مطالعه جمعیت و شاخص های رشد کرم خاکی Lumbricus terrestris L. در یک خاک شور شده با نمک کلرید سدیم و اهمیت مواد اصلاحی آلی در تعدیل اثر شوری

Abstract

Abstract Soil salinity in huge parts of the world, especially in arid and semi-arid regions, is a factor limiting growth of plant and other organisms. Earthworm can be considered as an indicator of soil quality in agroecosystems, because of a positive correlation between earthworm abundance and the productivity of cropped plants. The main objective of this study was to realize the interaction between soil salinity and organic amendments on the growth and populations of anecic earthworm (Lumbricus terrestris L.) under controlled greenhouse conditions. The experiment was a 4×4 factorial consisting of three levels of salinity (2, 4 and 8 dSm-1) obtained using NaCl (plus a control) and three organic amendments (alfalfa and corn residues, cow manure and control) arranged in a completely randomized design replicated three times. The experiment lasted 15 weeks. Results showed that increasing soil salinity caused a significant reduction (P ≤ 0.001) in all the earthworm's growth indices. The increase in salinity from 0.49 dS m-1 (control) to 8 dS m-1 reduced the number of earthworms (32%), fresh weight of worms (54%), dry weight of worms (54%), worms length (25%) and the number of cocoon (35%), suggesting the harmful effect of salinity on earthworms growth. The application of organic amendments has, to some extent, alleviated salinity effects on earthworms, and resulted in increases in earthworm growth rates at all salinity levels. Soils amended with alfalfa residues showed the highest alleviating outcomes. In summary, salinity reduced the growth and activity of earthworms L. terrestris and the added organic materials, however, lowered the detrimental effects of salinity on earthworms in the studied soil. Keywords: Earthworm, Growth index, Organic amendments, Salinity, Saline environments, Lumbricus terrestris L