Influence of microbial preparation and nitrogen fertilization on yield and quality of sugar beet root

Istraživanja su provedena u istočnoj Hrvatskoj na dva lokaliteta tijekom tri vegetacijske godine. U pokusu su uključena četiri hibrida hibrida šećerna repe, od kojih su dva tolerantna, a dva osjetljiva na patogenu gljivu Rhizoctonia solani Kühn. Pokusi su postavljeni po split – blok shemi u 4 ponavljanja na dva tipa tla, na svakom u 24 različite varijante. Elementi istraživanja bili su: A. Hibrid (A1 - tolerantan na patogenu gljivu R. solani (Santino – Strube); A2 - tolerantan na patogenu gljivu R. solani (Jadranka - KWS); A3 - osjetljiv na patogenu gljivu R. solani (Fred - Strube); osjetljiv na patogenu gljivu R. solani (Terranova – KWS)); B. Primjena mikrobiološkog pripravka EM Aktiv (B1 – kontrola; B2 - tretman tla (40 l/ha); B3 - tretman tla (30 l/ha) + folijarna primjena (10 l/ha)); C. Gnojidba dušikom (C1 - na osnovu rezultata analize tla; C2 - reducirana za 30%). Prisustvo patogene gljive R. solani potvrđeno je uzastopno 3 godine na oba tipa tla koja su se koristila u pokusu tzv. «brzom metodom» koja je prihvaćena u svijetu i uvrštena u standardne metode dokazivanja prisustva patogene gljive R. solani u biljkama (STRUBE – DIECKMANN; Alert LFTM) kao i izolacijom patogena korištenjem selektivnih podloga Potatoe dekstrose agar te Corn meal agar. Mikrobiološki pripravak EM Aktiv sadrži P. fluorescens, B. megaterium i B. subtilis. Ove benefitne bakterije svojim eksudatima mikrobicidno djeluju na patogene gljive u tlu – uzročnike truleži korijena šećerne repe. Nadalje, mikrobiološki pripravak sadrži i dušične bakterije Azotobacter chroococcum i Azospirillum brasilense. U varijantama gdje je primijenjen biopreparat, bilo samo apliciran u tlo ili apliciran u tlo i folijarno, u odnosu na kontrolnu varijantu, dobiven je niži prosječni postotak inficiranih i propalih biljaka, sadržaj kalija, natrija i alfa-amino dušika i šećera, kao i viši prinos korijena, sadržaj šećera, postotak iskorištenja šećera na repu i prinos čistog šećera. Tolerantni hibridi su u odnosu na osjetljive hibride ostvarili niži prosječni postotak inficiranih i propalih biljaka, sadržaj kalija, natrija i alfa-amino dušika i šećera, kao i viši prinos korijena, sadržaj šećera, postotak iskorištenja šećera na repu i prinos čistog šećera. Međutim, značajno veća je razlika između kontrolne varijante i varijanti u kojima je primijenjen biopreparat kod deklarirano osjetljivih hibrida u odnosu na deklarirano tolerantne hibride.The investigations were conducted in Eastern Croatia on two sites during three vegetation years. Four sugar beet hybrids were included in the experiment, two tolerant and two sensitive to the pathogenic fungus Rhizoctonia solani Kühn. The experiments were set up according to a split - block scheme in 4 repetitions on two soil types, each in 24 different variants. Elements of the study were: A. Hybrid (A1 - tolerant to pathogenic fungi R. solani (Santino – Strube); A2 - tolerant to pathogenic fungi R. solani (Jadranka - KWS); A3 - sensitive to pathogenic fungi R. solani (Fred - Strubs); sensitive to pathogenic fungus R. solani (Terranova - KWS)); B. Application of microbiological preparation EM Aktiv (B1 - control; B2 - soil treatment (40 l / ha); B3 - soil treatment (30 l / ha) + foliar application (10 l / ha)) C. Nitrogen fertilization (C1 - based on soil analysis results; C2 - reduced by 30%)). The presence of the pathogenic fungus R. solani was confirmed using the so-called „fast method“ repeatedly for all 3 years on both soil types used in the experiment. The "fast method" is accepted worldwide and is included in the standard methods of demonstrating the presence of the pathogenic fungus R. solani in plants (STRUBE - DIECKMANN; Alert LFTM). Also, R. solani was confirmed through the isolation of pathogens using selective media as Potato dextrose agar and Corn meal agar. The microbiological preparation EM Aktiv contains P. fluorescens, B. megaterium and B. subtilis. Because of their exudats, these beneficial bacteria have a microbicidal effect on pathogenic fungi in the soil - causative agents of sugar beet root rot. Furthermore, the microbiological composition contains nitrogenous bacteria A. chroococcum and A. brasilense. In variants where biopreparation was applied, either solely applied into the soil or applied into the soil and foliar, compared to the control variant, a lower average percentage of infected and failed plants, potassium, sodium and alpha-amino nitrogen and sugar content was obtained, as well as higher root yield, sugar content, percentage of sugar utilization in beet root and pure sugar yield. Tolerant hybrids achieved a lower average percentage of infected and failed plants, potassium, sodium and alpha-amino nitrogen and sugar content than sensitive hybrids, as well as higher root yield, sugar content, sugar beet yield and pure sugar yield. However, significantly higher is the difference between the control variants and variants with biopreparation observing sensitive hybrids than it is on the variants with tolerant hybrids