PATHOGENICITY OF THE ROOT-KNOT NEMATODE, Meloidogyne incognita RACE 2, IN SOYBEAN-MAIZE INTERCROP

The screenhouse study one field trial were conducted to investigate the effects of intercropping soybean TGX 1740-2F and 1440-1E and maize cv. Suwan 1 SR in the management of the rootknot nematode, Meloidogyne incognita race 2. In the screenhouse thirty six 5-litre plastic pots were filled with sterilized soil. In each pot four seeds of soybean cvs. TGX 1740-2F and TGX 1440-2E and or Suwan-1-SR or combination of both were sown. There were nine treatments in four replicates laid out in Randomized Complete Block Design (RCBD). The field experiment followed the same crop pattern. Under screenhouse conditions, the soybean lowest gall index was recorded in the combination of 25% soybean TGX 1440-1E + 75% maize. An increasing trend was observed in the gall index as the proportions of soybean in the intercrop increased. The population of M. incognita in the soil at the termination of the study followed the same trend for all the treatments. In the field trial, the gall index at the end of the experiment was highest in monocultures of the soybean cvs. while the combination of 25% soybean TGX 1440-1E + 75% maize had the lowest gall index. Similarly the highest percentage increase in nematode population was recorded in plots sown to soybean TGX 1740-2F alone, while that sown to maize alone had the lowest percentage increase The monoculture of soybean cv TGX 1740-2F had the highest soybean yield while 25% soybean TGX 1740 – 2F + 25% maize had lowest. Also maize alone had the highest maize yields while 50% soybean TGX 1440 – 1E + 50% maize had lowest. Seventy-five percent (75%) soybean TGX 1740 – 2F + 25% maize had the highest land Equivalent Ratio (LER) value of 2.24 while 50% soybean TGX 1440 – 1E + 50% Maize recorded the lowest value (1.14). These results indicate that there were weak yield advantages as a result of intercropping soybean and maize and different mixtures of the intercrop were effective for management of M. incognita.