Abiotic environmental factors associated with Broomrape (Orobanche cumana Wallr.) absence in some sunflower areas of Serbia and Argentina

MIGUEL CANTAMUTTO, DRAGANA MILADINOVIC, JOVICA VASIN, BOSKO DEDIC, DANIEL ALVAREZ, FACUNDO QUIROS AND MONICA POVERENE

Mar del Plata

Congreso; 18th International Sunflower Conference; 2012

Asociación Argentina de Girasol, International Sunflower Association

In several agricultural lands of the world, the parasitic weed Orobanche cumana (Broomrape) is the most serious biotic constraint of sunflower crop production. This parasitic weed, native of Caucasus region, has progressively migrated to the South of Eurasia. The geographic actual distribution comprises Black Sea region, Serbia, Spain, Turkey and Israel territories, with severely infested patches in close proximity of non-infested areas. Broomrape is also absent in the extended sunflower crop area of Argentina in South America. The differentiation between invaded and not invaded areas could be related to agriculture practices or to environmental factors. It is widely accepted that abiotic parameters of the environment could explain the geographic distribution of several plant species in natural or agricultural habitats. It is unknown if this could be the case of this dangerous sunflower parasite. The influence of 14 environmental factors on the geographical distribution of broomrape was studied. We collected geographic and climatic information from 15 sunflower habitats of Serbia with different natural infections levels and 22 Argentine habitats without the parasitic weed. The latter group was constituted by nine natural habitats of ruderal H. annuus and 13 sites of the ASAGIR sunflower cultivar evaluation. Data were kindly provided by the responsible of each experimental field. In Serbia, altitude, latitude, mean hottest month temperature, mean coolest month temperature, soil texture and soil chemical composition of infected habitats were no different to non infected habitats. Argentina habitats differed from Serbia invaded habitats only in latitude, mean coolest month temperature, soil pH and soil clay content. In spite of this difference the compared habitats showed notorious overlaps in the range of the two latter environmental parameters. Considering 10 abiotic factors by multivariate analysis, explaining more than a half of the total variability, there were found three clusters. The invaded and not invaded habitats of Serbia showed a semi-coincident distribution, but were clearly separated from non invaded habitats of Argentina. Mean month temperatures and latitude were more related with this separation. Excluding these two factors, the habitats differed mainly by clay content and P availability. According to this, Argentina seems to be a low susceptible region to broomrape attack. It is know than temperature regulates the weed seed dormancy process and this is one of the main differences found between regions. If P availability were confirmed as determinant of the broomrape geographic distribution, it could be used to develop a technical tool to limit the parasitic attack. In this sense, P fertilization could be used to limit the crop damage. These results point to the importance of an abiotic factors evaluation of sunflower crop areas with and without broomrape in order to develop tools to help limit the losses caused by this parasitic weed.