Publications - Faculty - Recently Submitted Faculty Publications 2008
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Singh - Weed Management and Biology
Influence of ecological factors on the germination and emergence of Spanish needles (Bidens pilosa) seeds
Shiv D. Sharma and Megh Singh
Abstract. The effects of environmental factors, e.g. temperature, photoperiod, pH, osmotic and salt stress, were examined on the germination of Spanish needles seeds utilizing controlled environment growth cabinets. The effect of seed burial depth and simulated flooding was examined under greenhouse conditions. Under optimal conditions germination of Spanish needles seeds was 87 to 92% at 25 to 30ºC temperature and 88% under 12/12 h light/dark. These seeds germinated within 72 h of imbibitions. The germination was reduced at sub-optimal (12.5 to 20ºC) and higher (42.5 to 45ºC) temperature levels. Also germination declined with increasing osmotic and salt stress and was completely inhibited at or after osmotic stress of -0.9 MPa and salt stress of 150 mM NaCl. Emergence of Spanish needles seedlings was greatest when seeds were placed on the surface and 0.5 cm deep below the surface, although a significant percentage of Spanish needles seedlings emerged from depths as deeper as 6 cm. Simulated flooding significantly affected the germination, and a flooding maintained for 7 days and beyond drastically reduced the germination.
