Studies On Niche Of Rice Sheath Blight And Ecological Management Tactics

Because of limitation of the Integrated Pest management (rPM) concept and social, economical, technical and organizational obstacles, the rate of adoption of 1PM by farmers has been very low. The principles and methods of ecological pest management (EPM) are proposed for development of 1PM. In the paper, theory of sustainable agriculture, theory of EPM and niche theory were used to study the niche of rice sheath blight and the tactics of rice sheath blight ecological management. The main results were Summarized as following: 1.Measure of niches of rice sheath blight (fungus) 1.1 Temporal and spatial niches of rice sheath blight Some indexes of temporal and spatial niches of rice sheath blight were measured. Structures and dynamics of temporal and spatial niches of rice sheath blight were analyzed. The results show: Index of temporal niche breadth of rice sheath blight in the last first leaf was the minimum, was 0. 1194. Index of temporal niche breadth of rice sheath blight in the last fourth leaf was the maximum, was 0.5463. In all, index of temporal niche breadth of rice sheath blight increased following the height of the leaf and sheath of rice lower. Index of vertical spatial niche breadth of rice sheath blight was the minimum on 22 in June, was 0. 1250. Index of vertical spatial niche breadth of rice sheath blight was the maximum on 22 in August, was 0.7759. In all, index of vertical spatial niche breadth of rice sheath blight increase following the rice grow. Indexes of horizontal spatial niche breadth of rice sheath blight in different date were similar. 1.2 Habitat niche of rice sheath blight fungus Indexes of habitat niche function were different in Iv different habitats at the same growth stages. Apparent was: Center of field > North Side, West Side, East Side > South Side > Corner of field. The result show: Affect of control rice sheath blight development for Habitats of corner and south side of field were the most forceful. 1.3 Host niches of rice sheath blight fungus At jointing stage, booting stage, heading stage and milking stage, the indexes of host niche breadth of rice sheath blight fungus separately were 0.913039, 0.858850, 0. 845239, 0. 963078, all approached l.This shows that Selection quality of fungus for cultivars was similar. In the treatment of more cultivars cultivated together, the index of niche breadth was smaller than that of the treatments of single cultivars cultivated. These show that the treatment of more cultivars cultivated together do not benefit fungus of rice sheath blight. 1.4 Nutrition of nitrogen fertilizer niches of rice sheath blight fungus At different growth stages of rice, Nutrition niche breadths were different. The index of niche breadth was the maximum at jointing stage and milking stage, separately were 0. 9741 and 0. 9815. The index at booting stage was the minimum, was 0. 6979. The show that utilization ratios of nitrogen fertilizer for rice sheath blight fungus were different at different growth stages of rice. 1.5 Mineral nutrition niches of rice sheath blight fungus At tiller stage, booting stage, heading stage and waxing stage, the indexes of mineral nutrition niche breadth of rice sheath blight...