The carbon and nitrogen cost associated with the growth, reproductive and dormant phases of two South African semi-arid geophytic species of Gethyllis (Amaryllidaceae)

2013 ◽  
Vol 61 (7) ◽  
pp. 528 ◽  
Author(s):  
Christiaan Daniels ◽  
Wilfred Mabusela ◽  
Jeanine Marnewick ◽  
Alexander Valentine
Keyword(s):  
South African ◽  
Physiological Responses ◽  
Natural Habitat ◽  
Resource Utilisation ◽  
Growth Phases ◽  
Succulent Karoo ◽  
Reproductive Growth ◽  
Carbon And Nitrogen ◽  
Flower Production ◽  
Vegetative And Reproductive Growth

Gethyllis multifolia L.Bolus and G. villosa Thunb. (Family: Amaryllidaceae) are deciduous and bulbous geophytes that occur in the succulent Karoo biome of South Africa. Both species occupy the same natural habitat, but G. multifolia is threatened and G. villosa not. Both G. multifolia and G. villosa require seasonal bulb reserves for initial vegetative and reproductive growth. In spite of G. villosa having smaller bulbs than G. multifolia, both species produce similar flower sizes and weights. The aim of the present study was to determine the carbon and nitrogen costs of vegetative and reproductive growth during the phases of growth, senescence, reproduction and dormancy of these bulbous species. The rates, costs and efficiencies of biomass production during various growth phases of the two species were determined in a comparative experiment. The results show that in spite of a significantly smaller bulb, G. villosa produced more leaves per unit bulb mass and invested more carbon and nitrogen resources into the bulbs during senescence. G. villosa also had a higher flower production, relative to bulb weight, than did G. multifolia. These physiological responses suggest that G. villosa may be more efficient at carbon and nitrogen resource utilisation.

scholarly journals Estimated abundance and diversity of heterotrophic protists in South African biocrusts

2016 ◽  
Vol Volume 112 (Number 7/8) ◽  
Author(s):  
Kenneth Dumack ◽  
Robert Koller ◽  
Bettina Weber ◽  
Michael Bonkowski ◽  
◽  
...  
Keyword(s):  
South African ◽  
Soil Nutrient ◽  
Ecosystem Functions ◽  
Turnover Rates ◽  
Succulent Karoo ◽  
Functional Roles ◽  
Carbon And Nitrogen ◽  
Different Types ◽  
Abundance And Diversity ◽  
Soil Protists

Abstract Biological soil crusts (biocrusts) occur widely in the uppermost millimeters of the soil in arid and semi-arid systems. Worldwide they cover large terrestrial areas and play a major role in the global terrestrial carbon and nitrogen cycles. However, knowledge of the microbial decomposer foodwebs within biocrusts is particularly scarce. Heterotrophic protists in soil are predominantly bacterivores, and because of their high biomass compared with other soil fauna and fast turnover rates, protists are considered an important factor for soil nutrient cycling and energy fluxes. Thus, knowledge of their biodiversity, abundance and functional roles is important to understand soil ecosystem functions. We investigated the diversity and abundance of heterotrophic soil protists in different types of biocrusts from the Succulent Karoo, South Africa. With an overall diversity of 23 distinct morphotypes, soil protist biodiversity was shown to be high. The most abundant groups were Spumella-like chrysomonads, gliding bodonids, glissomonads and heteroloboseans. Protist abundance was highly variable among samples. The abundance and diversity did not differ significantly among different types of biocrusts, indicating that microscale differences, but not macroscopic soil crust builders (e.g. cyanobacteria, lichens and bryophytes), have a major impact on the protist community.

scholarly journals CONTRIBUTION OF CARBON AND NITROGEN RESERVES TO VEGETATIVE AND REPRODUCTIVE GROWTH OF RABBITEYE BLUEBERRY

HortScience ◽  
1991 ◽  
Vol 26 (6) ◽  
pp. 682G-682
Author(s):  
Keith T. Birkhold ◽  
Rebecca L. Darnell
Keyword(s):  
Vegetative Growth ◽  
Growing Season ◽  
Full Bloom ◽  
Reproductive Growth ◽  
Vaccinium Ashei ◽  
Carbon And Nitrogen ◽  
Fruit Maturity ◽  
Leaf Drop ◽  
Vegetative And Reproductive Growth

Partitioning of carbon and nitrogen reserves were examined in two cultivars of rabbiteye blueberries (Vaccinium ashei] differing in their timing of vegetative budbreak relative to floral budbreak. Floral budbreak precedes vegetative budbreak in `Climax', while floral and vegetative budbreak occur concomitantly in `Bonita'. Twenty eight containerized plants from each cultivar were dual labeled in the fall with 105 μCi of 14C02 and 0.6 g of nitrogen enriched with 5% 15N. Plants were grown outdoors throughout the winter and the following growing season. At five dates, beginning 27 days prior to full bloom and ending at fruit maturity, plants were harvested into old shoots, roots, fruit, and vegetative growth. Fall leaf drop accounted for loss of 12% of applied N and 20% of applied 14C. In the first harvest, approximately 73% of the recovered 15N and 50% of the recovered 14C was in the roots for both cultivars. By fruit maturity, approximately 8% of the recovered 15N was in the fruits, 51% in new vegetative growth, and 41% in old shoots and roots. Approximately 1.2% of the recovered 14C was in fruit, 1.5% in vegetative growth, and 97% in old shoots and roots. Data suggest that differences in the timing of vegetative budbreak between these two cultivars do not influence overall partitioning patterns of reserve carbon and nitrogen.

scholarly journals CANOPY MANIPULATION EFFECTS ON VEGETATIVE AND REPRODUCTIVE GROWTH OF “TITAN” RED RASPBERRY

HortScience ◽  
1993 ◽  
Vol 28 (4) ◽  
pp. 259E-259
Author(s):  
Gina E. Fernandez ◽  
Marvin P. Pritts
Keyword(s):  
Light Stress ◽  
Significant Negative Correlation ◽  
Growth And Yield ◽  
Growth Phases ◽  
Fruit Removal ◽  
Reproductive Growth ◽  
One Year ◽  
Vegetative And Reproductive Growth ◽  
High Yields ◽  
Source Sink

The objective of this experiment was to determine the effects that altering the probable source-sink relationships would have on subsequent growth and yield components under field conditions. The balance between vegetative and reproductive growth was altered by imposing light stress (shading) on various growth phases, or removing primocanes, floricanes or fruit. Removal of primocanes significantly increased yield the year of removal. However, if primocane removal coincided with canopy shading, this increase in yield was not achieved. Overall, a significant negative correlation existed between 1991 and 1992 yields. Treatments with high yields in 1991 had low yields in 1992, and visa verca. This evidence-suggests that: 1) primocanes and floricanes are competing for light, not photosynthates during the flowering and fruiting period and 2) altering the balance of vegetative and reproductive growth one year had a significant effect on growth the subsequent year.

scholarly journals The Influence of the Organic Matter of Sewage Sediments on Biological Activity of Microorganisms which Carry Out the Transformations of Carbon and Nitrogen Compounds

2013 ◽  
Vol 62 (4) ◽  
pp. 445-452
Author(s):  
IZABELLA PISAREK ◽  
KATARZYNA GRATA
Keyword(s):  
Organic Matter ◽  
Biological Activity ◽  
Organic Nitrogen ◽  
Soil Microorganisms ◽  
Natural Habitat ◽  
Transformation Process ◽  
Nitrogen Compounds ◽  
Soil Environment ◽  
Carbon And Nitrogen ◽  
Cellulolytic Microorganisms

Soil microorganisms play an important role in the organic matter transformation process. The soil microorganisms also are in symbiotic relationship with plants. At the same time, soil microorganisms are sensitive to both anthropogenic and natural habitat changes. Particular characteristics of organic matter (the C:N relation, pH, the content the content of assimilated nutrients, the xenobiotics etc.) modify the biotic conditions of the soils. This particularly concerns the microorganisms which carry out the changes in the mineral and organic nitrogen compounds and the transformation of the external organic matter. The first aim of this work was to assess the influence of the sewage sediments and the manure on the phytosanitary potential of the soil environment. The second aim of this article was to estimate the number and activity of microorganisms which carry out the transformation of carbon and nitrogen compounds. This work showed the stimulating effect of the external organic matter both on the number and on the activity of most of the physiological groups. The manure mainly stimulated ammonificators, amylolitic microorganisms and Azotobacter sp. The sewage sediments mainly stimulated ammonificators, nitrifiers of I phase and cellulolytic microorganisms. The statistically significant impact of the physio-chemical soil habitat on the biological activity of the analyzed groups of microbes was also noted.

Resource Utilisation in Groups of Black South African Adolescents: Gender, Age, and Individual Differences

1997 ◽  
Vol 20 (2) ◽  
pp. 231-248 ◽  
Author(s):  
Christine Liddell ◽  
Chris McConville
Keyword(s):  
Academic Achievement ◽  
Individual Differences ◽  
Positive Affect ◽  
South African ◽  
Resource Utilisation ◽  
Older Children ◽  
Black South African ◽  
South African Township

This study uses a movie-viewing instrument to assess patterns of resource utilisation in South African township adolescents. The degree to which resource utilisation and other task behaviours were associated with gender, age, and individual differences form the focus. Boys used more gestures denoting dominant and subordinate status, were more physically aggressive, and were generally more coercive than girls. Older children shared the resource more equitably, showed more positive affect, and spent less time issuing directives. There were inequities in children’s access to the movie. However, neither on-task behaviours nor participants’ academic achievement were consistently associated with some children accessing the movie more than others.

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