THE INFLUENCE OF THE MICROCLIMATE CREATED BY THE FOREST BELT ON WEED INFESTATION IN THE SUNFLOWER CROPS.

The establishment of protective belt and the setting of crops within the microclimate created by them, also favourable to sunflower crop, represent one of the most effective measures for mitigating the effects of drought in Dobroudja region. The researches were carried out at Amzacea, Constanta County, in sunflower crops cultivated in the forest belt system. For each plot there have been drawn up weed infestation sheets that indicate the density, participation and the constancy. The data has been centralized for the determination of dominant species and problem weed species that require treatments. Data analysis showed that 16 species of weeds were identified, which, due to the favorable microclimate created mainly by reducing evapotranspiration, exceeded 190 plants per square meters. The Chenopodium vulvaria species, which had a density of 8 plants per square meters in sunflower cultivated plots without belt, became the dominant weed exceeding 20 plants per square meters and participating with C. album species almost 20% in weed infestation process. Due to the water conservation in the soil, the black nightshade (Solanum nigrum), a moisture species has doubled its density from 6% in sunflower plots without belt to 15% in plots between belts. The problem weeds identified in sunflower cultivated within the forest belts were C. vulvaria, C. album, Amaranthus spp., Polygonum spp., S. nigrum, Convolvulus arvensis and Setaria spp. Species that predominantly spread by the wind had a higher density in the plots within forest belt: Xanthium italicum, Cirsium arvense, Sonchus spp. [ABSTRACT FROM AUTHOR]