scholarly journals Maximising seed production potential in white clover: factors influencing seed set per floret

1996 ◽  
Vol 6 ◽  
pp. 41-44
Author(s):  
R.G. Thomas
Keyword(s):  
Seed Production ◽  
White Clover ◽  
Management Practices ◽  
Seed Set ◽  
Head Development ◽  
Light Intensities ◽  
Ovule Sterility ◽  
Growing Conditions ◽  
High Level ◽  
Seed Yields

The causes of low seed set per floret in white clover (Trifolium repens L.) are reviewed. Three stages of flower head development are distinguished as important for a high level of seed set: a pre-fertilisation stage, a stage of anthesis leading to pollination, and a postfertilisation stage in which seed provisioning occurs. In sunny conditions the percentage seed set is limited at the pre-fertilisation stage by up to 20-30% ovule sterility. Relatively low light intensities during the postfertilisation stage can lead to abortion of a high proportion of fertilised ovules and developing seeds. Experimental results suggest that seed yields under optimal growing conditions can be limited solely by the level of pre-fertilisation ovule sterility and probably cannot be bettered, but further understanding of the seed-provisioning requirements for photosynthate could lead to improved management practices for seed production under conditions of lower light intensities. Keywords: abortion, light intensity, ovule, seed provisioning, sterility, white clover

scholarly journals Effect of canopystructure and light intensity on seed production in white clover

1990 ◽  
pp. 107-110 ◽  
Author(s):  
S.V. Pasumarty ◽  
R.G. Thomas
Keyword(s):  
Light Intensity ◽  
Field Experiment ◽  
Seed Production ◽  
Seed Yield ◽  
White Clover ◽  
Weather Conditions ◽  
Open Canopy ◽  
Ovule Sterility ◽  
Growing Conditions ◽  
Artificial Shading

A field experiment was structure and light intensity on seed production A field experiment conducted during the summer of 1989-90 to determine to what extentand under what growing conditions the seed yield of white clover flower heads is influenced by canopy density and overcast weather conditions in plants of 'Grasslands Pitau'. Overcast weather was simulated by artificially shading the plants. The flower heads developed in a dense canopy produced 37% fewer seeds per head than those formed in an open canopy. Seed yield per flower head was also strongly affected by artificial shading. When plants were shaded only before pollination there was a 3 1% reduction in seed number per head; when shade was given only after pollination there was a reduction of 25%. It is argued that a major advantage of the practice of defoliation at the time of closing for seed production is enhancement of flower fertility; and that decreased seed set in duller, wetter summers is probably, at least in part; attributable to increased ovule sterility in the dense canopies formed under those conditions, Keywords: white clover, canopy, light intensity, seed yield

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 SIGNIFICANCE OF FLORAL CHARACTERISTICS IN SEED PRODUCTION OF FOUR SUMMER RAPE CULTIVAR A-LINES WITH pol CYTOPLASM

1989 ◽  
Vol 69 (3) ◽  
pp. 915-918 ◽  
Author(s):  
P. B. E. McVETTY ◽  
R. PINNISCH ◽  
R. SCARTH
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Floral Morphology ◽  
Flower Morphology ◽  
Seed Yields

pol CMS A-line plants of three summer rape cultivars with altered floral morphology showed greater degrees of sideworking by leaf cutter bees than their respective B-line plants with normal floral morphology. However, A-line seed yields were equal to or greater than those of the B-lines.Key words: Flower morphology, rape pol CMS, A-line seed set

scholarly journals Forage seed production: 75 years applying science and technology

2006 ◽  
pp. 15-23
Author(s):  
M.P. Rolston ◽  
R.J. Chynoweth ◽  
A.V. Stewart
Keyword(s):  
Seed Production ◽  
White Clover ◽  
Weed Species ◽  
Department Of Agriculture ◽  
Management Tools ◽  
Production History ◽  
The 1960S ◽  
Seed Crops ◽  
N Rates ◽  
Seed Yields

Forage seed (brassica, grass and legume species) is the delivery vehicle for new plant genetics to the pastoral sector. Seed production technology associated with the release of the first bred pasture cultivars in the 1930s was largely based around horse-drawn reaper and binders and stationary threshing machines. The development of authenticity and quality controls also started in the 1930s with the NZ Seed Certification Scheme. Management inputs were minimal with closing and harvest dates being the major tools available. Over a 75 year period, seed yields have increased, with top growers now achieving seed yields that are three times greater than those reported 50 to 75 years ago. In the 1950s, harvest mechanisation developed rapidly and in the 1970s on-farm seed drying was developed. The availability of nitrogen (N) fertiliser was the first major input available for grass seed growers. The paper follows the science and changing recommendations on N rates and the eventual maximum limit achieved by additional N identified in trials in 2004. From the 1960s onwards, new herbicides have allowed for the control of a wider range of difficult to control weed species, especially the control of other grasses in ryegrass seed crops and broadleaved weeds in white clover. New generation fungicides, insecticides and plant growth regulators have provided improved management tools for increased seed yields. The paper concludes with changes in extension from Government driven (Department of Agriculture) to farmer funded R&D and extension by the Foundation for Arable Research. Keywords: ryegrass, white clover, brassica, seed production, history

EFFECT OF LEAF AREA ON WHITE CLOVER SEED PRODUCTION

1985 ◽  
Vol 2 ◽  
pp. 25-31
Author(s):  
P.T.P. Clifford
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
White Clover ◽  
Management Practices ◽  
Leaf Size ◽  
Fold Increase ◽  
Yield Potential ◽  
Management Options ◽  
Moisture Management ◽  
Clover Seed

Leaf size is a major determinant of white clover seed yield. A three-fold increase in leaf size halves seed yield. From a survey of commercial crops, an optimum leaf size concept was used to explain the reduction in yield potential for extremes in leaf size. Overgrazing gave small leaves and lowered seed yields. Closing too early gave large leaves and lowered yields. With good management, optimum leaf size was the smallest size possible, consistent with ensuring an adequate bulk for efficient harvesting. A healthy highly-reproductive stolen population has to be developed before closing. Secondly, moisture regulation over the crop season, preventing excess watering to minimise plant exploitation of surplus fertility, reduces the potential for large leaves to develop. Mid-November closing coupled with maintaining soil moisture at about 25% plant available, over flowering, are sound management practices. Amongst cultivars, differences in seed yield potential may also be related to leaf size. In general the larger the mean cultivar leaf size the lower the seed yield. Keywords: Trifolium repens, white clover, seed production, leaf size, soil fertiity, moisture, management options.

Research in white clover seed production

1980 ◽  
Vol 1 ◽  
pp. 64-67
Author(s):  
P.T.P. Clifford
Keyword(s):  
Seed Production ◽  
White Clover ◽  
Growth Rates ◽  
Plant Density ◽  
First Year ◽  
Production Plant ◽  
Closing Date ◽  
General Management ◽  
Clover Seed ◽  
Seed Yields

White clover seed yields from crops derived from pure autumn broadcast sowings harvested in the first year after sowing were improved by increasing sowing rate from 3 to 6 kg/ha. On moisture-retentive soils or where irrigation was available, mid-November closings gave highest seed yields for crops derived from either spring undersowings of cereals or as ryegrass mixtures taken for ryegrass seed in the first year from sowing. Closing a month earlier gave similar yields if 30 cm rather than 15 cm row spacings were used. Harvest should be no later than one month from main flowering to reduce the numbers of seedheads lost. General management should aim to promote good primary stolon growth rates over the month prior to mid-December if high flowerhead densities are to be obtained. Therefore excessive grazing before closing and poor timing of herbicide spraying for grass control should be avoided. Keywords: Trifolium repens, seed production, plant density, closing date, pollination, seed harvesting, management.

Experimental studies on seed production of tropical grasses in Kenya. 5. The effect of time of nitrogen top dressing on seed crops of Setaria sphacelata cv. Nandi.

1972 ◽  
Vol 20 (4) ◽  
pp. 225-231
Author(s):  
J.G. Boonman
Keyword(s):  
Adverse Effect ◽  
Seed Production ◽  
Rainy Season ◽  
Seed Set ◽  
Experimental Studies ◽  
Late Season ◽  
Main Adverse Effect ◽  
Setaria Sphacelata ◽  
Seed Crops ◽  
Seed Yields

Effects of date of applying top-dressings of N to early-season and late-season seed crops of Setaria sphacelata cv. Nandi were studied in 4 trials in 1967-71. Highest seed yields were obtained when N was applied as soon as possible after the onset of the rainy season; a delay of 4 weeks reduced yields of pure germinating seed by >60%. Total yields of herbage DM and number of heads were also reduced, but to a lesser extent; the main adverse effect was on seed set/head. In late-season crops, applying N 2 weeks after the earliest possible date proved beneficial in 2 out of 3 years. (Abstract retrieved from CAB Abstracts by CABI’s permission)

The influence of density and nitrogen in seed production stands of S 37 cocksfoot (Dactylis glomerata L.)

1963 ◽  
Vol 61 (3) ◽  
pp. 361-373 ◽  
Author(s):  
D. A. Lambert
Keyword(s):  
Seed Production ◽  
Plant Density ◽  
Unit Area ◽  
The Third ◽  
Plant Densities ◽  
Dactylis Glomerata L ◽  
High Level ◽  
Seed Yields ◽  
Area Percentage ◽  
Lower Plant

1. Seed production stands of S 37 cocksfoot were obtained with varying plant densities by utilizing two drill widths, removing sections of drill, or over-sowing drilled material. All density treatments were operative at two levels of N, 87 or 174 lb. N per acre per annum.2. Tillers in selected quadrats were labelled at monthly intervals during autumn and/or winter for 3 years. Performances of tiller populations were assessed from these quadrats.3. Seed yields were increased in many cases by reducing plant density from a continuous drill pattern. Increased plant density reduced yields. With plant communities on a 1 ft. square arrangement at the high level of nitrogen, an increase of 33%, or 243 lb. seed, per year over a 3-year period was obtained compared with continuous rows at any level of N. The yield of gapped stands increased over the 3-year period, whilst the yields of continuous rows dropped in the final year.4. Nitrogen significantly increased the yield of cocksfoot, except in the third year, by increasing the weight of seed per ear.5. Tiller numbers per quadrat increased in most treatments over the course of the experiment, both within years and from year to year; seasonal peaks of tillering were apparent. The effect of N on tiller numbers differed each year, presumably due to the state of the populations when the N was applied.6. Higher tiller numbers per plant were obtained with lower plant numbers per unit area. Percentage fertility of tillers was generally higher with lower plant densities, and lower tiller numbers per plant, other factors being equal. The only significant effect of N on fertility was to decrease it in the third year.

The influence of environment on seed production capacity in white clover (Trifolium repens L.). I. Controlled environment studies

1961 ◽  
Vol 12 (2) ◽  
pp. 227 ◽  
Author(s):  
RG Thomas
Keyword(s):  
Seed Production ◽  
White Clover ◽  
Trifolium Repens ◽  
Production Capacity ◽  
Pollen Sterility ◽  
Day Length ◽  
Controlled Environment ◽  
Ovule Number ◽  
Trifolium Repens L ◽  
High Level

Ramets of New Zealand Government Stock white clover (Trifolium repens L.) were grown in all combinations of 18-, 14-, and 10-hr photoperiods at constant temperatures of 10, 20, and 30°C. Inflorescence initiation, inflorescence height, number of florets per inflorescence, floret size, ovule number, and pollen fertility were all strongly influenced by environment. Greatest inflorescence initiation occurred in long days at high temperatures, in which conditions, also, the ratio of peduncle to petiole length was highest. Long days and low temperatures led to maximal floret number per inflorescence, floret size, and ovule number per floret. Pollen sterility, as measured by percentage of aborted grains, was little affected by day length but a high level of sterility was induced by growth at 10°C. The relative importance of these factors and the interactions between them in determining seed production capacity are discussed.

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