The influence of the holoparasite Orobanche cumana Wallr. on some morpho-anatomical and physiological-biochemical traits in culture Helianthus annuus L.

The paper presents results regarding the influence of the angiosperm Orobanche cumana Wallr. on the sunflower harvest and some morpho-anatomical and physiological-biochemical parameters in sunflower hybrids susceptible to broomrape, under different environmental conditions. A negative influence of the parasite was revealed, especially on the background of drought, although under the hydric stress the degree of infestation was significantly lower than in the conditions favorable for crop development. According to the regression analysis, the 71%, 43%, 38%, 42% and, respectively, 30% of variation in sunflower harvest, plant height, leaf area, leaf area index and the amount of chlorophyll a can be explained by the intensity of the attack of broomrape. Strong negative correlations of the mentioned parameters with the incidence of broomrape were found, as follows: r=-0.68; -0.65; -0.66 and -0.59.