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)

scholarly journals Experimental studies on seed production of tropical grasses in Kenya. 3. The effect of nitrogen and row width on seed crops of Setaria sphacelata cv. Nandi II.

1972 ◽  
Vol 20 (1) ◽  
pp. 22-34
Author(s):  
J.G. Boonman
Keyword(s):  
Seed Production ◽  
Experimental Studies ◽  
Rapid Decline ◽  
Tropical Grasses ◽  
Seed Crop ◽  
Row Width ◽  
Setaria Sphacelata ◽  
Seed Crops ◽  
Germinable Seed

Setaria sphacelata sown broadcast or in rows up to 100 cm apart was given 0-260 kg N/ha applied to each seed crop. 100 kg N/ha increased herbage DM yields 3-fold and yields of germinable seed 7-fold. At 130 kg N/ha yields of germinable seed were 33% higher from rows 30 cm apart than from rows 90 cm apart. Percentage and yield of germinable seed varied very greatly between seasons, though DM yield and inflorescence number varied little. The highest yield of germinable seed was 48 kg/ha for a single harvest. Rapid heading was preceded by a rapid increase and a subsequent rapid decline in tiller numbers. Herbage DM response to 100 kg N was 65 kg DM/kg N. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Experimental studies on seed production of tropical grasses in Kenya. 2. Tillering and heading in seed crops of eight grasses.

1971 ◽  
Vol 19 (4) ◽  
pp. 237-249
Author(s):  
J.G. Boonman
Keyword(s):  
Seed Yield ◽  
Experimental Studies ◽  
First Year ◽  
Panicum Maximum ◽  
Linear Rate ◽  
Brachiaria Ruziziensis ◽  
Setaria Sphacelata ◽  
Chloris Gayana ◽  
Seed Crops ◽  
Seed Yields

Tillering in seed crops grown undisturbed for 6 months was studied over 2 years in cultivars of Setaria sphacelata, Chloris gayana, Panicum coloratum, Panicum maximum and Brachiaria ruziziensis. Tiller numbers rose to a maximum around the time of initial head emergence (5-10 heads/m2), followed by a decline and finally a levelling off. Head emergence was found to continue in some cv. for over 3 months. The weight/tiller increased at a linear rate. Tiller numbers never exceeded 1900/m2. Tillers were less numerous but were heavier in the year of sowing than in the subsequent year. Total dry weights of tillers were also highest in the first year. Seed yield was significantly correlated with degree of concentrated head emergence and percentage of heading tillers in a cultivar. It is suggested that, within cv., plants with heavier tillers may produce higher seed yields. Cv. within species can be identified according to date of initial head emergence. A type of culm branching is described in which tillers develop into flowering culms out of elevated nodes of erect parental culms. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Experimental studies on seed production of tropical grasses in Kenya. 1. General introduction and analysis of problems.

1971 ◽  
Vol 19 (1) ◽  
pp. 23-36
Author(s):  
J.G. Boonman
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Experimental Studies ◽  
General Introduction ◽  
Tropical Grasses ◽  
Melinis Minutiflora ◽  
Brachiaria Ruziziensis ◽  
Seed Retention ◽  
Setaria Sphacelata ◽  
Chloris Gayana

Problems in seed production of Setaria sphacelata (2 cv.), Chloris gayana (3 cv.), Panicum coloration, P. maximum, Brachiaria ruziziensis and Melinis minutiflora are discussed. Low yields and quality were due to varying combinations of prolonged heading season per plant and per cultivar, prolonged flowering within a given head, low seed set, low number of fertile tillers, low seed retention, disease and bird damage. Actual yields were only about 5% of potential yields.-R.B. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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.

scholarly journals Inter-annual variation in seed production has increased over time (1900–2014)

2017 ◽  
Vol 284 (1868) ◽  
pp. 20171666 ◽  
Author(s):  
Ian S. Pearse ◽  
Jalene M. LaMontagne ◽  
Walter D. Koenig
Keyword(s):  
Seed Production ◽  
Seed Set ◽  
Global Climate ◽  
Mast Seeding ◽  
Plant Seed ◽  
Subtle Change ◽  
Animal Populations ◽  
Wide Range ◽  
Seed Crops ◽  
Over Time

Mast seeding, or masting, is the highly variable and spatially synchronous production of seeds by a population of plants. The production of variable seed crops is typically correlated with weather, so it is of considerable interest whether global climate change has altered the variability of masting or the size of masting events. We compiled 1086 datasets of plant seed production spanning 1900–2014 and from around the world, and then analysed whether the coefficient of variation (CV) in seed set, a measure of masting, increased over time. Over this 115-year period, seed set became more variable for plants as a whole and for the particularly well-studied taxa of conifers and oaks. The increase in CV corresponded with a decrease in the long-term mean of seed set of plant species. Seed set CV increased to a greater degree in plant taxa with a tendency towards masting. Seed set is becoming more variable among years, especially for plant taxa whose masting events are known to affect animal populations. Such subtle change in reproduction can have wide-ranging effects on ecosystems because seed crops provide critical resources for a wide range of taxa and have cascading effects throughout food webs.

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

Seed production and its components in bred populations and cultivars of winter-green Setaria sphacelata at two levels of applied nitrogen fertiliser

1994 ◽  
Vol 34 (2) ◽  
pp. 153 ◽  
Author(s):  
JB Hacker
Keyword(s):  
Seed Production ◽  
Germination Percentage ◽  
Nitrogen Fertiliser ◽  
Setaria Sphacelata ◽  
Low Levels ◽  
Tiller Density ◽  
Seed Yields ◽  
Positive Effect ◽  
Inflorescence Length ◽  
Applied Nitrogen

Seed production of 2 experimental winter- green varieties of Setaria sphacelata, EHB (released as cv. Solander) and EHC, was compared with the winter-green cv. Narok in a split-plot experiment with 2 levels of applied nitrogen (N) fertiliser. The experiment continued for 3 years (6 harvests), and 3 subharvests at 1-2-week intervals were taken at each major harvest to allow for possible phenological differences between varieties. Total numbers of basal tillers, and of basal and aerial tillers with inflorescences, were counted at each harvest. Ripe and shedding inflorescences were counted, dried, and threshed by hand, and the seed was sieved and aspirated. The aspirated seed was stored for 6 months, the percentage of spikelets containing caryopses was evaluated, and samples were germinated in petri dishes. Aspirated seed yields of Solander were mostly 50-100% higher than those of Narok, except where yields were generally low, associated with low levels of applied N, and in later harvests of the experiment. All 3 entries showed a progressive decrease in seed production over time, and no consistent phenological difference was apparent. The improved seed production of Solander was associated with a markedly higher tiller fertility, lower basal tiller density, and slightly longer inflorescences. Germination percentage of Solander was consistently lower than that of Narok, and it was postulated that this was due to a higher level of seed dormancy. Nitrogen fertiliser had a marked positive effect on seed production, inflorescence numbers, tiller fertility, basal tiller density, and inflorescence length in all populations.

scholarly journals GRASS SEED PRODUCTION: WEEDS, HERBICIDES AND FERTILISERS

1985 ◽  
Vol 2 ◽  
pp. 15-22
Author(s):  
M.P. Ralston ◽  
K.R. Brown ◽  
M.D. Hare ◽  
K.A. Young
Keyword(s):  
Seed Production ◽  
Stem Elongation ◽  
Grass Species ◽  
Wild Oat ◽  
Weed Species ◽  
Grass Seed ◽  
Prairie Grass ◽  
Seed Crops ◽  
Seed Yields ◽  
Bromus Mollis

Four weed species (Bromus mollis, Vulpia sp., Poa annua, Steltaria media) occur in 30% or more of all perennial ryegrass seed samples. Of the listed undesirable species, Avena fatua (wild oat) and Hordeum murinum occurred respectively in 5.3 and 3.5% of ryegrass seedlots. Only 6 herbicides are registered for use in grass seed crops in New Zealand, 2 for wild oat, and 4 for broadleaved weeds. The results of research on weed control in seedling and established seed crops (ryegrass, cocksfoot, tall fescue, phalaris, prairie grass) are presented. Fertilisers for grass seed crops discussed are nitrogen (N), phosphorus (P), potassium (K), lime and zinc. Autumn N is commonly used and will increase seed yields in early flowering species (Pestuca rubra, F. arundinacea), but in ryegrass variable results have occurred. Spring N should be applied at stem elongation. No responses to P have been reported for ryegrass, while in established cocksfoot responses to P and K have been reported. Overliming can induce Zn deficiencies, and of the grass species only prairie grass may require lime. Keywords: Lolium, ryegrass, seed production, weed occurrence, Bromus mollis, herbicides, fertilisers, nitrogen, phosphorus, potassium, lime, zinc

scholarly journals Experimental studies on seed production tropical grasses in Kenya. 6. The effect of harvest date on seed yield in varieties of Setaria sphacelata, Chloris gayana and Panicum coloratum.

1973 ◽  
Vol 21 (1) ◽  
pp. 3-11
Author(s):  
J.G. Boonman
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Experimental Studies ◽  
The Other ◽  
Harvest Date ◽  
Tropical Grasses ◽  
Panicum Coloratum ◽  
Setaria Sphacelata ◽  
Chloris Gayana ◽  
Late Abstract

Setaria sphacelata cv. Nandi I and Nandi III, Chloris gayana cv. Mbarara, Masaba and Pokot, and Panicum coloratum cv. Solai were grown for seed and harvested on a range of dates beginning 3-4 weeks after initial head emergence (defined as 5-10 heads/m2). Harvesting date was not very critical, and harvesting could normally be spread over 1-2 weeks. The interval between initial heading and optimum harvest date was normally 6-7 weeks. In most crops considerable shedding of spikelets (up to 30-50% in P. coloratum, rather less in the other 2 species) could be tolerated before yield of pure germinating seed fell with delay in harvesting. It was suggested that most of the spikelets which were shed early were empty. Cultivars which headed early produced nearly twice as much seed as those which headed late. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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

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