Topic
Dichanthium
About: Dichanthium is a research topic. Over the lifetime, 89 publications have been published within this topic receiving 1048 citations.
Papers published on a yearly basis
Papers
TL;DR: Experimental and theoretical results indicated that potted grass is a suitable reference N transfer studies using 15N natural abundance, which suggests a direct N transfer from trees to grass, e.g. via root exudates or common mycorrhizal networks.
Abstract: Below-ground transfer of nitrogen (N) fixed by legume trees to associated non-N2-fixing crops has received little attention in agroforestry, although the importance of below-ground interactions is shown in other ecosystems. We used 15N natural abundance to estimate N transfer from the legume tree Gliricidia sepium (Jacq.) Kunth ex Walp. to C4 grass Dichanthium aristatum (Poir.) C.E. Hubb. in a silvopastoral system, where N was recycled exclusively by below-ground processes and N2 fixation by G. sepium was the sole N input to the system. Finding a suitable reference plant, a grass without contact with tree roots or litter, was problematic because tree roots invaded adjacent grass monocrop plots and soil isotopic signature in soil below distant grass monocrops differed significantly from the agroforestry plots. Thus, we used grass cultivated under greenhouse conditions in pots filled with agroforestry soil as the reference. A model of soil 15N fractionation during N mineralization was developed for testing the reliability of that estimate. Experimental and theoretical results indicated that 9 months after greenhouse transplanting, the percentage of fixed N in the grass decreased from 35% to <1%, due to N export in cut grass and dilution of fixed N with N taken up from the soil. The effect of soil 15N fractionation on the estimate of the reference value was negligible. This indicates that potted grass is a suitable reference N transfer studies using 15N natural abundance. About one third of N in field-grown grass was of atmospheric origin in agroforestry plots and in adjacent D. aristatum grassland invaded by G. sepium roots. The concentration of fixed N was correlated with fine root density of G. sepium but not with soil isotopic signature. This suggests a direct N transfer from trees to grass, e.g. via root exudates or common mycorrhizal networks.
108 citations
TL;DR: In tetraploid agamospecies with sexually reproducing diploid races, even partially sterile but fully sexual autotetraploids may provide a temporary genetic bridge between apomictic biotypes.
Abstract: It is generally accepted that most natural polyploids fall somewhere in between the classically recognized autoand alloploid in genome constitution (Stebbins, 1947; LOve, 1964). Although probably rare, genomic true alloploids are recognized to have played a major role in speciation, whereas true autoploids are usually assumed to have contributed relatively little towards the origin of variation in plants. No new genes are added to the population through autoploidy, the expression of mutations are successfully masked, the autoploid is often largely sterile, and is probably soon eliminated from the population in competition with the ancestral diploids. However, in tetraploid agamospecies with sexually reproducing diploid races, even partially sterile but fully sexual autotetraploids may provide a temporary genetic bridge between apomictic biotypes. Such a system, associated with possible haploidy, to insure continuous contact with sexuality, was observed in Dichanthium (Gramineae).
83 citations
TL;DR: The effect of shading by a shrub legume on the growth and nutrient uptake of a C4 tropical grass was studied during four regrowth cycles and the positive effects of shade may be only observed when N and water are limiting sward growth in the open.
Abstract: The effect of shading by a shrub legume on the growth and nutrient uptake of a C4 tropical grass was studied during four regrowth cycles. Regrowth periods were characterised by contrasting soil water availability. Dichanthium aristatum (Poir.) C. E. Hubbard swards were grown in full sun and under Gliricidia sepium (Jacq.) Walp. and Leucaena leucocephala (Lam.) de Wit with a light transmission level ranging from 80 to 30% of the incoming photosynthetically active radiation (PAR), depending on shrub regrowth. A treatment with high N and water supply was included in one of the cycles to quantify the effect of shade alone on potential growth.
66 citations
TL;DR: The mean relative decomposition rates of litter as well as of root material were found to be highest in rainy season and lowest in winter months, and Rainfall, particularly the frequency of rainfall, was an important factor affecting decompose rates.
Abstract: The decomposition of litter and roots ofChenopodium album, Desmostachya bipinnata and mixed grass samples for a period of 402 days and ofDichanthium annulatum andSesbania bispinosa for a period of 278 days was studied in a tropical grassland. Litter bags positioned at midcanopy height, soil surface and at five cm depth below the soil surface and root bags placed at 5, 15, 25 and 35 cm depths belowground were used. For the total study period, the cumulative weight loss in litter bags was: Chenopodium=76–100%; Desmostachya=33–98%; Dichanthium=26–96%; mixed grass=43–99% and Sesbania=25–99%. The weight loss in root bags was: Chenopodium=93–100%; Desmostachya=47–56%; Dichanthium=71–87%; mixed grass=61–82%; Sesbania=87–100%. The nature of plant species affected decomposition rates. The position of litter/root bags also affected the decomposition rates. The mean relative decomposition rates of litter as well as of root material were found to be highest in rainy season and lowest in winter months. Rainfall, particularly the frequency of rainfall, was an important factor affecting decomposition rates. The litter species characterized by highest concentration of nitrogen, ash, acid detergent cell wall component and lowest concentration of carbon, cellulose and lignin, decomposed rapidly. In the case of roots, the material having high nitrogen, carbon, cellulose and ash content and low C/N ratio and lignin content decomposed rapidly.
61 citations
TL;DR: In the subtropical environment of this experiment the removal of ground cover by burning or other means significantly increased the average maximum temperature of the surface soil, which favoured the germination of buried H. contortus seed at a time when ambient temperatures were too low for this to occur in unburnt situations.
Abstract: The factors underlying the increasing dominance of Heteropogon contortus (bunch or black spear grass) as a result of regularly burning native pastures in eastern Queensland have been investigated. In the subtropical environment of this experiment the removal of ground cover by burning or other means significantly increased the average maximum temperature of the surface soil. Burning favoured the germination of buried H. contortus seed at a time when ambient temperatures were too low for this to occur in unburnt situations. In late seasons and in the seasonally dry tropics insufficient soil moisture would tend to limit growth and germination until ambient temperatures are high, in which case the burning effect would be less pronounced. The efficient seed burial mechanism of H. contortus places it at an establishment advantage over other commonly associated species such as blue grasses (Bothriochloa, Dichanthium) and others whose seeds remain largely in the surface litter. Fire destroys much of this litter, the microhabitat for seed germination at ground level, and some of the weaker perennial plants. The implications of these results in relation to the increased dominance of either H. contortus or Themeda australis (kangaroo grass) are discussed.
51 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2019 | 2 |
| 2018 | 1 |
| 2017 | 1 |
| 2016 | 2 |
| 2014 | 3 |
| 2012 | 4 |