Вплив бур'янів на приріст верби енергетичної

Abstract

Under the conditions of 2012, willow height when kept clean of weeds amounted to 138 cm. Joint vegetation with weeds during 30 days (accumulated weed mass of 143 g/m 2 ) resulted in a decrease in plant height to 132 cm (by 4.5 %). This can be explained by low weed mass weight and specifics of the weather conditions. April 2012 was characterized by high rainfall, namely 71.7 mm, which exceeded the average long-term value by 152%, while May was hot (air temperature of 18 °C) and dry (rainfall only 6.8 mm) In the next month, when plants grew together with weeds for 60 days, the weed mass weight increased 4.8 times to 696 g/m 2 and height of willow decreased to 105 cm (by 31.4%). The greatest suppression of willow plants was observed at joint vegetation with weeds for 90 days. The height of willow plants dropped more than 2 times to 66 cm and weight of weeds reached 3095 g/m 2 . Later willow height did not decrease significantly. Under the conditions of 2013, which was characterized by cold and rainy March and hot and dry summer, the height of energy willow plants for vegetation without weeds was 156 cm. Mid-April and May marked a sharp increase in temperature to 10.0 and 18, 5 °C, respectively, which was above average long- term values by 1.6 and 4.5 °C, respectively, while the amount of rainfall was normal. Such weather conditions contributed to the development of weeds in crops. To illustrate, for 30 days of joint vegetation (from 10/04 to 10/05) the weight of weeds increased to 165 g/m 2 , then at the 60th day increased to 800 g/m 2 . On the 120th day, weed mass weight reached its peak of 3689 g/m 2 . Later, on the 150th day, weed mass weight dropped by 378 g/m 2 while willow height amounted to only 70 cm, that was 45% of the potential . In 2014, willow height for 30 days of joint vegetation with weeds decreased slightly. To compare, it was 143 cm against 149 cm in the control treatment . This can be explained by the low weed mass (154 g/m 2 ) and weather conditions. April and May of 2014 were warmer by 1.4 and 2.2 °C, respectively, compared to the average long-term data, and the rainfall exceeded the norm by 110 and 256%, respectively. In general, in this year similar to the other years of the experiment trends were observed. Despite the high air temperatures combined with low rainfall in 2015, we have recorded the greatest height of willow plants in the treatment without weeds, which amounted to 158 cm. A significant decrease in willow plants heights to 120 and 76 cm was noted for joint vegetation with weeds for 60 and 90 days, with the mass of weeds amounted to 787 and 3497 g/m 2 , respectively. Based on the experiment data we have established a regression equation describing weed mass accumulation and height of willow plants when growing jointly : y = 0.3124 x 2 – 109.01 x + 9336.5, where y ˗ weight of weeds; x ˗ height of willow plants. The correlation coefficient of the characteristic under study has closely positive bonding force (r = 0.93). To sum up, on the average of the years of experiment, the height of energy willow plants decreased twice while grown together with weeds for 90 days, and plants reached only 45% of their potential for 150 days. The weed mass increased 4.8 and 4.4 times for 60 and 90 days of joint vegetation, respectively, reaching its peak of 3497 g/m 2 on the 120th day of joint vegetation.