Distribution of Hirschmanniella oryzae in the province of Laguna, Philippines
1990
Prot, J.C. (International Rice Research Inst., Los Banos, Laguna (Philippines))
A survey was conducted to estimate the infestation level by Hirschmanniella oryzae and its distribution pattern in Laguna province [Philippines]. Soil and root samples were collected from 84 fields (10 samples per field) at different rice growth stages (17 at minimum tillering, 18 at flowering, and 49 at maturity). Only 19 samples out of the 840 collected did not contain detectable numbers of H. oryzae in the soil and the roots. The average number of nematodes detected per dm3 of soil and g of roots were 516 (range: 0-19075) and 30 (range : 0-927), respectively. Population densities of more than 200 nematodes per dm3 of soil or 20 per g of roots were detected in 539 samples. The average number of nematodes detected per dm3 of soil at maturity (764) was significantly higher than at maximum tillering (154) and flowering (181). The average number of nematodes detected per g of roots at maximum tillering (64), flowering (34) and maturity (18) were significantly different of each other. After chi-square goodness-of-fit tests, none of the population distribution differed significantly from a negative binomial distribution at P0.01. Moreover, the six distributions may be described by the Taylor power function (S2
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