IMPACT OF SPACING ON DENSITIES OF PHYTOPARASITIC NEMATODES ASSOCIATED WITH SORGHUM-BAMBARA GROUNDNUT INTERCROPPING SYSTEM IN BENUE STATE

Abstract

Sorghum is popularly intercropped with Bambara groundnut in Benue State, Nigeria using different spatial arrangements. This study investigated the possible impact of such practice on the presence and multiplication rates of some phytoparasitic nematodes  (PPNs)  associated  with  the  intercropping.  A  field  experiment  was conducted in 2019 at the Teaching and Research Station of Federal University of Agriculture, Makurdi, Nigeria. The experiment was laid out in Randomized Complete Block  Design  (RCBD)  with  three  varieties  of  sorghum  and  four  intercropping spacings (0 cm, 10 cm, 15 cm and 20 cm) with Bambara groundnut in four replicates. The initial and final populations of PPNs in each plot were obtained and reproduction factor (Rf) was calculated for each nematode genus identified. The Rf values were subjected to analysis of variance (ANOVA) and means separated using Duncan’s New  Multiple  Range  Test  at  5%  level  of  probability.  Results  showed  that  six nematode  genera;  Pratylenchus,  Meloidogyne,  Helicotylenchus,  Criconema, Tylenchus and Trichodorus were recovered from all experimental plots. Even though found, the distribution of Rotylenchus, Xiphinema, Tylenchulus and Longidorus were sporadic and limited only to a few experimental plots. The Rf values of Meloidogyne spp.   (6.98,   5.38   and   6.08),   Pratylenchus   spp.   (7.36,   7.27   and   6.67)   and Helicotylenchus spp. (5.06, 5.87 and 5.67) calculated from plots where only sorghum var. Deko, CRS.01 and SK.5912 were planted, were generally higher compared to intercropped plots, especially at 10 cm intra-row spacings with Bambara groundnut. Irrespective of the sorghum varieties planted, the nematode multiplication rates of Criconema spp. (6.00, 5.75 and 6.33), Trichodorus spp. (5.00, 5.67 and 4.75) and Tylenchus  spp.  (8.00,  7.00  and  7.00)  were  also  the  highest  in  plots  where  only sorghum was planted as sole crops. On the contrary, the least multiplication rates of these nematodes were recorded in plots intercropped with sorghum and Bambara groundnut  at  a  spacing  of  10  cm.  Populations  of  PPNs  in  sorghum-Bambara groundnut intercropping system can be managed by maintaining an intra-row spacing of 10 cm. Such spatial arrangement can also be introduced during the sequence of any crop rotation scheme.