Dormancy, germination and emergence of Urochloa panicoides regulated by temperature

作者：Ustarroz D^*; Kruk B C; Satorre E H; Ghersa C M

来源：Weed Research, 2016, 56(1): 59-68.

DOI：10.1111/wre.12181

• Liver seed grass
• after-ripening condition
• base temperature
• dormancy release
• thermal amplitude
• thermal time

Urochloa panicoides is an annual weed of summer crops. In Argentina, in subhumid areas with monsoon rainfall, it germinates and establishes in a single flush. To (i) identify the environmental factors that modify its seed dormancy level and germination and (ii) quantify the parameters describing the thermal behaviour of the germination and emergence dynamics of this weed under non-limiting water conditions, we established a set of germination experiments performed (i) under controlled conditions using seeds after ripened for 3 or 6months in different thermal and hydric conditions and (ii) under field conditions, where the soil temperature was modified by applying different shading levels. Seed dormancy level remained high with 3months after ripening in all treatments. After 6months, seeds stored at 4 degrees C in dry conditions did not germinate at any temperature, while seeds stored at 25 degrees C in dry conditions and insitu germinated c.20% and 60% respectively. Germination percentage was higher in seeds harvested before their natural dispersal. The base, optimum and maximum temperatures for seed germination were 6, 35 and 45 degrees C respectively. Shading reduced the number of emerged seedlings, possibly by reducing the soil thermal amplitude. The results explained the dormancy-breaking mechanism of U.panicoides that allows a high germination rate in the field when rainfall occurs.

• 出版日期2016-2