scholarly journals Effects of season, altitude and daylength on floral initiation of two contrasting genotypes of Trifolium repens L.

1986 ◽  
Vol 106 (1) ◽  
pp. 149-154 ◽  
Author(s):  
F. Von Sury ◽  
J. Nösberger
Keyword(s):  
Low Temperature ◽  
Seed Production ◽  
Floral Initiation ◽  
Cool Season ◽  
Production Potential ◽  
Low Latitude ◽  
Specific Effects ◽  
Trifolium Repens L ◽  
Growth Chambers ◽  
Main Factors

SUMMARYThe effects of season and altitude on floral initiation of two Trifolium repena L. cultivars, Haifa and California Ladino, were tested in the area of Ayacucho, Peru (2730 m, 13° S), with regard to their seed production potential. Specific effects of daylength at a constant temperature (20 °C) were examined in growth chambers.In Ayacucho, the proportion of inflorescence-bearing nodes was found to be lowest between December and June (Haifa 10–20%, Ladino 0–10%) and highest in August (Haifa 30%) and September–October (Ladino 15%). Late in the cool season, floral initiation of Ladino, but not that of Haifa, increased strongly at a high altitude (3250 m). In growth chambers, Haifa initiated few inflorescences and Ladino none in a 10 h daylength. In 16 h, the floral initiation of Haifa was very limited but Ladino formed many inflorescences. Floral initiation of Haifa was most pronounced and lasted longest after a daylength shift from 10 to 13 h.It is concluded that seasonal and altitudinal variations in low temperature were the main factors influencing floral initiation in the region of Ayacucho. Haifa is considered to be an intermediate-day plant, suited for seed production in the region because of its marked and early flowering. Ladino was classified as a quantitative longday plant, unsuitable for seed production at this low latitude because of its retarded floral response to low temperature.

Evaluation of seed production potential in white clover (Trifolium repens L. varietal improvement programmes

1998 ◽  
Vol 53 (2) ◽  
pp. 197-207 ◽  
Author(s):  
T. A. Williams ◽  
M. T. Abberton ◽  
W. J. Thornley ◽  
D. R. Evans ◽  
I. Rhodes
Keyword(s):  
Seed Production ◽  
White Clover ◽  
Trifolium Repens ◽  
Production Potential ◽  
Varietal Improvement ◽  
Trifolium Repens L

Weed Seedling Emergence and Survival as Affected by Crop Canopy

2008 ◽  
Vol 22 (4) ◽  
pp. 736-740 ◽  
Author(s):  
Randy L. Anderson
Keyword(s):  
Winter Wheat ◽  
Seed Production ◽  
Spring Wheat ◽  
Seedling Emergence ◽  
Crop Canopy ◽  
Cool Season ◽  
Common Lambsquarters ◽  
Green Foxtail ◽  
Seedling Emergence And Survival ◽  
Weed Dynamics

This study measured impact of cool-season crops on seedling emergence, survival, and seed production of weeds common in corn and soybean. Weed dynamics were monitored in permanently marked quadrats in winter wheat, spring wheat, and canola. Three species, green foxtail, yellow foxtail, and common lambsquarters, comprised more than 80% of the weeds observed in the study. Seedling emergence was reduced by winter wheat, but not by spring wheat or canola, when compared with adjacent quadrats without a crop canopy. Approximately 10% of seedlings in spring wheat and canola developed into seed-bearing plants, but no seed-bearing plants were present in winter wheat at harvest. Common lambsquarters produced more than 1,100 seeds/plant, whereas a foxtail plant produced 85 seeds, averaged across spring wheat and canola. At harvest, new seedlings were present in all crops; thus, control after harvest will be required to prevent seed production in the fall. Winter wheat may provide an opportunity to disrupt population dynamics of weeds common in corn and soybean without requiring herbicides.

Determination of spikelet number in wheat. I. Effect of varying photoperiod on ear development

1977 ◽  
Vol 28 (2) ◽  
pp. 265 ◽  
Author(s):  
MS Rahman ◽  
JH Wilson
Keyword(s):  
Floral Initiation ◽  
Wheat Cultivars ◽  
Spikelet Number ◽  
Shoot Apices ◽  
Rate Of Development ◽  
Ear Development ◽  
Main Factors ◽  
Photoperiod Control

The effects of constant photoperiods (8, 9, 10, normal and 24 hr) and of transfer to another photoperiod at floral initiation (from 24 hr to 10 and vice versa) on rate of development and spikelet number per ear were studied in eight wheat cultivars grown at 20°C. The objective was to know what factors related to photoperiod control spikelet number. The lengths of the vegetative, spikelet and ear elongation phases, the numbers of spikelets and leaves, the numbers of phytomers and lengths of the shoot apices at floral initiation increased, but the rate of spikelet initiation decreased, as the photoperiod decreased from 24 to 8 hr. Responses to varying photoperiod for all these parameters were similar in the different cultivars but the sizes of the responses differed. Within a given cultivar, an increase in spikelet number was always associated with longer durations of the vegetative and spikelet phases and longer apices at floral initiation. The results of the transfer treatments suggest that spikelet number is not fully determined by the time of floral initiation, but can be altered significantly by manipulating the environment during the spikelet phase. It was concluded that the main factors determining spikelet number are rate and duration of spikelet initiation.

Seed production in Brachiaria decumbens and Paspalum plicatulum as influenced by system of residue disposal

1987 ◽  
Vol 38 (5) ◽  
pp. 869
Author(s):  
WW Stnr ◽  
LR Humphreys
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Nitrogen Supply ◽  
Floral Initiation ◽  
Spikelet Number ◽  
Brachiaria Decumbens ◽  
Short Day ◽  
Cotton South ◽  
Defoliation Treatment

Long-established swards of Brachiaria decumbens cv. Basilisk and of Paspalum plicatulum cv. Rodds Bay at Mt Cotton, south-east Queensland, were cut, field dried and burnt, or cut and the residues removed in late November or early January. Burning initially reduced tillering, especially when the interval between cutting and burning was 7 days, but this difference disappeared in P. plicatulum when there was a long interval to floral initiation. A juvenility requirement was evident in the short day P. plicatulum swards, where late burning or cutting delayed floral initiation 11 days relative to early defoliation. Strong compensatory and hierarchical effects on the components of seed yield occurred, and seed yield was similar in cut or burnt treatments, except for 23% decrease in late cut P. plicatulum. Late defoliated B. decumbens yielded 31% more seed than early defoliated swards, due mainly to reduced spikelet number per raceme (branch). Burning slightly increased synchrony of inflorescence exsertion in P. plicatulum and reduced crop lodging, although in a subordinate experiment with P. plicatulum lodging was positively related to level of nitrogen supply rather than to defoliation treatment.

Seed Production of Wiregrass in Central Florida Following Growing-Season Prescribed Burns

1994 ◽  
Vol 4 (2) ◽  
pp. 123 ◽  
Author(s):  
KW Outcalt
Keyword(s):  
Seed Production ◽  
Seed Viability ◽  
Pinus Palustris ◽  
Growing Season ◽  
Production Potential ◽  
Prescribed Burns ◽  
Central Florida ◽  
Major Species ◽  
Burned Site ◽  
June July

Wiregrass (Aristida stricta Michx.) is a major species in the long leaf pine (Pinus palustris Mill.) sandhills areas of central Florida, providing a major portion of the fuel for the recurring ground fires necessary to maintain the community. Growing season burning promotes flower and seed production. The objective of this study was to assess the seed production potential of wiregrass following prescribed burns from May through August. Four longleaf wiregrass sites were prescribed burned, one each in May, June, July, and August. Information on bunch size, bunch density, seed stalk density, seed density, and seed germination were collected. The four sites differed significantly in the density of wiregrass bunches, average bunch size, wiregrass cover and seed viability. The density of seed stalks was fairly consistent across sites. Viable seed production was lowest on the June burned site and highest on the July burned site. The study shows good quantities of seed are comparatively easy to produce with growing season bums.

Lotus uliginosus (greater lotus) breeding line LUX97: a high seed producing, low condensed tannin population

2007 ◽  
Vol 47 (1) ◽  
pp. 116 ◽  
Author(s):  
W. M. Kelman ◽  
M. J. Blumenthal ◽  
J. W. O'Connor ◽  
P. A. Borchard
Keyword(s):  
New Zealand ◽  
Seed Production ◽  
Condensed Tannin ◽  
Early Flowering ◽  
Breeding Line ◽  
Plant Industry ◽  
Tannin Content ◽  
Production Potential ◽  
Selection For ◽  
Lotus Uliginosus

A Lotus uliginosus polycross population (LUX97) was developed from high seed producing Portuguese accessions and locally adapted New Zealand germplasms. Two cycles of selection for early flowering and low condensed tannin content were successful in producing a population with lower condensed tannin content than the Portuguese parents, while maintaining high seed production potential. Seed of this population will be stored at the CSIRO Plant Industry, Canberra.

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