Assessment of Effects of Soil Allelotoxicity and Toxicity of Fungicides on the Development of Grain Crops

摘要

Allelotoxicity of soils has a negative effect on plant growth, which was evident in the delay of germination under field conditions, namely, a time shift in the development of crops. The technique for determining the time shift under laboratory conditions has been developed. It has been possible to assess the impact of soil allelotoxicity on the yield by comparing the results obtained with the available literature data on the effect of sowing time on yield reduction. For this purpose, a time delay in seed germination and the development of seedlings in soils was compared with the time required for the same development stages for crops sown on the quartz sand, which does not contain toxins. It was found out that the dependence of time shift, expressed in percentage of the value of soil allelotoxicity, has an exponential character. Therefore, time shift may at times exceed the period of seeds development on an inert substrate in case of high soil allelotoxicity. It has been shown that the pre-sowing seed treatment with fungicides in some cases greatly increased the joint inhibition effect of soils and fungicides on seed germination and development of seedlings. Hence, in order to prevent a decrease in yield before application of fungicides for specific crops (varieties) and soils, it is necessary to check up the possibility of their application with developed laboratory technique.