The effects of salinity on growth, nodulation and nitrogen fixation ofCasuarina equisetifolia

Abstract

The growth, nodulation and nitrogen fixation of Casuarina equ&etifolia were compared at six levels (0~500 mM NaCI) of salinity in sand culture. Dry weight of nodules, shoots and roots and N content of shoots increased at intermediate levels of salinity (50-100 mM) but decreased at 500 mM NaC1. Nodulation occurred at all NaC1 levels, but at 500 mM NaC1 level, the nodule dry weight declined by 50% from the control. Increasing NaC1 concentration of up to 200mM had little effect on the N2-fixation rate, but at 500mM NaCI level the rate decreased to 40% of the control value.

Salt tolerance ofElaeagnus macrophyllaandFrankiaEma1 strain isolated from the root nodules ofE. macrophylla

“…These results indicate that Frankia can withstand a high NaCI environment by prevention of Na+ influx into the cells due to their thick and short hyphae. Ng (1987) suggested that the growth of Frankia in the rhizosphere of C. equisetifolia was not inhibited by the increase of salt concentrations up to 500 mM NaCI based on the fact that the inoculated plants could nodulate in sand culture at all NaCllevels. Accordingly, salt tolerance of Frankia appeared to be generally higher than that of the host plant, although the magnitude of tolerance may vary among Frankia strains.…”

Proline accumulates inCasuarina equisetifoliaseedlings under salt stress

“…Casuarina species, which form nitrogen-fixing nodules on their roots by infection with the actinomycete Frankia, generally display a high salt tolerance (El-Lakany and Luard 1982;Ng 1987). They are widely planted in coastal areas of tropical and subtropical regions as windbreaks or to stabilize dunes against wind erosion (Dawson and Gibson 1987;Diem and Dommergues 1990).…”

The effect of short term withdrawal of NaCl stress on nodulation of white clover

“…The nodules in Treatments 3 and 4 were probably derived from infection during the NaCI removal period rather than due to the recovery of earlier formed nodules. Ng (1987) reported the effect of shoot growth on nodulation. However, in this experiment, that effect was small, because no significant difference in shoot weight was observed among the treatments.…”