Effect of Environmental Factors on Germination and Emergence of Eastern Dodder (Cuscuta monogyna)

In order to study the effect of environmental factors (light, temperature, salinity and drought stress, acidity and burial depth) on germination and emergence of eastern dodder (Cuscuta monogyna Vahl), experiments were conducted at the Research Laboratory of Faculty of Agriculture, Birjand University in 2009. Results showed that seeds of this parasite weed had identical germination under light/dark and continuous dark conditions, indicating this weed species is non-photoblastic. Seeds of this weed species showed average germinability greater than 84% over a wide range of temperatures (10/5, 20/10, 25/15, 30/20 and 35/25 C) at both light/dark and continuous dark regimes and the maximum germinability (98.3%) was observed at 25/15ºC. Eastern dodder could retain its germinability at high salinity levels and even at salinity level of 320 mM NaCl 66.67% of seeds germinated, although its germination was ceased at 640 mM NaCl. Seeds germinated greater than 80% until the drought level of -0.8 MPa, while further increasing of drought stress caused a remarkable reduction of seed germination. This weed seeds showed averagely greater than 90% germination at pH range of 4-10 and seed germination was not notably affected by pH. Seed burial depth had a great impact on eastern dodder seedling emergence, so that no seedling emerged from seeds buried deeper than 3cm and maximum emergence (100%) occurred where seeds placed on the soil surface covered with 2 layers of filter paper. The information of this study would be helpful for estimating the potential of this species to spread to new areas.