Zinc Nutrition of Jarrah (Eucalyptus marginata Donn ex Smith) Seedlings

Abstract

The relationships of seven levels of zinc supply to dry matter and zinc concentration were assessed for jarrah (Eucalyptus marginata Donn ex Smith) seedlings grown for 84 days in a zinc-deficient sand in the glasshouse. Zinc deficiency symptoms appeared within 28 days of sowing as a change in leaf colour of young leaves from green to bronze. Later, red areas developed and these became necrotic in severe cases. These symptoms were accompanied by decreased shoot and root dry weights. Zinc concentrations in various plant parts were low and, with the exception of the shoot apex, showed little response to zinc supply. Concentrations at the shoot apex varied from 3�g/g in deficient plants to 12�g/g in plants with adequate zinc supply. We suggest that of the plant parts analysed, the shoot apex is the only one which may be useful in defining zinc status of jarrah seedlings. Critical zinc concentration for this tissue was between 10 and 12 �g/g dry matter. Phosphorus concentrations in all plant parts, except the shoot apex, increased to very high levels with increasing zinc deficiency. It is suggested that some zinc deficiency symptoms of jarrah seedlings, e.g. necrosis, may have resulted from phosphorus accumulation due to zinc deficiency.

Zinc nutrition and leaf carbonic anhydrase activity ofEucalyptus maculata seedlings andTrifolium subterraneum

“…In a zinc trial with Eucalyptus marginata Wallace et al (1986) found that the relationship between dry matter and zinc concentration of the YFEL was too low to be useful for diagnostic purposes and recommended that the shoot apex, with a critical zinc concentration of 10-12 #g g-~ dry matter be used for diagnosis. In E. maculata it appears that older tissues such as the YFEL may also be appropriate for analysis.…”

“…The development of small necrotic leaves is parallelled by reduced biomass and lower zinc concentrations in young leaves. Leaf tissues were generally poorly responsive to the level of zinc supply (Wallace et al, 1986). To overcome the disadvantages of relating zinc concentrations in dry material to yield, alternative approaches such as assaying the level of metallo-enzymes may be more appropriate.…”

Effect of the Concentration of Phosphorus on Growth and Nutrition ofLeucospermum cordifolium‘Flame Spike’

“…It is possible that the activity of P i transporters depends mainly on the level of P i in the whole plant rather than in the proximity of the root (Smith, 2002). It was observed (in Lupinus albus) that the formation of proteoid roots can be inhibited by foliar application of P (Forde and Lorenzo, 2001) and that plants with zinc (Zn) deficiency undergo a significant accumulation of P (Wallace et al, 1986;Smith et al, 2003). In certain cases, foliar application of Zn (Verticordia plumosa L.) eliminates P toxicity symptoms and lowers the level of hexose phosphate in leaves (Silber et al, 2002).…”

Symptoms of mineral nutrient deficiencies and the nutrient concentration ranges in seedlings of Eucalyptus maculata Hook.

“…For many northern hemisphere trees, there is extensive information on the use of plant analysis for diagnosing the nutritional status of tree seedlings (Duryea and Landis, 1984;Landis et al, 1989). However, only a few critical concentrations have been set for eucalypt seedlings (Wallace et al, 1986;Dell et al, 1987) and, nutrient concentration ranges that have been m e a s u r e d in trees in the field (Lamb, 1977;Bell and Ward, 1984) may not be relevant to young plants. Eucalyptus maculata (spotted iron gum) was chosen for this study because, in addition to copper deficiency (Dell and Bywaters, 1989), a wide range of nutrient d i s o r d e r s is c o m m o n l y e n c o u n t e r e d in this species on r e v e g e t a t e d bauxite mine sites in W e s t e r n A u s t r a l i a .…”