|Keywords (Extracted from title, table of contents and abstract of thesis)
parasitic nematodes, cereal, vegetable crops, heterodera zeae, h. avenae, epicharinematinae, karachinema, corn, H. zeae, cereal, H. avenae
Surveys for plant parasitic nematodes were carried out from plains and mountainous areas of Pakistan during 1985-88. Out of 750 soil and root samples collected 18 genera and 41 species of nematodes belonging to 14 subfamilies were identified. Of these a subfamily EPICHARINEMATINAE Maqbool and Shahina, 1985; a genus Karachinema Maqbool and Shahina, 1985; and 26 species viz., Tylenchus skarduensis Maqbool and Shahina, 1987; I bhitai Maqbool and Shahina. 1987; Cephalenchus sacchari Maqbool, Fatima and Shahina, 1984; Malenchus tabiatus Maqbool and Shahina. 1985: M. Maqbool and Shahina, 1985; Ottolenchus azadkashmirensis Maqbool and Shahina, 1985; O. Tongicauda Maqbool and Shahina, 1985; Neothada major Maqbool and Shahina, 1989; Karachinema elongatum Maqbool and Shahina, 1985; Merlinius montanus Maqbool and Shahina, 1987; Nagelus saifulmulukensis Maqbool and Shahina. 1987; Pratylenchoides maqsoodi Maqbool and Shahina. 1989; Rotylenchus fragaricus Maqbool and Shahina, 1986; R. pakistanensis Maqbool and Shahina, 1986; R. alii Maqbool and Shahina. 1986; Helicotylenchus obliquus Maqbool and Shahina, 1986; H. epiptygmata n.sp; Deladenus pakistanensis n.sp; Heterodera pakistanensis Maqbool and Shahina, 1986; H. bergeniae Maqbool and Shahina, 1988; H. cynodontis Shahina and Maqbool, 1989; Ogma sadabhari n.sp; O. multiannulata n.sp; O. qamari n.sp; Hemicycliophora veechi Maqbool, Shahina and Zarina. 1986; Aulophora karachiensis Maqbool, Shahina and Zarina, 1986 have been described and illustrated. Besides 15 known species viz., Tylenchus butteus Thorne and Malek., 1968; I. hamatus Thorne and Malek, 1968; I. sandneri Wasilewska. 1965; Malenchus nanellus Siddiqi, 1979; M. andrassyi Merny, 1970; Ottolenchus facultativus (Szczygiel, 1969) Brzeski. 1982; Tylenchorhynchus maximus Allen. 1955; I. penniseti Gupta and Uma,
1980; I. brevilineatus Williams, 1960; Rotylenchus cypriensis Antoniou. 1980; Xiphinema basiri Siddiqi, 1959; X. brevicolle Lordello and da Costa, 1961; X. index Thorne and Allen. 1950; X. intermedium Lamberti, 1979; X. insigne Loos, 1949 are reported for the first time from Pakistan. Using SEM Heterodera fici Kirjanova, 1954 has been redescribed.
Detailed studies on the distribution of corn (H. zeae) and cereal (H. avenae) cyst nematodes were undertaken. H. zeae was found fairly well distributed throughout the country, while H. avenae was observed mostly in the NWFP region. Life cycle of H. zeae completed within 19-20 days at 25-30°C, while at lower and higher temperatures it took 40-50 days. Maximum hatching of larvae of H. avenae was observed at 15°C and life cycle completed within 75-85 days at 18-20°C. Maximum reduction in fresh and dry weight of root and shoot was noted at an inoculum level of 150 cysts/pot. In H. avenae 100-150 cysts/pot the inoculum was threshold where the root and shoot growth was significantly reduced while at a inoculum level of 10-50 cysts/pot no significant reduction in root and shoot weight was observed. Host range studies revealed that all the gramineous plants are good host of H. zeae and H. avenae while nongramineous plants
tested failed to support the reproduction of cyst nematode. Sandy + sandy loam (1: 1) was observed as the best soil of the reproduction of H. zeae and H. avenae. Thirteen varieties of maize and ten varieties of barley were tested for screening resistance against H. zeae and H. avenae respectively but none was found to be immune to infection of these cyst nematodes. Aldicarb was more effective in reducing the cyst population and increasing the yield in both the H. zeae and H. avenae as compared to carbofuran. Moreover, nine wheat cultivars were also screened for theirresistance against Anguinatritici,Cvs Zamindar and Local white were found resistant while Pak-70 was found to be highly susceptible.