Photoperiod and temperature effects on growth and development of Emex australis and E. spinosa |
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| Authors: | PW WEISS DM SIMMONS |
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| Institution: | Divison of Plant Industry, CSIRO, P.O. Box 1600, Canberra City, A.C.T. 2601, Australia |
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| Abstract: | The effects of temperature and photoperiod on Emex australis and E. spinosa were studied in a pot experiment. E. spinosa was more precocious than E. australis in terms of earlier flowering, runner and seed formation under conditions similar to those of daylength and mean daily temperatures in the field and it produced three times more seeds. Optimum day/night temperatures for both species, however, were between 15/10 and 20/15°C. Both the lowest (10/5°C) and highest (30/25°C) temperatures tested delayed flowering and there was a terminal necrosis of runners at high temperatures. Flowering in both species also was generally hastened and seed production greater at the longest photoperiod (16 h) compared with the shortest (8 h). The results are discussed in terms of the distribution of E. australis, the similar environmental requirements of both species and the possible encroachment of the less desirable E. spinosa, which is as yet more restricted in distribution in Australia, into areas already colonised by E. australis. |
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