Specificity of potential contamination of rice checks with weed seeds

Abstract

Goal. To analyze the potential level of contamination of arable soil layer weed seeds and to establish the specificity of the changes in such reserves during the vegetation period of crops. The study was performed on rice checks of the Institute of rice of NAAS in the Kherson region in the 2017—2019 biennium.
 Methods. Research field, small and laboratory. To determine the factor of seeds and vegetative reproductive organs of weeds in certain soil horizons of rice fields per unit area (pieces/m2) was selected soil samples by the method of A. N. Kiseleva — twice per season, in spring and after harvest of rice. The arable soil was divided into three layers (10 cm each). To determine the viability of seeds used method of staining their tetrazoles. The results were compiled and analyzed.
 Results. A comparison of the level of potential contamination between horizons showed the highest number of weed seeds in the horizon of 0—10 cm on average, 16041 pieces/ m2, which is 47.6% of the overall presence of weeds in the soil (33650,2 pieces/ m2). In the soil horizon 10—20 cm the number of weed seeds reached 10489.2 pieces/m2, or 31.2% of the debris of the upper horizon. In the lower horizon of 20—30 cm level of the presence of weed seeds was low — 7119.8 pieces/ m2, which amounts to 21.2% from that of the top horizon of the soil. Among the weed species whose seeds were present in soil samples of the top horizon of 0—10 cm, the largest part was Kuga Astrakhantseva Scirpus mucronatus L. — 59.8%, in another place Boule seeds Kuga razveseloj Scirpus supinus L. — 31.8%, Polygonum Persicaria hydropiper L. percetage — 1004.7 pieces/ m2 (6,3%), chicken millet Echinochloa crus galli L. — 329.1 pieces/m2 (2.1%). Other types were less in the stocks of weed seeds.
 Conclusions. During the vegetation period inventory quantities of seeds of change and by autumn are increasing. The largest amplitude value of the stock of weed seeds is manifested in the upper 0—10 cm horizon of the arable layer and reaches to 12.3%. Qualitative and timely implementation of measures to protect rice crops from sowing to the presence of weeds provides a gradual reduction in the volumes of their Bank of seeds in the soil.