Effect of Azotobacter chroococcum application type on microorganisms in the rhizosphere and sugar beet yield

Abstract

Plant growth promoting rhizobacteria (PGPR) are a group of diverse soil bacteria which stimulate the growth of the host plant. It has been shown that Azotobacter chroococcum may be used as biofertilizer for increasing the yield and improving technological characteristics of sugar beet. The effect of three different ways of inoculation of sugarbeet with Azotobacter chroococcum on the production features of sugar beet and microbiological status of rhizosphere soil has been tested. One variety of sugar beet, Drena, was included in the tests in the region Rimski Šančevi, Novi Sad, during 2008 and 2009. Five strains of Azotobacter chroococcum (1, 5, 8, 10 and 14) were used as microbiological fertilizers. There were three variations of inoculation: (A) incorporation in the soil, (B) before the fi rst cultivation, and (C) applying the liquid culture of strain on the seed before sowing. The highest increase in yield of sugar beet roots 6.25 t ha-1 and yield of white sugar 0.91 t ha-1 was achieved with strain 10 with variant of inoculation of soil before the first cultivation. In both years, a positive effect of Azotobacter chroococcum was observed on the total number of microorganisms in the rhizosphere.

Ispitan je efekat tri različita načina inokulacije šećerne repe sa sojevima Azotobacter chroococcum na parametre prinosa šećerne repe i mikrobiološki status zemljišta. U ispitivanjima je korišćena sorta Drena, a eksperiment je bio lociran na Rimskim Šančevima u toku 2008. i 2009. Kao mikrobiološko đubrivo korišćeno je pet sojeva Azotobacter chroococcum. Inokulacija je izvršena na tri načina: (A) inkorporacijom sojeva u zemljište pre setve, (B) inkorporacija sojeva u zemljište pred prvu međurednu kultivaciju i (C) nanošenjem inokuluma na seme pre setve. Najveće povećanje u prinosu korena od 6,25 t ha-1 i u prinosu kristalnog šećera od 0,91 t ha-1 dobijeno je sa sojem 10 na varijanti inokulacije zemljišta pre prve međuredne kultivacije. U obe godine dobijen je pozitivan efekat na ukupan broj mikroorganizama i broj azotobaktera u rizosferi.