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Sulfate-sulfur was applied to sulfur (S)-deficient canola at several growth stages in a field experiment at Cargo near Orange, New South Wales. Applications of 0, 10 or 40 kg S/ha (S0, S10 and S40) as mixtures of potassium sulfate and potassium chloride were made at sowing, the 5-6 leaf rosette stage, flower buds visible, stem elongation and first flowering. The plots received either 80 or 160 kg nitrogen (N)/ha at sowing. Plants from the S0 plots showed symptoms of severe S deficiency during rapid stem elongation, and had a 52% reduction in seed yield and a 21% reduction in seed oil concentration compared with the S40 plants. Application of S10 at sowing, or topdressing S-deficient plants with this rate of S, was inadequate because, although seed oil concentrations were normal (39-42%), seed yields were 25% lower than those from plots that received S40. Topdressing S-deficient plants with S40 at either the 5-6 leaf rosette stage, flower buds visible or stem elongation resulted in the same seed yields and seed oil concentrations as obtained when S40 was applied at sowing. However, there was a 15% reduction in seed yield but no reduction in seed oil concentration when the S40 topdressing was delayed until flowering. Although S10 was inadequate to correct the S deficiency, there was no reduction in either seed yield or seed oil concentration when S10 was topdressed as late as flowering, when compared with this rate of S applied at sowing. Seed meal protein levels were increased by the S40 topdressings. Concentrations of S in seed from the S0 and S10 plants were below the critical value of 0.36% for canola. Seed N:S concentration ratios of S-deficient plants were greater than 10, but 7.5 for plants which received adequate S. Total glucosinolates in seed were increased by the application of S, but the levels were still well below the limit set for the canola standard.

Edible-oil linseed (Linola, CSIRO Australia) was grown in a sand culture experiment in a glasshouse to develop tissue tests for assessing the nitrogen (N) status of the crop. Seven rates of N, provided as nitrate, were used to obtain critical N concentrations. Plants were tissue-tested at 3 developmental stages: early tillering (TL), flower buds visible (BV), and the start of flowering (SF). Suitable tissues for tests based on nitrate-N were the upper half of the main stem and the whole main stem. Leaves were unsuitable as their nitrate-N concentration was unresponsive to N supply until well above the rate for maximum growth. For tests based on total N, suitable tissues were upper stem, upper leaves, total stem, total leaves, and whole shoot. Critical N supply rates for vegetative growth at TL, BV, and SF, respectively, were 85, 145, and 145 mg/L. The critical N supply rate for seed yield was 65 mg/L. Excessive N supplies (350, 700 mg N/L) reduced both seed oil percentage and seed yield. Critical nitrate-N concentrations in fresh, upper stem tissue for vegetative growth decreased from-0.26 to 0.16 mg/g fresh weight (FW) between stages TL and BV. A critical nitrate-N concentration for seed yield could only be obtained for fresh stem tissue at TL, and this value was 50% lower than that for vegetative growth. Critical nitrate-N concentrations [mg/g dry weight (DW)] in dried stem tissue for vegetative growth at TL, BV, and SF, respectively, were 2.3, 1.7, and 0.7 (upper stem); and 2.1, 1.1, and 0.6 (whole stem). Critical nitrate N values (mg/g DW) for seed yield at TL, BV, and SF were 1.1, 0.8, and 0.3 (upper stem); and 1.0,0.7, and 0.2 (whole stem). Critical total N concentrations (% DW) for vegetative growth at TL, BV, and SF, respectively, were 3.0, 2.3, and 2.2 (upper stem); 5.3, 5.8, and 4.5 (upper leaves); 2.2, 1.7, and 1.6 (whole stem); 5.5, 4.9, and 4.5 (total leaves); and 4.5, 3.1, and 2.7 (whole shoot). Corresponding total N values (% DW) for seed yield at TL, BV, and SF, respectively, were 2.9, 2.2, and 2.0 (upper stem); 5.2, 4.8, and 4.3 (upper leaves); 2.1, 1.4, and 1.4 (whole stem); 5.2, 4.4, and 4.2 (total leaves); and 4.3,2.8, and 2.6 (whole shoot). The upper stem is the preferred tissue when testing for nitrate-N, and the whole shoot is the most convenient tissue for total N. Tissue testing for N status of Linola needs to be matched closely to plant age or stage of development because of the decline in critical N concentrations between early tillering and flowering.

Field studies were made at Ariah Park and Cowra to investigate the accumulation and distribution of dry matter and 12 mineral nutrients in fruits (pods) of canola (oilseed rape), and to assess the significance of redistribution of nutrients from the pod walls to the seeds. Flowers 4-6 from the base of the primary inflorescence were tagged at anthesis, and pods which developed from these were harvested at weekly intervals until maturity. Pods reached maturity 82 days after anthesis of the parent flowers. N fertilizer increased seed yields at both sites, but had negligible effects on the dry matter per pod, pod length, 1000 seed wt, seed number per pod, seed oil concentration, and concentrations of mineral nutrients in the pod walls and seeds. Similarly, there were no differences in these parameters due to locality, with the exceptions that seed oil per cent and concentrations of S and Mn in the pod walls and IVln in seeds were higher at Cowra than at Ariah Park. Pods had attained their maximum length and fresh and dry weights by the end of the first half of their development, but seeds had accumulated only 35% of their mature dry weight at this stage. Seeds gained dry matter after dehydration of the fruit began, but the pod walls did not. Seeds had 61% of the pod's dry matter, >70% of its P, N, Zn, Fe and Mg, 30-55% of its K, S, Mn, Cu and Ca, but

Atmospheric CO2 levels are increasing, but little is known about how this will affect tissue concentrations and the partitioning of agriculturally important nutrients such as nitrogen (N) within crop plants. To investigate this, a glasshouse experiment was conducted in which wheat, a C3 species, and maize, a C4 species, were grown for 8 weeks at high CO2 (1500 cm3 m-3) on N supplies ranging from deficient (0.5 mol m-3) to more than adequate for maximum growth (25 mol m-3). Wheat responded to both CO2 enrichment and N supply; maize responded only to N supply. CO2-enriched wheat produced about twice the dry matter of control plants at all levels of N supply. Tiller and ear numbers were increased by CO2 enrichment irrespective of N supply. Enriched wheat plants had a lower Leaf Area Ratio but higher Net Assimilation Rate and Relative Growth Rate than control plants. There was no effect of CO2 enrichment on specific leaf weight. The enriched plants had lower shoot to root dry matter ratios than the controls at 6 mol m-3 N and higher. Shoot to root dry matter ratios of both wheat and maize increased with increasing N supply. CO2-enriched wheat plants accumulated more N than the controls but the proportional increase in N content was not as great as that in dry matter, with the result that concentrations of total-N and nitrate-N were lower in all organs of enriched plants, including ears. Nitrate reductase activity was lower in enriched than in control wheat plants. N-use efficiency by wheat was increased by CO2 enrichment. From a practical point of view, the study indicates that critical total-N and NO3-N concentrations used to diagnose the N status of wheat will need to be reassessed as global CO2 levels increase. Elevated CO2 may also reduce the protein content of grain and thus the baking quality of hard wheats.

Seed reserves of eight species of Proteaceae from south-western Australia were examined by chemical analysis, microscopy and scanning X-ray microanalysis. Cotyledons were the principal reserve organs of all species. Seeds had 30-500 times the level of P, 8-100 times the level of N, Cu and Zn and, on most species, higher levels of Mg, K, Mn and S than leaves or woody parts of fruits. Levels of Ca, Fe, Na and Cl in leaves and fruit parts were the same as or higher than those in seeds. The K:Ca ratios of seeds were very low (1:2). Seeds had only 1-16% of total fruit dry matter but contained 83-98% of a fruit's P, 43-78% of its N and much of its Zn, Mn and Cu. Seeds had no more than 3% of a fruit's Na or Cl. Oil (14-31%) and protein (15-64%) were major organic reserves of seeds; starch was absent. Protein bodies occurred at high density throughout the parenchyma of cotyledons of all species, and in epidermal and provascular tissues of some species. Globoids occurred in some protein bodies; crystalloids were absent. Globoid-containing protein bodies were confined to central mesophyll layers of cotyledons of Hakea spp. and Grevillea annulifera, to subepidermal parenchyma of Banksia spp. and Xylomelum angustifolium, but occurred in most cotyledonary tissues of Grevillea leucopteris; X-ray microanalysis of cotyledon tissues suggested that the globoids were rich in P, Ca, S and Mg, and in some species also in Fe, Zn and K. The species of Proteaceae investigated were considered to be very effective in channelling essential nutrients to their seeds.

The heathland form of Banksia marginata Cav. regenerates rarely from seed but commonly by resprout- ing from buds on lateral roots, whereas Banksia ornata F. Muell. regenerates only from seed, usually released after fire. The two species co-occur in heath vegetation on nutrient-poor soils in south-eastern South Australia and western Victoria. Shoots were sampled from stands of B. marginata aged from 1 to 25 years and of B. ornata aged from 1 to 50+ years after fire in the Little Desert National Park, western Victoria. B. marginata, the resprouter, distributed a greater proportion of the total shoot dry matter and content of all nutrients to vegetative growth over its shorter life span than B. ornata, the non-sprouter. About 50% of the total phosphorus in B. ornata shoots at 50+ years was present in cones (including seeds) compared with only about 20% in B. marginata shoots at a comparable stage of senescence (25 years). This difference between the species was also true to a lesser degree for nitrogen. There were considerable differences between other nutrients in their distribution patterns in shoots. Nutrients could be grouped together on the basis of distribution in shoots more satisfactorily than on presumed physio- logical roles. Stems were major sites of nutrient accumulation in both species. The content of a particular nutrient in seeds as a proportion of the content in the living parts of the shoot ranged from 0.03% (Na, Mn) to 2.0% (P) in B. marginata, and from 0.3% (Na) to as high as 31% (P) in B. ornata. Concen- trations of all nutrients except sodium were much higher in seeds than in the woody cones or vegetative organs of both species; seeds of B. ornata were particularly rich in calcium and manganese. We conclude that the different patterns of distribution of biomass and nutrients, especially nitrogen and phosphorus, within shoots of the two species reflect their different regenerative modes after fire. Introduction Phosphorus and, to a lesser extent, nitrogen limit the growth of sclerophyllous shrubs on nutrient-poor soils in southern Australia

The economy of water and dry matter in fruits of white lupin (L. albus L.) was studied by measuring transpiration, CO2 exchange and weight changes over an 8-week growth period. These data were combined with analyses of upper stem tracheal (xylem) sap and fruit tip phloem sap to estimate rates of import of dry matter and water through xylem and phloem. Assuming unidirectional mass flow to operate, phloem carried 97 % of the dry matter and 27 % of the water entering the fruit, and xylem supplied the remainder of the water, 30 % of the minerals and 10 % of the amino compounds. The structure of fruit stalks of various age was examined by light microscopy. Cross-sectional areas occupied by different tissues were measured, and numbers and mean transverse areas of conducting elements estimated. Sieve tubes comprised 0.66-1.13% of the stalk's cross-sectional area, vessels plus tracheids 0.27 - 0.50%. Secondary xylem consisted mainly of fibres. Sieve tubes occupied 18 - 27% of the phloem cross-sectional area. The fully grown stalk showed approximately three times as many sieve tubes in transverse section as vessels plus tracheids. Transfer of dry matter and water through the fruit stalk was highest during the exponential phase of fruit growth. Peak specific mass transfer in sieve tubes was 3.95 g dry matter per square centimetre of sieve tube per hour, in tracheids plus vessels 0.28 g cm2 h-1. Maximum flow velocity in sieve tubes was 22 cm h-1, in tracheids plus vessels, 147 cm h-1. Values for specific mass transfer and flow velocities were several times less in stalks of very young or near-mature fruits.

A study was made of the shape, dimensions and possible nutritional significance of the main root of the hemi parasite Nuytsia floribunda. Levels of nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, sodium, iron, manganese, zinc and copper were determined in the main root: haustoria, xylem sap, mucilage, trunk and leaves. The main root was approximately turnip-shaped and there was no evidence of a tap-root. Haustoria were confined to the top 15-20 cm of the soil and were attached to a variety of woody and herbaceous host plants. Haustoria contained the highest levels of nitrogen and phosphorus, the trunk and main root the highest levels of calcium, magnesium and sodium. Potassium and sodium accounted for 75% of the minerals in xylem sap. calcium and magnesium for 60% of the minerals in mucilage which exuded from wounds in the main root. Concentration gradients of most minerals existed across the main root. Nitrogen, phosphorus, potassium, sulfur and sodium were more concentrated in the outer zone of the root, calcium, magnesium, manganese and copper in the central part. Nuytsia appears to draw on stored nutrients in some situations. Conservative estimates suggested that nutrient reserves in the main root could not provide the amounts required for flower and fruit production. It was concluded that reproductive and vegetative growth draws on reserves in organs other than the main root and the extensive lateral root system may be important in this respect.

The nutrition of developing fruits of K. prostrata was studied in natural habitat near Perth, Western Australia. Changes in the contents of specific nutrients in pods and seeds are described. Seeds accumulated > 80% of the N and P of the fruit, 36-58% of its K, S, Ca, Mg, Fe and Zn but < 25% of its Na. Pods lost 77-87% of their N and P, 20-39% of their Mg, Zn, Mn and Cu, and 9-15% of their K, S, Ca and Fe during senescence. Na was not withdrawn from pods. Retranslocation from pods were considered to be capable of providing > 50% of the N and P accumulated by seeds, although the values for most nutrients and DM ranged from 16 to 35%. Fruit-tip exudate had some characteristics of phloem sap (e.g. alkaline pH, 15-2096 sucrose, a high level of K-), but contained 2 . 5 mg/ml Mg2+ and appeared to be contaminated with mucilage. The testa contained 75% of the seed's dry matter and the major part of its K, Ca, Mg, Mn and Ca; the embryo most of the seed's N, P and S. Information for Kennedla is discussed in relation to data for cultivated legumes as there is no comparable study on another native legume.

The response of T. domingensis, a large emergent macrophyte, to salinity and manganese was studied under glasshouse conditions. Plants were grown in saline solutions ranging in concentration from 0.5 to 100 mM NaCI. and in manganese sulfate solutions ranging in concentration from 0.01 to 10 mM. Growth was reduced slightly at 50 mM NaCl and severely at 100 mM NaC1, suggesting that T. domingensis is moderately salt tolerant. Plant parts had highest chloride levels at 25 mM NaCl and highest sodium levels at 100 mM NaCl. The highest sodium chloride treatment reduced the level of potassium in the rhizomes, but not in roots or leaves. Sodium chloride had no effect on the concentration of nitrate in organs, but total nitrogen levels in roots and rhizomes increased at 100 mM NaCI. Sodium was considered to be more toxic than chloride. Growth in manganese solutions was unaffected except at the highest concentration used. Manganese accumulated quickly in leaves to levels which would be toxic to livestock; leaves retaining over 70% of the total manganese in the plant. Manganese applied at high concentrations substantially reduced the levels of calcium, magnesium and phosphorus in the leaves. In a field experiment, there were seasonal changes in the levels of selected elements in the leaves of T. domingensis. During leaf senescence. concentrations of sodium, manganese and calcium increased by 20-80%, but levels of phosphorus, nitrogen, potassium and maganesium fell by 65-84%. The results are discussed in relation to the use of T. domingensis in Hastewater reclamation.

The mineral nutrition of L. albus and L. angustifolius was studied under nutrient-sufficient conditions in sand culture. Mineral accumulation by both species was closely synchronized with dry matter accumulation. Fruits acquired major proportions of the nitrogen, phosphorus, potassium, magnesium and zinc of both species. Leaflets were major sites of accumulation of calcium, iron and manganese; stem and petioles accumulated substantial amounts of potassium, phosphorus, magnesium, copper and sodium. Intensities of intake of calcium, magnesium and iron by roots of L. angustifolius were higher than in L. albus. The situation was reversed for sodium. Cotyledon reserves of nitrogen, phosphorus, potassium and zinc were mobilized to seedling parts with 85–97% efficiency, other elements much less effectively. During fruiting, vegetative parts of the shoot showed net losses of 60–80% of their nitrogen, phosphorus and potassium, 20–50% of their magnesium, iron, zinc, manganese and copper, and less than 15% of their calcium and sodium. Mobilization from vegetative structures was generally more efficient in L. albus than in L. angustifolius. Leaflets showed higher mobilization efficiencies than stem and petioles. Post-anthesis mobilization furnished the equivalent of 23–59% of the fruit's intake of nitrogen, phosphorus, potassium, magnesium and manganese, 10–25% of the zinc, calcium, iron and copper, and 2% or less of the sodium. Nitrogen, phosphorus and potassium attained higher concentrations in fruits than in mature, non-reproductive parts; less mobile elements (calcium, sodium, iron and manganese) showed the opposite effect. Concentrations of sodium and manganese were especially low in fruits of L. angustifolius compared with L. albus.