-CROP FOR THE CONTROL OF Striga IN MAIZE

I. Kureh, U.F. Chiezey and B.D. Tarfa
Faculty of Agriculture, Ahmadu Bello University, PMB 1044, Zaria, Nigeria

(Received 13 July, 1999; accepted 10 July, 2000)

Code Number: CS00031

INTRODUCTION

The major obstacles to maize (Zea mays L.) production in the West and Central African savanna are nitrogen deficiency and Striga hermo-nthica parasitism (Berner and Kling, 1995). Striga is endemic in West and Central African savannas and can cause serious devastation to maize especially on the fields of resource-poor farmers (Parker, 1991; Lagoke et al., 1994; Abayo et al., 1997). Even under good management condition, about 79% reduction in yield was observed in susceptible hybrid maize . The value of total annual crop loss due to Striga in Africa has been estimated at 7 billion US Dollars.

Traditional African cropping systems which have included prolonged fallow, rotation and inter-cropping were common management practices that were used in the past to improve soil fertility and keep the infestation of Striga spp at tolerable levels. However, increasing human population has resulted in intensive land use and a shift away from traditional cropping systems, which in turn has resulted in the depletion of soil fertility and decrease in Striga control (Berner et al., 1996). Inter-cropping of maize with non host crops has been reported to increase the efficiency of land use through improved soil productivity and reduction of Striga hermonthica soil seed bank as a result of the stimulation of suicidal germination of Striga seeds by non hosts (Berner et al., 1996; Lagoke et al., 1997; Oswald et al., 1997). Carson (1988), for example, found that Striga densities were reduced when sorghum was intercropped with groundnuts. Similarly, Odhiambo and Ranson (1993) and Carsky et al. (1994) tested maize/sorghum/cowpea combinations and achieved a significant reduction of Striga population. The spreading vegetation of non-host crops (trap-crops) also smother emerging Striga plants. There is considerable variability among non-host crops and within crop cultivars in their ability to fix nitrogen and stimulate Striga seed germination. Varieties of soybean, cowpea, groundnut, pigeon pea and cotton with very high Striga seed germination potential have been identified (Carson, 1988; Ariga et al., 1994; Carsky et al., 1994). These non-hosts, if identified for various production and cropping systems would reduce soil seed bank and incidence of Striga hermonthica in maize.

MATERIALS AND METHODS

Field trials were conducted in 1997 and 1998 wet seasons at Samaru (11°11’N, 7°36’E; 686 m above sea level) in the Northern Guinea savanna agroecology of Nigeria. Treatments included a mixture of Striga tolerant maize hybrid (Oba super 1) and two soybean varieties (TGX 1019-2E and TGX 1440-1E - identified as potential trap-crop varieties) with a sole maize crop as control. The treatments which were supposed to be evaluated on-farm were verified on-station in a complete randomised block design replicated three times.

The trials were established on Striga sick plots which were further inoculated with about 3,000 germinable Striga seeds hill-1 at about 50 cm apart. Maize seeds were planted on the spots one week later. Intercropped soybean was drilled, on the same day, along the edges of the 75 cm spaced ridges. Spot application of fertiliser was carried out at the rate of 100 kg N ha-1, 50 kg P2O5 ha-1 and 50 kg K2O ha-1 to maize using 20-10-10 compound fertiliser and urea. The intercropped soybean received a basal application of 20 kg N ha-1 as starter dose using urea and 50 kg P2O5 using single super phosphate (SSP - 18% P2O5). Hoe weeding was carried out at 3 and 5 weeks after sowing (WAS) followed by hand pulling of other weeds which was carried out at 7 WAS. The plot size was 22.5 m2. Data collected included Striga incidence (percentage of crop plants infested), infestation (Striga shoot count), crop syndrome reaction score (where 1 = healthy plants to 9 = dead plants), stand count, yield and yield components of maize and soybean. The data were subjected to analysis of variance as described by Coc’hran and Cox (1957). Significant differences among treatment means were compared using Fisher's protected least significant difference (LSD) test at P=0.05.

RESULTS AND DISCUSSION

Striga incidence and infestation as reflected in the Striga shoot count and number of maize plants infested by Striga at 9 and 12 WAS were significantly (P=0.05) affected by the type of cropping system (Table 1). Intercropping maize with soybeans supported lower incidence and infestation of Striga and exhibited significantly (P=0.05) lower crop syndrome reaction score than sole maize. Earlier reports indicated that intercropping maize with non-host crops increase the efficiency of land use through improved soil productivity and reduction of Striga hermonthica soil seed bank (Ariga et al., 1997). In our study, emerged Striga plants in the intercrop were etiolated in growth and died earlier than the Striga that emerged in the sole crop probably as result of the smothering effect of soybeans. This finding confirmed earlier report by Carson (1988) who found that the spreading vegetation of non-host crops (trap-crops) also smother emerging Striga plants.

The mixture of maize with soybean produced significantly (P=0.05) higher grain yield than sole maize crop under Striga infestation (Table 2). Likewise, the mixture of local sorghum variety with soybean or cowpea produced significantly (P = 0.05) higher head weight, 1000-seed weight and grain yield than sole sorghum. Traditional African cropping systems which included rotation and intercropping were common management practices in the past that improved soil fertility, kept Striga infestation at tolerable levels and increased seed yields of crops (Berner et al., 1996). Intercropping maize with the two soybean varieties (TGX 1019-2EB and TGX 1440-1E) did not significantly (P=0.05) affect Striga incidence, infestation, crop syndrome reaction score and grain yield. This suggested that the soybean varieties tested had similar potential for use as trap-crop varieties.

The soybean varieties tested differed only significantly (P=0.05) in lodging and 100-seed weight (Table 3). TGX 1019-2EB was moderately susceptible to lodging but produced significantly higher 100-seed weight than TGX 1440-1E. Being an early maturing variety, TGX 1019-2EB was probably able to translocate enough assimilate for seed filling before the end of the season. Thus, it produced heavier seeds than TGX 1440-1E which is medium maturing.

As shown in Table 4, intercropping maize with soybean for Striga suppression produced three times more crop value than sole maize crop. Kureh et al. (1997, unpubl.) similarly reported that the highest crop value was obtained when soybean was intercropped with either the farmer’s local sorghum or improved sorghum variety than sole sorghum.

In conclusion, intercropping is a good agronomic practice for Striga management in maize due to reduced striga infestation and high total crop value obtained. Soybean varieties TGX 1019-2EB and TGX 1440-1E exhibited similar potential for use as trap-crops.

REFERENCES

  1. Abayo, G.O., Oswald, A., Ransom, J.K. and Ariga, E.S. 1997. Stimulation of Striga hermonthica germination by plant species indigenous to Eastern Africa. In: In: Proceedings of the 16th Biennial Weed Science conference for Eastern Africa, Kampala 15-18 September 1997. Adipala, E., Tusiime, G. and Okori, P. (Eds.), pp. 231-239.
  2. Ariga, E.S., Berner, D.K. and Chweya, J. 1994. Effects of previous season cotton and cowpea on Striga hermonthica parasitism on maize. Phytopathology 84: 1151.
  3. Ariga, E.S., Ransom, J.K. Odhiambo, G.D., Abayo, G.O. and Ndung’u, D.K. 1997. Potential of using cotton and other trap crops for Striga hermonthica management in cereals in Kenya. In: Proceedings of the 16th Biennial Weed Science conference for Eastern Africa, Kampala 15-18 September 1997. Adipala, E., Tusiime, G. and Okori, P. (Eds.), pp. 247-253.
  4. Berner, D.K., Alabi, M.O., Di-Umba, U. and Ikie, F.O. 1996. Proposed integrated control program for Striga hermonthica in Africa. In: Proceedings 6th Parasitic Weeds Symposium, April 16-18th 1996, Cordoba, Spain. Moreno, M.T., Cubero, J.I., Berner, D.K., Joel, D., Musselman, L.J. and Parket, C. (Eds.), pp. 817-825.
  5. Berner, D.K., Kling, J.G. and Singh, B.B. 1995. Striga research and control: a perspective from Africa. Plant Disease 79:652-660.
  6. Carson, A.G. 1988. Development and testing of a control package for Striga hermonthica on small-scale holdings in the Gambia. Tropical Pest Management 34:97-101.
  7. Carsky, R.J., Singh, L. and Ndikawa, R. 1994. Suppression of Striga hermonthica on sorghum using a cowpea intercrop. Experi-mental Agriculture 30:349-358.
  8. Coc’hran, W.G. and Cox, G.M. 1957. Experimental Designs. 2nd Edition. John Wiley and Sons, New York. 611 pp.
  9. Lagoke, S.T.O., Shebayan, J.A.Y, Weber, G. , Olufajo, O.O., Elemo, K.A., Adu, J.K., Emechebe, A.M., Singh, B.B. and Adeoti, A.A. 1994. Survey of Striga problem and evaluation of Striga control methods and packages in crops in the Nigerian Savanna. In: Improving Striga Management in Africa. Proceedings, 2nd General Workshop of PASCON, 23-29 June, 1991, Nairobi, Kenya. Lagoke, S.T.O., Hoever, R., M’boob, S.S. and Traboushi, R. (Eds.), pp. 91-120. FAO, Accra, Ghana.
  10. Odhiambo, G.D. and Ransom, J.K. 1994. Preliminary evaluation of long term effects of trap cropping and maize management on Striga. In: Biology and Management of Orabanche. Proceedings of the 3rd International Workshop on Orabanche and related Striga research. Pieterese, A.H., Verklejj, J.A. and ter Borg, S.J. (Eds.), pp. 505-512. Royal Tropical Institute, Amsterdam, The Netherlands.
  11. Oswald, A., Ransom, J.K., Abayo, G., Kroschel, J. and Sauerborn, J. 1997. Intercropping - an option for Striga control. In: Proceedings of the 16th Biennial Weed Science conference for Eastern Africa, Kampala 15-18 September 1997. Adipala, E., Tusiime, G. and Okori, P. (Eds.), pp. 261-266.
  12. Parker, C. 1991. Protection of crops against parasitic weeds. Crop Protection 10:6-22.
TABLE 1. Effects of sole and intercropping of maize and soybean on Striga incidence and infestation of maize at Samaru during the 1997 and 1998 wet seasons
Cropping systems Stand count per plot at harvest Striga count per plot No. of infested plant per plot Crop reaction score3
9 WAS1 12 WAS 9 WAS 12 WAS 9 WAS
1997 1998 1997 1998 1997 1998 1997 1998 1997 1998 1997 1998
Oba super 1 Sole 54.1b2 55.3b 31.0a 27.3a 35.0a 30.6a 21.7a 19.0a 24.0a 21.0a 4.5a 4.3a
Oba super 1 + TGX 1019-2EB 60.3a 61.5a 13.0b 10.3b 15.3b 12.2b 6.3b 4.7b 6.7b 5.0b 3.0b 2.3b
Oba super 1 + TGX 1440-1E 61.7a 62.0a 11.7b 9.7b 14.3b 11.4b 5.1b 3.3b 5.4b 4.1b 2.7b 2.0b
SE± 1.19 1.20 2.51 2.32 5.01 4.21 2.67 2.41 2.92 2.62 0.30 0.24
1WAS = Weeks after sowing
2Means followed by the same letter or no letter within a column are not significantly different at 5% level of probability (LSD)
3Crop syndrome reaction score using a scale of 1-9 where 1 = healthy plants and 9 = dead plants
TABLE 2. Effects of sole and intercropping of maize with soybean varieties on yield and yield components of maize at Samaru during the 1997 and 1998 wet seasons
Cropping systems No of cobs/plot Cob dry weight (kg ha-1) 100-seed weight (g) Grain yield (kg ha-1)
1997 1998 1997 1998 1997 1998 1997 1998
Oba super 1 Sole 50.3 56.7 1910.7 2807.3 19.3 19.9 1217.3b1 1408.7b
Oba super 1 + TGX 1019-2EB 64.3 65.0 2901.1 2659.0 19.7 21.2 2340.3a 2568.7a
Oba super 1 + TGX 1440-1E 69.0 68.7 2986.5 2980.3 19.8 20.5 2970.0a 3141.9a
SE± 6.63 7.21 315.52 187.31 0.30 0.47 264.35 275.53
1Means followed by the same letter or no letter within a column are not significantly different at 5% level of probability (LSD)
TABLE 3. Plant height, lodging, 100-seed weight and seed yield of soybean varieties in a maize/soybean mixture at Samaru, 1997 and 1998 wet seasons
Cropping systems 1997 Plant height (cm) Lodging score2 100-seed weight (g) Seed yield (kg ha-1)
1998 1997 1998 1997 1998 1997 1998  
Oba super 1 Sole - - - - - - - -
Oba super 1 + TGX 1019-2EB 81.0 81.9 3.7a1 4.0a 24.4a 15.2a 1302.1 1437.0
Oba super 1 + TGX 1440-1E 67.9 68.1 2.0b 2.0b 12.7b 9.9b 1113.2 1140.7
SE± 3.20 3.15 1.46 1.52 0.73 1.09 109.99 153.35
1 Means followed by the same letter or no letter within a column are not significantly different at 5% level of probability (LSD)
2 Lodging score using a scale of 1-5 where 1 = all plants errect and 5 = all plants lodged
TABLE 4. Crop values of maize and soybean in sole and intercropping of soybean with maize at Samaru, 1997 and 1998 wet seasons1
Cropping systems Maize grain yield (kg ha-1) Maize value at N20 kg-1 Soybean yield (kg ha-1) Soybean value at N25 kg-1 Total value (N)
1997 1998 1997 1998 1997 1998 1997 1998 1997 1998
Oba super 1 (Sole) 1217 1409 24340 28180 - - - - 24340 28180
Oba super 1 + TGX 1019-2EB 2340 2569 46800 51380 1302 1437 32550 35925 79350 87305
Oba super 1 + TGX 1440-1E 2970 3142 59400 62840 1113 1141 27825 28525 87225 91365
1Crop values were calculated using the prevailing prices of test crops; 1 US$ = 90N
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