FACTORS AFFECTING SEED PRODUCTION IN TRIFOLIUM MEDIUM

1964 ◽  
Vol 44 (4) ◽  
pp. 337-343 ◽  
Author(s):  
R. W. Robertson ◽  
J. M. Armstrong
Keyword(s):  
Seed Production ◽  
Red Clover ◽  
Corolla Tube ◽  
Bumble Bee ◽  
Nectar Secretion ◽  
Seed Setting ◽  
Eastern Canada ◽  
Factors Affecting ◽  
Production Studies ◽  
Seed Yields

Seed production studies in field nurseries revealed that the bumble bee is the most important pollinator of zigzag clover (Trifolium medium L.) and that seed-setting is directly correlated with the frequency of their visits. The long corolla tube of this clover precludes its pollination by the honey bee. Nectar secretion is approximately the same in amount and concentration as in red clover, the most important competing species for pollinators.T. medium has a high chromosome number (2n = 80) but meiosis is regular and a high percentage of good pollen is formed. Improved seed-producing strains were established by combining high-seed-producing plants in polycross nurseries. Seed yields are increased by cutting back the plants in late May. Seed yield appears to be genetically controlled.The species occurs in isolated areas in uncultivated pastures in Eastern Canada. All plants within each area examined are intersterile but cross readily with plants from other sources. This suggests that each area may have originated from a single seedling which spread by stolons.

EMBRYO-SAC PRODUCTION IN RELATION TO SEED YIELDS OF DIPLOID DOLLARD RED CLOVER

1959 ◽  
Vol 39 (3) ◽  
pp. 364-374 ◽  
Author(s):  
Bronius Povilaitis ◽  
J. W. Botes
Keyword(s):  
Seed Production ◽  
Environmental Conditions ◽  
Genetic Factors ◽  
Embryo Sac ◽  
Red Clover ◽  
Limiting Factor ◽  
Adverse Environmental Conditions ◽  
Seed Yields

Evidence that red clover plants of the Dollard variety differ in production of fertile ovaries is presented. The amount of ovary sterility arising through failure of the embryo sac to complete its development is apparently controlled by genetic factors and influenced by environmental conditions. Consideration of the data on frequencies of ovary fertility of plants in nursery lines and in progenies of crosses, together with data on their seed production, leads to the conclusion that ovary sterility is an important limiting factor on the ability of a plant to produce seed. Even under adverse environmental conditions; appreciable ovary sterility is still the primary limiting factor in restricting seed production and hence, among plants affected by ovary sterility, it is not surprising that we found significant correlation between the percentages of ovary fertility and seed yields.

Seed production and persistence of Carnamah and other early strains of Trifolium subterraneum in the wheatbelt of Western Australia

1967 ◽  
Vol 7 (24) ◽  
pp. 25 ◽  
Author(s):  
GB Taylor ◽  
RC Rossiter
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Western Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growing Season ◽  
Early Flowering ◽  
The Other ◽  
Factors Affecting ◽  
Seed Yields

Seed production and persistence of the Carnamah, Northam A, Dwalganup, and Geraldton strains of subterranean clover (Trifolium subterraneum L.) were examined in undefoliated swards in the wheatbelt of Western Australia. The early flowering characteristic of Carnamah was not always associated with higher seed yields. Only when there was a well-defined, early finish to the growing season, or when flowering was very much earlier in Carnamah (viz., following an early 'break' to the season), did this strain clearly outyield both Northam A and Geraldton. The seed yield of Dwalganup was generally inferior to that of the other strains. Factors affecting regeneration are discussed. Under low rainfall conditions, poorer germination-regulation of Carnamah, compared with Geraldton and Northam A, would be expected to result in poorer persistence unless offset by higher seed yields in the Carnamah strain.

scholarly journals Drastic historic shifts in bumble-bee community composition in Sweden

2011 ◽  
Vol 279 (1727) ◽  
pp. 309-315 ◽  
Author(s):  
Riccardo Bommarco ◽  
Ola Lundin ◽  
Henrik G. Smith ◽  
Maj Rundlöf
Keyword(s):  
Seed Yield ◽  
Red Clover ◽  
Wild Plants ◽  
Bumble Bee ◽  
Management Schemes ◽  
Relative Abundances ◽  
Bee Community ◽  
Flower Visiting ◽  
Clover Seed ◽  
Seed Yields

The species richness of flower-visiting insects has declined in past decades, raising concerns that the ecosystem service they provide by pollinating crops and wild plants is threatened. The relative commonness of different species with shared ecological traits can play a pervasive role in determining ecosystem functioning, but information on changes in abundances of pollinators over time is lacking. We gathered data on relative abundances of bumble-bee species in Swedish red clover fields during three periods in the last 70 years (1940s, 1960s and present), and on clover seed yields since 1921. We found drastic decreases in bumble-bee community evenness, with potential consequences for level and stability of red clover seed yield. The relative abundances of two short-tongued bumble-bees have increased from 40 per cent in the 1940s to entirely dominate present communities with 89 per cent. Average seed yield declined in recent years and variation in yield doubled, suggesting that the current dependence on few species for pollination has been especially detrimental to stability in seed yield. Our results suggest a need to develop management schemes that promote not only species-rich but also more evenly composed communities of service-providing organisms.

BUMBLE BEE MANAGEMENT OPTIONS TO IMPROVE 'GRASSlANDS PAWERA' RED CLOVER SEED YIELDS

1983 ◽  
pp. 47-53 ◽  
Author(s):  
R.P. Macfarlane ◽  
R.P. Griffin ◽  
P.E.C. Read
Keyword(s):  
Food Source ◽  
Seed Set ◽  
Local Food ◽  
Red Clover ◽  
Bumble Bee ◽  
Field Placement ◽  
Management Options ◽  
Colony Management ◽  
Clover Seed ◽  
Seed Yields

Three options of bumble bee management for red clover pollination are discussed: spring supplementation with queens caught outside the locality; colony introduction at flowering; and permanently sited hives close to the crop. The first two options must be carried out annually whereas the last option presupposes an adequate local food source prior to flowering. It is contended that even with successful permanent siting further annual introductions would be required where the area in crop is to be considerably increased. Details of hive construction, field placement and colony management are outlined. In 1982 the amount of seed set, on a machine dressed basis, for one colony of B. hortorom and B. ruderatus was 130 kg and 56 kg respectively Keywords: Pawera red clover, seed yields, Bombus hortorum, B. ruderatus, hive construction, colony management.

Further Studies on the Food-Gathering Behaviour of Bumble Bees (Hymenoptera: Apidae)

1962 ◽  
Vol 94 (5) ◽  
pp. 538-541 ◽  
Author(s):  
G. A. Hobbs
Keyword(s):  
Food Preferences ◽  
Red Clover ◽  
Corolla Tube ◽  
Bumble Bees ◽  
Bumble Bee ◽  
Experimental Field ◽  
Foraging Experience ◽  
Innate Behaviour ◽  
The Individual

Brian (1954) discussed the evidence in the literature concerning whether the correlation between the length of the proboscis of a bumble bee and the length of the corolla tube of the flower it visits for nectar results from learned or innate behaviour. She hesitated to accept the views of Kugler (1943), who supported the ‘learned’ hypothesis and considered that the individual bumble bee is instinctively attracted to a flower by its colour, scent, etc., but must learn which flowers are suited to its bodily build, because he had done no work on bees raised in isolation and therefore known to be without foraging experience. The work of Cumber (1949), which reported that there were differences in proboscis lengths between individuals of a species that visited different flowers and which therefore also supported the learned hypothesis, was suspect because he gave no data on corolla lengths. Hobbs et al. (1961), who recorded the food-preferences of certain of the workers, queens, and males of honey, bumble, and leaf-cutter bees on an isolated experimental field containing plots of alfalfa, red clover, alsike clover, and sweetclover, concluded that the preference exhibited by a bee was linked with the ease with which it could gather nectar from a flower. They found, as did Cumber, that differences in prolboscis-lengths between individuals of a species resulted in preferences for flowers of different corolla-tube lengths, e.g., the queens of Bombus hunti Greene (mean length of proboscis 8.7 mm.) greatly preferred red clover, whereas the workers (m.l.p. 6.3 mm.) preferred sweetclover.

Factors affecting the yield of seed produced by different varieties of red clover

1965 ◽  
Vol 65 (2) ◽  
pp. 245-253 ◽  
Author(s):  
R. P. Hawkins
Keyword(s):  
Seed Set ◽  
Red Clover ◽  
Corolla Tube ◽  
Dominant Factor ◽  
Potential Yield ◽  
Factors Affecting ◽  
Set Size

Yields of varieties of red clover were found to vary from year to year and relative to each other.Apart from losses in harvesting the seed, which were not studied, yields of seed were found to be correlated with seed set, size of seed and numbers of heads in the crop. In 1958 the dominant factor affecting yields was Kabatiella.Because of the value of seed set in indicating potential yield, its relation to other characters was studied. Data are given for length of corolla tube, numbers of positive pollinators and size of head as indicated by the number of florets, and their relationship to seed set and to one another.

Bumble Bee Pollinators in Red Clover Seed Production

Crop Science ◽  
2009 ◽  
Vol 49 (6) ◽  
pp. 2207-2214 ◽  
Author(s):  
Sujaya Rao ◽  
William P. Stephen
Keyword(s):  
Seed Production ◽  
Red Clover ◽  
Bumble Bee ◽  
Clover Seed

scholarly journals Seed-Production Potential of Tephrosia vogelii in Puerto Rico

1969 ◽  
Vol 53 (3) ◽  
pp. 207-212
Author(s):  
D. K. Barnes ◽  
R. H. Freyre
Keyword(s):  
Puerto Rico ◽  
Seed Production ◽  
Seed Yield ◽  
Correlation Coefficients ◽  
Physiological Factors ◽  
Production Studies ◽  
Tephrosia Vogelii ◽  
Agricultural Experiment ◽  
The University ◽  
Seed Yields

T. vogelii seed-production studies were established at the Isabela Substation of the Agricultural Experiment Station of the University of Puerto Rico in 1963 and 1964. Average seed-yields of the best producing lines ranged from approximately 450-500 kg./hectare, but this was only a fraction of the crop's potential production. A large percentage of florets failed to set pods. This was partly attributed to lack of insect pollinators, but unknown environmental and physiological factors were also thought to be important. Small but significant correlation coefficients indicated that the best seed-producing plants tended to be tall and to flower early. No significant relationship was observed between rotenoid content and seed-yield. A breeding program that simultaneously selects for both seed-yield and rotenoid content is suggested.

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