Plant growth promoting bacteria: significance and application in modern agricultural production

U suvremenoj poljoprivrednoj proizvodnji neselektivna uporaba gnojiva, posebno dušičnih i fosfornih, dovela je do značajnog onečišćenja tla, vode i zraka. Uz sve veći porast svjetskog stanovništva rastu i potrebe za većom količinom hrane, što posljedično dovodi do primjene velikih količina kemijskih sredstava kojima se ubrzava i poboljšava rast i razvoj biljnih kultura. Međutim, kontinuirana primjena mineralnih gnojiva i pesticida dovela je do smanjenja plodnosti tla, njegovog oštećenja, niske poljoprivredne produktivnosti, gubitka biološke raznolikosti, nepovoljnih ekonomskih posljedica i ozbiljnih opasnosti za okoliš. Kako bi se vratila ravnoteža u ekonomski, ali i ekološki aspekt poljoprivredne proizvodnje, moguće rješenje vidljivo je u primjeni bakterija promotora biljnog rasta (PGPB- engl. Plant growt promoting bacteria). Putem raznih direktnih i indirektnih mehanizama PGPB stimuliraju biljni rast i razvitak. Najpoznatiji rodovi bakterija kao što su Azospirillum, Azotobacter, Bacillus, Pseudomonas i Rhizobium pokazali su najširi pozitivni spektar djelovanja na rast i razvoj različitih biljnih vrsta. Navedeni rodovi osiguravaju povećanu opskrbu hranjivima i vodom, povećan sadržaja klorofila, veću toleranciju na abiotički stres, povećanu asimilaciju dušika i fosfora i ukupnu biljnu biomasu.In the modern agricultural production, the non-selective use of fertilizers, especially nitrogen and phosphorus, has led to significant soil, water and air pollution. As the world's population grows, so does the need for more food, which in turn leads to the use of large amounts of chemicals that accelerate and improve the growth and development of crops. However, the continuous application of mineral fertilizers and pesticides has led to a reduction in soil fertility, its damage, low agricultural productivity, loss of biodiversity, adverse economic consequences and serious environmental hazards. In order to restore the balance in the economical and ecological aspect of agricultural production, a possible solution is visible in the application of plant growth promoting bacteria (PGPB). PGPBs stimulate plant growth and development through various direct and indirect mechanisms. The most well-known genera of bacteria such as Azospirillum, Azotobacter, Bacillus, Pseudomonas and Rhizobium have shown the widest positive spectrum of action on the growth and development of various plant species by increasing nutrient and water supply, increasing chlorophyll content, increasing tolerance to abiotic stress, increasing the assimilation of nitrogen and phosphorus and total plant biomass