The study of broomrape diversity in different sunflower cultivating countries based on morphological arameters of parasite seeds

Abstract

The root holoparasite Orobanche cumana Wallr. produces a very high number of extremely small seeds, which remain viable in the soil for decades and could be easily disseminated through the use of machinery or contaminated seeds. Due this fact and considering the global scale of sunflower seeds exchange, the control of parasite is extremely difficult. Currently broomrape is present in the majority of sunflower cultivation countries and spreads very quickly to new areas. In this context, it is of interest to analyze and highlight distinctive morphological features of O. cumana seeds collected from different European and Asian countries, such as the Republic of Moldova, Romania, Bulgaria, Ukraine, Serbia, Spain, Turkey and China. The morphometric analysis (seed length, width and length/width ratio) of broomrape samples did not show significant differences in their size. O. cumana seeds ranged between 0.316-0.393 mm x 0.148- 0.176 mm, with a L/W ratio of 2.022-2,596. A moderate positive correlation (r=0.485) between length and width of broomrape seeds has been revealed. The mean value of L/W ratio in all investigated populations (38) was around 2.3, being in agreement with the results obtained by other authors and showing that O. cumana has preferentially elongated shape of seeds comparative to other broomrape species. Comparing to other studies, the mean value of L/W ratio was higher than 2.0 (2.18) even in Chinese populations. The coefficients of variation indicated low values, especially in the case of seed length (6.73-19.56%), which suggests a moderate level of intrapopulational variability, all studied populations being relative homogenous. The analysis of Euclidean distance showed small distances (0.001-0.577) between broomrape populations, the most distant being those collected from Seville (Spain), Tulcea (Romania), Xin Jiang (China), ORSR11 (Serbia), Popeasca and Sarata Mereseni (Republic of Moldova) and Edirne, Kesar (Turkey) in different combinations.