Influence of environmental factors on seed germination and emergence of Iresine diffusa

ACOSTA, JUAN MANUEL; BENTIVEGNA, DIEGO; PANIGO ELISA; DELLAFERRERA, IGNACIO; ALISIO, MAURO; PERRETA, MARIEL

WEED RESEARCH

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 54 p. 584 - 592

0043-1737

Iresine diffusa has become more abundant under no-till soybean in Argentina. The influence of temperature, light, cold-wet storage, osmotic potential, dry storage and depth of seed burial on germination and emergence of I. diffusa were examined in a growth chamber experiment. Iresine difussa seeds germinated at the highest proportion (> 0.80) in all fluctuating day/night temperature tested. Conversely, under a constant temperature regime, maximum germination rates occurred at 15 ºC (0.78) and 20ºC (0.82), and minimum germination rates occured at 10 ºC (0.19) and 30ºC (0.36). While seed germination was not influenced by light exposure, it was affected after 12 (0.76) and 16 (0.65) weeks in cold-wet storage. To reduce germination significantly, -0,4 MPa of osmotic potential (induced by PEG-6000) or 120 mM of salt (NaCl) concentration were required. Seeds of I. diffusa showed high viability (0.85) after 720 days of dry storage. Low emergence was recorded for seeds buried at 2 cm, and seedling emergence was completely inhibited when seeds were buried at 5 and 10 cm. Iresine diffusa seeds had high viability and were capable of emerging in a broad range of environmental conditions. The thermal germination conditions, shallow soil depths and high moist conditions in germination phase for Iresine diffusa are congruent with the conditions in Argentina no tillage soybean. Thus, no-tillage could provide better conditions for germination than conventional tillage systems. Additionally, salt tolerance levels indicate that in saline soils seeds could germinate. These results explain, in part, why I. diffusa has increased in no-till soybean systems over the last decade and become a problematic weed.