梨树叶片黄化与根际土壤微生物及养分关系

以甘肃景泰叶片黄化梨园土壤为例，比较黄化和非黄化梨园0～20 cm和20～40 cm土壤微生物及养分，以探讨与梨树叶片黄化相关因子，为解决黄化问题提供科学依据。研究表明：黄化土壤细菌、放线菌数量都显著少于非黄化土壤的数量，浅层（0～20 cm）黄化土壤的细菌数量少于非黄化土的4662%，放线菌数量少5249%；深层（20～40 cm）黄化土的细菌数量少于非黄化土的7822%，放线菌少5013%。两者的真菌数量差异不显著。黄化土壤20～40 cm的有机质、全氮、全铁、全镁含量显著低于非黄化土壤和黄化土壤0～20 cm土层的含量。因此，梨树叶片黄化与土壤中细菌、放线菌数量减少、20～40 cm土层的有机质、全氮、全铁、全镁含量过低有关。建议重点增施黄化梨园20～40 cm土层的腐熟有机肥。

Relationships between leaf yellowing and soil microorganisms/nutrients in pear orchards

The microorganisms and nutrients in the rhizosphere soil of leaf yellowing and normal pear trees in Jingtai County， Gansu Province were studied to find out the factors related with leaf yellowing. The results showed that bacteria and actinomyce in soil of the leaf yellowing pear trees were significantly lower than those in the soil of normal trees. The bacteria and actinomyce in the shallow layer （0-20 cm） of soil in leaf yellowing orchard were 4662% and 5249% less than those of normal orchard; while in the deeper layer （20-40 cm） of soil of leaf yellowing pear orchard， bacteria and actinomyce were 7822% and 5013% less than those from normal orchard. There was no significant difference between the two kinds of pear trees in the amount of fungus. In 20-40 cm deep soil from the leaf yellowing pear orchard， the content of organic matter， total N， total Fe and total Mg were significantly lower than those from normal pear tree soil and those in 0-20 cm deep soil from the leaf yellowing orchard. Therefore， decrease of bacteria， actinomyce and organic matter， total N， total Fe and total Mg in 20-40 cm deep soil were the main factors related to leaf yellowing. Thus， applying decomposed manure to soil of 20-40 cm deep in leaf yellowing pear orchards should be suggested.