Submitted to: Biodiversity of Soil International Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/24/2007
Publication Date: 9/29/2007
Citation: Arevalo, G.E., Canto, M., Baligar, V.C., Zuniga, C.L., Marquez, D.K. 2007. Population of helicotylenchus sp and aphelenchus sp nematodes in the rhizosphere of cacao (theobroma cacao l.) under traditional and improved forest management systems. Biodiversity of Soil International Conference Proceedings. 9.29.2007.
Technical Abstract: Nematode population associated with cocoa rhizosphere was investigated at field experiment at Tropical Crop Institute (ICT) Tarapoto, San Martin-Peru. This study was carried out under two cacao management systems: traditional management system (ST) and under improved forest management system (SBB). In both systems of management 10 cacao genotypes (ICT-2142, CCN-51, ICT-1112, ICT-1026, ICT-2162, ICT-2171, ICS-95, UF-613, U-30 y H-35) and a hybrid cacao as a control; were planted in random manner and a complete random block design was adapted. Nematodes were determined from soil samples collected at three soil depth (0-20, 20-40, 40-60 cm). In each plot 10 sample sites were selected in zigzag fashion and soil was sampled in each site at desired depth and samples of each depth from 10 sites were mixed and a composite sample was selected for nematode extraction. The nematodes were extracted from soil by sieving and “bandejita” methods. Before the installation of the different cocoa management systems, nematodes population in the experimental area was 87 nemat/100cc soils, of this total, Helicotylenchus sp and Aphelenchus sp represented 12.5% and 5.7% respectively. Two years after the initiation of two cacao management systems the nematode population in SBB system was 172 nemat/100cc of soil, of which 16.11% represented Helicotylenchus sp with a growing rate of 8.38 nemat/100cc of soil per year and 0.93% of Aphelenchus sp with a growing rate of -1.67 nemat/100cc of soil per year. While the nematode population in the ST system was 321 nemat/100cc of soil of which 6.3% represents Helicotylenchus sp with a growing rate of 4.63 nemat/100cc of soil per year and 22.78% of Aphelenchus sp with a growing rate of 34.03 nemat/100cc of soil per year. In the SBB system the first 20 cm soil depth was dominated with Helicotylenchus sp and especially it was major component in the rhizosphere of cacao genotypes U-30 (78 nemat/100cc of soil) followed by cacao genotypes CCN-51 ICT-2162 and H-35 (50, 42and 40 nemat/100cc of soil, respectively); while in the ST system the Helicotylenchus sp population was major component in the cacao genotypes of ICT-2142, ICT-1026 and ICS-95 (44, 36 and 31 nemat/100cc of soil, respectively). The Helicotylenchus sp population decreased considerably with soil depth. While the Aphelenchus sp was major component in the ST system at 20 cm of soil depth for cacao genotypes CCN-51, ICS-95 and H-35 (133, 89 and 71 nemat/100cc of soil respectively), where as at 20-40cm of soil depth cacao genotypes ICS-95 and CCN-51 (60 and 56 nemat/100cc respectively) recorded the highest; and at 40-60cm of soil depth the population decreased considerably. The Helicotylenchus population was predominant in the SBB