Day and night temperature effects on vegetative growth of Erodium cicutarium

The vegetative growth response of Erodium cicutarium (L.) L'Her, ex Ait. to various day:night temperature regimes was studied under controlled environment conditions. Dry matter production was greatest with day temperatures of 18 to 34 degrees C combined with night temperatures of 12 to 18 degrees C. A high night temperature of 24 degrees C was very detrimental, reducing dry matter production to 15 to 25% of that attained at 12 degrees C. The optimum mean daily temperature for growth of E. cicutarium is predicted to be in the range 17 to 20 degrees C. Little growth is predicted at mean daily temperatures below 5 degrees C and above 30 degrees C. Partitioning of biomass in leaves, stems and roots was markedly affected by day and night temperatures. Stem weight ratio was greatest at day temperatures of 18 to 34 degrees C and night temperatures of 18 to 24 degrees C. Maximum leaf weight ratio occurred at day and night temperatures of 10 to 18 degrees C. Root biomass was little affected by day temperatures, but was greatest at a night temperature of 12 degrees C, declining substantially as night temperature increased from 12 to 24 degrees C. Results are discussed in terms of the potential for E. cicutarium to become an increasingly troublesome weed in crops of the Canadian prairies and in terms of possible management strategies for its control.