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Identification, Pathogenicity, Suscept, and Life Cycle of Tylenchorhynchus Species Associated with Sugarcane (Saccharum Offlcinarium L.) in the Philippines
Thesis Abstract:
Two species of Tylenchorhynchus, T. annulatus (T. martini), and T. cylindricus, were found in sugarcane in provinces of Laguna, Batangas, Pampanga, and Tarlac in the Philippines. T. annulatus was found in samples collected in all the provinces tested whereas T. Cylindricus was found only in Tarlac. T. annulatus was pathogenic to potted sugarcane var. Phil. 56226.
Height of sugarcane at 400, 600, and 1,000 inoculum level/pot was significantly lower than the control by 10.44 percent, 11.41 percent, and 11.79 pertent, respectively, 20 weeks after inoculation.
Top weight reduction at 400, 600, and 1,000 inoculum level/pot were 29.99 percent and 39.29 percent, respectively, as compared with the control. With 400, 600, and 1,000 inoculum level/pot, fresh root weight were reduced by 46.55 percent, 47.14 percent, and 48.90 percent, respectively, as compared with the control.
The average nematode population at 50, 100, 200, 400, 600, and 100 inoculum level/pot, increased by 493; 2,248; 2,616; 5,828; 6,039; and 7.184; or 9.86, 22.48, 13.08, 14.57, 10.06, and 7.18 folds, respectively. T. annulatus reproduced on several plant species.
Based on reproduction indices, corn and sorghum were considered excellent hosts; rice, intermediate host; purple nutsedge and Bermuda grass, very poor hosts; and soybean, tomato, cotton, tobacco, peanut, mungbean, itch grass, spiny amaranth, and wire grass, non-hosts.
The life cycle of T. annulatus on rice seedling on one percent plated sterile water agar was completed in 20-22 days. The egg stage lasted 4-5 days; the second stage larvae, 3-4 days; the third stage larvae, 5-6 days; and the fourth stage larvae, 3-4 days. The developmental stages of T. annulatus required four molts. A female can lay 6-9 eggs in 4-6 days. Sometimes two eggs are laid in one day. T. annulatus fed only on epidermal cells in the region cell elongation, never invading the roots. Hence, they were classified as ectoparasitic nematodes.