Abstract: To explore the adaptive strategy of ruderal species in response to highly heterogeneous habitats in the context of urbanization, diversity and distribution of ruderal species were investigated in the urban area of Harbin City. The results showed that there were 175 ruderal species in the urban area of Harbin, belonging to 38 families and 128 genera, with a large proportion as monotypicgenus and geographically diverse types reflecting a substantially heterogeneous habitat condition. Ruderal species in the urban area resided mainly on gaps of forests and shrub-grasslands, abandoned fields and roadsides, indicating a progressively declined living space with increased heterogeneity and
unstability. The widespread ruderal species with strong plasticity and short life cycle exhibited a relatively great tolerance with respect to intensive and frequent human disturbance. Based on their habitat properties and adaptive ability, the 175 urban ruderal species could be classified into four ecological groups: eurytopic species, shady and wettolerant species, mesophytic species, and trample and mowingtolerant species.

Key words: early rice, P and K fertili-zer, low temperature, yield, leaf temperature, panicle primordium differentiation stage, physiological characteristics