Phosphorus efficiency in pasture species. VI. A comparison of Italian ryegrass, phalaris, red clover and white clover over time

1991 ◽  
Vol 42 (3) ◽  
pp. 541 ◽  
Author(s):  
PD Kemp ◽  
GJ Blair

Two problems in comparative studies of the P efficiency of pasture species are the choice of measurement to define P efficiency and the basis of comparison to use. Therefore, the degree to which the level of P supply and plant age, or time of harvest, influence a variety of measures of P efficiency was examined in four temperate pasture species grown in a soil at a range of P levels in a glass house. The four species were Italian ryegrass, phalaris, red clover, and white clover. Italian ryegrass was the most P efficient and red clover the least P efficient species in terms of the broad scale measures of P effiency, shoot yield per unit of P applied and total P uptake over the first 40 days after sowing (DAS), and shoot P concentration at 68 DAS. Nevertheless, by 68 DAS the shoot fresh weight yield of the four species was similar at both the low (5 kgP ha-1) and the high (80 kg P ha-1) P rate. The superior shoot biomass production at lower P rates over 40 DAS of Italian ryegrass and phalaris compared with red and white clovers was largely the result of a greater root weight and P uptake per plant. Early root weight was determined by the relationship between seed weight and root relative growth rate (PGR), whereas P uptake per plant was influenced by root weight and plant P demand as measured by relative P uptake rate (RPR). The understanding of such relationships was shown to be essential to the effective interpretation of broad scale measures of P efficiency. The comparative broad scale P efficiences of the four species changed over time. When Italian ryegrass and phalaris were compared on an ontogenetic basis, number of leaves per plant, shoot yield and P uptake per plant were similar. The comparison of the P efficiency of species on both an ontogenetic and temporal basis is proposed.

1991 ◽  
Vol 42 (3) ◽  
pp. 531 ◽  
Author(s):  
DC Godwin ◽  
GJ Blair

Seed collections of 'naturalized' white clover (Trifolium repens L.) accessions, believed to have been derived from a Dutch 'wild white' clover introduced into the Northern Tablelands area of New South Wales were made. The collections were made from areas with low, high, and intermediate concentrations of extractable soil phosphorus. In a controlled environment pot experiment, the shoot and root growth and P uptake of each of these accessions was compared over a range of six P rates to three commercially available accessions-Ladino, Grasslands Huia, and Haifa and an accession from Algeria. Various methods of determining the efficiency of ultilization of P were examined. By all methods studied, Ladino generally was more efficient at utilizing applied P. Ladino produced a larger shoot biomass and greater length of root than other accessions, had a higher P uptake, and was more efficient in utilizing this P for the synthesis of biomass. The rankings of the clover accessions in terms of P efficiency changed according to the definition used. The study suggests that some scope exists for selection for P efficiency in clover accessions.


2012 ◽  
Vol 58 (No. 5) ◽  
pp. 230-235 ◽  
Author(s):  
Manoj-Kumar ◽  
A. Swarup ◽  
A.K. Patra ◽  
J.U. Chandrakala ◽  
K.M. Manjaiah

In a phytotron experiment, wheat was grown under two levels of atmospheric CO<sub>2</sub> [ambient (385 ppm) vs. elevated (650 ppm)], two levels of temperature (ambient vs. ambient +3&deg;C) superimposed with three levels of phosphorus (P) fertilization: 0, 100, and 200% of recommended dose. Various measures of P acquisition and utilization efficiency were estimated at crop maturity. In general, dry matter yields of all plant parts increased under elevated CO<sub>2</sub> (EC) and decreased under elevated temperature (ET); however, under concurrently elevated CO<sub>2</sub> and temperature (ECT), root (+36%) and leaf (+14.7%) dry weight increased while stem (&ndash;12.3%) and grain yield (&ndash;17.3%) decreased, leading to a non-significant effect on total biomass yield. Similarly, total P uptake increased under EC and decreased under ET, with an overall increase of 17.4% under ECT, signifying higher P requirements by plants grown thereunder. Although recovery efficiency of applied P fertilizer increased by 27%, any possible benefit of this increase was negated by the reduced physiological P efficiency (PPE) and P utilization efficiency (PUtE) under ECT. Overall, there was ~17% decline in P use efficiency (PUE) (i.e. grain yield/applied P) of wheat under ECT. &nbsp;


2020 ◽  
Vol 13 (5) ◽  
pp. 554-562
Author(s):  
Eamon Haughey ◽  
Jennifer C McElwain ◽  
John A Finn

Abstract Aims Research on the effects of extreme rainfall events on ecosystem function has primarily focussed on drought or flooding events, which usually include changes to mean or total rainfall, annually or over a season. However, less is known about the effects of increased rainfall variability without change to mean or total amounts. We investigated the effects of increased variation of water supply on shoot and root biomass as well as the distribution of root biomass of four grassland plant species, grown in monoculture and mixture communities. Methods Perennial ryegrass (Lolium perenne L., shallow-rooting grass), chicory (Cichorium intybus L., deep-rooting forb), white clover (Trifolium repens L., shallow-rooting legume) and red clover (Trifolium pratense L., deep-rooting legume) were established in mesocosms. Four plants of the same species were grown in monoculture communities and one of each species grown in four-species communities. Water supply was manipulated such that; compared with a baseline level with low variation in water supply, there was a treatment with medium variation (±40%) and another with high variation (±80%). Shoot and root biomass were measured, and vertical root distribution models fitted. Important Findings Compared with the low variation treatment, shoot biomass was significantly reduced under high variation for white clover, red clover and four-species communities. Under all conditions, four-species communities produced more shoot and root biomass than predicted by species performance in monoculture (overyielding). Under increased water variation, chicory monocultures allocated a higher proportion of root biomass to deeper soil layers while the total root biomass of white clover monocultures was significantly reduced. These results indicate that increased variability of water supply can negatively affect the shoot and root biomass production of single and multi-species grasslands. There is a need for further investigation of water variation effects on the functioning of multi-species grassland systems at field scale.


1988 ◽  
Vol 39 (5) ◽  
pp. 807 ◽  
Author(s):  
RH Chisholm ◽  
GJ Blair

Two solution culture experiments were conducted to compare the efficiency of phosphorus use and indicies for measuring it in a tropical and a temperate pasture legume. The species chosen were Stylosanthes hamata cv. 'Verano' (Caribbean stylo) and Trifolium repens cv. 'Ladino' (white clover).The first experiment used two solution P concentrations (2, 16 8M) to investigate differences between species in the rate and extent of P uptake. The second experiment used five solution P concentrations (1, 2, 4, 8, 16 8M ) to evaluate differences between species in internal efficiency of P utilization.There was no difference between white clover and stylo in the capacity to remove P from the same solution P concentrations. However, in both species the extent of depletion of solutions by plants grown at high P was not as great as that plants grown at low P. The ranking of species in terms of their internal efficiency or relative growth rate changed with time and P concentrations.Growth of white clover was better than stylo where there was a moderate deficiency of phosphorus. Alternatively, growth of stylo was better than white clover where phosphorus deficiency was more severe. The relative growth rate of stylo at low (2 8M ) P was maintained above 8% per day after prolonged P stress, whilst in white clover at the same P concentration RGR fell to less than 2% per day.Internal P efficiency or the amount of dry matter accumulated per unit P accumulated per unit time showed that white clover was more P efficient than stylo in the early stages of growth.


1984 ◽  
Vol 62 (1) ◽  
pp. 38-43 ◽  
Author(s):  
A. H. Khadhair ◽  
R. C. Sinha ◽  
J. F. Peterson

The effect of white clover mosaic virus infection on several factors relevant to symbiotic N2 fixation was determined in nodulated red clover (Trifolium pratense L.) plants at 10-leaf, preblooming, blooming, and flower-senescence stages of growth, corresponding to 3, 6, 9, and 12 weeks after virus inoculation, respectively. Virus infection caused a significant [Formula: see text] reduction of plant growth (top and root weight), nodulation (number and weight of nodules), rhizobial population, nitrogenase activity, and leghemoglobin concentration in the nodules. The presence of a high concentration of virus within nodules at all harvest times was indicated by infectivity assays. The leghemoglobin was shown to be localized in the peribacteroidal space by a cytochemical technique. A significant increase in inducible nitrate reductase activity was associated with virus infection of plants.


1994 ◽  
Vol 45 (3) ◽  
pp. 669 ◽  
Author(s):  
PD Kemp ◽  
GJ Blair

The P efficiency of Italian ryegrass (Lolium multiflorum Lamk. cv Grasslands Tama) and phalaris (Phalaris aquatica L. cv Sirosa) was compared on both a temporal and ontogenetic basis. As ontogeny and growth are interrelated, such a comparison allowed the growth and physiological responses to P level of the two species to be separated from responses due to the species being at different ontogenetic stages at the time of comparison. Plants were grown from seed through to anthesis under P deficient and P sufficient conditions in soil in a glasshouse. The ontogenies of Italian ryegrass and phalaris were similar, but the rate of development of Italian ryegrass was greater at both P rates. P deficiency resulted in arrested reproductive development in phalaris. At both P levels shoot, root and total biomass and net P uptake per plant by Italian ryegrass were greater than by phalaris when the two species were compared on a temporal basis, but when compared on an ontogenetic basis the two species were similar. There were some differences in the allocation of P between the acid-soluble P, lipid P, and residue P fractions, but biomass production was not determined by the efficiency of P utilization. The superior biomass production of Italian ryegrass on a temporal basis was due to its greater seed size and rate of ontogeny rather than differences in photosynthetic rate, unit leaf rate, leaf area ratio or shoot: root ratio. Similarly, the greater P uptake per plant of Italian ryegrass on a temporal basis was driven by its greater plant size and faster root extension rate rather than by P uptake per unit root length. The level of vesicular arbuscular mycorrhizal (VAM) infection in the roots of the two species was similar under P deficiency but greater in phalaris under P sufficient conditions. Overall, the different temporal responses to P of Italian ryegrass and phalaris were largely related to their different rates of ontogeny and the interrelationships between ontogeny and growth rate rather than to differences in their physiology in relation to P acquisition and utilization.


Soil Research ◽  
1996 ◽  
Vol 34 (6) ◽  
pp. 1015 ◽  
Author(s):  
SN Trolove ◽  
MJ Hedley ◽  
JR Caradus ◽  
AD Mackay

The breeding of phosphate (P) efficient pastoral legumes could reduce the amount of fertiliser required on pastoral farms. In this study, Lotus pedunculatus and 3 genotypes of white clover (Trifolium repens L.) known to differ in their ability to respond to added P were grown on unfertilised soil and soil to which either monocalcium phosphate (MCP) or North Carolina phosphate rock (NCPR) were added. White clover genotype 8D (a selection line from Crau) had a greater (P < 0.05) internal P efficiency (shoot DM production per unit plant P) than 1A (a selection line from Gwenda) or lotus on unfertilised soil, whereas on fertilised soil, lotus had a significantly higher (P < 0.05) internal P efficiency than 2 of the white clover genotypes on MCP-fertilised soil (P < 0.01) and all 3 white clover genotypes on NCPR-fertlised soil (P < 0.01). Lotus also had a higher (P < 0.01) external P efficiency (total P uptake) than all 3 white clover genotypes on the 2 fertilised treatments. This was due to a greater root length, not a greater P uptake per unit length.


1990 ◽  
Vol 41 (6) ◽  
pp. 1071 ◽  
Author(s):  
GJ Blair ◽  
EJ Wilson

An experiment was conducted under controlled environment conditions in nutrient solution over four P levels (1,4, 8, 16 8mol P m-3) to evaluate the yield performance and P uptake of two accessions of white clover (Trifolium repens). The two accessions used were Naturalized, which was grown from a seed collection made from a low P soil on the Northern Tablelands of N.S.W., and cv. Ladino. Nutrient solutions were renewed when the P concentrations fell by a maximum of 10% and were pumped so that there was a flow rate of 4.4 L min-1 over the plant roots. The shoot and root fresh weight yield of Ladino was higher than Naturalized at all P levels. At 16 8mol P m-3 the shoot yield of Ladino was fourfold that of Naturalized; however, the relative yield response of Ladino between 1 and 16 8mol P m-3 was only 20% of the response of that in Naturalized. Phosphorus uptake was highest in Ladino at all P levels. The minimum shoot labile P concentrations recorded in this study were 1.1 and 2.5 8mol P g F.wt-1for Ladino and Naturalized respectively, indicating that Naturalized is capable of maintaining relatively high soluble tissue P levels under low P supply. The generally higher labile, lipid and residue P levels in new leaf, old leaf, stem and root in the Naturalized white clover accession indicate a lower efficiency of nutrient utilization in this collection compared to Ladino. In contrast to Ladino, Naturalized white clover may be able to control its P accumulation at high levels of supply, as toxic levels do not accumulate in old leaf. Ladino was the more efficient accession when P efficiency was defined as shoot yield per unit of P in solution. When P efficiency was defined as shoot or plant yield per unit of P absorbed or as the inverse of P concentration (utilization quotient), Ladino was the more efficient accession at 1 and 4 8mol P m-3, with only small differences between the accessions at 8 and 16 8mol P m-3. The results suggest that Naturalized may be adapted to low P supply through its low inherent growth rate which lowers its demand for exogenous P.


1992 ◽  
Vol 43 (3) ◽  
pp. 479 ◽  
Author(s):  
JB Baon ◽  
SE Smith ◽  
AM Alston ◽  
RD Wheeler

The influence of indigenous vesicular-arbuscular mycorrhizal infection on the assessment of phosphorus (P) efficiency in wheat ( Triticum aestivum L. cv. Spear), barley (Hordeum vulgare L. cv. Galleon) and rye (Secale cereale L. cv. S.A. Commercial) was studied. P efficiency was defined in terms of uptake (mg P pot-1) or utilization (g dw mg-1 P). Experiments were set up with two soils which had low concentrations of plant available P and had been used in a previous study of P efficiency in cereals. Numbers of spores and infective propagules were significantly different in the two soils. In the soil with low propagule density, the extent of mycorrhizal infection of barley, wheat and rye increased with time. Twenty days after transplanting 3-day old seedlings, there was no difference in the percentage of root length infected (2.0%), but at 40 days, wheat (22.4%) and barley (19.3%) had significantly greater percentage of infected root than had rye (10.7%). At 30 days, wheat had a significantly higher percentage of root length infected than barley. In the soil with high propagule density, infection occurred more rapidly, so that the percentage of root length of wheat and barley infected was not significantly different at the three times of harvest. However, infection of rye significantly increased with time and was higher (31.8%) than that of barley (19.8%) at the final harvest. Mycorrhizal infection was positively correlated with efficiency of P uptake in barley, but not in wheat or rye. However, efficiency in utilization of P by barley and wheat was negatively correlated with infection. The colonization of cereals by the indigenous mycorrhizal fungi decreased with the addition of P to the soils. The results of these studies indicate the potential importance of mycorrhizal infection in assessment of P efficiency in cereals.


1988 ◽  
Vol 39 (5) ◽  
pp. 827 ◽  
Author(s):  
RH Chisholm ◽  
GJ Blair

Results of an experiment over five solution P concentrations ( 1 , 2, 4, 8, 16 8M P) and five harvests were used in a response surface approach to determine the size and incorporation rates of major plant P pools in white clover (Trifolium repens cv. Ladino) and stylo (Stylosanthes hamata cv. Verano).At low P stylo had a greater total flux of P from the soluble P (inorganic P, ester P) pool to supply lipid and residue P (RNA, DNA, phosphoprotein) pools.At high P concentrations large soluble P pools in tops were associated with depressed dry weight accumulation in stylo compared to white clover. Possible reasons for this effect of soluble P, as related to photosynthetic rate, are discussed.Since both pool size and incorporation rate affected the efficiency of phosphorus use, the two measures were combined in a model of plant P use to assist in understanding reaction to high or low P. The model demonstrated the importance of maintenance of P supply to structural P pools, particulary phospholipids, at low P levels.Pool size and incorporation rate were combined as a transfer coefficient of P. RGR was best correlated with the transfer coefficients of structural (lipid, residue) pools in the roots rather than the tops. R2 values as high as 0.99 were obtained for relationships between structural P pools and dry weight. Strong correlations were also found when the data of both species were combined, including that the same factors were associated with RGR in different species. Selection for 'P efficiency' based on biochemical parameters is possible, but must take account of roots rather than simpler tops P concentrations.


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