ABSTRACT
The main goal of our research work is to search for nodule bacteria of local soybean varieties and to identify and study their nodule-forming properties. In the present study, soil samples from fields in the Tashkent, Andijan, Bukhara, Jizzakh, Kashkadarya, Navoi, Namangan, Samarkand, Surkhandarya, Syrdarya, Fergana, and Khorezm regions of Uzbekistan were studied for the formation of symbiotic nodules in local soybean varieties. Nodules formed only in the soils of the Tashkent region in the root systems of local soybean varieties (Madad, Sevinch, Dostlik, Parvoz, Gavkhar, Khasildar, Baraka, Tashkent, Uzbekistan-6, Tumaris, Nafis, Orzu) were formed from 22 to 40 nodule. Forty-one bacterial species belonging to the genus Bradyrhizobium were isolated from the nodules of the different varieties. The specificity, virulence, and symbiotic efficacy of 12 active nodule bacteria were compared in the local Madad, Sevinch, Dostlik, and Parvoz varieties. The root systems of these varieties formed from 2 to 14 symbiotic pink nodules 0.5 - 10 mm in size. Inoculation of the Madad and Dostlik varieties with their specific M5-1 and D24-1 nodule bacteria resulted in a symbiotic efficiency 46.6% - 54.4% higher than in uninoculated control plants. Notably, the foreign inoculum “Rizovit” (Kazakhstan), created on the basis of Bradyrhizobium japonicum, did not form any nodules on the roots of the local Uzbekistan varieties. The main reason for this may be the difference in the genetic origin of foreign soybean varieties and domestic Uzbekistan varieties. The nucleotide sequences of 16S rRNA genes of nodule bacteria M5-1, S7-2, D24-1, and P12-1 showed 97.07% similarity with the 16S rRNA genes of Bradyrhizobium japonicum PRY65 (AF239848.2) and 98.98% similarity with Bradyrhizobium japonicum PRY62 (AF239847.2).