Fresh vegetables are essential product of human nutrition. Cucumber is one of the most popular vegetables for eating fresh. No heat treatment leads to increased demands on their quality and safety.

Many scientists consider it is impossible to get high yields without using chemical pesticides. Percent of biological plant protection products in vegetable production is 60-70%, the remaining 30-40% is given to chemicals. The utilization of low-toxic chemicals in modern vegetable production is actual. Chemical entities on base of guanidine are low-toxic chemicals with wide range of antimicrobial properties. The most advanced for use in agriculture is polyhexamethyleneguanidine hydrochloride (PGMG).

The aim of our study was to substantiate environmental and agronomic feasibility of using PHMG (ecoton) in agriculture.

The study was carried out during the 2008-2012 period in the Laboratory of Microbial Ecology, Institute of Agroecology and Environmental Management of NAAS.

Epiphytic mycoflora of seeds can be represented by facultative or obligate pathogens. Pretreatment of seeds protects the plant from seminal, soil or aerogenic infection. The influence of ecoton on epiphytic mycoflora of cucumber seeds was studied. The use of 0,1, 0,2 and 0,5% aqueous solutions of ecoton decreased the abundance of epiphytic mycoflora in 75-90%. The use of 1,0% aqueous solution led to complete sterilization of seeds.

Pretreatment of seeds also should cause the better growth of plants. The effect of different concentrations of ecoton aqueous solutions (from 0,1 to 1,0%) on cucumber seed vigor and length of the roots was studied. The use of 0,5% aqueous solution of ecoton increased seed vigor in 5-7% and led to major root growth. Thus, 0,5% aqueous solution of ecoton was chosen for feather research.

The effect of ecoton on seed vigor and rhizosphere micromycetes was determined by field experiment. In 2008 and 2009 years the weather conditions were not favorable for plant growth. The root rot of cucumbers was wide spread. The use of preparation increased seed vigor in 9,9% (2008th year) and 5,0% (2009). In 2010 the weather conditions were more suitable for cucumber growth. The use of preparation increased seed vigor in 7,5%. The use of ecoton reduced the quantity of rhizosphere micromycetes in 50% (2008th), 25% (2009th) and 15% (2010th).

Phytotoxicity of ecoton was determined by pot-culture method. The effect of different concentrations of PGMG (from 0,2 to 25,6 g·kg-1 of soil) on the length of the test-culture roots was estimated. The utilization of PGMG in concentration of 0,2 g·kg-1 of soil led to 100 % seed vigor. But the length of the roots reduced in 32 %. The usage of PGMG in concentration 0,4-12,8 g·kg-1 of soil led to 53-
100 % seed vigor, length of the roots reduced in 7-56 %. The concentration of PGMG less than 1 g·ha-1 was used for pretreatment of cucumber seeds. So, the utilization of ecoton in concentration 0,5 % for pretreatment of cucumber seeds is not toxic.

Our results showed that the increase in cucumber seed vigor through the use of ecoton can be attributed mainly to disease control. Thus the pretreatment of seeds with ecoton decreased the abundance of epiphytic and rhizosphere mycoflora. Low toxicity and high antimicrobial activity, growth-stimulating properties make ecoton advanced in technologies of cucumber production.

Key words: cucumber, phytotoxicity, polyhexamethyleneguanidine hydrochloride, micromycetes, seed vigor.