Growth promotion of alfalfa, Medicago sativa L.: By inoculation of a preceding crop with rhizobacteria

Abstract

In the greenhouse experiment, the possibility of alfalfa (Medicago sativa L.) growth promotion by inoculation of preceding barley (Hordeum vulgare L.), with plant growth promoting rhizobacteria (PGPR) was examined. The aim of experiment was to select the effective strains as biofertilizer applied in plant rotation. Effects of inoculation with two Azotobacter and two Pseudomonas strains as well as one Sinorhizobium, Enterobacter and Bacillus strain on shoot dry weight and total N content of alfalfa were determined. The results pointed out significant plant growth promotion abilities of strains A1, A2 and P1 which increased alfalfa shoot dry weight over untreated control Ø, by 41, 39 and 35 %, respectively. These three strains increased total N content of alfalfa plants by 34.92 - 40.45% in respect to control Ø. The presented study showed a significant positive influence of preceding barley inoculation with rhizobacteria alone and their mixture on shoot yield and total N content of alfalfa. Results indicated that strains of Azotobacter sp., Pseudomonas sp. and Enterobacter sp. alone can be investigated in further researches as potential agents of biofertilizer for plant growth promotion of alfalfa.

U eksprimentu u sudovima ispitana je mogućnost poboljšanja rasta lucerke (Medicago sativa L.) pomoću inokulacije ječma (Hordeum vulgare L.) kao preduseva bakterijama koje poboljšavaju rast biljaka (PGPR). Cilj eksperimenta je bio odabiranje efikasnih sojeva koji bi se primenili u plodoredu u formi biološkog đubriva. U radu je korišćeno sedam sojeva koji pripadaju sledećim bakterijskim vrstama: Sinorhizobium meliloti, Bacillus megaterium, Enterobacter sp, Azotobacter sp, kao i vrsti Pseudomonas sp. Efekat inokulacije ječma primenjenim sojevima je određen na osnovu suve nadzemne mase (SDW) i sadržaja ukupnog azota (N) u biljnoj masi lucerke. Rezultati su ukazali na sposobnost nekih sojeva da poboljšaju rast biljaka. Značajno je povećan prinos lucerke u odnosu na kontrolu Ø (lucerka gajena posle neinokulisanog ječma kao preduseva) inokulacijom sojevima Azotobacter-a A1 (41%) i A2 (39%) i Pseudomonas-a P1 (35%). Sadržaj ukupnog N je bio u korelaciji sa vrednostima SDW. Rezultati su ukazali na uticaj inokulacije ječma kao preduseva na prinos lucerke i njen kvalitet kao i da sojevi Azotobacter sp., Pseudomonas sp. i Enterobacter sp. imaju PGPR potencijal što daje osnovu za dalja ispitivanja i mogućnost primene kao bio­đubriva.