The Biological Method of Increasing Seed Germination and Productivity of Grain Crops

Abstract

Cereals such as wheat, barley, and oat are the main strategically important crops cultivated in Kazakhstan. At the same time, more than 23--30% of grain crops were lost in the fields in 2014--2015 due to low seed germination and various diseases. The main tasks of this research were to develop a biological method to enhance seed germination and protect root rots caused by fungal pathogens. From the rhizosphere of grain crops were isolated more than 50 isolates of cellulolytic bacteria. After the testing, two strains which showed no phytotoxicity and possessing growth-stimulating ability were selected. The mixture of strains when applied more actively promoted seed germination and increased seedling growth compared to single strain application. The increase of seed germination was up to 80--92%. Treatment with the association of the strains significantly suppressed root rot diseases caused by Fusarium, Alternaria, and Bipolaris in cereals. Molecular genetic characterization of PGPR strains used was shown to belong to the genera of Bacillus and Cellulomonas and species B. cytaseus and C. flavigena. Mode of action studies for seed germination by these strains was showed due to the synthesis of cellulase enzymes. The efficacy of these strains to enhance plant growth of grain crops was shown to be associated with the synthesis of biologically active substances such as B-group vitamins and amino acids. It was also established that the strain B. cytaseus VKPM B-4441 could fix molecular nitrogen from the atmosphere (62.5 {\texttimes} 10−5 N2/ml/h). The tested strains could colonize the hard seed coat and then began to synthesize cellulase enzymes to partially degrade the seed coat to form microcracks. The seed coats then become less firm and allow the increase of water transport and dissolved mineral substances and nutrients to the seed embryo. We hypothesize that the enhanced seed germination and stimulated seedling growth are due to the process of ``the biological scarification.'' Seeds treated with these strains prior to seeding significantly increased their germination up to 80--89% compared to control (61--65%). The root rot rating was decreased 7.3 times compared to control. The yield of grain increased in the range of 2.6--3.2 centner/ha compared with the control. On the basis of this association of strains, the new biological preparation ``Batsirin A'' was developed. When use biopreparation enhanced seed germination and seedling growth and protected against root rots caused by fungal pathogens.