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The biology and autecology of Nitraria L. in Australia. II. Seed germination, seedling establishment and response to salinity
Author(s) -
NOBLE J. C.,
WHALLEY R. D. B.
Publication year - 1978
Publication title -
australian journal of ecology
Language(s) - English
Resource type - Journals
eISSN - 1442-9993
pISSN - 0307-692X
DOI - 10.1111/j.1442-9993.1978.tb01167.x
Subject(s) - germination , atriplex , seedling , biology , perennial plant , competition (biology) , agronomy , salinity , halophyte , botany , horticulture , ecology
Detailed investigations were undertaken to determine the requirements for optimal germination and establishment of Nitraria billardieri. Germination of N. billardieri on the Riverine Plain is aided considerably by prior ingestion of the fruit by the emu (Dromaius novaehollandiae). Experiments suggested that the increase in germination of emu‐ingested seed is largely a response to the removal of the saline outer pericarp during digestion. In one experiment, 62% of emu‐ingested seed germinated after 24 days compared with 6% of the hand‐picked seed.Studies of field populations of N. billardieri seedlings indicated that they are susceptible to competition from cool season annual species. A competition experiment in sand boxes between seedlings of N. billardieri and Atriplex vesicaria showed N. billardieri to have a slower growth rate and to be susceptible to competition by the seedlings of the perennial A. vesicaria. Studies of the root extension of N. billardieri and Atriplex nummularia in root observation boxes demonstrated the poor performance by the Nitraria roots which grew only 53 cm in 7 weeks whereas the Atriplex roots grew 160 cm in 4 weeks. These data suggest that N. billardieri establishes and successfully competes in the field only with severely weakened saltbush stands. Other important factors are the availability of 'safe sites’ and the degree of competition from annual species.Glasshouse experiments using sand culture indicated that both Nitraria and Atriplex vesicaria could survive in salinities of 0.9 M NaCl and both responded in terms of dry matter production to low salt inputs (e.g. 0.3M NaCl) although growth of Nitraria decreased more rapidly as salinity increased.