Relationship between inoculum density levels of Pratylenchus scribneri, and growth and yieldof maize, Zea mays

摘要

The relationship between Pratylenchus scribneri and growth and yield of maize was evaluated using seven different inoculum density levels of the nematode, ranging from 10.5-671 nematodes/100 ml of soil, in pot experiments. The results showed that thedamp root system, the dry shoot weight and height, and the cob and grain yields were reduced with an increase in the inoculum density level. The decrease became critical at inoculum density level of 168 nematodes/100 ml of soil, suggesting this to be theinoculum damage threshold level. The highest decrease in root system (44.3%) far exceeded the decrease of dry shoot weight (18.4%), shoot height (14.5%), and cob (22.5%) and grain (36.9%) yields at the highest inoculum density level of 671 nematodes/100ml of soil. Based on the average maize grain yield of 902 kg/ha, the grain loss of 26% at the inoculum damage threshold of 168 nematodes/100 ml of soil, is equivalent to 234.52 kg/ha. This, in monetary terms, equates to N35,178 (approximately, USD $232)which is of great economic concern to the local farmers.