The influence of water stress on nitrogen and phosphorus uptake and concentrations in Townsville stylo (Stylosanthes humilis)

The phosphorus concentrations of Townsville stylo (TS) grown in the Northern Territory are lower than in Queensland, and fall below the requirements of grazing cattle for much of the year. An explanation was sought by measuring N and P in swards subjected to water stress at various times during growth. Stresses during early vegetative (EV), late vegetative (LV) and flowering (F) stages were compared with a well watered control. While nitrogen concentrations were affected little, water stress greatly reduced phosphorus concentrations, the relative effects being EV > LV > F. The EV stress depressed phosphorus concentration to 0.08% compared with 0.20% in the control. Phosphorus level recovered on the relief of stress to the same level as the control. Phosphorus concentration in stems was more sensitive to stress than that in leaves. These results show that if chemical analysis of plants is to be used to indicate the phosphorus status of the soil, the analyses will be unreliable unless the plants have grown without water stress for at least six weeks.

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The influence of water stress on the growth and development of Townsville stylo (Stylosanthes humilis) in pure ungrazed swards at Katherine, Northern Territory

Australian Journal of Experimental Agriculture ◽

10.1071/ea9770598 ◽

1977 ◽

Vol 17 (87) ◽

pp. 598 ◽

Cited By ~ 2

Author(s):

MJ Fisher ◽

NA Campbell

Keyword(s):

Water Stress ◽

The Other ◽

Stylosanthes Humilis ◽

Relative Water ◽

Influence Of Water ◽

Leaf Relative Water Content ◽

Final Yield ◽

Townsville Stylo ◽

Effect On Yield

In order to understand more fully the effect of water stress on the growth of Townsville stylo (Stylosanthes humilis) (TS), five drought treatments, imposed by the use of rain shelters, were compared with an unstressed control in a field experiment. Droughts were imposed during the early vegetative (EV) and late vegetative (LV) stages, and during flowering (F) until leaf relative water content at 2.30 p.m fell to 60 per cent. Further unrelieved drought was re-applied to these three treatments when seeding was well advanced. The other two treatments were subjected to unrelieved drought, one starting at late flowering (LF) and the other seeding (S). The drought treatments had no effect on the final yield of dry matter compared with the control. Stress during the vegetative stage reduced growth, but the relief of stress was followed by a period of rapid growth which largely compensated for the loss. However, because the EV stress killed 40 per cent of the sward (the plants were unable to use water from depths below 75-1 00 cm), the compensatory phase in this treatment was less marked, but more sustained. Because of the decline in growth rate with approaching maturity, stresses during and after flowering had little effect on yield. Stress during vegetative growth hastened flowering by two weeks; however, pod yields were only reduced in the LF treatment. In general these observations demonstrate important aspects of the plants' good adaptation to the dry monsoonal tropics, and explain its stable long-term yields when maintained in near-pure swards.

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Land Condition in the Tropical Tall Grass Pasture Lands. 2. Effects on Herbage Quality and Nutrient Uptake.

The Rangeland Journal ◽

10.1071/rj9950086 ◽

1995 ◽

Vol 17 (1) ◽

pp. 86 ◽

Cited By ~ 8

Author(s):

AJ Ash ◽

JG Mcivor

Keyword(s):

Nitrogen Concentration ◽

Phosphorus Uptake ◽

Phosphorus Concentration ◽

In Vitro Digestibility ◽

Nitrogen And Phosphorus ◽

Tall Grass ◽

Herbage Quality ◽

Land Condition ◽

Nitrogen And Phosphorus Uptake

Herbage quality (in vitro digestibility, nitrogen and phosphorus concentrations) of plucked samples, and above ground nutrient uptakes (nitrogen and phosphorus) were compared on plots differing in land condition at 10 sites in northern Australia. Over all sites there was a significant increase in digestibility and nitrogen concentration, and a significant decrease in phosphorus concentration, as land condition declined. Both nitrogen and phosphorus uptake decreased as land condition declined. The results indicate that diet quality may be higher from land in poor condition. However, the large decrease in pasture productivity associated with declining land condition may more than offset this apparent improvement in feed quality.

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Performance of Townsville stylo (Stylosanthes humilis) lines in pure swards and with the annual grass (Digitaria ciliaris) under various defoliation treatments at Katherine, N.T

Australian Journal of Experimental Agriculture ◽

10.1071/ea9740495 ◽

1974 ◽

Vol 14 (69) ◽

pp. 495 ◽

Cited By ~ 3

Author(s):

JR Ive ◽

MJ Fisher

Keyword(s):

Dry Matter ◽

Certified Seed ◽

Phosphorus Concentration ◽

Annual Grass ◽

Nitrogen And Phosphorus ◽

Matter Production ◽

Stylosanthes Humilis ◽

Townsville Stylo ◽

Better Than ◽

Late Sowing

Townsville stylo (Stylosanthes humilis) selections collected from twelve naturalized populations, in Queensland and the Northern Territory, and certified seed of the Katherine ecotype ('lines'), were grown for three years in a field experiment at Katherine, N.T. (latitude 14.3�S). In the third year, the experiment was oversown with Digitaria ciliaris. Flowering of all lines was delayed by late sowing, but was hastened by drought. However, the order in which the lines flowered was basically the same for all three years, and similar to that at Lansdown, Queensland (latitude 19.7�S). Although seasonally dependent, highest dry matter production was associated with erect mid- or late mid-season maturity lines which were often lowest in nitrogen and phosphorus concentration. There were no differences between lines in their ability to compete with Digitaria. Grazing reduced the proportion of grass in the swards compared with the forage harvested and non-defoliated treatments largely because Townsville stylo appeared to withstand grazing and trampling better than Digitaria.

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Effects of variation in density and phosphate application on growth and composition of Townsville stylo (Stylosanthes humilis)

Australian Journal of Experimental Agriculture ◽

10.1071/ea9700442 ◽

1970 ◽

Vol 10 (45) ◽

pp. 442 ◽

Cited By ~ 2

Author(s):

KG Rickert ◽

LR Humphreys

Keyword(s):

Nitrogen Concentration ◽

Phosphorus Concentration ◽

Dihydrogen Phosphate ◽

Positive Density ◽

Nitrogen And Phosphorus ◽

Area Index ◽

Stylosanthes Humilis ◽

Plant Densities ◽

Townsville Stylo ◽

Phosphorus Application

Townsville stylo (Stylosanthes humilis) was grown at Brisbane from February to June 1967 at initial densities of 10, 50, 250, 1250, and 6250 plants per m2 in boxes of sand which received basal nutrients and applications of 0, 10, and 50 kg P per hectare as calcium dihydrogen phosphate. Plots were irrigated frequently. Wide differences in dry matter yield between plant densities and a positive density phosphorus yield interaction persisted throughout the experiment. Peak yield was 1050 g per m2 with leaf area index (LAI) of 6.8. Intraspecific plant competition was evident in high densities 35 days after emergence, extending to the lower densities by 58 days. Plant mortality at the highest density was independent of phosphorus treatment. Maximum growth rates were reached earlier at high than at low plant densities ; the subsequent decreases in growth rate were expressed through drifts in both LA1 and NAR and were associated with progressively more unfavourable environmental conditions for growth. Nitrogen and phosphorus concentration of both shoots and roots decreased with increasing density. Phosphorus application did not affect nitrogen concentration. Exploitation of native soil phosphorus and recovery of applied phosphorus was greatest in high density swards. The data illustrate the loss in potential production which may occur in sparse swards of Townsville stylo and the limitations to efficient phosphorus response inherent in low density swards.

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