The effect of some environmental conditions on seed development and hard-seededness in subterranean clover (Trifolium subterraneum L.)

1979 ◽  
Vol 30 (1) ◽  
pp. 65 ◽  
Author(s):  
GB Taylor ◽  
MJ Palmer
Keyword(s):  
Seed Development ◽  
Seed Size ◽  
Field Experiments ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Moisture Stress ◽  
Effect Of Temperature ◽  
Temperature Regimes ◽  
Increasing Temperature ◽  
Dry Out

Subterranean clover (cv. Daliak) was grown in boxes with provision for unrestricted lateral growth. At the commencement of flowering, plants were allocated to three day/night temperature regimes of 12/7°, 18/13° and 24/19°C in controlled-temperature glasshouses and well watered until maturity (unstressed). In two additional treatments at 18/13°, plants were either subjected to intermittent moisture stress throughout the flowering period (stressed) or well watered for the first 6 weeks of flowering and then allowed to dry out (droughted). Increasing temperature resulted in more rapid inflorescence production, seed development and earlier plant maturation. The overall mean seed size was lower at 24/19° than at the other two temperatures. The stressed and droughted treatments produced fewer and smaller seeds than the corresponding unstressed treatment. There was a small effect of temperature on the degree of hard-seededness as determined from the mean softening time of seed subjected to daily alternating temperatures of 60/15°. Softening time was not significantly affected by watering treatments. There were small differences in softening time due to the position of the burr on the lateral, with a slight trend for seeds from the first-formed burrs to soften more rapidly. Most of the variation in softening time between seeds was due to variation within burrs. The sequence of seed softening within burrs was related to seed size, the larger seeds generally softening first, but no single regression could be used to describe this relationship for different burr positions or treatments. The absence of major treatment effects on the degree of hard-seededness indicates that varying the length of the seed development period does not necessarily result in differences in hard-seededness, as has been suggested from field experiments.

The inhibitory effect of light on seed development in subterranean clover (Trifolium subterraneum L.)

1976 ◽  
Vol 27 (2) ◽  
pp. 207 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Seed Development ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Moisture Stress ◽  
Inhibitory Effect ◽  
Atmospheric Moisture ◽  
Dark Treatment ◽  
Poor Seed ◽  
Development Processes ◽  
Effect Of Light

Explanations were sought for the poor seed development commonly found in unburied burrs of subterranean clover. In the first of two experiments, the effects of light and of atmospheric moisture stress on seed development in subterranean clover (cv. Daliak) were examined. Burrs produced from spaced laterals were enclosed in plastic tubes variously shaded to permit the entry of 0, 5, 19, 48 and 100% daylight. The tubes were further allocated to two groups. Air was continuously passed through tubes of one group to produce an atmospheric moisture stress, while those of the other group were not subjected to air flow. There was a marked effect of light on seed development. Mean seed weight was reduced from c. 11 mg in the dark treatment to 4 mg at only 5% daylight and to 2 mg in the 100% daylight treatment. Seed numbers were reduced significantly, from four to c. two seeds per burr, in the 100% daylight treatment only. There was virtually no effect of atmospheric moisture stress on either seed set or seed size. In the second experiment, a study was made of the effect of timing of burr burial on seed development processes. Fertilization does not appear to be implicated but both cell division and cell enlargement were influenced by the state of burial and, presumably, by light.

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.

Flower initiation in pasture legumes. I. Factors affecting flower initiation in Trifolium subterraneum L.

1955 ◽  
Vol 6 (2) ◽  
pp. 211 ◽  
Author(s):  
Y Aitken
Keyword(s):  
Low Temperature ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Cold Period ◽  
Effect Of Temperature ◽  
Flower Initiation ◽  
Temperature Level ◽  
Factors Affecting ◽  
Pasture Legumes ◽  
Precise Knowledge

The value of the annual legume Trifolium subterraneum L. (subterranean clover) in Australian agriculture warrants more precise knowledge of factors affecting flowering and prolific seeding. The effect of temperature and photoperiod on flower initiation in early and later flowering varieties has been investigated in an effort to determine the geographical limits of the use of subterranean clover in Australia. At any time of sowing, the length of the growing season of a variety depends greatly on the variety's response to the temperature level and to the photoperiod of the first few weeks after germination. In all varieties of subterranean clover so far examined flower initiation is accelerated by a period of low temperature. In the later varieties, flower initiation is prevented by an insufficient period of low temperature. The length of the necessary cold period is shortened under longer photoperiod. Early varieties are early flowering because they do not require so long a cold period or so low a temperature as late varieties.

Comparing different sources of sulfur for high-rainfall pastures insouth-western Australia

2003 ◽  
Vol 43 (10) ◽  
pp. 1221 ◽  
Author(s):  
M. D. A. Bolland ◽  
J. S. Yeates ◽  
M. F. Clarke
Keyword(s):  
Western Australia ◽  
Field Experiments ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Residual Value ◽  
Single Superphosphate ◽  
Pasture Production ◽  
Leaching Losses ◽  
S Deficiency ◽  
Different Sources

The dry herbage yield increase (response) of subterranean clover (Trifolium subterraneum L.)-based pasture (>85% clover) to applications of different sources of sulfur (S) was compared in 7 field experiments on very sandy soils in the > 650 mm annual average rainfall areas of south-western Australia where S deficiency of clover is common when pastures grow rapidly during spring (August–November). The sources compared were single superphosphate, finely grained and coarsely grained gypsum from deposits in south-western Australia, and elemental S. All sources were broadcast (topdressed) once only onto each plot, 3 weeks after pasture emerged at the start of the first growing season. In each subsequent year, fresh fertiliser-S as single superphosphate was applied 3 weeks after pasture emerged to nil-S plots previously not treated with S since the start of the experiment. This was to determine the residual value of sources applied at the start of the experiment in each subsequent year relative to superphosphate freshly-applied in each subsequent year. In addition, superphosphate was also applied 6, 12 and 16 weeks after emergence of pasture in each year, using nil-S plots not previously treated with S since the start of the experiment. Pasture responses to applied S are usually larger after mid-August, so applying S later may match plant demand increasing the effectiveness of S for pasture production and may also reduce leaching losses of the applied S.At the same site, yield increases to applied S varied greatly, from 0 to 300%, at different harvests in the same or different years. These variations in yield responses to applied S are attributed to the net effect of mineralisation of different amounts of S from soil organic matter, dissolution of S from fertilisers, and different amounts of leaching losses of S from soil by rainfall. Within each year at each site, yield increases were mostly larger in spring (September–November) than in autumn (June–August). In the year of application, single superphosphate was equally or more effective than the other sources. In years when large responses to S occurred, applying single superphosphate later in the year was more effective than applying single superphosphate 3 weeks after pasture emerged (standard practice), so within each year the most recently applied single superphosphate treatment was the most effective S source. All sources generally had negligible residual value, so S needed to be applied each year to ensure S deficiency did not reduce pasture production.

Increased seed production of subterranean clover pastures in response to fertilizers supplying calcium

1974 ◽  
Vol 14 (71) ◽  
pp. 749 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes
Keyword(s):  
Seed Production ◽  
Calcium Concentration ◽  
Field Experiments ◽  
Seed Set ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Unit Weight ◽  
Gypsum Plaster ◽  
Total Seed ◽  
Seed Yields

The effects of four common fertilizers containing calcium on seed production in subterranean clover (Trifolium subterraneum) were measured at six locations over five years in a total of fifteen field experiments. Calcium as a sulphate, carbonate or phosphate salt was applied to subterranean clover pastures either at the start of the growing season (autumn) or at flowering (spring). Gypsum, plaster of Paris, or lime gave large increases in seed yield per unit area and also per unit weight of tops. Spring applications of superphosphate increased seed yields in only two out of four experiments. Gypsum applied in spring at 200-500 kg ha-1 was as effective as 2,000 kg ha-1 of lime applied in autumn. Applications of lime in spring were much less effective. Increased seed yields were due to increases in burr yield, seed number per burr, and mean weight per seed. They were usually accompanied by increases in calcium concentration in the seed. Responses in seed production to calcium applications were obtained in all three sub-species of Trifolium subterraneum. In two experiments, newly sown on a soil type on which subterranean clover regeneration and persistence is commonly very poor, applied calcium doubled or quadrupled seed set. In 13 experiments using soils on which subterranean clover had persisted as the major component of the pasture for several years, calcium in the year of application increased the total seed bank by 6 to 31 per cent, and the current seed set by a greater amount.

The growth of barley grass (Hordeum leporinum) in annual pasture. 3. Some factors affecting balance with subterranean clover (Trifolium subterraneum)

1968 ◽  
Vol 8 (35) ◽  
pp. 702 ◽  
Author(s):  
DF Smith
Keyword(s):  
Soil Nitrogen ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Moisture Stress ◽  
Nitrogen Addition ◽  
The Other ◽  
Early Start ◽  
Factors Affecting ◽  
Two Factors ◽  
Hordeum Leporinum

Mixed swards of barley grass (Hordeum leporinum) and subterranean clover (Trifolium subterraneum) of two densities were grown at two levels of nitrogen. Growth was started at two different times mid- April and mid-May-and at each time half the plots were subjected to moisture stress. The swards were harvested after nine weeks of growth. The survival of clover plants was reduced by an early start, moisture stress and nitrogen addition : much more so than barley grass. The root : shoot ratios of both species were calculated ; both showed some sensitivity to the time of break and moisture stress, and the grass was also affected by the other two factors. Total sward production and the ratios of clover to grass varied widely Grass daminance was favoured by moisture stress or a late break, and both of these factors tended to override the effect of higher soil nitrogen in determining clover-grass balance. Total sward production more dependent on density than any other factor, especially with the later start. Higher nitrogen was effective in boosting production only if the break was early and there was no moisture stress.

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.

scholarly journals Leaf development and dry matter production of subterranean clover cultivars in relation to autumn sward management

2003 ◽  
Vol 11 ◽  
pp. 193-200
Author(s):  
D.J. Moot ◽  
A.D. Black ◽  
W.R. Scott ◽  
J. Richardon
Keyword(s):  
White Clover ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Physical Damage ◽  
Trifoliate Leaf ◽  
Temperature Regimes ◽  
Matter Production ◽  
Wide Range ◽  
Leaf Appearance ◽  
Lincoln University

Seeds of five cultivars of subterranean clover, together with one of white clover, were sown in a wide range of temperature regimes under both controlled environment and field conditions. Results were consistent across temperature regimes and showed that the first trifoliate leaf emerged after 230 °Cd for all subterranean clover cultivars and 309 °Cd for the white clover cultivar. For subterranean clover, exponential leaf appearance commenced after 434 °Cd at the six total leaf stage. At this time, subterranean clover can be defoliated without causing permanent physical damage to seedlings. The field study at Lincoln University showed that subterranean clover that germinated in March produced 44 kg DM/ha/day for 158 days to yield approximately 7 000 kg DM/ha by mid-September. Subterranean clover that germinated in May produced 15 kg DM/ha/day for 120 days to yield only 1 800 kg DM/ha by mid September. These results are discussed in relation to the time of autumn grazing management for subterranean clover, including extrapolation to other climatic areas of New Zealand. Key words: herbage yield, phyllochron, seedling establishment, thermal time, Trifolium subterraneum, T. repens, white clover

scholarly journals Effects of influent temperature variation on floc blanket behavior and effluent water quality

2020 ◽  
Vol 20 (6) ◽  
pp. 2275-2283
Author(s):  
Wasantha Illangasinghe ◽  
Jagath Manatunge ◽  
Niranjanie Ratnayake ◽  
Niranjali Jayasuriya
Keyword(s):  
Field Experiments ◽  
Settling Velocity ◽  
Effect Of Temperature ◽  
Temperature Phase ◽  
Strong Positive Correlation ◽  
Inertial Forces ◽  
Effluent Water ◽  
Particle Collisions ◽  
Strong Negative Correlation ◽  
Increasing Temperature

Abstract The temperature of the water in clarifier tanks has been shown to have a significant influence on floc blanket stability. The objective of this research was to determine the effects of variations in the influent temperature on a floc blanket using laboratory and field experiments and to assess whether the cohesivity of the blanket expressed as the sludge cohesion coefficient (SCC) can be used to interpret the effect of temperature variations. Effluent turbidity exhibited a strong positive correlation with inflow temperature during the increasing temperature phase and a strong negative correlation during the temperature recession phase. An increment of 2 °C in the influent temperature caused the effluent turbidity to increase by 1 NTU. The SCC of the blanket exhibited a significant relationship with the influent temperature. The optimum blanket cohesivity (SCC of 0.7 mm/sec) was observed at a temperature of 23.2 °C, above which the cohesivity decreased. At higher temperatures, frequent particle collisions owing to high inertial forces cause particle motion with the upward flow and increase the effluent turbidity. No correlation between SCC and blanket settling velocity was observed.

Studies on nodulation responses to pelleting of subterranean clover seed.

1961 ◽  
Vol 12 (4) ◽  
pp. 578 ◽  
Author(s):  
JA Thompson
Keyword(s):  
Seed Coat ◽  
Field Experiments ◽  
Chemical Constituents ◽  
Chemical Properties ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Coating Materials ◽  
Physical Separation ◽  
Clover Seed

In a series of field experiments on seven soils of pH 6.0 or higher, nodulation of subterranean clover (Trifolium subterraneum L. var. Tallarook) was improved by pelleting the seed with various glues and coating materials, prior to inoculation with dry peat inoculum. On these soils the responses were not related to the chemical properties of the pellet materials. The beneficial effect was apparently the result of physical separation of the seed coat and inoculum. It is postulated that pelleting of seed protects the inoculum from an antibiotic, whlch has been found in subterranean clover seed coats, and which is active against Rhizobium in culture. On a soil of pH 5.1 a nodulation response to two types of pelleting materials was apparently related to the chemical constituents of the coating materials. In this soil there was less evidence of the importance of physical separation of the inoculum from the seed coat. It seems likely that soils may differ considerably in their ability to inactivate the antibiotic. Nodulation was not improved by in situ fumigation, prior to sowing, of two soils of pH 6.0 and 6.6, which indicated that antagonism by soil microorganisms was not the cause of poor nodulation in these soils. Significant nodulation responses to pelleting were obtained in sowings in these fumigated soils.

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