Effects of seed inoculation and incorporation of different nitrogen rates on nitrogen fixation parameters

Abstract

From the point of view of agricultural production, nitrogen deficiency in the soil results in significant yield losses and yield quality reduction. Symbiotic fixation of atmospheric nitrogen plays a significant role in the supply of plants with nitrogen. Soybean (Glycine max. (L.) Merr.) is one of the most important legumes in Serbia and the world, most notably because of the outstanding chemical composition of its grain. The objective of this paper was to use nitrogen fixation parameters to determine the optimum amounts of mineral nitrogen needed when growing soybean using inoculation with the biofertilizer NS-Nitragin. A trial on a chernozem soil was set up at the Bački Petrovac experiment field of the Institute of Field and Vegetable Crops using a randomized block design with four replicates. The soybean cultivar Balkan and four rates of nitrogen fertilizer (0, 30, 60, and 90 kg N/ha) were used in the experiment. Each of the nitrogen treatments had two variations, with and without inoculation. Just before sowing, the seed was inoculated the soybean biofertilizer NS-Nitragin. The effects of inoculation and different nitrogen fertilizer rates on the effectiveness of symbiotic association were determined at soybean flowering based on the number of nodules formed on the root and the dry matter weight and nitrogen content of the above-ground plant parts, root, and nodules. On an average for all the fertilization treatments, the above-ground weight of the inoculated plants increased by 19% relative to the uninoculated treatments, while the nitrogen content increased by 23%. The nitrogen content of the root system in the inoculated treatments increased by 15% relative to uninoculated plants, and the root system was also more developed (11%) in the former than in the latter. The incorporation of 60 kg N/ha before sowing along with inoculation produced the greatest above-ground and root weights as well as the highest nitrogen content of the above-ground parts and root. Inoculation had a positive effect nodule number (205% increase), weight (59% increase), and nitrogen content (60% increase). Inoculation accompanied by a nitrogen rate of 30 kg/ha produced the best nodulation and the largest weight and highest nitrogen content of nodules.

Sa stanovišta poljoprivredne proizvodnje, nedostatak azota u zemljištu značajno utiče na smanjenje prinosa i njegov kvalitet. U obezbeđivanju biljaka azotom značajnu ulogu ima simbiotska fiksacija atmosferskog azota. Soja (Glycine max. (L.) Merr.) je jedna od najznačajnijh leguminoza i u svetu i kod nas, pre svega zbog izuzetnog hemijskog sastava zrna. Cilj rada je bio da se preko parametara azotofiksacije utvrdi optimalna količina mineralnog azota u gajenju soje uz inokulaciju mikrobiološkim preparatom NS-Nitragin. Ogled je postavljen na oglednom polju Instituta za ratarstvo i povrtarstvo u Bačkom Petrovcu, na zemljištu tipa černozem, po slučajnom blok sistemu u četiri ponavljanja. U eksperimentu je korišćena sorta soje Balkan, i primenjena su četiri različita nivo đubrenja azotom (kontrola, 30, 60, 90 kg N/ha). Ogled je postavljen u dve varijante, sa inokulacijom (NS-Nitragin za soju) i bez inokulacije. Uticaj inokulacije i različitih koncentracija primenjenih azotnih đubriva na efektivnost simbiotske zajednice određena je u fazi cvetanja soje preko broja formiranih kvržica na korenu, mase suve materije i sadržaja azota u nadzemnom delu biljke, korenu i kvržicama. U proseku za sve varijante đubernja masa nadzemnog dela inokulisanih biljaka povećana je za 19% u odnosu na neinokulisane, dok je sadržaj azota povećan za 23%. Rezultati istarživanja pokazali su da je u korenovom sistemu inokulisanih biljaka sadržaj azota bio veći (15%), a sam korenov sistem razvijeniji (11%) od biljaka koje nisu inokulisane. Predsetvenim unošenjem 60 kg N/ha i inokulacijom ostvarena je najveća masa nadzemnog dela biljke i korena, kao i najveći sadržaj azota u nadzemnom delu i korenu. Inokulacija je na svim ispitivanim varijantama đubrenja pozitivno uticala na broj (205%), masu (59%), ali i na sadržaj azota u kvržicama (60%). Inokulacijom soje i dodatkom mineralnog azota u količini 30 kg/ha ostvarena je najbolja nodulacija, najveća masa i sadržaj azota u kvržicama.