Root distribution in space and time in Trifolium subterraneum

1985 ◽  
Vol 36 (4) ◽  
pp. 601 ◽  
Author(s):  
CJ Pearson ◽  
BC Jacobs
Keyword(s):  
Leaf Area ◽  
Root Length ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Coarse Sand ◽  
Horizontal Distribution ◽  
Dry Matter Partitioning ◽  
Rooting Zone ◽  
Root Death ◽  
Vertical And Horizontal Distribution

Distribution of length and weight of roots of subterranean clover cultivars Northarn and Nungarin were measured in the field throughout a growing season. Plants were grown at seven populations from 2 to 1510 plants per m2 in coarse sand which had a bulk density of 1.4 g cm-3. Root growth was described by its vertical and horizontal distribution as functions of population and time after emergence. Differences in growth between cultivars were small. Root depth, which reached a maximum (plateau) at about 90 days, did not vary with plant population. Root density (length per volume of soil) increased faster at high population due to a higher density of' roots beneath the mainstream and an attenuation with distance away from the mainstem which did not appear to be affected by population. Root densities were 10 cm cm-3 in the uppermost core (0-10 cm depth) and 1.6 -3.5 cm cm-3 throughout the rooting zone (0-50 cm) at 119 days after emergence. Root death, estimated from dichlorotrianzinyl staining, was negligible. Leaf area per plant declined with population above 16 plants per m2; leaf area per unit root length (in cores beneath the mainstream) declined 90-fold with increase in population. Top weight and burr yield per plant at final harvest also declined with increasing population; burr yield per m2 also fell significantly at the highest population. It is concluded that the amount of root per unit area increases with population and that plants appear to adjust conservatively in some respects (to much lower leaf area per root length) while being unable to sustain dry matter partitioning (reducing burr/top yields) at the highest population studied.

The influence of seed size and depth of sowing on pre-emergence and early vegetative growth of subterranean clover (Trifolium subterraneum L.)

1956 ◽  
Vol 7 (2) ◽  
pp. 98 ◽  
Author(s):  
JN Black
Keyword(s):  
Leaf Area ◽  
Seed Size ◽  
Vegetative Growth ◽  
Dry Matter ◽  
Relative Rate ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Total Leaf Area ◽  
Pot Culture

Changes in the pre-emergence distribution of dry matter in subterranean clover (Trifolium subterraneum L.) variety Bacchus Marsh were followed at 21°C, using three sizes of seed and three depths of sowing, ½, 1¼, and 2 in. Decreasing seed size and increasing depth of sowing both reduce the weight of the cotyledons a t emergence. Seed of the three sizes were sown a t three depths in pot culture a t staggered intervals so that emergence was simultaneous. Dry weight in the early vegetative stage was proportional to seed size, and total leaf area and leaf numbers showed similar trends. Plants of each seed size grew at the same relative rate. No effect of depth of sowing could be detected, and this was shown to be due to the cotyledon area a t emergence being constant for any given seed size, regardless of varying depth of sowing and hence of cotyledon weight. It was concluded that seed size in a plant having epigeal germination and without endosperm is of importance: firstly, in limiting the maximum hypocotyl elongation and hence depth of sowing, and secondly, in determining cotyledon area. Cotyledon area in turn influences seedling growth, which is not affected by cotyledon weight. Once emergence has taken place, cotyledonary reserves are of no further significance in the growth of the plants.

The significance of petiole length, leaf area, and light interception in competition between strains of subterrranean clover (Trifolium subterraneum L.) grown in swards

1960 ◽  
Vol 11 (3) ◽  
pp. 277 ◽  
Author(s):  
JN Black
Keyword(s):  
Leaf Area ◽  
Leaf Development ◽  
Plant Competition ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Sampling Period ◽  
Dry Weight ◽  
Petiole Length ◽  
Petiole Elongation ◽  
Light Profiles

Three strains of subterranean clover differing in leaf development were grown in pure swards and in all combinations in mixtures. The strain Yarloop has relatively few large leaves held on long petioles; Tallarook has many small leaves and short petioles; Bacchus Marsh is intermediate in all these respects. The swards were grown in boxes and were sampled on four occasions during the period of vegetative growth. Leaf area in each 2 cm layer of the sward was determined separately, and for both strains in the mixed swards, and measurements of the light intensity reaching each layer were obtained. Root weights were determined for all swards and separately for each component of the mixed swards. Examination of the dry weights showed that the growth of the strain having the lesser petiole elongation was suppressed. In the extreme instance Tallarook was so suppressed when grown with Yarloop that in the final inter-sampling period it grew completely in the dark, and lost about half its dry weight. Bacchus Marsh also suppressed Tallarook, but to a lesser extent, while Bacchus Marsh was itself suppressed in competition with Yarloop. The amount of light energy intercepted by the two components of the mixed swards was calculated from the leaf area and light profiles, and confirmed the importance of the spatial distribution of leaves in plant competition. It was concluded that, in the absence of defoliation, the success of a strain under competition was associated with its potential petiole elongation.

Growth of skeleton weed (Chondrilla juncea L.) as affected by growth of subterranean clover (Trifolium subterraneum L.) and infection by Puccinea chondrillina Bubak and Syd

1975 ◽  
Vol 26 (6) ◽  
pp. 975 ◽  
Author(s):  
RH Groves ◽  
JD Williams
Keyword(s):  
Leaf Area ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Competition ◽  
Leaf Number ◽  
Root Weight ◽  
Large Reduction ◽  
Plant Parts ◽  
Chondrilla Juncea

Growth of skeleton weed (Chondrilla juncea, form A) and subterranean clover (Trifolium subterraneum) was studied in a glasshouse experiment in which the species were grown alone or together and the resultant effects of shoot and root competition assessed. The leaf number and weight of plant parts of C. juncea were reduced by competition vith subterranean clover, especially when shoots of the two species were competing. The leaf area of C. juncea was reduced, especially when roots of the two species were growing together. Puccinia chondrillina on C. juncea rosettes reduced leaf number, leaf area, and weight of plant parts. Subterranean clover grown with C. juncea infected with P. chondrillina further reduced the size and weight of the weed. The large reduction in leaf area and root weight of C. juncea (form A) plants in the presence of both subterranean clover and P. chondrillina suggests that growth of this form of C. juncea in Australia will be greatly reduced in pastures containing these species. In the long term, densities of this form may possibly be so lowered that a significant level of control will be reached in a cereal cropping-pasture system.

Seed size as a factor in the growth of subterranean clover (Trifolium subterraneum L.) under spaced and sward conditions

1957 ◽  
Vol 8 (4) ◽  
pp. 335 ◽  
Author(s):  
JN Black
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Seed Size ◽  
Seed Weight ◽  
Agricultural Research ◽  
Incident Light ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Area Index ◽  
Significant Difference

The significance of seed weight in the growth of subterranean clover (Trifolium subterraneum L) , of the Bacchus Marsh strain, has been assessed under both spaced plant and sward conditions at the Waite Agricultural Research Institute. Under conditions of spacing, plants of three widely separated seed size grades were grown a t a density of 1 per 25 sq. links. The dry weights of the plants were proportional to seed weight from the time of sowing (in May) till the end of October – over almost the entire growing period of the crop. Three sets of swards were grown a t a density of 25 plants per sq. link, each sward being planted with seed of one of the three sizes. Dry weight was proportional to seed weight in the early part of the season but when the swards reached a leaf area index of about 4 (i.e. when there were 4 sq. links of leaf surface on 1 sq. link of ground), a reduction in growth rate occurred. This critical leaf area index was reached first in "large seed" swards, followed later by "medium seed" and finally by "small seed" swards. Thus there was a period in which the swards were growing at different rates, and in which the dry weights came to parity, so that on the final sampling occasion (in December) there was no significant difference between the dry weights of the swards from the three seed sizes. It is concluded that a t a leaf area index of about 4, interception of incident light energy is complete.

Effects of early defoliation on the seedling growth of subterranean clover

1992 ◽  
Vol 43 (3) ◽  
pp. 717
Author(s):  
RC Rossiter
Keyword(s):  
Linear Relationship ◽  
Leaf Area ◽  
Seedling Growth ◽  
Shoot Growth ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Relative Reduction ◽  
Insect Damage ◽  
Leaf Production ◽  
Plant Densities

Two experiments were conducted in an open-sided glass shelter at Perth during winter. Subterranean clover (Trifolium subterraneum, L.) seedlings were grown in shallow seed boxes at low plant densities, 2 4 and 2 0 plants/dm2. The effects of a single defoliation involving mainly the removal of cotyledons only, on shoot growth and leaf production were measured at harvest, c. 5 weeks after sowing. Total shoot dry weights were reduced by 15-30% when 40-60% of the leaf area was removed by single defoliations from days 7 to 19 after planting. However, the growth was reduced by almost 70% when both cotyledons were removed (days 7 to 9) before emergence of the unifoliate leaf, i.e. when all of the leaf area was removed. In general, the relative reduction in growth largely depended on the percentage of leaf area removed, rather than on time of removal. Defoliation also reduced the size of trifoliate leaves, and total numbers of trifoliate leaves at harvest. There was a linear relationship between total leaf numbers and shoot dry weights. In the field, these findings are probably of more relevance in terms of insect damage, especially from redlegged earth mites, than for grazing by sheep.

Understanding subsoil acidification: effect of nitrogen transformation and nitrate leaching

Soil Research ◽  
2000 ◽  
Vol 38 (4) ◽  
pp. 837 ◽  
Author(s):  
Z. Rengel ◽  
C. Tang ◽  
C. Raphael ◽  
J. W. Bowden
Keyword(s):  
Soil Ph ◽  
Nitrate Leaching ◽  
Root Length ◽  
Root Length Density ◽  
Soil Column ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Nitrogen Transformation ◽  
Column Experiments ◽  
Excess Water

Nitrification and nitrate leaching have been suggested to be major causes of soil acidification. However, it is unknown whether these processes cause subsoil acidification. Soil column experiments examined the effect of the addition of Ca(NO3)2 or (NH4)2SO4 to the topsoil horizon on subsoil acidification under nodulated lupins (Lupinus angustifolius L.) and subterranean clover (Trifolium subterraneum L.). Nitrate leaching was achieved by adding excess water to the surface of the columns. Where basal nutrients were applied only to the top 10-cm layer, about 60–70% of the total root length of lupin and over 50% of subterranean clover were distributed in that layer. Plants grown without added nitrate for 105 days decreased soil pH at all layers but more significantly in the top 20 cm (by up to 0.7 units); the decrease in pH correlated well with increased root length density of both species (r 2 = 0 .9 8 , n = 9). The addition of Ca(NO3)2 to the top 10-cm layer caused less acidification by about 0.1 pH units at all depths than the treatment without Ca(NO3)2 . Where basal nutrients were applied uniformly throughout the column, root length density of lupin and subterranean clover tended to increase with depth. The addition of (NH4)2SO4 in the top 10 cm significantly increased NO3– concentration in all layers but NH4+ was mainly retained in the top 30-cm layer. Lupin and subterranean clover grown without added NH4+ for 82 days decreased soil pH by 0.3 units at all depths. Compared with the plants receiving no (NH4)2SO 4 , lupin grown with (NH4)2SO4 at 0–10 cm depth in the column caused more acidification by 0.05–0.2 pH units in the top 10 cm but less acidification by 0.15–0.17 units at 10–40 cm depth in the column; subterranean clover grown with (NH4)2SO4 caused more acidification by 0.35–0.46 units in the top 10 cm and less acidification by 0.14–0.19 units in the 20–50 cm layer. The results suggest that the leaching of nitrate from topsoil is unlikely to cause subsoil acidification. In contrast, the uptake of nitrate by the roots reduces net acid production in subsoil layers.

The tolerance of three transgenic subterranean clover (Trifolium subterraneum L.) lines with the bxn gene to herbicides containing bromoxynil

2003 ◽  
Vol 54 (2) ◽  
pp. 203 ◽  
Author(s):  
B. S. Dear ◽  
G. A. Sandral ◽  
D. Spencer ◽  
M. R. I. Khan ◽  
T. J. V. Higgins
Keyword(s):  
Leaf Area ◽  
Seed Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
Biochanin A ◽  
Leaf Stage ◽  
Agronomic Characteristics ◽  
Herbage Yield ◽  
Transgenic Lines

A bxn gene, coding for the nitilase enzyme that catalyses the detoxification of the herbicide bromoxynil, was inserted into subterranean clover (Trifolium subterraneum L. subsp. yanninicum). The agronomic characteristics of 3 transgenic lines (BXN 5, 7, 10) and their response to herbicides containing bromoxynil, were compared with that of the non-transgenic parent, cv. Gosse, in 1 glasshouse and 2 field experiments.The application of bromoxynil at 1.5 L/ha resulted in a 50% reduction in the spring herbage yield of the non-transgenic control but no reduction in BXN 5 and 7. The level of the phyto-oestrogens, genistein and biochanin A, in the leaf tissue were low in Gosse and the 2 transgenic lines, BXN 7 and 10, but the level of genistein increased significantly (P < 0.05) from 0.85% in Gosse to 1.43% dry weight in BXN 5, and biochanin A increased from 0.35% in Gosse to 0.73% in BXN 5. The application of the herbicides bromoxynil, bromoxynil+MCPA, and Jaguar (bromoxynil+diflufenican) at the cotyledon stage in a glasshouse study significantly reduced the leaf area of the non-transgenic Gosse, but did not reduce the leaf area of the 3 transgenic lines. When applied at the 4–5 leaf stage, the leaf area of Gosse was again reduced by all the herbicides, but only the bromoxynil+MCPA treatment reduced the leaf area of the transgenic lines relative to the control. The application of bromoxynil or Jaguar at the 4–5 leaf stage depressed the herbage yield of Gosse by about 62% compared with 0–24% in the 3 transgenic lines. In the field studies, BXN 5 and 10 had similar seed yields to Gosse in the absence of herbicide application, but the seed yield of BXN 7 was significantly less than the other 2 transgenic lines. The level of hard-seed in BXN 7 was also lower at 25% compared with 55–57% in the other transgenic lines and Gosse.These findings stress the need to carefully assess the agronomic qualities of transgenic lines prior to release as although tolerance to bromoxynil may be greatly increased by the bxn gene, other important agronomic characteristics, such as seed yield, hardseededness, and isoflavone content, may change as result of the gene or transformation process.

scholarly journals The effect of continuous grazing on the seed production of Subterranean clover (Trifolium subterraneum).

2003 ◽  
Vol 11 ◽  
pp. 155-160
Author(s):  
M.L. Smetham ◽  
B.S. Dear
Keyword(s):  
Leaf Area ◽  
Seed Production ◽  
Seed Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Area Ratio ◽  
Area Index ◽  
Plant Weight ◽  
Continuous Grazing ◽  
Intensive Sampling

Three pure swards of subterranean clover were either (a) left ungrazed with a leaf area index (LAI) of 4.6, or (b) continuously grazed leniently to leave 1 600 kg DM/ha herbage mass equivalent to an LAI of 1.0, or (c) hard grazed to leave 1 400 kg DM/ha herbage mass equivalent to an LAI of 0.6 throughout the flowering period. These swards yielded 1 250, 320 and 70 kg/ha of seed, respectively. One intensive sampling during the middle of flowering showed that seed yield was positively correlated with plant weight, leaf area per plant, and area per leaf, specific leaf area and leaf area ratio. Grazing reduced numbers of both inflorescences and burrs and hence seed yield. Whilst reduced leaf area and plant weight may have also been partly responsible, under hard grazing, only 58% of potential reproductive sites were occupied which suggests that grazing animals also reduced seed yield by consuming these. It is recommended that continuous grazing during flowering and seed maturation should be controlled to leave at least 1 600 kg DM/ha of residual herbage mass, equivalent to an LAI of 1.0, if adequate seed is to be produced to be ensure the establishment of a high producing sward in the following growing season. Key words: flowering, grazing, herbage mass, leaf area, seed production, Trifolium subterraneum

The role of calcium in alleviating aluminium toxicity

1986 ◽  
Vol 37 (4) ◽  
pp. 375 ◽  
Author(s):  
AK Alva ◽  
CJ Asher ◽  
DG Edwards
Keyword(s):  
Ionic Strength ◽  
Root Growth ◽  
Root Length ◽  
Protective Action ◽  
Primary Root ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Aluminium Toxicity ◽  
Solution Ionic Strength ◽  
Soybean Root

Effects of varying calcium (Ca) concentration at constant or varying solution ionic strength on root elongation of soybean (Glycine max (L.) Merr.) and subterranean clover (Trifolium subterraneum L.) were determined in aluminium (Al) free nutrient solution or solutions containing monomeric Al activities (+aAl mono) of 8-10 8M for subterranean clover and 20-22 8M for soybean. In Al-free solutions, the root length for subterranean clover was not significantly influenced by Ca or ionic strength. However, soybean root length was greater at 500 8M Ca than at higher Ca concentrations. Raising the ionic strength at 500 and 5000 8M Ca significantly decreased root length. In the presence of Al, maximum root length of both species occurred at 15 000 8M Ca. Soybean root length at 500 and 5000 8M Ca was 35% and 87% respectively of that at 15000 8M Ca. The corresponding values for subterranean clover were 53% and 81%. The positive effect of Ca concentration on root length, despite a nearly constant +aAL mono, confirms the existence of a protective action of Ca against Al toxicity. Raising the solution ionic strength at 500 8M Ca in the presence of Al improved the root growth of soybean by 86% and that of subterranean clover by 45%. At 5000 8M Ca, a small beneficial effect of increased ionic strength (14%) was found only in subterranean clover. Increasing Ca concentration in solution decreased water extractable and 0-1 M HNO3 extractable Al in roots of both plant species. Transfer of soybean seedlings to Al-free nutrient solutions containing 500, 1500 or 5000 pM Ca after 24, 48 or 96 h in a solution containing +aAL mono of 22 8M resulted in a substantial recovery in primary root growth. Relative root lengths were in each case significantly higher at 5000 8M Ca than at 1500 or 500 pM Ca. Roots transferred to 500 8M Ca after exposure to Al for 6 or 18 h underwent a period of accelerated elongation after a lag period of 30-40 h. By 138 h there were no significant differences in root length between the unstressed control plants and those subjected to 6 or 18 h Al-stress.

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