Nutrient potential and capacity. III. Minimum value of potassium potential for availability to Trifolium subterraneum in soil and in solution culture

1967 ◽  
Vol 18 (1) ◽  
pp. 55 ◽  
Author(s):  
NJ Barrow ◽  
CJ Asher ◽  
PG Ozanne

Plants of subterranean clover (Trifolium subterraneum L.) were grown in a range of soils until the supplies of potassium were exhausted. The potassium potential of each soil was then measured by determining the free energy of exchange of potassium for calcium plus magnesium. In soils of very high buffering capacity the potassium potential of the exhausted soil was about –6000 cal/equiv. In soils of lower buffering capacity the potential of the exhausted soil was higher but this may have been an artefact due to release of potassium from fine root material left in the soil at harvest. Subterranean clover plants were also grown in large volumes of well-stirred nutrient solutions which were held at a range of potassium concentrations. Again it was found that the plants were unable to take up potassium when the potassium potential was about –6000 cal/equiv. It is suggested that the potentials were similar because diffusion gradients were negligible in the exhausted soil and also in the swiftly flowing solutions. At potentials above –6000 cal/equiv. availability of potassium appeared to be greater in the solution cultures than in soils. It is suggested that this occurred because, in soils, the uptake of potassium causes the potential at the plant root to be lower than in the bulk of the soil.

1966 ◽  
Vol 17 (6) ◽  
pp. 849 ◽  
Author(s):  
NJ Barrow

The potassium status of 22 soils with low reserves of non-exchangeable potassium was assessed by measuring: (a) the potassium potential (the free energy of exchange of potassium for calcium plus magnesium); (b) the soil's capacity to resist a change in potential ("buffering capacity"); (c) the amount of exchangeable potassium and its percentage saturation. The ability of these measures to predict the supply of potassium was tested by growing subterranean clover (Trifolium subterraneum L.) in pots and determining its potassium content at successive harvests. The soil's buffering capacity was found to affect the supply of potassium even when uptake was small. It is suggested that this was partly because buffering capacity affects the rate of supply by diffusion to plant roots. As the uptake of potassium became progressively larger, the potential became increasingly unsuitable as a single index of availability, but a multiple regression containing terms for potential and for buffering capacity continued to account for a large proportion (89%) of the variation. The relationship obtained can be used to indicate the amount of potassium required to bring a deficient soil to a desirable status.


1985 ◽  
Vol 36 (4) ◽  
pp. 569 ◽  
Author(s):  
MK Kim ◽  
DG Edwards ◽  
CJ Asher

Eleven cultivars of Trifolium subterraneum and Trifolium semipilosum cv. Safari were grown with adequate combined nitrogen for 27 days in flowing solution culture with controlled nutrient concentrations at constant pH values ranging from 3.5 to 6.5. A solution pH of 3.5 was lethal to all cultivars, but growth was in all cases vigorous at pH 4.0 (RGR 15.2-16.9 g 100 g-1 day-1). There were no significant effects of pH over the range of 4.0-6.5 on the yield of any clover cultivar. The results are discussed in relation to an earlier study suggesting greater tolerance of subterranean clover to pH values below 4.0. Phosphorus toxicity symptoms developed in all subterranean clover cultivars with the intensity of symptom development increasing with solution pH from 4.5 to 6.5. The concentration of phosphorus in the older leaves decreased as the solution pH was increased from 4.0 to 4.5, and then increased with further increase in pH, reaching values = 1.0%. Rates of phosphorus absorption followed a similar pattern of response to solution pH. Results are discussed with reference to previously reported effects of pH on phosphorus uptake.


1990 ◽  
Vol 41 (3) ◽  
pp. 499 ◽  
Author(s):  
BJ Scott ◽  
AD Robson

The objectives of this study were to examine Mg distribution in subterranean clover (Trifolium subterraneum L.), to identify an appropriate tissue for diagnosis of deficiency and to establish minimum tissue concentrations associated with maximum plant growth. Plants were grown in solution culture with both discontinued (40 8M and 160 8M reduced to nil) and constant supply (0, 5, 10, 20, 40, 80, 160 8M Mg). Magnesium was depleted from old leaves when Mg supply to the roots was interrupted. However, deficiency symptoms occurred first on the young tissue under these conditions. Under constant but inadequate supply, initial deficiency symptoms occurred in old tissue. Symptoms in leaves were associated with Mg concentrations in the leaf of < 1046 8g g-1 with constant root supply and 586 8g g-1 when supply was interrupted. At luxury constant supply, concentrations of Mg tended to be higher in the older leaves than in the young leaves; the reverse occurred with inadequate supply. Tissue choice for diagnosis was not critical, but the minimum Mg concentration in tissue commensurate with maximum shoot growth varied from 740 8g g-1 for the unifoliate leaf to 1310 8g g-1 in the youngest open leaf (YOL), when plants were grown under constant Mg supply. Current supply of Mg to roots was reflected more rapidly in the concentrations in young leaf than in old leaf tissue.


1967 ◽  
Vol 20 (1) ◽  
pp. 51 ◽  
Author(s):  
D Bouma

Young subterranean clover plants (Trifolium subterraneum L. cv. Mt. Barker) were grown at several levels of phosphorus or sulphur supply and their growth changes examined and compared during a period of 7 days after transfer to complete nutrient solutions.


1958 ◽  
Vol 9 (6) ◽  
pp. 730 ◽  
Author(s):  
DS Riceman ◽  
GB Jones

Subterranean clover (T. subterraneum L. var. Bacchus Marsh) was grown to maturity in a culture solution containing zinc labelled with the radioactive isotope 65Zn. The distribution of zinc in the plants at different stages of growth was determined by means of radioautographs. These show that zinc is always present in very high concentration in the terminal portions of the main axis, runners, and laterals, in young, expanding leaves and petioles, in root tips and at points along the roots, in parts of the inflorescences, and in developing and mature seeds. The concentrations decrease in the vegetative organs as they expand and mature. In mature vegetative organs there is usually a higher concentration of zinc in the vascular tissue than in the tissue surrounding it. A higher concentration of zinc is found in the nodes of the runners and laterals than in the internodes. In the nodes themselves the concentration is highest where the amount of vascular tissue is increased by the presence of the vascular traces of petioles and of runners, laterals, or branches.


1991 ◽  
Vol 42 (5) ◽  
pp. 859 ◽  
Author(s):  
MJ McLaughlin ◽  
TR James

Experiments using split-root sand/solution culture and reconstituted soil profiles were undertaken to examine the influence of P supply to surface roots of subterranean clover (Trifolium subterraneum var. Woogenellup) on root penetration into Al-toxic subsurface strata. In sand/solution culture increasing P supply to surface (0-40 mm) roots enchanced root penetration into Al-toxic nutrient solutions in the subsurface (40-100 mm), but only at low to moderate concentrations of Al. At high concentrations of Al, surface P supply had no effect on root penetration into the lower compartment. Results from the soil experiments confirmed the observations obtained in sand/solution culture. Topdressed P (as single superphosphate-SSP) enhanced root penetration into the Al-toxic subsurface stratum. Plants suffering P stress showed poor root growth in the acidic subsurface stratum. Gypsum in the SSP confounded P treatment effects at high rates of P application. The gypsum quickly dissolved and was able to move through the limited surface soil (0-40 mm, pH 5. O), to the acidic subsurface stratum, as evidenced by Ca concentrations in soil solution. This raised the ionic strength and reduced the pH of the soil solution, and raised solution Al concentrations. Under conditions of limiting leaching, and where the subsurface horizon was very acidic (pH 3.9), the gypsum in SSP caused yield reductions at high rates of application and produced a quadratic yield response curve to topdressed SSP.


1995 ◽  
Vol 35 (2) ◽  
pp. 199 ◽  
Author(s):  
A Pinkerton ◽  
PJ Randall

Sulfur (S) requirements for early growth were determined for 3 legumes (Trifolium balansae, T. subterraneum, Medicago murex) and 1 grass (Phalaris aquatica). Plants were grown in sand culture in a glasshouse and supplied with nutrient solutions containing 6 rates of S (1-32 �g/mL). Legumes were supplied with nitrogen (N) at 168 �g/mL, and phalaris with 28 or 168 pg N/mL. Plants were sampled twice, the second sampling coinciding with flowering of the legumes. Diagnostic indices [total S (St), HI-reducible S (sulfate-S), oxidised S (S6+)], and ratios (sulfate-S/St, S6+/St) were derived for whole shoots (WS), youngest open leaves (YOL) of legumes, and youngest expanded blades (YEB) of the grass. The largest responses to S by the legumes were made by balansa clover and murex medic, which both outyielded subterranean clover, but subterranean clover was the most efficient user of S and had the lowest external S requirement. Concentrations of S6+ were always higher than concentrations of sulfate-S, but the 2 were highly correlated and much lower than St. No S fraction or plant part sampled was consistently superior as an indicator of S status. The larger relative increases and sharper breaks in gradient of the relationships between yield and sulfate-S or S6+ compared with St were offset by their greater relative variability. All indices were subject to Piper-Steenbjerg effects, although these did not seriously affect the critical values. Critical values of St and S6+ in YOL, St in WS of balansa clover, and S, and S6+ in WS of subterranean clover changed little up to 60 days after sowing, but it was necessary to know plant age when assessing the S status of murex medic or phalaris. Critical concentrations of S, in phalaris were little affected by N supply, but critical concentrations of sulfate-S and S6+ were higher with 28 than 168 �g N/mL. Critical values for subterranean clover agreed well with previously published data.


1956 ◽  
Vol 7 (6) ◽  
pp. 495 ◽  
Author(s):  
DS Riceman ◽  
GB Jones

Changes in the distribution of zinc, copper, and dry matter in seedlings of Trifolium subterraneum L. var. Bacchus Marsh grown in solution cultures which were supplied with copper but not with zinc have been traced during the first 40 days after germination. Increase in total dry weight was accompanied by a rapid decline in the concentration of zinc in the plant parts examined. Symptoms of zinc deficiency were recognizable in the third trifoliate leaf by the time the leaflets opened, 33 days after germination. At that time the concentration of zinc in leaf plus petiole had fallen to 14 p.p.m. in the dry matter. There was a continual net loss of zinc from the cotyledons. A marked increase in the amount of copper present in roots, and in leaf plus petiole, occurred soon after the addition of copper to the cultures 20 days after germination, but no substantial change was observed in the amount of copper present in the cotyledons or in the hypocotyl plus growing point. These latter tissues had previously lost small amounts of copper.


1984 ◽  
Vol 11 (2) ◽  
pp. 101 ◽  
Author(s):  
RO Nable ◽  
JF Loneragan

The mobility of manganese from old leaves and cotyledons during vegetative growth has been examined by following manganese content and radioactive manganese redistribution in parts of subterranean clover plants grown into manganese deficiency. In plants transferred from nutrient solutions with 1 �M Mn2+ to solutions without Mn2+, the amount of manganese in the roots decreased markedly. During the same period there was no net loss of manganese from cotyledons and old leaves, although plants developed severe manganese deficiency symptoms in young leaves. Old leaves of plants given an early supply of 54Mn lost no 54Mn when the plants were transferred to non-radioactive solutions without manganese for 14 days. Silicon, which is known to influence the distribution of manganese within leaves of some plants, had no effect on the loss of total manganese or 54Mn from old leaves. Detached green, mature leaves lost 40% of their manganese within 24 h when aerated in water. If leaching by rain removes substantial amounts of manganese from leaves of plants grown in the field, this may account for reports of manganese mobility in plant phloem. The present results establish that manganese is not mobile in the phloem of subterranean clover plants during vegetative growth.


1991 ◽  
Vol 42 (3) ◽  
pp. 559 ◽  
Author(s):  
DC Edmeades ◽  
FPC Blamey ◽  
CJ Asher ◽  
DG Edwards

A flowing solution culture experiment was conducted in which four temperature pasture grasses and 11 temperate pasture legumes were grown in solutions of low ionic strength for 29 days at six aluminium (Al) levels with average Al3+ activities {Al3+} of 1.0, 5.1, 5.9, 9.9, 20.8, 41.6 8M at pH 4.5. Growth of these species was also measured at pH 5.5 in the absence of Al. In the absence of added Al, lucerne (Medicago sativa) cv. Hunter River and phalaris (Phalaris aquatica) cv. Grasslands Maru grew better at pH 5.5 than at 4.5. The reverse was so for ryegrass (Lolium perenne) cv. Grasslands Nui and subterranean clover (Trifolium subterraneum) cv. Tallarook. Increasing the pH from 4.5 to 5.5 had no effect on the growth of the other 11 species and cultivars tested. Micromolar activities of Al (<10 8M) markedly reduced the growth of all species. Four groups were tentatively identified in terms of their tolerance to Al. The two cultivars of ryegrass and the two red clover (Trifolium pratense) cultivars, together with Lotus corniculatus cv. Maitland, were relatively sensitive to Al. A 50% reduction in total dry matter (TDM) was associated with {Al3+} of 2-3 8M. The four white clover (Trifolium repens) cultivars, tall fescue (Festuca arundinacea) cv. Grasslands Roa, phalaris cv. Grasslands Maru, and Lucerne cv. Hunter River were intermediate in their tolerance, with {Al3+} of 3-5 8M reducing TDM by 50%. The two subterranean clover cultivars were more tolerant to Al than white clover (50% TDM reduction at 5-6 8M {Al3+}. Lotus pedunculatus CV. Grasslands Maku was exceptional in its tolerance to Al. Its growth was unaffected by {Al3+} up to 5 8M and 50% growth reduction was associated with {Al3+} of 7 8M The results of this study emphasize the need to conduct solution culture experiments at realistic solution concentrations and ionic strengths when examining the effects of Al on plant growth.


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