THE EFFECTS OF SALT WATER AND SOIL TYPE UPON THE GERMINATION, ESTABLISHMENT AND VEGETATIVE GROWTH OF HOLCUS LANATUS L. AND LOLIUM PERENNE L.

Abstract

SUMMARYHolcus lanatus is the dominant grass over large areas of thin peat soil on the western sea-cliffs of Lundy Island, exposed to salt spray. Its tolerance of artificial sea water (ASW) on peat or loam soils when grown alone or in mixture with either an agricultural cultivar of H. lanatus, Massey Basyn or with ' Aberystwyth S. 23 ' Lolium perenne was investigated. Under salt spray, on peat soil, 'Lundy' H. lanatus had the highest tillering ability and, unlike the others, its yield was unaffected by the spray. When high levels of salt were applied to the soil, the yield of L. perenne was lowest when it was grown on peat and was also in competition with 'Lundy' H. lanatus. On peat soil, the agricultural cultivar oiH. lanatus was more productive than L. perenne. It was also at least as productive as 'Lundy' H. lanatus when grown on peat with a high level of salt in the soil solution.When immersed in a solution of ASW, the leaves of L. perenne retained approximately 17 times more salt than did those of either ' Lundy' or 'Massey' H. lanatus. There was no evidence for sodium ions being adsorbed on to the cuticle of any of the grasses. ' Seeds' of both L. perenne and 'Massey' H. lanatus germinated readily in 40% ASW. However, germination of 'Lundy' fl. lanatus 'seeds' was much reduced at this salt level, especially from intact spikelets, although they germinated readily when transferred to fresh water. The establishment of 'Lundy' H. lanatus under 120 kg ha~' day"' of sea-salt was slower than that of the other two grasses.

The effect of salinity on the growth of some New Zealand sand dune species

“…Members of the grass family (Poaceae) are among the dominant families of halophytic vegetation (WaiseI1972) and most of the exotic grasses sampled in this study are halophytic. Cliff ecotypes of Holcus lanatus have been reported as salt tolerant (Chapman 1964;Watt 1983). It seems that dune populations of H. lanatus are also salt tolerant (Fig.…”

The potential for evolution of tolerance to sodium chloride, calcium chloride, magnesium chloride and seawater in four grass species

“…1 986a) and/^./«««/!« (Watt, 1983) but not in A. capillaris or L. perenne. The results of expts 2 and 3 suggest that within the material examined of A. stolonifera and H. Ianatus, heritable variation in response to NaCl, CaCl.^, and MgCl., occurs that could, potentially, through the action of selection, yield adults of superior tolerance to these three salts.…”

“…Exposure to salitie sea spray, atid submergetice of plants by seawater at high tides will be other features of such soils. E. perenne lacks salt spray toleratice atid after subtnergetiee iti seawater tts leaves contaiti large qitatitities of salt (Watt, 1983), a feature whieh distitigt.tishes salt-spray tolerant (low leaf Na*) atid tioti-salt-spray toleratit (high leaf Na^) A. stolonifera after submergetiee iti or sprayitig with saline solutioti (Ahtnad & Wainwright, 1977). llius, it may be that Eoliiim is jireeluded from coastal salitie sites because of its inability to withstand the effects of salt spray or submergence in seawater.…”

“…The occurrence of natural salt tolerance iti //. lanatus shows that such individuals must be present in at least some populations of this species (Watt, 1983).…”

“…Coastal salt-marsh plant communities range from A. stolonifera L. (Aston & Hradshaw, 1966; Tiku & groups of highly salt-tolerant species occurring in Snaydon, 1971;Ahmad & Wainwright, 1977), lower marsh zones subjected to almost daily in-Pi'stuca ruhro "L. {WumpUreys, \9'&2), Holciis lanaliis undation by saline waters, to those on upper marsh L. (Watt, 1983; Ashraf, McNeilly & Bradshaw, areas submerged in saline waters only at the high 1986/;) and Dactylis glomerata L. (Ashraf el al., tides of spring and autumn equinoxes. I>ower salt-1986/;).…”