Effect of pollen load, self-pollination and plant size on seeds and germination in the endangered pink-lipped spider orchid, Caladenia behrii

2009 ◽  
Vol 57 (4) ◽  
pp. 307 ◽  
Author(s):  
Sophie Petit ◽  
Manfred Jusaitis ◽  
Doug Bickerton
Keyword(s):  
Seed Size ◽  
Plant Size ◽  
Stem Length ◽  
Leaf Width ◽  
Pollen Load ◽  
Seed Number ◽  
Pollinator Effectiveness ◽  
Conservation Programs ◽  
Self Pollination ◽  
Hand Pollination

Caladenia behrii Schltdl. (Orchidaceae) (syn. Arachnorchis behrii) is a sexually deceptive, endangered orchid that produces aggregated pollen as pollinia. It is pollinated by a thynnine wasp, and may also be pollinated incidentally by other insects. Pollinator effectiveness may depend on the number of pollinia that pollinators carry and deposit, and on whether they mediate cross-pollination or self-pollination. To understand the role of pollinators and guide conservation programs, we determined the effect of pollen load (one pollinium v. two pollinia) and self-pollination on seed number, seed (embryo) size and germination at 35 days. We also examined the effect of plant size on seed size and seed number. By using partial correlations with leaf width, seed size, seed number, capsule volume and stem length, we found that leaf width was a good predictor for seed number, and that seed size was not correlated with any of the variables examined. Flowers pollinated with one pollinium and two pollinia did not produce seeds that differed in size or number. Cross-pollinated flowers produced fewer but larger seeds, which germinated faster than did seeds from self-pollinated flowers. We conclude that seed production in the field may be estimated from leaf size, that pollinators carrying one pollinium are as effective as those carrying two pollinia and that selfing affects germination negatively, partly because of the smaller size of selfed seeds. Conservation programs aiming to perform hand-pollination of this species should use crossing with a single pollinium.

scholarly journals Seed size, number and strategies in annual plants: a comparative functional analysis and synthesis

2020 ◽  
Vol 126 (7) ◽  
pp. 1109-1128
Author(s):  
John G Hodgson ◽  
Gabriel Montserrat Marti ◽  
Bozena Šerá ◽  
Glynis Jones ◽  
Amy Bogaard ◽  
...  
Keyword(s):  
Life History ◽  
Seed Size ◽  
Seed Yield ◽  
Gold Standard ◽  
Seed Mass ◽  
Positive Function ◽  
Plant Size ◽  
Seed Number ◽  
Negative Function ◽  
Ecological Importance

Abstract Background and Aims Plants depend fundamentally on establishment from seed. However, protocols in trait-based ecology currently estimate seed size but not seed number. This can be rectified. For annuals, seed number should simply be a positive function of vegetative biomass and a negative function of seed size. Methods Using published values of comparative seed number as the ‘gold standard’ and a large functional database, comparative seed yield and number per plant and per m2 were predicted by multiple regression. Subsequently, ecological variation in each was explored for English and Spanish habitats, newly calculated C-S-R strategies and changed abundance in the British flora. Key Results As predicted, comparative seed mass yield per plant was consistently a positive function of plant size and competitive ability, and largely independent of seed size. Regressions estimating comparative seed number included, additionally, seed size as a negative function. Relationships differed numerically between regions, habitats and C-S-R strategies. Moreover, some species differed in life history over their geographical range. Comparative seed yield per m2 was positively correlated with FAO crop yield, and increasing British annuals produced numerous seeds. Nevertheless, predicted values must be viewed as comparative rather than absolute: they varied according to the ‘gold standard’ predictor used. Moreover, regressions estimating comparative seed yield per m2 achieved low precision. Conclusions For the first time, estimates of comparative seed yield and number for >800 annuals and their predictor equations have been produced and the ecological importance of these regenerative traits has been illustrated. ‘Regenerative trait-based ecology’ remains in its infancy, with work needed on determinate vs. indeterminate flowering (‘bet-hedging’), C-S-R methodologies, phylogeny, comparative seed yield per m2 and changing life history. Nevertheless, this has been a positive start and readers are invited to use estimates for >800 annuals, in the Supplementary data, to help advance ‘regenerative trait-based ecology’ to the next level.

scholarly journals Control Recommendations for Black Medic (Medicago lupulina) Based on Growth and Development in Competition with Strawberry

Weed Science ◽  
2017 ◽  
Vol 66 (2) ◽  
pp. 226-233 ◽  
Author(s):  
Shaun M. Sharpe ◽  
Nathan S. Boyd ◽  
Peter J. Dittmar ◽  
Greg E. MacDonald ◽  
Rebecca L. Darnell ◽  
...  
Keyword(s):  
Growth And Development ◽  
Plant Size ◽  
Control Measures ◽  
Stem Length ◽  
Plastic Mulch ◽  
Flower Buds ◽  
Medicago Lupulina ◽  
Hand Weeding ◽  
Spray Timing ◽  
Time Frames

Strawberries are an important horticultural crop in Florida. Black medic is among the most problematic weeds within the production system. To better coordinate control measures, black medic growth and development while in competition with strawberry was studied. Twelve plants were randomly selected at each of four field sites in Hillsborough County, FL, in 2014. Plants were repeatedly measured over the growing season for stem length and number of primary branches, flower buds, flowers, and seed clusters. Growing degree days (GDD) were calculated (Tbase=0 C) starting from the hole-punch application of the plastic mulch (October 8, 2014, to October 10, 2014) from weather station data generated from the Florida Automated Weather Network. Strawberry height and width increased consistently across all sites, but black medic growth and development varied considerably. Strawberry suppressed black medic growth up to 1,805 cumulative GDD at three of four sites where black medic remained beneath the strawberry canopy. After 1,805 GDD, the black medic stems still remained below but experienced exponential growth for total stem length and, in turn, flower buds, inflorescence, and immature seed clusters. Ideal clopyralid spray timing based on susceptible plant size was 890 to 1,152 GDD. Optimal hand-weeding time frames would likely occur as the plant stems expand beyond the strawberry canopy (to improve visibility) and before flower production to prevent seed return to the seedbank. First seed production was observed at 1,200 GDD at the earliest site and between 1,966 to 2,365 GDD across all the other sites. Overall, consistent trends were observed across sites, but between-site variability was observed that could not be accounted for by differences in temperature.

Clopyralid Dose Response for Two Black Medic (Medicago lupulina) Growth Stages

2016 ◽  
Vol 30 (3) ◽  
pp. 717-724 ◽  
Author(s):  
Shaun M. Sharpe ◽  
Nathan S. Boyd ◽  
Peter J. Dittmar
Keyword(s):  
Dose Response ◽  
Growth Stage ◽  
Plant Size ◽  
Stem Length ◽  
Effective Dosage ◽  
Growth Stages ◽  
Response Curves ◽  
Measured Range ◽  
Large Growth ◽  
Small Growth

Black medic is a troublesome weed in commercial strawberry fields in Florida. It emerges during crop establishment from the planting holes punched in plastic mulches that are installed on raised beds. Clopyralid is registered for posttransplant applications at 140 to 280 g ae ha−1but growers typically report suppression, not control. An outdoor potted experiment was designed to model the black medic dose-response curve and determine the effect of plant size at application on control. Two plant sizes were selected: designated small (0.5- to 1-cm stem length) and large (3- to 6-cm stem length). Dose-response curves were generated using a log-logistic four-parameter model. At 22 d after treatment (DAT), there was a significant interaction between clopyralid rate and black medic growth stage on both epinasty (P = 0.0022) and chlorosis (P = 0.0055). The effective dosage to induce 90% (ED90) epinasty were 249.5 and 398.3 g ha−1for the small and large growth stages, respectively. The ED90 for chlorosis was 748.2 for the small growth stage, whereas the estimated value for the large was outside the measured range. For necrosis there was no significant effect of growth stage, and the ED90 was 1,856.3 g ha−1. The aboveground dry biomass ED90 for the small growth stage was 197.3 g ha−1, and the estimated ED90 value for the large was not within the measured range. Results indicate that clopyralid adequately controls black medic when applied at maximum label rates when stems were 0.5 to 1 cm long but not when plants were larger. Poor efficacy typically observed in commercial fields is likely due to black medic plant size or lack of herbicide coverage via shielding by strawberry plants.

The effect of twig architecture and seed number on seed size variation in subtropical woody species

2009 ◽  
Vol 183 (4) ◽  
pp. 1212-1221 ◽  
Author(s):  
Hong Chen ◽  
Karl J. Niklas ◽  
Dongmei Yang ◽  
Shucun Sun
Keyword(s):  
Seed Size ◽  
Size Variation ◽  
Woody Species ◽  
Seed Number ◽  
Seed Size Variation

Yield response of narrow-leafed lupin plants to variations in pod number

1998 ◽  
Vol 49 (1) ◽  
pp. 63 ◽  
Author(s):  
J. A. Palta ◽  
C. Ludwig
Keyword(s):  
Seed Size ◽  
Seed Yield ◽  
Plant Density ◽  
Yield Response ◽  
Seed Number ◽  
Subsequent Removal ◽  
Seed Filling ◽  
Specific Number ◽  
Pod Number ◽  
Number Of Seeds

The effect of pod number on the seed yield and components of seed yield was examined for narrow-leafed lupin (Lupinus angustifolius L.) grown at a plant density of 36 plants/m2 in both the glasshouse and the field. Diflerent numbers of pods per plant in the glasshouse-grown lupin were generated by the application of N6-benzylaminopurine (BAP) to a specific number of flowers to ensure artificially that they set pods, and the subsequent removal of the remaining untreated flowers. Pod number ranged from 6 to 65 pods/plant in the glasshouse and was naturally distributed from 2 to 22 pods/plant in the field. Increases in seed yield per plant occurred as pod number per plant increased from 2 to 30 pods. No further increases in seed yield resulted when pod number per plant increased from 30 to 55 pods. Seed yield per plant was depressed as pod number increased from 55 to 65 pods. Seed size fell as pod number per plant increased over 20 pods and was less affected once the number of seeds per pod was reduced. The reduction in seed number per pod resulted from an increase in the number of seeds that aborted during seed filling. The data suggest that at a plant density of 36 plants/m2 there is potential for improving seed yield per plant by increasing the number of pods that reach maturity, provided it does not exceed 30 pods/plant. However, if consideration is given to producing large seeds, often preferred by buyers, the number of pods per plant should not exceed 20 pods.

Simultaneous effects of reintroduction strategy and seed size on the initial development of two tropical tree species in an abandoned eucalyptus plantation

2020 ◽  
Vol 68 (6) ◽  
pp. 439
Author(s):  
Julie Christine Scaloppi ◽  
Andréa Lúcia Teixeira de Souza
Keyword(s):  
Seed Size ◽  
Tree Species ◽  
Survival Rates ◽  
Plant Size ◽  
Plant Performance ◽  
Initial Development ◽  
Eucalyptus Plantation ◽  
Hymenaea Courbaril ◽  
Stem Size ◽  
Direct Sowing

Seedling planting is the most common strategy used to reintroduce tropical native tree species; however, direct sowing has simplicity and operational ease advantages. Functional traits such as seed size and growth rates have been shown to be relevant for better plant performance. We evaluated the effects of intraspecific variation in seed size and the reintroduction strategy simultaneously on the development of Hymenaea courbaril (L.) and Enterolobium timbouva (Mart.) introduced in an abandoned eucalyptus plantation over 462 days. Plants from small, medium and large seeds were reintroduced by planting seedlings and direct seeding. Both species achieved high rates of emergence and survival was high in the two reintroduction strategies. Seed size was not related to emergence and mean time to emergence for either species. The survival of both species was higher than 74% in the field, and seed size had little effect on survival rates. In general, H. courbaril plants introduced by direct sowing had higher growth, and seed size correlated positively with stem size. In contrast, the growth of E. timbouva plants introduced by seedling planting was higher than in plants introduced by direct sowing regardless of seed size. The light requirements of this species seem higher than for H. courbaril. Our results suggest the feasibility of reintroducing species by direct sowing in eucalyptus understory, but since plant growth varies between species, there may be a balance between the advantage of the initial plant size provided by planting seedlings and the advantage of a better root development provided by direct sowing.

Effect of blossom thinning on fruit density, fruit size and seed count of Williams' Bon Chretien and Packham's Triumph pears

1971 ◽  
Vol 11 (49) ◽  
pp. 248 ◽  
Author(s):  
A Selimi
Keyword(s):  
Fruit Set ◽  
Fruit Size ◽  
Seed Number ◽  
Cross Pollination ◽  
Hand Pollination ◽  
Bud Removal

Effects on fruit density, fruit size, and fruit fertilization (seed count) of several degrees of fruit bud removal three to four weeks before bloom, was studied on Williams Bon Chretien and Packham's Triumph pears. The effects were studied in the presence or absence of cross pollination. Fruit set increased with increasing severity of blossom bud removal, indicating that poor setting was not due to faulty flowers. This was also confirmed by hand pollination of the clusters on unthinned limbs, where fruit set was much higher than on unthinned unpollinated limbs. Fruit density in Packham's was not reduced even by 80 per cent of fruit bud removal, and in Williams' fruit density was significantly reduced at 60 or 40 per cent of fruit bud removal, in a heavy or intermediate flowering years, respectively, whereas in a poor flowering year, fruit density was not significantly reduced even by 80 per cent of bud removal. Heavy thinning resulted in increased fruit size in Williams' but not in Packham's pears. Hand poIlination or bouquets increased seed number and fruit size greatly in \Villiams7 and increased seed number but not fruit size in Packham's.

Effect of seed weight on height growth of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii) seedlings in a nursery

1985 ◽  
Vol 15 (6) ◽  
pp. 1109-1115 ◽  
Author(s):  
Frank C. Sorensen ◽  
Robert K. Campbell
Keyword(s):  
Seed Size ◽  
Seed Weight ◽  
Germination Rate ◽  
Plant Size ◽  
Height Growth ◽  
Douglas Fir ◽  
Genetic Makeup ◽  
Practical Implications ◽  
Filled Seeds

Different mean seed weights were produced within each of 10 young Douglas-fir trees by leaving some developing cones unbagged and enclosing others in Kraft paper bags for two different durations. On the average, 10 days in the bag increased filled-seed weight by about 1%. Unbagged cones and cones from the 117-day bagging duration were wind pollinated. Seeds from these cones were, therefore, of comparable genetic makeup and were used in further nursery growth tests. To eliminate the effect of germination rate or time, samples of filled seeds from each treatment on each parent tree were sown as germinant seedlings on one date. Cotyledon number was counted and 1st-year epicotyl lengths and 2nd-year total heights were measured on all seedlings. Seedling volumes were estimated by assuming diameters were proportional to heights. On the average, bagging cones for 117 days increased seed weight by 10.7%, 1st-year epicotyl length by 9.1%, and 2-year total height by 4.0%. All differences were statistically significant. Results were compared with other reports of the relations between seed weight and growth and reasons for inconsistencies were discussed. Size differences were projected to later ages with a growth model and practical implications of long-term seed effects on plant size, of increasing seed size through cultural techniques, and of grading seed lots by size were considered.

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