关键词: 夏闲期, 深翻, 覆盖, 旱地麦田, 土壤水分, 产量

Abstract: Dust pollution is much heavier in winter than in other seasons in the cities of Northeast China，because the urban heating system consumes mainly coal as energy resources．Deciduous trees can hardly abso rb dust because of their
defoliation．and hence，urban conifer trees become more important in dust abso rption in winter This paper studied the dust absorption ability of 7 conifers under the same and小fferent dust pollution status in Shenyang city，
Northeast China．The results showed that the dust absorption ability of conifers was decreased in the order of Abies holophilla > Picea mongolica > P ． koraiensis> Taxus cupidata > Pinus bungeana > P ． armandi> P ．
tabulaeformis．Different conifers had different suHace structures．Pinus bungeana，P armandi and P．tabulaeJormis had smooth suHaces，their cells and stomata arranged in order，and hence，their dust abso rption ability
was po r．P ．koraiensis， Abies holophilla and Ta：cus cupidata had coarse surfaces，and their cells and stomata arranged out of order．There were even m any tubercular things on the surface of P ．koraiensis，and hence，their
dust absorption ability was stronger．The dust absorption ability of conifers was related the shape of their leaf sections．The upper leaf surface of Pinus bungeana and P．tabulaeformis was arc，not opted to absorb the dust
The leaf section of P．armandi was prism．and its upper surface was narrow，and hence。its dust absorption ability was also po r．The leaves of Picea mongolica and P koraiensis had four edges．their upper surfaces were
broader and flatter than the form er three species，and hence，they had stronger dust absorp tion ability，The leaf section’s shape of Abies holophiUa and Taxus cupidata was also broad and fiat，which made the dust absorption
ability of the two latter’S WaS stronger than other three Pinus species and two Picea species．

Key words: fallow period, deep plowing, mulch, dryland wheat, soil water, yield.