UNDER-SOWING EFFICIENCY FOR WEED MANAGEMENT IN SPRING CEREALS

The data on weediness from the ongoing crop rotation experiment at the State Priekuli Plant Breeding institute were analysed on the basis of hypothesis that under-sowing in spring cereals can improve weed management. Grass/clover mixture (Trifolium pratense L. and Phleum pratense L.) as under- sowing in spring barley (Hordeum vulgare L.) was grown for one and two seasons in six field crop rotation. Numbers of weed plants in spring (BBCH 20 – 29) were recorded using 0.1 m2 big frame in 10 places; plant biomass of under-sown crops and weeds were sampled within 1.0 x 1.0 m squares after the first cut in the following year after harvesting of main crop (barley). The total of 28 weed species were registered. The most common species were Chenopodium album L.; Tripleurospermum inodorum L., Raphanus raphanistrum L., Centaurea cyanus L., and Spergula arvensis L. were also amongst the five common species. In addition, to examine the efficiency of under-sowing in weed management in the fields, the data obtained from the monitoring under the project PRODIVA were used. Weediness data from twenty fields in Vidzeme and Latgale regions were summarized and compared with the results from the long term experimental field. The aim of this study was to investigate the effect of under-sowing spring cereal fields with grass/clover mixture on weediness