Physiological responses of semiarid grasses. I. The influence of phosphorus supply on growth and phosphorus absorption

1975 ◽  
Vol 26 (3) ◽  
pp. 423 ◽  
Author(s):  
EK Christie ◽  
J Moorby
Keyword(s):  
Optimal Growth ◽  
Yield Response ◽  
Phosphorus Concentration ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Buffel Grass ◽  
Phosphorus Absorption ◽  
Low Concentrations ◽  
Nutritional Characteristics ◽  
Phosphorus Requirements

Experiments were carried out under controlled conditions to investigate the physiological bases for species differences in yield and nutrient responses to variations in phosphorus supply. Buffel grass (Cenchrus ciliaris), and to a less extent Mitchell grass (Astrebla elymoides), showed a much larger yield response to increasing phosphorus supply than mulga grass (Thyridolepis mitchelliana). Mitchell and mulga grasses had much lower relative growth rates than buffel grass. Mulga grass required a lower external phosphorus concentration for optimal growth than Mitchell and buffel grasses; this was attributed to its superior system for absorbing and transporting phosphate from low concentrations, but was not associated with any yield advantage, yield being related more to the photosynthetic than to the nutritional characteristics of the plants. Differences between species in their external phosphorus requirements for growth and their distribution in semiarid Queensland are discussed.

A study of phosphorus nutrition and water supply on the early growth and survival of buffel grass grown on a sandy red earth from south-west Queensland

1975 ◽  
Vol 15 (73) ◽  
pp. 239 ◽  
Author(s):  
EK Christie
Keyword(s):  
Seedling Growth ◽  
Growth Rates ◽  
Phosphorus Concentration ◽  
Root Penetration ◽  
Buffel Grass ◽  
Phosphorus Absorption ◽  
South West ◽  
Red Earth ◽  
Drought Survival ◽  
Phosphorus Application

The influence of phosphorus application on the growth and drought survival of buffel grass on a sandy red earth in south west Queensland was studied in a series of pot experiments. An omission nutrient trial showed phosphorus was the principal nutrient limiting seedling growth, the severity of the deficiency increasing with time. A further pot experiment showed that at rates greater than 24 kg P ha-1 luxury consumption occurred. The critical phosphorus concentration for the plant was estimated to be 0.26 per cent. The available (0.01 NH2SO4 extractable) soil phosphorus concentration corresponding to this critical tissue concentration was 25 p.p.m. Beyond the 2-leaf seedling stage, the seedling depended increasingly on external phosphorus for growth. Under conditions of phosphorus deficiency, phosphorus absorption rates were insufficient to maintain tissue phosphorus at the concentrations necessary for healthy growth, and relative growth rates were low. In the presence of phosphorus, absorption and growth rates increased. Maturity of phosphorus deficient plants was characteristically delayed but with little yield loss. The addition of phosphorus increased seedling growth rate, root development and drought survival. The depth of root penetration is considered to be the major factor responsible for survival.

Physiological responses of semiarid grasses. III.* Growth in relation to temperature and soil water deficit

1975 ◽  
Vol 26 (3) ◽  
pp. 447 ◽  
Author(s):  
EK Christie
Keyword(s):  
Soil Water ◽  
Growth Rates ◽  
Soil Water Potential ◽  
Dry Weight ◽  
Phosphorus Concentration ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Ample Supply ◽  
Net Assimilation ◽  
Tissue Phosphorus

The optimum temperature for vegetative growth of mulga grass was about 25°C, and for Mitchell and buffel grasses 30°. Buffel grass had the highest yield at all temperatures, partly because of its higher growth rate which in turn can be ascribed to both a higher net assimilation rate and the diversion of a greater proportion of dry weight into leaf area. Seedlings with an ample supply of phosphate had higher relative growth rates than phosphorus-deficient seedlings at the commencement of the soil drying cycle, but their growth rates declined more rapidly as the soil water potential fell. This decline was associated with a reduction in the rate of phosphate absorption as well as a decrease in the tissue phosphorus concentration. *Part II, Aust. J. Agric. Res., 26: 437 (1975).

A Measure of Economic Growth in East and in West Pakistan

1961 ◽  
Vol 1 (2) ◽  
pp. 49-54
Author(s):  
S. U. Khan
Keyword(s):  
Regional Planning ◽  
National Income ◽  
Future Planning ◽  
Correct Evaluation ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
National Planning ◽  
Income Data ◽  
Regional Basis ◽  
The Difference

It is sometimes said that "national planning will simply have no meaning if it completely ignores the economic disparities between the two wings and fails to evolve a sensible pattern of regional planning"2. The lack of much essential data on a regional basis, however, renders any precise estimate of the relative growth rates almost impossible. Data either are not available or are inadequate on such important variables as production, income, consumption and trade, so that even a correct evaluation of past development efforts is not possible. The implications of such a situation for future planning are not difficult to understand. In this article an attempt is made to estimate the absorption of specified commodities in East and West Pakistan separately3. This will indicate the pattern of consumption and also give a rough idea about the growth rate of the two wings. With this purpose in view, quantity indices of absorption are prepared for each wing separately, taking data on availability of goods and prices from the Institute's monograph on Inflation. The quantity indi¬ces, however, are not of course strictly comparable with national income estimates because of the difference in coverage of the two series. National income data include government, services, trade, etc., while the quantity indices cover only specified goods available for each region.

CHANGES IN ENZYMES AND PROTEINS IN SALT-SHOCKED VS. GRADIENT INCREASES IN NACL IN `POINSETT' CUCUMBER ROOTS

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1091G-1091
Author(s):  
Anne K. Hurley ◽  
B. Greg Cobb
Keyword(s):  
Invertase Activity ◽  
Shock Treatment ◽  
Cucumis Sativus L ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Salt Shock ◽  
Gradient Solution ◽  
Cucumber Roots ◽  
Average Plant ◽  
Plastochron Index

Cucumis sativus, L., `Poinsett' seedlings were grown under artificial light in 40% modified Hoagland's solution until an average plant plastochron index of 4.73 was reached. Plants were then placed in solutions of (1) 0 mM NaCl, (2) 80 mM NaCl (salt-shock), or (3) placed in a dropwise gradient solution of NaCl and Hoagland's until the final concentration of 80 mM NaCl was reached at 41 hours. Leaves of the 80 mM shock treatment wilted immediately, but recovered turgor within 6 hours. Leaves of 80 mM gradient did not wilt at anytime. The control and gradient treatments had relative growth rates which were similar to each other, but RGR decreased in the shock treatment. Invertase activity was measured in the roots at 24, 41, and 48 hours after initial treatment. Invertase activity of shock treatment increased significantly over the controls at 24 hours. The 80mM gradient was not significantly different than either treatment. Four isozymes of α– galactosidase were detected. The relative intensities of the bands varied with time and treatment. One invertase band was resolved in roots on 8% native acrylamide gels. SDS gels indicated increases in proteins in the gradient treatment compared to the control and the 80 mM shock treatment.

Rates of growth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) (Hymenoptera: Formicidae) on different substrates gathered by the ants

1979 ◽  
Vol 69 (1) ◽  
pp. 141-148 ◽  
Author(s):  
A. Mudd ◽  
G. L. Bateman
Keyword(s):  
Nutrient Availability ◽  
Plant Material ◽  
Growth Inhibitors ◽  
Atta Cephalotes ◽  
Leaf Extracts ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Foraging Preferences ◽  
Leaf Cutting ◽  
Rates Of Growth

AbstractGrowth of the food fungus of the leaf-cutting ant Atta cephalotes (L.) on extracts of plants selected by the ants was shown to be affected by the plant species, the pH of the extract, the concentration of the sap or plant extract and pretreatment of the substrate by the ants. It was not possible to establish an unambiguous relationship between the rate of growth of the fungus on leaf extracts and the foraging preferences of the ants for the leaves. There were indications, however, that the fungus grows most rapidly on extracts of plant material preferred by A. cephalotes. Relative growth rates of the fungus on different substrates may be related to the presence of growth inhibitors rather than to nutrient availability.

Selection for biomass production based on respiration parameters in eucalypts: effects of origin and growth climates on growth rates

1996 ◽  
Vol 26 (9) ◽  
pp. 1556-1568 ◽  
Author(s):  
Thimmappa S. Anekonda ◽  
Richard S. Criddle ◽  
Lee D. Hansen ◽  
Mike Bacca
Keyword(s):  
Temperature Dependence ◽  
Growth Rates ◽  
Heat Rate ◽  
Eucalyptus Species ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Metabolic Heat ◽  
Respiratory Parameters ◽  
Metabolic Heat Rate ◽  
Different Climates

Seventeen Eucalyptus species and 30 rapid-growing Eucalyptuscamaldulensis trees (referred to as plus trees), growing in a plantation were studied to examine relationships among measured plant growth and respiratory parameters, geographical origins, and growth climate. The respiratory parameters measured at two different temperatures by isothermal calorimetry were metabolic heat rate, rate of CO2 production, and the ratio of heat rate to CO2 rate. Metabolic heat rate was also measured as a continuous function of temperature by differential scanning calorimetry in the range of 10 to 40 °C. Tree growth was measured as rates of height and stem volume growth. The values of respiratory and growth variables of Eucalyptus species are significantly correlated with latitude and altitude of origin of their seed sources. The maximum metabolic heat rate, the temperature of the maximum heat rate, the temperature coefficients of metabolic rate, and the temperatures at which the slopes of Arrhenius plots change are all genetically determined parameters that vary both within and among species. Measurement of growth rate–respiration rate–temperature relationships guide understanding of why relative growth rates of Eucalyptus species and individual genotypes differ with climate, making it possible to identify genotypes best suited for rapid growth in different climates. The temperature dependence of respiration rates is an important factor determining relative growth rates of eucalypts in different climates. To achieve optimum biomass production the temperature dependence of individual plants must be matched to growth climate.

Studies on the sowing dates of cotton in the Sudan Gezira: I. The influence of date of sowing on plant growth and development

1967 ◽  
Vol 69 (3) ◽  
pp. 305-315 ◽  
Author(s):  
J. E. Jackson
Keyword(s):  
Growth Rates ◽  
Slow Growth ◽  
Seasonal Pattern ◽  
Relative Growth ◽  
Relative Growth Rates ◽  
Research Division ◽  
Sowing Dates ◽  
Net Assimilation ◽  
State Growth ◽  
Sudan Gezira

Growth analysis of cotton crops sown in the Sudan Gezira at monthly intervals between August and May revealed a marked seasonal pattern of growth. Irrespective of plant age and fruiting state growth of non-senescent plants was slowest during the cool winter months. Relative growth rates of young plants were highest in August, September and early October due to the high specific leaf areas and fairly high net assimilation rates found then. They were lowest when minimum temperatures were lowest. Net assimilation rates were also lowest in the coolest months, probably as a result of restricted growth. High temperatures in the spring reduced fruiting. It is concluded that low minimum temperatures and high evaporation rates are both associated with slow growth, and play a large part in determining the characteristic decline of growth rates of cotton sown at the usual date in August.I wish to thank the Chief of the Research Division, Ministry of Agriculture, Sudan, for permission to publish this paper and to record my gratitude to the team of field and laboratory assistants, especially Salih Saad and Hassan Osman, who helped in the work.

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