Six Hakea species varying greatly in seed size were selected for cotyledon damage experiments. The

growth of seedlings with cotyledons partially or completely removed was monitored over 90 days. All

seedlings perished by the fifth week when both cotyledons were removed irrespective of seed size.

Partial removal of cotyledons caused a significant delay in the emergence of the first leaf, and reduction

in root and shoot growth of the large-seeded species. The growth of seedlings of small-seeded species

was less impacted by cotyledon damage. The rate of survival, root and shoot lengths and dry biomass

of the seedlings were determined after 90 days. When seedlings were treated with balanced nutrient

solutions following removal of the cotyledons, survival was 95–98%, but 0% when supplied with

nutrient solutions lacking N or P or with water only. The addition of a balanced nutrient solution failed

to restore complete growth of any species, but the rate of root elongation for the small-seeded species

was maintained. Cotyledons provide nutrients to support early growth of Hakea seedlings, but other

physiological roles for the cotyledons are also implicated. In conclusion, small-seeded Hakea species can

tolerate cotyledons loss better than large-seeded species.

Abstract-A series of polyelectrolyte hydrogels ranging from 92-98wt% were synthesized by copolymerization of acrylamide,

AAM with 2-acrylamido-2-methyl propane sulphonic acid, AMPS using 0.001g APS as initiator in the presence of 30wt% H2O

and 1.0wt% ethylene glycol dimethacrylate,EDMA as cross-linking agent. The final copolymers was obtained in the form of

glassy and transparent roads at room temperature, these roads were soaked in water for two days to remove unreacted

monomers. The swelling behavior of the hydrogels was studied in distilled water and salt solutions of 1.5 mol/l each of NaCl

and KCl. The Swelling in water shows decreasing values of q, LE, Ø1, EWC% and increasing polymer volume fraction, Ø2 by

increasing acrylamide, due to increasing hydrophobicity and decreasing the hydrophilicity. The swelling in salt solutions

shows a decreasing in the values of ESSNa%, WCNa%, SCNa%, ESSK%, WCK% and SCK% by increasing acrylamid

monomer in the feed due to increasing the hydrophobicity and decreasing the ionized ionic groups (SO3H). The increasing

values of ESSNa%, WCNa% and SCNa% compared with the values of ESSK%, WCK% and SCK% respectively, is due to

the higher charge density of sodium ion than that of potassium ion.

The present research was implemented to analyses the seedling tolerance of three species Eucalyptus gomphocephala DC (Myrtaceae) (common name 'Tuart'), Eucalyptus marginata Sm. (common name 'Jarrah') and Corymbia calophylla (Lindl.) K.D. Hill & J. A. S. Johnson (common name 'Marri') to soil-induced stressor, namely soil alkalinity (limestone). Seeds germinated in shallow trays filled with white sand in a naturally lit glasshouse (control treatment). A liming treatment was conducted with 20% w/w crushed and sifted Tomala limestone adds to potting mix to increase soil pH. The experiment was conducted over 82 days. E. gomphocephala is restricted soils overlying limestone on study area and according to total seedling dry weight data and calculated relative growth rates coped best in a limestone-enriched soil. However, when examining all the growth and physiological data collected C. calophylla appeared to be the middling tolerant, with no significant difference in leaf allocation or leaf water loss between the well-watered controls and the limestone-enriched treatments whereas the E. marginata was the least tolerant with a 14% reduction in stomatal conductance.