Population dynamics of phytoparasitic nematodes in pigeon pea (Cajanus cajan)

Abstract

The effect of planting date, year and pigeon pea line on the population fluctuations of phytoparasitic nematodes associated with pigeon pea was evaluated. Plots were established at the Isabela Agricultural Experiment Station between 1992 and 1994. The pigeon pea lines evaluated were 1-8-2, 1-13, 1-58-1, 1-58-3 y 11-56. Although some differences in the levels of nematode population were observed among years and lines, the maximum population levels were observed from May to July, and the minimum levels from February to April. These levels were more affected by the year than by the pigeon pea line. For each particular year, the maximum or minimum population growth consistently occurred at the same planting date, except in 1994 when the minima populations were erratic. Statistical analysis showed a significant three-way interaction between planting date, pigeon pea line and year, both for Rotylenchulus reniformis and for the total population (R. reniformis, Helicotylenchus sp. and Pratylenchus sp.). For this interaction the most influential factor was year, because the rainfall periods were different over three years. There was a positive correlation between precipitation and both the reniform nematode population and the total population, thus indicating that drastic changes in precipitation, such as those occurring in 1993 and 1994, may significantly affect the population dynamics of phytoparasitic nematodes associated with pigeon pea.