Characterization of microorganisms with PGP characteristics and their survival in the rhizosphere

PGP mikroorganizmi (Plant Growth Promoting) su predmet mnogobrojnih istraživanja, čiji je glavni cilj pronalaženje adekvatnog načina njihove primene u poljoprivredi, hortikulturi, šumarstvu i zaštititi životne sredine. Cilj ovih istraživanja bio je izolacija i karakterizacija mikroorganizama sa PGP svojstvima iz rizosfere engleskog ljulja, ispitivanje sposobnosti njihovog preživljavanja nakon unošenja u zemljište, kao i praćenje uticaja njihove primene na parametre prinosa i mikrobiološku aktivnost u rizosferi biljke. Karakterizacija izolata roda Pseudomonas, Bacillus i Streptomyces obuhvatila je određivanje fizioloških, biohemijskih i PGP osobina. Uticaj introdukcije odabranih izolata i gljive Trichoderma asperellum na brojnost i mikrobiološku aktivnost u rizosferi engleskog ljulja, određivan je standardnim metodama na selektivnim hranljivim podlogama, a dehidrogenazna aktivnost spektrofotometrijskom metodom. U laboratorijskim uslovima ispitivan je efekat primene izolata na klijavost, dužinu korenka i stabaoca klice semena engleskog ljulja. U toku godine, uzimana su tri otkosa i pri tome su određivani dužina nadzemnog dela i korena biljke (cm) i prinos zelene i suve materije nadzemnog dela biljke po otkosu (t/ha). Na osnovu morfoloških, fiziološko-biohemijskih, kao i PGP osobina koje su izolati pokazali, te na osnovu rezultata mnogobrojnih dosadašnjih istraživanja, može se zaključiti da izolati P1 i P9 pripadaju vrsti Pseudomonas putida, izolat P12 Pseudomonas fluorescens, izolati B1, B3 i B6 vrsti Bacillus subtilis, a izolati A1, A2, A3 rodu Streptomyces. Brojnost pojedinih sistematskih i fizioloških grupa mikroorganizama kao i enzimatska aktivnost u rizosferi engleskog ljulja, zavisila je od primenjenih inokulanata. Primena izolata Pseudomonas sp. P12 pozitivno je uticala na povećanje ukupnog broja mikroorganizama, brojnost gljiva, aminoheterotrofa i aktinomiceta. Izolat Bacillus sp. B1 uticao je na povećanje ukupnog broja mikroorganizama, brojnosti gljiva i azotobaktera. Primena izolata Streptomyces sp. A3 dovela je do povećanja broja aktinomiceta i oligonitrofila, dok je primena Trichoderma asperellum uticala pozitivno na povećanje broja aminoheterotrofa i azotobaktera. Primena izolata Pseudomonas sp. P12 i Streptomyces sp. A3 imala je najveći efekat na dehidrogenaznu aktivnost. Inokulacija je imala pozitivan uticaj na klijavost, svežu i suvu masu biljke, visinu i dužinu korena biljaka. Primena gljive Trichoderma asperellum i izolata Streptomyces sp. A3 delovala je pozitivno na klijavost, dužinu korenka i stabaoca klice. U proseku, najbolji efekat na prinos sveže i suve materije, kao i na visinu nadzemnog dela i dužinu korena biljke, imala je primena izolata Pseudomonas sp.P12 i Bacillus sp. B1.U proizvodnji krmnih trava mikroorganizmi još nisu našli značajniju praktičnu primenu iako je veći i kvalitetniji prinos jedan od ciljeva stočarske proizvodnje. Rezultati ovih istraživanja su pokazali da se primenom mikroorganizama mogu postići pozitivni efekti i u proizvodnji engleskog ljulja. Zbog toga je veoma značajno da se vrše dalja ispitivanja uzajamnog odnosa primenjenih mikroorganizama i engleskog ljulja u poljskim uslovima, kako bi se optimizirao način i vreme primene inokulanataPGP microorganisms (Plant Growth Promoting) have been the subject of many research projects, whose main goal is to find appropriate methods of their use in agriculture, horticulture, forestry and environmental protection. The aim of this study is the isolation and characterization of microorganisms with PGP characteristics from the rhizosphere of perennial ryegrass, testing their ability to survive after entering the soil, and monitoring the impact of their application on yield parameters and microbial activity in the rhizosphere of plants. Characterization of Pseudomonas, Bacillus and Streptomyces included determination of the physiological, biochemical and PGP characteristics. Impact of the introduction of selected isolates and fungi Trichoderma asperellum on quantity and microbial activity in the rhizosphere of ryegrass was determined by using the standard method of selective media; dehydrogenase activity by the spectrophotometric method. The effects of the implementation of isolates on germination, seedling length sprouts seeds of perennial ryegrass were studied under laboratory conditions. During the year, three cuttings were taken. At each of the three cuttings, length of stem and roots of plants (cm) and yields of fresh and dry matter of the plant (t / ha) were measured. Based on morphological, physiological and biochemical characteristics and PGP characteristics observed in the isolates, and based on the results of many previous studies, it can be concluded that (1) P1 and P9 isolates belong to the species Pseudomonas putida, (2)Pseudomonas fluorescens P12 isolate, isolates of B1, B3, B6, belong to the species Bacillus subtilis, and (3) A1, A2 and A3 isolates belong to the ordo Streptomyces. The quantity of systematic and physiological groups of microorganisms and enzymatic activity in the rhizosphere of ryegrass depended on the applied inoculants. Application of Pseudomonas sp. P12 had positive effects on increasing the total number of microorganisms, fungi, aminoheterotrophs and actinomycetes. Isolate Bacillus sp. B1 affected the increase of the total number of micro-organisms in the fungi and Azotobacter. Application of Streptomyces sp. isolates A3 led to an increase in the number of actinomycetes and oligonitrophyls, while the application of Trichoderma asperellum had positive impact on increasing the number aminoheterotrophs and Azotobacter. Application of Pseudomonas sp. P12 and Streptomyces sp. A3 had the greatest effect on dehydrogenase activity. Inoculation had a positive effect on germination, fresh and dry weight of plant, height and rootlength of plants. Introduction of fungus Trichoderma asperellum and Streptomyces sp. A3 isolate acted positively on germination, length of seedling of germs. On average, the best effects on the yield of fresh and dry matter, the height of the stem of the plant and the length of the root were attained by the application of Pseudomonas sp.P12 and Bacillus sp. B1 isolates. Microorganisms have not yet found significant practical use in the production of forage grasses, even though more qualitative yield has been sought in livestock production. The results of this study demonstrate that positive results in the production of perennial ryegrass can be achieved by the use of microorganisms. Therefore, it is very important to carry out further studies of the relationship between applied microorganisms and ryegrass under field conditions in order to optimize the method and time of application of inoculants