Identification and control of plant parasitic nematoues associated with nee using organic amendments in Thatta district, Sindh.

Abstract

Rice is the most important food crop of the world being staple food for more than half of the world's population. lt is infested· by a number of pathogens including nematodes which eventually reduce its yield. During the study period from June 1, 1997 to May 31, 1998, a total of eight nematodes namely Hirschmanniella oryzae (van Breda de Haan, 1902) Luc & Goodey, 1964; Tylenchorhynchus ann?latus (Cassidy, 1930) Golden, 1971; Hop/olaimus indicus Sher, 1963; Pratylenchus zeae Graham, 1951; Helicotylenchus dihystera (Cobb, 1893) Sher, 1961; Basiria graminophila Siddiqi, 1959; Aphelenchus avenae Bastian, 1865 and Tylenchus Bastian, 1865 sp. larvae were isolated from rice variety lRRl-6 and Lateefy 1 while from variety Kharai Ganja Hirschmannie//a oryzae; Hoplolaimus indicus and Tylenchorhynchus annulatus were recorded. During the present studies association of nematode species were disclosed by principal component ordination. Distribution pattern of different nematodes species was also studied from ordination of localities. Group structure of localities was exposed by means of cluster analysis that yielded homogenous groups of localities with similar nematode composition. In dry fields (during October) the population of Tylenchorhynchus annulatus was higher as compared to Hirschmanniella oryzae while in wet fields H. oryzae population was high while that of T. annulatus was low. There seemed to be a significant inverse correlation between the population of these two nematodes. Rice varieties IRRl-6 and Lateefy seemed to be more susceptible to nematodes as compared to variety Kharai Ganja. Density data of H. oryzae was compared of aH the three varieties and it seemed to be non-significant. The effect of three organic amendments and carboturan on the populations of nematodes associated with rice variety IRRl-6 and growth parameters of

(vi)

rice were investigated. Population density of H. oryzae was significant1y lowered by the organic amendments (mustard oil cake, castor oil cake and sugarcane bagasse) and carbofuran while that of T annulatus was slightly but not significantly reduced. Root weight and root and shoot lengths were significantly elevated by all the amendments and carbofuran. Of the three organic amendments castor oil cake was the most effective in the control of H. oryzae populations while growth parameters were elevated most in mustard oil cake. In the second year effect of nine organic amendments viz, castor oil cake, mustard oil cake, sugarcane bagasse, horse manure, farmyard manure, sawdust, poultry manure, neem leaves (coarsely crushed) & wheat straw and a chemical nematicide carbofuran on the growth parameters of rice and population density of Hirschmannie/la oryzae, Tylenchorhynchus annulatus, Hoplolaimus indicus and Praty/enchus zeae were investigated. Poultry manure, horse manure and neem leaves significantly increased shoot length while root length was markedly increased by castor-oil cake, poultry manure, neem leaves and horse manure as compared to control. Shoot weight was significantly elevated by poultry manure and horse manure and root weight by poultry manure only over the controls. Grain yield was significantly enhanced over the controls by carbofuran, castor-oil cake, mustard-oil cake, poultry manure and horse manure. Population density of H. oryzae was significantly reduced over the controls by carbofuran, mustard oil cake, sawdust, neem leaves, and wheat straw, that of T. annu/atus by castor-oil cake, mustard oil-cake, carbofuran, sugarcane bagasse and farmyard manure. Population level of H. indicus was markedly reduced by castor-oil cake, mustard-oil cake, carbofuran, sugarcane bagasse, sawdust, horse manure, poultry manure, farmyard manure and neem leaves while that of P. zeae by castor-oil cake, carbofuran, mustard-oil cake, sugarcane bagasse, horse manure, poultry manure,

farmyard manure, wheat straw and neem leaves. In studies on soil amendments alongwith nerbicioes it was observed that carbofuran either alone or in combination with the herbicide gesapex significantly Increased shoot length. oesapex by itself did not alter shoot length but Increased it significantly in combination with rice husk. Similarly, rice straw did not influence shoot length. Gesapex along with rice husk did increase root length but gesapex alone had no significant effect on root length. Rice straw alone or in combination did not alter root length. Gesapex in conjunction with rice straw, husk and carbofuran increased the shoot weight, while root weight was significantly elevated by carbofuran in conjunction with gespex. Carbo?ran either singly or in combination with g?sapex increased the grain yield. Likewise, gesapex together with rice husk significantly promoted the grain yield. The population density of H. oryiae was significantly decreased over the controls by gesapex alone or in combination with carbofuran as well as rice husk. The density of T. enninetus was reduced by gesapex together with rice husk and carbofUran. Carbofuran alone did not reduce the population density of both the nematodes.