Resource limitation of fruit and seed production in some Asclepias species

1980 ◽  
Vol 58 (20) ◽  
pp. 2229-2233 ◽  
Author(s):  
Mary F. Willson ◽  
Peter W. Price
Keyword(s):  
Seed Production ◽  
Resource Availability ◽  
Seed Weight ◽  
Mineral Fertilizer ◽  
Resource Limitation ◽  
Leaf Removal ◽  
Asclepias Syriaca ◽  
Resource Limited

Effects of modifying resource availability were studied on three species of milkweed, Asclepias syriaca, A. verticillata, and A. incarnata. The influence of mineral fertilizer, leaf removal, and shading were investigated to test the hypothesis that milkweed species are resource limited. Addition of mineral fertilizer resulted in increased numbers of mature pods per stem in A. syriaca and A. verticillata, and numbers of seeds per pod and seed weight in A. syriaca. Defoliation tended to result in a reduction of number of mature pods produced per stem. Results from shading showed a similar trend but few significant differences were observed.

Limitations on reproduction in alpine Ranunculus acris

1997 ◽  
Vol 75 (1) ◽  
pp. 137-144 ◽  
Author(s):  
Ørjan Totland
Keyword(s):  
Seed Production ◽  
Resource Availability ◽  
Seed Weight ◽  
Pollen Limitation ◽  
Resource Limitation ◽  
Limiting Factors ◽  
Perennial Herb ◽  
Plant Variation ◽  
Hand Pollination ◽  
Ranunculus Acris

This study examines experimentally the influence of limiting factors on seed to ovule ratio and seed weight in three alpine populations of the perennial herb Ranunculus acris L. at Finse, southwest Norway. To test for pollen and resource limitation, seed production of supplementally pollinated or completely defoliated plants was compared to that of untreated plants. In one population the experiment was repeated twice during the season. In mid-season, supplemental hand-pollination had no significant effect on seed to ovule ratio, but significantly increased the seed weight, whereas complete defoliation resulted in a significant decrease in seed to ovule ratio and a marginally significant decrease in seed weight. These results indicate that pollen limitation occurred on seed weight and resource limitation mainly on seed to ovule ratio. Seed production in late-flowering control and defoliated plants in one population was nearly completely absent, whereas supplemental pollination increased seed production substantially. Most seeds were produced at the lowest elevation, and frost damage on developing seeds was most pronounced at the highest elevation population, suggesting that severe weather conditions at the highest altitudes had a negative influence on reproductive processes. Significant positive relationships between seed number and seed weight were found, possibly reflecting a large among-plant variation in total resource availability. Key words: altitude gradient, climate, defoliation, pollen and resource availability, seasonal variation, seed size.

The effect of defoliation on seed production by capeweed (Arctotheca calendula)

1973 ◽  
Vol 13 (65) ◽  
pp. 676 ◽  
Author(s):  
JG McIvor ◽  
DF Smith
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Yield Components ◽  
Seed Weight ◽  
Leaf Removal ◽  
Late Flowering ◽  
Individual Seed ◽  
Number Of Seeds

Two experiments were done in pots to assess the effect of defoliation at different times on the seed yield of capeweed (Arctotheca calendula). Yield components measured were: number of seedheads per plant, number of seeds per seedhead, number of seeds per plant, and weight of individual seeds. Of the components of yield, number of florets per seedhead and individual seed weight were maintained under all treatments; number of seedheads and number of seeds per seedhead were more affected by defoliation. Whether grown as spaced plants or in swards, leaf removal did not significantly reduce the number of seeds produced unless combined with bud and flower removal at late flowering only. The results are discussed in relation to the growth and persistence of capeweed in pastures.

Common Milkweed Seed Maturation

Weed Science ◽  
1973 ◽  
Vol 21 (6) ◽  
pp. 568-569 ◽  
Author(s):  
L. L. Evetts ◽  
O. C. Burnside
Keyword(s):  
Seed Production ◽  
Seed Weight ◽  
Close Association ◽  
Seed Maturation ◽  
Time Interval ◽  
Viable Seed ◽  
Asclepias Syriaca ◽  
Hypocotyl Length ◽  
Viable Seeds ◽  
Germinated Seeds

A 2-year experiment was conducted to determine the time interval between flowering and viable seed production in common milkweed (Asclepias syriacaL.). A high percentage of seeds harvested 6 weeks after flowering germinated. Seeds harvested 6 and 7 weeks after flowering resulted in seedlings with significantly shorter radicles and hypocotyls than seeds harvested 8 weeks after flowering. There was a close association between seed weight and radicle and hypocotyl length. Common milkweed produced viable seeds 5 to 6 weeks after flowering.

Effect of burr burial on seed production of Trifolium subterraneaum subsp. brachycalycinum and other annual legumes

1986 ◽  
Vol 26 (1) ◽  
pp. 59 ◽  
Author(s):  
MDA Bolland ◽  
WJ Collins
Keyword(s):  
Seed Production ◽  
Sandy Soil ◽  
Seed Weight ◽  
Trifolium Subterraneum ◽  
Annual Legumes ◽  
Seed Yields

On sandy soil near Esperance, W.A., prevention of burr burial compared with covering developing burrs with sand drastically reduced the seed production of three subspp. of Trifolium subterraneum (brachycalycinum, subterraneum and yanninicum) and of T. israeliticum by reducing burr production and seed weight. However, T. globosum produced similar amounts of seed from unburied and buried burrs. On sandy soil at Shenton Park, Perth, W.A., prevention of burr burial also reduced seed production of T. subterraneum subspp. brachycalycinum and subterraneum, this being due to fewer burrs, fewer seeds per burr and lighter seed. For subsp. brachycalycinum, seed yields were two to five times greater from burrs which developed within loose gravel than from those developed over sand (in which fewer burrs were able to bury) as a result of increased production of burrs, more seeds per burr and heavier seed. However, for subsp. subterraneum seed yields were similar from burrs whether developed over gravel or sand.

scholarly journals Habitat-mediated population limitation in a colonial central-place forager: the sky is not the limit for the black-browed albatross

2014 ◽  
Vol 281 (1778) ◽  
pp. 20132883 ◽  
Author(s):  
Ewan D. Wakefield ◽  
Richard A. Phillips ◽  
Jason Matthiopoulos
Keyword(s):  
Resource Availability ◽  
Net Primary Production ◽  
Strong Dependence ◽  
Resource Limitation ◽  
Central Place ◽  
Population Limitation ◽  
Animal Populations ◽  
Temporal Predictability ◽  
Spatio Temporal ◽  
The Cost

Animal populations are frequently limited by the availability of food or of habitat. In central-place foragers, the cost of accessing these resources is distance-dependent rather than uniform in space. However, in seabirds, a widely studied exemplar of this paradigm, empirical population models have hitherto ignored this cost. In part, this is because non-independence among colonies makes it difficult to define population units. Here, we model the effects of both resource availability and accessibility on populations of a wide-ranging, pelagic seabird, the black-browed albatross Thalassarche melanophris . Adopting a multi-scale approach, we define regional populations objectively as spatial clusters of colonies. We consider two readily quantifiable proxies of resource availability: the extent of neritic waters (the preferred foraging habitat) and net primary production (NPP). We show that the size of regional albatross populations has a strong dependence, after weighting for accessibility, on habitat availability and to a lesser extent, NPP. Our results provide indirect support for the hypothesis that seabird populations are regulated from the bottom-up by food availability during the breeding season, and also suggest that the spatio-temporal predictability of food may be limiting. Moreover, we demonstrate a straightforward, widely applicable method for estimating resource limitation in populations of central-place foragers.

scholarly journals Heliotropism and water availability effects on flowering dynamics and seed production in Macroptilium lathyroides

2006 ◽  
Vol 28 (2) ◽  
pp. 45-52 ◽  
Author(s):  
Armando Martins dos Santos ◽  
Luis Mauro Gonçalves Rosa ◽  
Lucia Brandão Franke ◽  
Carlos Nabinger
Keyword(s):  
Seed Production ◽  
Water Availability ◽  
Yield Components ◽  
Seed Weight ◽  
Field Capacity ◽  
Leaf Movements ◽  
Independent Effects ◽  
Total Seed ◽  
Macroptilium Lathyroides ◽  
Response To Water

The experiment was carried out in pots in a glasshouse, with one plant per pot and nine repetitions per treatment. The treatments consisted of free or restricted leaves, submited to 90-100% or 60-70% soil field capacity (FC). Only independent effects of water availability or leaf movement were observed on yield components. Plants under well-watered conditions and with freely orienting leaves were taller, and had a larger number of ramifications. The greater development favored the setting of a higher number of inflorescences per plant in these treatments. This behavior resulted in a high number of flowers, green and mature legumes per plant, thus resulting in high seed production which was the most evident response to water availability. Although individual seed weight was higher in the water stress treatment, total seed production was higher for well-watered plants, with no statistically significant effect of leaf movements.

scholarly journals Evaluation of Performances of Cowpea (Vigna ungiculata) Genotypes in Agronomy Farm of Lamjung Campus

2017 ◽  
Vol 5 (3) ◽  
pp. 382-385
Author(s):  
Chandan Bhattarai ◽  
Dinesh Marasini ◽  
Prabin Dawadi ◽  
Sadkishya Aryal
Keyword(s):  
Data Collection ◽  
Grain Yield ◽  
Plant Height ◽  
Seed Production ◽  
Seed Weight ◽  
Harvest Index ◽  
Yield Parameters ◽  
Cowpea Varieties ◽  
Pod Length ◽  
The Given

Seed to seed production experiments for cowpea (Vigna ungiculata) was conducted at Agronomy farm at IAAS Lamjung, and to compare production potentialities of given cowpea genotypes under the given sets of conditions. The treatment consists of two cowpea varieties viz. Prakash (Standard Check) and Malepatan (Local check) and four genotypes; IT 99K-573-2-1, IT 86F-2062-5, IT 93K-452-1, IT 98K-205-8. The experiment was conducted on RCBD design. .All other activities were carried out according to prepared working calendar almost from August 2016 to December 2016.  Data collection were done for pre-determined growth and other yield parameters and was analyzed using MSTAT. Major parameters were Grain yield, Seeds/plant, Pods/plant, plant height, pod length, harvest index and test weight. Result shows maximum grain yield and harvest index was found for Prakash (Standard Check).Plant height and Pods /Plant was found highest for IT 99K-573-2-1. Similarly highest seed weight was found for Prakash (Standard Check) and Seeds/Plant and Pod length was maximum for IT 86F-2062-5.Int. J. Appl. Sci. Biotechnol. Vol 5(3): 382-385

Seed-setting in subterranean clover (Trifolium subterranean L.). III. The effect of plant density

1961 ◽  
Vol 12 (1) ◽  
pp. 10 ◽  
Author(s):  
JJ Yates
Keyword(s):  
Seed Production ◽  
Seed Weight ◽  
Plant Density ◽  
Plant Cover ◽  
General Pattern ◽  
Strain Differences ◽  
Subterranean Clover ◽  
Seed Setting ◽  
Below Ground ◽  
Australian Wheat

Various aspects of seed production in a number of strains of subterranean clover sown at fire seeding rates at two sites in the Western Australian wheat-belt were investigated. Dry matter yields and percentage leaf in the foliage were also recorded. Percentage leaf increased with plant density in the earlier-maturing, stemmy strains, so that differences amongst strains diminished as density increased. The differences amongst strains in number of inflorescences when grown as single plants were largely eliminated under dense sward conditions, so that the two main factors in seed production were number of seeds per inflorescence and mean seed weight. The proportion of burrs above and below ground varied widely amongst strains, and was influenced by plant density in some strains. It is postulated that the extent of burr burial depends on the interaction between strain, environment, and condition of the surface soil. Burr burial improved the efficiency of seed-setting, particularly in the more severe environment. Strain differences in seeds per inflorescence below ground were relatively small, but within each strain, values were higher in the more favorable environment. The efficiency of seed-setting above ground differed considerably amongst strains and between the two environments, and tended to increase with plant density particularly in the earlier-maturing strains. Correlations were established between seeds per inflorescence above ground and the amount of plant cover in these strains. An artificial covering of wood-wool also improved seed-setting above ground. Mean seed weight followed the same general pattern as seeds per inflorescence.

scholarly journals Enrichment, quality, and productivity of soybean seeds with cobalt and molybdenum applications

2019 ◽  
Vol 41 (2) ◽  
pp. 144-150
Author(s):  
Dionatam Cortese ◽  
Clovis Pierozan Junior ◽  
Jilvana Barbara Walter ◽  
Diaine Cortese ◽  
Silas Maciel de Oliveira
Keyword(s):  
Seed Production ◽  
Seed Weight ◽  
Nitrogen Assimilation ◽  
Nutrient Content ◽  
Soybean Seeds ◽  
Application Time ◽  
Biological Fixation ◽  
Mo Content ◽  
Thousand Seed Weight

Abstract: Cobalt (Co) and molybdenum (Mo) are vital nutrients for biological fixation and nitrogen assimilation by soybean. This study aimed to evaluate the increase of Co and Mo contents in soybean seeds by leaf applications. The experiment was carried out in a seed production field in a 3 × 3 factorial scheme with three Co and Mo doses and three treatments (times). Each treatment consisted of two application times: R3+R5.1 (T1), R3+R5.4 (T2), and R5.1+R5.4 (T3). Doses were 0, 400, and 600 g.ha−1 of Mo and 0, 40, and 60 g.ha−1 of Co. No difference was observed for productivity, one thousand-seed weight, and germination. An interaction was observed between dose and application time in the Mo content. The application of 400 g ha−1 of Mo in T1 (R3+R5.1) provided a higher Mo content in the seeds (13.5 g.kg−1), which is 1350% higher when compared to the control. For Co, there was a difference only for doses, and the application of 40 or 60 g.ha−1 of Co increased seed nutrient content by 30%. Therefore, a higher enrichment of Co and Mo was observed in seeds with applications of 40 and 400 g.ha−1, respectively, applied in R3+R5.1.

scholarly journals Effect of Defoliation and Fe and Mn Spraying on Quality and Quantity Characteristics of Sunflower (Helianthus annuus L.)

2011 ◽  
Vol 3 (3) ◽  
pp. 113-119 ◽  
Author(s):  
Farshid VAZIN ◽  
Mojtaba HASSANZADEHDELOUEI ◽  
Mohamadjavad KHERADMAND
Keyword(s):  
Seed Yield ◽  
Seed Weight ◽  
Foliar Application ◽  
Antagonistic Effect ◽  
Leaf Removal ◽  
Negative Effects ◽  
Combined Use ◽  
Fe And Mn ◽  
Defoliation Treatment ◽  
Severe Leaf

The study was aimed at identifying the amount of reduction in the negative effects of leaf removal on both quality and quantity of sunflower as a result of foliar application of Fe and Mn. Severe leaf removal reduced the seed yield and seed weight to 11% and 10.5% respectively. The use of Fe in comparison to control increased the seed yield and seed weight up to 12% and 10% respectively. The use of Mn in comparison to control caused an increase in seed number up to 11.6% but caused a reduction in seed weight to 10%. The use of Fe in normal foliar defoliation treatment (40% defoliation) caused a significant increase in seed yield but no significant effect was observed in sever defoliation treatment (80% defoliation). Although using Mn in all treatments led to a rise in seed yield, the effect was not significant, it could be concluded that the combined use of Mn and Fe had no significant influence on sunflower yield, so there might be an antagonistic effect between the two.

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