Impact of some Environmental Factors on Germination and Emergence Characteristics of Black Henbane (Hyoscyamus niger), Ground Cherry (Physalis divaricata) and Curly Dock (Rumex crispus)

To understand germination and emergence characteristics of black henbane, ground cherry and curly dock a laboratory experiment, based on randomized complete block design with four replications, was carried out at the Faculty of Agriculture, Ferdowsi University of Mashhad in 2012. Treatments were temperature ranges (5/15, 10/20, 15/25, 15/30 and 20/35 ° C night / day) and different levels of salinity (0, 10, 20, 40, 80, 160 and 320 mM of NaCl). The effect of pH adjusted to 5-9 by using acid buffer solution. Seeds were planted at different depth (0, 1, 2, 3 and 4 cm) to study their effects on seedling emergence. Results showed that black henbane exhibited highest germination percentage at 25/15 diurnal tempratures, with 86.50 and 60.50 respectivly for daylight and complete darkness. Germination of ground cherry was highest (93%) at 10/20 diurnal temprature and 41% in complete darkness. Highest germination percentage for curly dock at diurnal temperatures of 20/10, 25/15 and 30/20 with light / dark regime of constant darkness was abserved. The seeds at diurnal temprature of 35/25 in both light regimes did not germinate. Increasing salinity reduced germination. Increasing the osmotic potential, also reduced germination significantly. Highest germination percentage of black henbane (97%) was observed at pH 7, and lowest germination (17%) at pH 9. Increasing planting depth reduced seedling emergence significantly. Germination percentages of ground cherry and curly dock at pH 6 and 7 were highest (97% and 96% respectively) and lowest 26 and 25 % respectively at pH 9.