Dynamics of plant parasitic and free living nematode populations in sugarcane <i>Saccharum officinarum</i> in Fiji
Parasitic nematodes are one of the main constraints in the production of sugarcane, Saccharum officinarum, in Fiji and other sugarcane-growing countries. Both plant parasitic and free-living nematodes are associated with roots of the plant, and the level of infestation affects both soil health and cane yield. This study examined the dynamics of plant parasitic and free-living nematode populations in sugarcane crops in Drasa Estate, Lautoka, Fiji. Soil samples to quantify nematode populations were collected ve times during the crop cycle. There was an exponential increase in the plant parasitic nematode population with time after planting (nematode population=64.316e0.0112x; R2=0.56, x=days after planting). However, the increase was not consistent among the different nematode groups. Significant increases in Lesion (P<0.05), Rootknot (P<0.05), Spiral (P<0.01), and Ring (P<0.03) nematode populations were found but not for Reniforms (P>0.05). Populations of free-living nematodes built up 90 days after planting and remained elevated in the ratoon crop. Populations of parasitic nematodes increased with the growth of cane (as measured by cane height) with increases occurring faster in the ratoon than in the plant crop (P=0.001). The number of free-living nematodes may have affected population growth of parasitic nematodes.