Diplotaxis Research Paper

870 Words 4 Pages
Gorai M, Neffati M, and Tlig T (2007). Germination responses of Diplotaxis harra to temperature and salinity. Flora 203: 421–428

2a) Successful colonization of plant species is reliant on fruitful seed germination, which is consequently influenced by various environmental factors such as temperature, salinity and soil moisture. The authors hypothesized that temperature is a determining factor in relation to germination behaviour, affecting seeds’ tolerance to salt. Testing germination response in Diplotaxis harra under a wide range of salt levels and temperatures, the authors predicted that the seeds will suffer reduced or delayed germination as a result of increased salinity levels. However, the effect of salinity is more limited at optimum
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harra. At an optimum temperature of 15 degrees celsius, 71% percentage of germination was observed. Consequently, temperatures increases or decreases from this optimum range, resulted in inhibited germination. Increasing salinity levels contributed to delayed germination, however suitable temperature requirements resulted in less pronounced inhibition. This supports the prediction that the effects of temperature is more detrimental to germination behaviour than salinity.

3a.

El-Keblawy, A., 2004. Salinity effects on seed germination of the common desert range grass, Panicum turgidum. Seed Sci. Technol. 32, 943–948. Hegazy, A.K., 2001. Reproductive diversity and survival of the potential annual
Diplotaxis harra (Forssk) Boiss (Brassica-ceae) in Egypt. Ecography 24, 403–412. Khan, M.A., Gulzar, S., 2003. Germination responses of Sporobolus ioclados: a saline desert grass. J. Arid Environ. 53, 387–394.

3b. Several environmental factors such as temperature, salinity, light, and soil moisture simultaneously influence germination (El-Keblawy and Al-Rawai, 2005, 2006; Huang et al., 2003; Ungar, 1995; Zia and Khan,
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Bioresource Technol. 97, 292–298. Evans, C., Etherington, J.R., 1990. The effect of soil water potential on seed germination of some British plants. New Phytol. 115, 539–548.

4b.
Yet, seeds of some species germinate to higher percentages in darkness than in light (Baskin and Baskin, 1998; El-Keblawy and Al-Rawai, 2005; Zhu et al., 2007)
Although higher salinity generally decreases germination, the detrimental effect of salinity is less severe at the optimum germination temperature (Al-Khateeb, 2006; Esechie, 1993; Gorai and Neffati, 2007; Gulzar et al., 2001; Khan and Gulzar, 2003; Khan et al., 2000).
Seed imbibition rate, germination percentage and germination rate generally decrease as soil water potential decreases (Evans and Etherington, 1990; Oberbauer and Miller, 1982), either by drought or by higher salinity.

4c.
The results indicated that D. harra did not require light to germinate. The authors use this to emphasize that all seeds have different requirements for germination, supporting their argument that successful germination of D. harra will have different requirements for germination when compared with other species in the same

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