Lentinus squarrosulus
, an indigenous Nigerian mushroom species, was cultured on six different media that were inoculated separately with three different spawn grains and amended with six different oils at five different rates. The results revealed that the interaction of the different spawn grains with the various oil types produced a highly significant effect (p<0.01) on the stipe length, dry weight, and stipe and pileus diameters of
Lentinus squarrosulus.The interactions of corn x coconut and corn x butterfat, respectively produced stipe lengths that were statistically longer than the comparable stipe lengths produced by the interaction of corn x groundnut and wheat x cotton, respectively. The shortest stipe lengths were, however, produced by the interaction of palm kernel oil with wheat and corn grains, respectively. The interaction of millet x groundnut produced stipe diameters, which were statistically wider than those produced by the interaction of corn x coconut that was statistically wider than the comparable diameters induced by the interaction of wheat x cotton and corn x butterfat, respectively. The poorest stipe diameters were produced by the interaction of wheat x palm kernel, wheat x palm, and corn x palm kernel oil. The carpophore dry weight produced by the interaction of corn x coconut was statistically heavier than the comparable dry weights produced by the interaction of corn x groundnut, corn x butterfat, and millet x palm oil. The comparable mean carpophore dry weights produced by the interaction of wheat x coconut, millet x coconut, wheat x cotton, millet x cotton, and wheat x groundnut oil, respectively were statistically heavier than the mean dry weights produced by the interaction of wheat x palm kernel, which was the poorest. The mean pileus diameters produced by the interaction of corn x coconut was statistically comparable to those produced by the interaction of wheat x coconut and corn x butterfat, but statistically heavier than the comparable mean diameters produced by the interaction of wheat x cotton and corn x groundnut oil. The comparable pileus diameters induced by the interaction of palm kernel oil with wheat and corn grain, respectively produced the poorest results. The current findings illustrate the importance of oil amendment in mushroom culture.