Phosphorus and Carbon Budgets of Eucalyptus pilularis Smith Seedlings During Their Cotyledonary Phase of Growth

1985 ◽  
Vol 12 (5) ◽  
pp. 535 ◽  
Author(s):  
DR Mulligan ◽  
JW Patrick
Keyword(s):  
Seedling Growth ◽  
Dry Matter ◽  
Soil Phosphorus ◽  
Phosphorus Acquisition ◽  
Carbon Distribution ◽  
Phosphate Ion ◽  
Eucalyptus Pilularis ◽  
Available Soil Phosphorus ◽  
Partitioning Pattern ◽  
Phosphorus Export

The budgeting of phosphorus and carbon in Eucalyptus pilularis Smith seedlings raised in a phosphorus-deficient sandy podzol was examined for the first 35 days of seedling growth. During this period, the photosynthetic cotyledons were a major source of both phosphorus and carbon. At 7 days from sowing, the cotyledons were gross importers of assimilated phosphorus but switched to gross (day 15) and then net (day 20) export in response to the current rate of phosphorus acquisition and the phosphorus demand by other organs. However, the cotyledons retained the capacity to revert to phosphorus import. This strategy would permit the seedlings to take advantage of any favourable fluctuations that may occur in soil phosphorus supply. Initial cotyledonary phosphorus export was directed basipetally to the roots and soil. From 20 days after sowing the partitioning pattern altered, with exported phosphorus moving solely to the expanding leaves. Carbon exported from the cotyledons initially supplied all sinks although, once the first leaf pair was self-supportive for carbon, the roots and stem received a higher proportion of exported cotyledonary carbon. The efficiency of phosphorus redistribution was considered to minimize the consequences of a rapidly depleted pool of readily available soil phosphorus on seedling growth. The seedlings also possessed a strategy of maximizing the investment of carbohydrate into dry matter by keeping respiratory losses to a minimum. A proposed link between the distribution of the limiting phosphate ion and carbon distribution may be a contributing factor to the success of E. pilularis in the phosphorus-deficient soil.

Growth of and Phosphorus Partitioning in Eucalyptus pilularis Smith Seedlings Raised in a Phosphorus-Deficient Soil

1985 ◽  
Vol 33 (3) ◽  
pp. 245 ◽  
Author(s):  
DR Mulligan ◽  
JW Patrick
Keyword(s):  
Growth Rate ◽  
Dry Matter ◽  
Soil Phosphorus ◽  
Phase 1 ◽  
Dry Matter Production ◽  
Phase 2 ◽  
Phosphorus Acquisition ◽  
Leaf Production ◽  
Matter Production ◽  
Eucalyptus Pilularis

Eucalyptus pilularis Smith seedlings were raised in a glasshouse for 260 days in a phosphorus-deficient forest soil. Over this period, growth was divided into two major phases. Phase 1 was characterized by an initially high but rapidly declining relative growth rate and, at least after 26 days from sowing, a very low rate of phosphorus acquisition. Phase 2, delineated at around 116-134 days from sowing and previously correlated with the degree of ectomycorrhizal development, commenced with an abrupt increase in the rate of both parameters. Over the last 90 days of Phase 1 the roots received an increasing proportion of shoot dry matter production and accumulated 86% of current phosphorus acquisition. Continued, but slow, shoot development during this time was made possible by high re-use of phosphorus within the shoot. During Phase 2, increased transfer of phosphorus to the shoot (50% of total net uptake) reduced the dependence on remobilized phosphorus and resulted in a marked stimulation of leaf production. In addition to utilizing the limited phosphorus available for dry matter production very efficiently, it is proposed that the success of this typically fast-growing species under such a degree of phosphorus stress was aided by the finely tuned responsiveness of both phosphorus deployment and growth rate to fluctuations in the soil phosphorus supply.

Response of annual medic pasture to superphosphate applications and the correlation with available soil phosphorus

1972 ◽  
Vol 12 (54) ◽  
pp. 43 ◽  
Author(s):  
CL Rudd
Keyword(s):  
Regression Analysis ◽  
Dry Matter ◽  
Soil Phosphorus ◽  
South Australia ◽  
Sandy Soils ◽  
Effective Index ◽  
Soil Test ◽  
Phosphorus Level ◽  
Available Soil Phosphorus ◽  
Pasture Yield

The response of annual medic dominant pastures to residual and currently applied phosphorus was examined in twelve experiments in cereal areas of South Australia. The experimental sites had been sown in the previous year to wheat with nine rates of phosphorus ranging from 0-48 kg P/ha applied as superphosphate. The 0.5M NaHCO3 extraction provided an effective index of residual available soil phosphorus after the crop and the amount of phosphorus detected by this soil test varied from 24-43 per cent of the total phosphorus applied as superphosphate on sandy and heavier textured soils respectively. Regression analysis showed that an available soil phosphorus level of 32-38 kg P/ha 10 cm was sufficient to produce 90 per cent of maximum pasture yield on the sandy soils but 41-47 kg P/ha 10 cm was required on heavier textured soils. Percentage phosphorus in the dry matter in spring was not correlated with pasture response.

Carbon and Phosphorus Assimilation and Deployment in Eucalyptus pilularis Smith Seedlings With Special Reference to the Role of the Cotyledons

1985 ◽  
Vol 33 (5) ◽  
pp. 485 ◽  
Author(s):  
DR Mulligan ◽  
JW Patrick
Keyword(s):  
Photosynthetic Capacity ◽  
Soil Phosphorus ◽  
Phosphorus Uptake ◽  
Relative Growth ◽  
Normal Seedling ◽  
Seed Reserves ◽  
Eucalyptus Pilularis ◽  
Available Soil Phosphorus ◽  
Essential Contribution

Early growth of glasshouse-raised Eucalyptus pilularis Smith seedlings in a phosphorus-deficient soil was divided into a cotyledonary and a post-cotyledonary phase. The delineation was made on the basis of cotyledon excision experiments which ascertained the stage (between 32 and 39 days from sowing) beyond which the cotyledons no longer made an essential contribution to normal seedling development. The relative growth rate of the E. pilularis seedlings during the cotyledonary phase was at least comparable with that of many fertilized tree species. The expression of this characteristic in such a phosphorus-deficient soil was considered a consequence of the contributions of both carbon and phosphorus from the cotyledons. Since the seed reserves of both elements were low, these organs were established as major sources largely through immediate post-emergence events. The cotyledons rapidly developed photosynthetic capacity and were the dominant sink for assimilated phosphorus during the week following emergence. Phosphorus gains by the seedlings over this period (up to 16 days from sowing) doubled the seed reserve level of phosphorus (7.5 μg). Beyond this time, however, due to the rapid depletion of readily available soil phosphorus, phosphorus uptake abruptly declined. Concurrent with this decline, the cotyledons switched from being net importers to net exporters of phosphorus. Transfers of seedlings between high and zero phosphorus conditions demonstrated that this switch in cotyledonary role was induced when demand for phosphorus by other sinks could not be met by the current rate of phosphorus assimilation.

Nutrition of irrigated crops on an alkaline brown clay soil at Trangie, New South Wales. 1. Lucerne

1986 ◽  
Vol 26 (4) ◽  
pp. 445
Author(s):  
DK Muldoon
Keyword(s):  
Dry Matter ◽  
Soil Phosphorus ◽  
Dry Matter Production ◽  
Yield Response ◽  
Phosphorus Concentration ◽  
Alkaline Soil ◽  
Phosphorus Level ◽  
South Wales ◽  
Matter Production ◽  
Available Soil Phosphorus

The elements nitrogen, phosphorus, potassium, sulfur and zinc were sequentially omitted from a 'complete' fertiliser applied to plots on an alkaline soil, and lucerne (Medicago sativa) was sown immediately afterwards. The dry matter production of lucerne was measured in repeated cuts over 2 years; its mineral composition was determined periodically. In a second experiment 4 rates of phosphorus were applied to a l -year-old stand of lucerne and dry matter production recorded for 1 year. Lucerne yields in the first year were reduced from 17-1 8 t/ha to less than 14 t/ha by omitting phosphorus. Yields universally decreased in the second year as the 50 kg/ha P applied at sowing was depleted through the removal of 40 kg/ha P in forage. Following this depletion a linear yield response up to 80 kg/ha P was found (experiment 2). Omitting phosphorus fertiliser reduced the plant phosphorus concentration from 0.23 to 0.21% when sampled 15 months after sowing. The plant phosphorus concentration decreased with time in all treatments. The available soil phosphorus level decreased from an initial 12 to 6-7 �g/g after 6 months and further to 2 �g/g after 30 months. Fertiliser phosphorus raised the soil phosphorus level but this also was depleted to 2-3 �g/g in 30 months. Omitting zinc reduced the plant zinc concentration. However, neither the omission of nitrogen, potassium, sulfur nor zinc from the fertiliser had any effect on lucerne yields.

Effect of quantity and frequency of application of superphosphate on the seasonal yield of annual pasture

1983 ◽  
Vol 23 (120) ◽  
pp. 64
Author(s):  
AA McGowan ◽  
IH Cameron ◽  
DH White
Keyword(s):  
Decay Rate ◽  
Dry Matter ◽  
Initial Rate ◽  
Soil Phosphorus ◽  
Total Response ◽  
Initial Application ◽  
Model Yield ◽  
Subsequent Application ◽  
Available Soil Phosphorus ◽  
Spring Yield

An experiment compared the effectiveness of annual and quadrennial applications of superphosphate (totalling 24,48 or 72 kg P/ha over four years) in increasing the winter and spring yield of annual pasture. Initial levels of superphosphate of 12, 84 or 156 kg P/ha had been applied in the preliminary year of the experiment. Over the next four years there was no response to subsequent application of superphosphate after an initial application of 156 kg P/ha, or early in the experiment, after an initial application of 84 kg P/ha. However, whenever the pasture did respond to subsequent topdressing, annual applications produced a greater total response in winter over four years than did a single initial application of four times the annual rate; with the low initial rate of application, this benefit was 1.5 t dry matter/ha overthe four year period. Frequency of application did not affect responses in the spring. Pasture yield was described by the model: yield =a - b exp (- c.SP) where SP is available soil phosphorus based on the model SPn = +i =i0 Pi (1 - V) n -I n being the year of experiment, Pi the rate of phosphorus applied in year i, and V the annual decay rate of applied phosphorus in the soil. The level of soil phosphorus, extractable by acetic acid at the end of the experiment, was related to the total amount of fertilizer applied during the previous five years, but was not shown to be related to the frequency of application. Estimates of the annual decay rate of the applied phosphorus ranged from 19 to 75%.

Phosphorus Acquisition in the Soil-Root System of Eucalyptus pilularis Smith Seedlings. II the Effect of Ectomycorrhizas on Seedling Phosphorus and Dry Weight Acquisition

1986 ◽  
Vol 34 (4) ◽  
pp. 445 ◽  
Author(s):  
PA Heinrich ◽  
JW Patrick
Keyword(s):  
Seedling Growth ◽  
Unit Root ◽  
Root Length ◽  
Infection Intensity ◽  
Dry Weight ◽  
Available Phosphorus ◽  
Second Phase ◽  
Phosphorus Acquisition ◽  
Eucalyptus Pilularis ◽  
Inoculation Study

Ectomycorrhizas were visible on Eucalyptus pilularis Smith seedling root systems 30 days after sowing when seedlings were grown under glasshouse conditions in a severely phosphorus-deficient A1 horizon soil collected from a study area in the Myall Lakes National Park, N.S.W. The types of ectomycorrhizas were similar to those observed on seedlings collected from the study area. Black ectomycorrhizas were the initial and dominant symbiont on seedlings until at least 6 months after sowing. The ectomycorrhizal component of the A1 horizon soil could not be eliminated by partial sterilisation of the soil without a significant change in the available phosphorus supply. However, a comparison of seedlings grown in autoclaved soil with or without black ectomycorrhizas showed that this symbiont had the capacity to increase the phosphorus acquisition of seedlings. A correlative approach, quantifying the relationship between black ectomycorrhizal infection intensity and seedling growth, was utilised to indicate whether the black ectomycorrhizas improved phosphorus and dry weight acquisition of seedlings grown in A1 horizon soil. The pattern of phosphorus acquisition and the dry weight increment of seedlings grown in the A1 horizon soil under glasshouse conditions were characterised by two phases, the second indicated by a three-fold increase in both seedling parameters 116 days after sowing. At a harvest in the first phase of growth (96 days after sowing) seedlings with larger numbers of black ectomycorrhizas per unit root length had significantly higher phosphorus contents (P< 0.05) but not dry weights. In comparison, a harvest selected in the second phase of growth (176 days after sowing) showed that both seedling phosphorus content and dry weight were highly correlated with the numbers of black ectomycorrhizas per unit root length (r² = 0.81 and r² = 0.88 respectively). These results, when considered in combination with the inoculation study, indicate that black ectomycorrhizas do improve the phosphorus acquisition of seedlings grown in A1 horizon soil. The black ectomycorrhizas increased the inflow of phosphorus by 2.2 x 10-6μg P cm infected root length-1 s-1. We propose that dry weight was promoted by this increase only when substantial amounts of phosphorus were transferred to the shoot. This has been shown to occur primarily in the second phase of seedling growth.

Improved Plant Diversity as a Strategy to Increase Available Soil Phosphorus

2019 ◽  
Vol 103 (1) ◽  
pp. 43-45 ◽  
Author(s):  
Carlos Crusciol ◽  
João Rigon ◽  
Juliano Calonego ◽  
Rogério Soratto
Keyword(s):  
Crop Yields ◽  
Soil Phosphorus ◽  
Cropping System ◽  
P Availability ◽  
P Fractions ◽  
Crop Species ◽  
Soil P ◽  
Residue Decomposition ◽  
Available Soil Phosphorus ◽  
Crop Residue Decomposition

Some crop species could be used inside a cropping system as part of a strategy to increase soil P availability due to their capacity to recycle P and shift the equilibrium between soil P fractions to benefit the main crop. The release of P by crop residue decomposition, and mobilization and uptake of otherwise recalcitrant P are important mechanisms capable of increasing P availability and crop yields.

Response of Forage Chicory Seedlings to Available Soil Phosphorus in Two Soils in a Controlled Environment

2013 ◽  
Vol 44 (13) ◽  
pp. 1992-2007
Author(s):  
K. A. Cassida ◽  
J. G. Foster ◽  
J. M. Gonzalez ◽  
R. W. Zobel ◽  
M. A. Sanderson
Keyword(s):  
Soil Phosphorus ◽  
Controlled Environment ◽  
Available Soil Phosphorus
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