Influence of weed hemp (Canabis Ruderalis) on the elements of productivity and grain damage by wheat thrips and cereal bugs in the agrocenosis of winter soft wheat

Abstract

Field studies were conducted in the forest-steppe zone of the Samara region on the experimental fields of the Volga Research Institute of Breeding and Seed Production in 2013 and 2015. The plots that were not littered (control) and were littered with weed hemp were compared. Due to its high plasticity to weather conditions and well-developed root system, weed hemp has a great competitiveness in relation to winter wheat. The spread of сannabis Ruderalis is focal in nature. Cannabis Ruderalis has contributed to the decrease in aboveground dry mass of wheat in 17-32 %, weight of ears per 13-18 %, the number of productive stems per 16-23 %, grain weight per spike on 4-51 %, mass of 1000 grains for 1-7 %, biological yield grain for 16-20% increase in the length of the ear by 7-10%, and the number of grains per spike by 3-8 %. The influence of weed hemp on the damage of grain by pests was ambiguous. The weather conditions of the spring–summer growing season of winter wheat have a great influence on the damage caused by wheat thrips. In the year with a dry and warm spring (2013), the number of grains damaged by wheat thrips was higher in the clogged areas than in the control. In the year with a wet and warm spring (2015), on the contrary, more wheat thrips-damaged grains were in control. During two years of research, an increase in grains damaged by bread bugs was observed in the clogged areas. Weed hemp has both a direct effect on winter wheat (a decrease in the elements of productivity) and an indirect effect (on the feeding process of wheat thrips and bread bugs).