烟草赤星病(Alternaria alternata)发生与综合农艺措施关系的研究

Study on the Relation Between the Occurrence Degree of Tobacco Brown Spot [Aternatria alternat]and Comprehensive Farming Measure

本研究自1989年至1992年在冀东晒烟区进行。主要采用五元二次通用旋转回归组合设计,研究了烟草赤星病(Alternaria altemata)发生程度(病级)与综合农艺措施(播期x_1、密度x_2、氮x_3、磷x_4、钾x_5)之间的量化关系。结果为:(1)病级发生程度与综合农艺措施存在着密切关系,其中,与播期曲线呈有极大值的抛物线,通过调整播期可以躲开易感病季节,随密度的增加病级上升,到一定程度趋于平稳,与氮、磷、钾的关系曲线均呈近直线,但作用方向、程度存在差别。五因素中起关键作用的是播期、氮、钾;(2)措施间存在交互作用,各因素合理组配,可以减轻发病程度;(3)根据试验结果建立起在冀东生态条件下的病级与农艺措施之间的数学模型:y=1.11-0.33x_1+0.11x_2+0.38x_3+0.15x_4-0.29x_5+0.13x_1x_2-0.28x_1x_3-0.16x_1x_4-0.16x_3x_5-0.15x_1~2,依此模拟寻优筛选出最佳措施组合。经两年示范和多点调查验证,该模型能够表达烟草赤星病发病程度与各项农艺措施的关系,根据研究结果选配的农艺措施组合在一定程度上能够减轻病害。

Using the commonule combination design of quadyatic regression, the quantity rela- tion between the occurence degree of tobacco brown spot and comprehensive farming measure (seeding--time x_1, density of plant x_2, Netrogen x_3, Phosphorus x_4, Potassium x_5) Was studied from 1989 to 1992 in northeast of Hebei. It showd then: (1) disease level had close relation with comprehensive farming measure, seeding time curve was a parabola of maximum, to change seedingtime could avoid the season of the infection; with the density increasing, the disease level increased and up to some level. It was nearly stable. It also near- ly had line relation with Netrogen. Phosphorus. Potassium, but it was difference on the affective direction and degree; Those had most important effect among five factors were seeding-time, Netrogen and Potassium. (2) It could affect each other among the measure. Reasonable factor's combination could decrease infective level; (3) A mathematic equation of relation between disease levels and farming measure in northeast of Hebei ecological condition was set up: v =1. 1--0. 33x_1+0. 11x_2+0. 38x_3+0. 15x_4--0. 29x_5+0._13x_1x_2 - 0. 28x_1x_3--0. 16x_1x_4--0. 16x_3x_4 - 0. 15x^2_1 According to this model, the best measure combination could express the relation between the occurrence degree of tobacco brown spot and comprehensive farming measure. It was verified through two years demenstration in many places.