Özet:

Community level physiological profiles (CLPP) and molecular diversity of bacteria in soil under rice–rice (RR), rice-fallow (RF), rice-wheat (RW), legume (LG), mango orchard (MO), and grass land (GL) cropping systems occurring in South West Bengal, India (22°22'N latitude and 86°26'E longitude) were studied. The soils were mostly acidic (pH 5.4 to 6.85). The GL soil recorded the highest organic carbon (20.23 g kg-1) and total nitrogen (1.96 g kg-1). The RF soil was the most acidic and had the poorest nutrient contents. The CLPP, as studied by carbon source utilization in BIOLOG Ecoplates, revealed that the bacteria in soils under different cropping systems could differentially utilize all the groups of carbon sources viz. carbohydrate, amino acid, carboxylic acid, polymer, amine/amide, and phenolic compound. Carbohydrate was most utilized and amine/amide and phenolic compound were least utilized. Bacterial communities in RF soil utilized the highest amount of carbohydrate and carboxylic acid and also utilized a balanced amount of other individual carbon substrates. Molecular diversity was studied by polymerase chain reaction followed by amplified ribosomal DNA restriction analysis (ARDRA) of soil DNA. Variations in ARDRA banding pattern followed by cluster analysis and the resulting dendrogram indicated that the cropping systems induced changes in soil bacterial communities. The grouping of uncultivated soils (MO and GL) in a separate cluster clearly indicated the presence of different bacterial communities.

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