scholarly journals Experimental study of gene flow between wild and cultivated Pennisetum glaucum

1997 ◽  
Vol 75 (6) ◽  
pp. 925-931 ◽  
Author(s):  
J. -F. Renno ◽  
T. Winkel ◽  
F. Bonnefous ◽  
G. Bezançon
Keyword(s):  
Experimental Study ◽  
Gene Flow ◽  
Pearl Millet ◽  
Pennisetum Glaucum ◽  
Morphological Differentiation ◽  
Time Dependent ◽  
Natural Conditions ◽  
Experimental Conditions ◽  
Viable Seeds ◽  
Wild Sample

Under natural conditions, wild and cultivated pearl millet, Pennisetum glaucum (L.) R.Br., exchanged genes for millenia and, nevertheless, maintain high morphological differentiation. Under experimental conditions in the Sahel, hybridization between wild and cultivated pearl millet was measured using isozymic markers and interpreted in relation to the phenology of the plants. Gene flows were asymmetric, engendering 8% of hybrids in the progeny of the wild phenotype, 45% in that of the cultivated phenotype, and 39% in that of the intermediate "shibra" phenotype; these last two phenotypes constitute the sample of cultivated pearl millet. The proportion of hybrids in the progeny of the wild sample was time dependent during the flowering phase of cultivated pearl millet. The proportion of hybrids produced by the cultivated pearl millet was not time dependent. In the seeds produced by the cultivated phenotype along its reproductive phase, the proportion of viable seeds was negatively correlated with the frequency of hybrids. Likewise, the speed of germination of seeds produced by the cultivated or the shibra phenotypes was negatively correlated with the frequency of the hybrids that they contained. The effects of balancing among genetic intermixing, isolation and reproduction barriers, and differential anthropic and natural selection pressures are discussed to better understand the evolution and the maintenance of the polymorphism of Pennisetum glaucum. Key words: pearl millet, wild pearl millet, Pennisetum glaucum, gene flow, domestication, hybrid.

scholarly journals Experimental study of the European river lamprey Lampetra fluviatilis (L.) downstream migrating smolts rheoreaction under various illuminations

2019 ◽  
Vol 487 (4) ◽  
pp. 469-472
Author(s):  
A. O. Zvezdin ◽  
D. S. Pavlov ◽  
I. A. Tsimbalov ◽  
A. V. Kucheryavyy
Keyword(s):  
Experimental Study ◽  
Active Form ◽  
Downstream Migration ◽  
Natural Conditions ◽  
Experimental Conditions ◽  
Lampetra Fluviatilis ◽  
River Lamprey

Rheoreaction of the downstream migrating smolts of the European river lamprey was studied in the experimental conditions at illuminations of day and night intensity. It was found that at the daytime the smolts are mostly dormant and if move downstream then in active-passive form (with the head against the stream, and their speed going beyond the velocity). This data is well within the findings on the night downstream migration of the smolts during the 24 h period in natural conditions. Thus, the downstream migration of the smolts has an active form.

scholarly journals Phenology and reproductive effort of cultivated and wild forms of Pennisetum glaucum under experimental conditions in the Sahel: implications for the maintenance of polymorphism in the species

1996 ◽  
Vol 74 (6) ◽  
pp. 959-964 ◽  
Author(s):  
J.-F. Renno ◽  
T. Winkel
Keyword(s):  
Pearl Millet ◽  
Reproductive Effort ◽  
Pennisetum Glaucum ◽  
Wild Plants ◽  
Cultivated Plants ◽  
Flowering Period ◽  
Experimental Conditions ◽  
Plant Parts ◽  
Sahel Region ◽  
Average Individual

In the Sahel region of Africa, the wild and the cultivated forms of pearl millet, Pennisetum glaucum (L.) R.Br., are sympatric and interfertile and yet have remained distinct for millenia. Reproductive barriers are not sufficient to explain this situation. To elucidate other possible mechanisms, the two forms were compared under experimental conditions in the Sahel for their phenology and reproductive effort. The length of the flowering period of each type was much longer than the average individual flowering period. When the last cultivated plants were finishing flowering, 65% of the wild plants were still flowering and 30% were just starting to flower. Thus, the last group was completely isolated from cultivated pearl millet gene flow (endogamic reproduction). The two forms of pearl millet also differed in the distribution of aboveground biomass among different plant parts, except for the number of seeds per plant. Both phenological behaviour and reproductive effort contribute to the maintenance of distinct forms of wild and cultivated pearl millet. Keywords: Pennisetum glaucum, pearl millet, wild pearl millet, reproductive effort, phenology, endogamy.

Effects of Provocation on Emotions and Aggression: An Experimental Study with Aggressive Children

2006 ◽  
Vol 65 (2) ◽  
pp. 117-124 ◽  
Author(s):  
Christina Stadler ◽  
Sonja Rohrmann ◽  
Sibylle Steuber ◽  
Fritz Poustka
Keyword(s):  
Experimental Study ◽  
Positive Emotions ◽  
Skin Conductance Level ◽  
Physiological Measures ◽  
Competitive Reaction ◽  
Experimental Conditions ◽  
Conduct Disordered ◽  
Physiological Variables ◽  
Aggressive Children ◽  
Conductance Level

In this study, the effects of an experimental-induced provocation on emotions and aggression were examined in 34 aggressive conduct-disordered children using a competitive reaction time paradigm. Two experimental conditions were created, an increasing provocation and a low constant provocation condition. Self-rated anger was assessed directly after provocation on a 5-point-visual scale. In addition, negative and positive emotions as well as physiological measures (heart rate and skin conductance level) were measured at baseline and after provocation. Results revealed that participants’ aggressive behaviour and subjective emotions differed as a function of the opponent’s level of provocation. Concerning physiological parameters, no significant differences were found between the experimental conditions. These results suggest that affective, but not physiological variables characterize reactive aggression in conduct-disordered children.

scholarly journals Constraints to Pearl Millet (Pennisetum glaucum) Production and Farmers’ Approaches to Striga hermonthica Management in Burkina Faso

2021 ◽  
Vol 13 (15) ◽  
pp. 8460
Author(s):  
Armel Rouamba ◽  
Hussein Shimelis ◽  
Inoussa Drabo ◽  
Mark Laing ◽  
Prakash Gangashetty ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Pearl Millet ◽  
Management Practices ◽  
Pennisetum Glaucum ◽  
Control Measures ◽  
Striga Hermonthica ◽  
Soil Conditions ◽  
Management Options ◽  
Central Plateau ◽  
South Central

Pearl millet (Pennisetum glaucum) is a staple food crop in Burkina Faso that is widely grown in the Sahelian and Sudano-Sahelian zones, characterised by poor soil conditions and erratic rainfall, and high temperatures. The objective of this study was to document farmers’ perceptions of the prevailing constraints affecting pearl millet production and related approaches to manage the parasitic weeds S. hermonthica. The study was conducted in the Sahel, Sudano-Sahelian zones in the North, North Central, West Central, Central Plateau, and South Central of Burkina Faso. Data were collected through a structured questionnaire and focus group discussions involving 492 participant farmers. Recurrent drought, S. hermonthica infestation, shortage of labour, lack of fertilisers, lack of cash, and the use of low-yielding varieties were the main challenges hindering pearl millet production in the study areas. The majority of the respondents (40%) ranked S. hermonthica infestation as the primary constraint affecting pearl millet production. Respondent farmers reported yield losses of up to 80% due to S. hermonthica infestation. 61.4% of the respondents in the study areas had achieved a mean pearl millet yields of <1 t/ha. Poor access and the high cost of introduced seed, and a lack of farmers preferred traits in the existing introduced pearl millet varieties were the main reasons for their low adoption, as reported by 32% of respondents. S. hermonthica management options in pearl millet production fields included moisture conservation using terraces, manual hoeing, hand weeding, use of microplots locally referred to as ‘zaï’, crop rotation and mulching. These management techniques were ineffective because they do not suppress the below ground S. hermonthica seed, and they are difficult to implement. Integrated management practices employing breeding for S. hermonthica resistant varieties with the aforementioned control measures could offer a sustainable solution for S. hermonthica management and improved pearl millet productivity in Burkina Faso.

scholarly journals Adaptive Divergence under Gene Flow along an Environmental Gradient in Two Coexisting Stickleback Species

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 435
Author(s):  
Thijs M. P. Bal ◽  
Alejandro Llanos-Garrido ◽  
Anurag Chaturvedi ◽  
Io Verdonck ◽  
Bart Hellemans ◽  
...  
Keyword(s):  
Gene Flow ◽  
Brackish Water ◽  
Environmental Gradient ◽  
Spatial Scales ◽  
Morphological Differentiation ◽  
Genotyping By Sequencing ◽  
Adaptive Divergence ◽  
Linkage Groups ◽  
Closely Related Species ◽  
Genomic Patterns

There is a general and solid theoretical framework to explain how the interplay between natural selection and gene flow affects local adaptation. Yet, to what extent coexisting closely related species evolve collectively or show distinctive evolutionary responses remains a fundamental question. To address this, we studied the population genetic structure and morphological differentiation of sympatric three-spined and nine-spined stickleback. We conducted genotyping-by-sequencing and morphological trait characterisation using 24 individuals of each species from four lowland brackish water (LBW), four lowland freshwater (LFW) and three upland freshwater (UFW) sites in Belgium and the Netherlands. This combination of sites allowed us to contrast populations from isolated but environmentally similar locations (LFW vs. UFW), isolated but environmentally heterogeneous locations (LBW vs. UFW), and well-connected but environmentally heterogenous locations (LBW vs. LFW). Overall, both species showed comparable levels of genetic diversity and neutral genetic differentiation. However, for all three spatial scales, signatures of morphological and genomic adaptive divergence were substantially stronger among populations of the three-spined stickleback than among populations of the nine-spined stickleback. Furthermore, most outlier SNPs in the two species were associated with local freshwater sites. The few outlier SNPs that were associated with the split between brackish water and freshwater populations were located on one linkage group in three-spined stickleback and two linkage groups in nine-spined stickleback. We conclude that while both species show congruent evolutionary and genomic patterns of divergent selection, both species differ in the magnitude of their response to selection regardless of the geographical and environmental context.

scholarly journals Effects of Cover Crops, Compost, and Vermicompost on Strawberry Yields and Nitrogen Availability in North Carolina

2016 ◽  
Vol 26 (5) ◽  
pp. 604-613 ◽  
Author(s):  
John E. Beck ◽  
Michelle S. Schroeder-Moreno ◽  
Gina E. Fernandez ◽  
Julie M. Grossman ◽  
Nancy G. Creamer
Keyword(s):  
North Carolina ◽  
Pearl Millet ◽  
Cover Crops ◽  
Cover Crop ◽  
Crop Yields ◽  
Pennisetum Glaucum ◽  
Organic Production ◽  
Organic N ◽  
N Availability ◽  
Soil N

Summer cover crop rotations, compost, and vermicompost additions can be important strategies for transition to organic production that can provide various benefits to crop yields, nitrogen (N) availability, and overall soil health, yet are underused in strawberry (Fragaria ×ananassa) production in North Carolina. This study was aimed at evaluating six summer cover crop treatments including pearl millet (Pennisetum glaucum), soybean (Glycine max), cowpea (Vigna unguiculata), pearl millet/soybean combination, pearl millet/cowpea combination, and a no cover crop control, with and without vermicompost additions for their effects on strawberry growth, yields, nutrient uptake, weeds, and soil inorganic nitrate-nitrogen and ammonium-nitrogen in a 2-year field experiment. Compost was additionally applied before seeding cover crops and preplant N fertilizer was reduced by 67% to account for organic N additions. Although all cover crops (with compost) increased soil N levels during strawberry growth compared with the no cover crop treatment, cover crops did not impact strawberry yields in the first year of the study. In the 2nd year, pearl millet cover crop treatments reduced total and marketable strawberry yields, and soybean treatments reduced marketable strawberry yields when compared with the no cover crop treatment, whereas vermicompost additions increased strawberry biomass and yields. Results from this study suggest that vermicompost additions can be important sustainable soil management strategies for transitional and certified organic strawberry production. Summer cover crops integrated with composts can provide considerable soil N, reducing fertilizer needs, but have variable responses on strawberry depending on the specific cover crop species or combination. Moreover, these practices are suitable for both organic and conventional strawberry growers and will benefit from longer-term studies that assess these practices individually and in combination and other benefits in addition to yields.

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