Some peculiarities of ontogenesis of Orobanche cumana Wallr., parasitizing on sunflower in Rostov region of Russian federation

Abstract

SUMMARY In the tubercle of O. cumana of high-virulent populations from Rostov region of Russian Federation some changes were found, which helped to improve the seed productivity and to decrease the development period of fruiting shoots. The maintenance of high level of seed productivity can be realized by setting multiple meristematic zones in a tubercle and simultaneous development of several adventive shoots from them. The maintenance of viability of tubercle and the formation of new shoot apexes after the seed ripening on one or several stems, grown out of it and finished in the vegetation period, also go in the favour of the improvement of seed productivity. The development of the apexes of tubercle rudimentary roots into adventive shoots was observed in this paper. The polymorphism of inflorescence in the quantity of the setting flowers and their distribution along the stem and even below the soil level was observed. The flowering ability of flowers, hidden in the soil, and the seed formation in them, was defined. All that leads to the improvement of seed productivity of individual plant. On the whole, the described peculiarities of the development of O. cumana show that there is an accumulation of traits, which goes in the favour of the high potential of reproductive function in parasite’s ontogenesis.