Agrotechnical measures for protecting peas of the winter sowing period from root rot in the conditions of the Forest-Steppe of Ukraine

Abstract

Purpose. To establish the symptoms, distribution and types of manifestation of root rots of peas of different subwinter sowing dates in a typical farm in the conditions of the Forest-Steppe of Ukraine, to determine the harmfulness of the disease, the influence of sowing dates on the phytosanitary condition of the crop, to assess the influence of meteorological factors and sowing dates on the development of the disease, as well as to substantiate the biological and economic effectiveness of agrotechnical measures for crop protection. Methods. Field – to determine the harmfulness of the disease, the influence of sowing dates on the phytosanitary condition of the crop, grain yield, quantitative, linear and biometric measurements of plants; observation – to determine the phases of growth and development of plants, the general condition of the crops and the appearance of harmful organisms; laboratory – to determine the structure of the crop, statistical – to assess the reliability of the data. Results. It was found that the highest field germination rates of seeds and germination energy were observed at the optimal sowing date (25.09), where field germination was 88.9%, which is 3.5% more compared to the early and 10.6% more compared to the late sowing date. As a result of the research, it was found that the prevalence of root rot increased during the growing season in all variants of the experiment. The lowest level of damage was observed at the optimal sowing date (25.09), where in the flowering phase the prevalence was 34.2%, which is 5.4% less compared to the early and 15.3% less compared to the late sowing date. The highest level of plant overwintering was established at the optimal sowing date (25.09) – 93.6%, which is 3.8% higher than the early sowing date and 12.2% higher than the late sowing date. The high percentage of overwintering at this date is explained by the formation of a well-developed root system and the optimal degree of hardening of plants before the onset of stable low temperatures. The late sowing date (05.10) was characterized by the lowest level of overwintering (81.4%), which is due to insufficient plant development in autumn, a decrease in the accumulation of plastic substances and increased sensitivity to stress factors of the winter period. Analysis of the obtained data showed that the development of root rot was the lowest at the optimal sowing date and amounted to 23.8% before harvesting, while at the early date – 28.2%, and at the late date – 37.1%, which is 4.4% less compared to the early and 13.3% less compared to the late sowing date. The indicators of the mass of 1000 seeds also varied depending on the sowing dates. The maximum value (252.8 g) was recorded at the optimal date, which corresponds to the varietal characteristics of Moroz NV (240–260 g). The correlation-regression relationship between the degree of root rot development (%) and pea yield (t/ha) at different terms of pre-winter sowing demonstrates a clearly expressed inverse (negative) linear relationship: with an increase in the intensity of root rot development, the yield significantly decreases. The highest yield (2.91 t/ha), formed with minimal disease development (23.8%) – the optimal sowing date (25.09). Conclusions. The terms of pre-winter sowing significantly affect plant overwintering, the development of root rot and the formation of pea yield. The optimal sowing date (25.09) provides the highest level of overwintering – 93.6%, the lowest development of root rot – 23.8% and the highest mass of 1000 seeds (252.8 g) and yield (2.91 t/ha). A close inverse correlation was established between the development of root rot and yield (r ≈ –0.999). Regression analysis showed that every 1% increase in the intensity of the disease reduces the yield by 36.5 kg/ha. The experimental data obtained indicate that the timing of winter sowing is an effective agrotechnical factor for regulating the phytosanitary condition of pea crops and can be used as an important element of an integrated system for protecting crops from root rot.