Differential response of wheat to retained crop stubbles. II. Other factors influencing allelopathic potential; intraspecific variation, soil type and stubble quantity

1990 ◽  
Vol 41 (2) ◽  
pp. 243 ◽  
Author(s):  
CE Purvis ◽  
GPD Jones
Keyword(s):  
Intraspecific Variation ◽  
Wheat Seedlings ◽  
Allelopathic Potential ◽  
Sand Mixture ◽  
Stubble Retention ◽  
Factors Influencing ◽  
Threefold Increase ◽  
Allelopathic Effects ◽  
High Degree ◽  
Approximate Doubling

The allelopathic potential of the unweathered stubble of field-grown sorghum and sunflower was examined under controlled conditions in a series of glasshouse experiments. Wheat emergence was significantly inhibited in the presence of stubble from the eleven sorghum, and ten of the twelve sunflower cultivars tested. Inhibition of wheat emergence in the presence of sorghum stubbles ranged from 10 to 31%, and in the presence of sunflower stubbles from 4 to 33%, demonstrating a high degree of intraspecific variation in allelopathic potential. Many of the wheat seedlings emerging in stubble treatments exhibited an abnormal geotropic response. A threefold increase in stubble quantity, from 0.5 to 1.5% w/w soil, resulted in an approximate doubling of phytotoxicity. Wheat emergence was significantly reduced when stubble was incorporated into all three soils tested, with greater inhibition recorded in chocolate soil and a 50: 50 chocolate soi1:sand mixture than in sand. The choice of crop cultivar and the management of stubble quantity, especially in harvester trails, have important implications for the minimization of negative allelopathic effects in stubble retention systems.

A review of Cryphocricos Signoret, 1850 (Naucoridae: Cryphocricinae) with descriptions of three new species

Zootaxa ◽  
2021 ◽  
Vol 4958 (1) ◽  
pp. 72-94
Author(s):  
ROBERT W. SITES
Keyword(s):  
New Species ◽  
Molecular Phylogeny ◽  
Intraspecific Variation ◽  
New World ◽  
Morphological Features ◽  
Type Specimens ◽  
Three New Species ◽  
Aquatic Bugs ◽  
High Degree

The genus Cryphocricos Signoret, 1850 was recently determined in a molecular phylogeny to be distantly related to other taxa of the subfamily Cryphocricinae to the extent that it is now once again the sole member of the subfamily. This exclusively New World group of aquatic bugs lives in fast and usually turbulent current and respires by means of a plastron. Efforts to identify morphological features to distinguish among the species have largely fallen short, and some species have been established based on features that exhibit a high degree of intraspecific variation overlapping those of other species. Presented here is a review of the 13 described species with discussions of their features and photos of type specimens, and three new species from Venezuela and Colombia are described. Also presented is a diagnostic attribute unique to the enigmatic Cryphocricos barozzii Signoret, 1850. 

scholarly journals ALLELOPATHIC POTENTIAL OF Cyperus rotundus L. EXTRACTS ON GERMINATION AND COWPEA SEEDLING ESTABLISHMENT

Nativa ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 261
Author(s):  
João Alves Ferreira Pereira ◽  
Tatiana Maria da Silva ◽  
Andreza Raquel Barbosa de Farias ◽  
Alexandre Bosco de Oliveira
Keyword(s):  
Seed Germination ◽  
Vigna Unguiculata ◽  
Early Growth ◽  
Shoot Length ◽  
Cyperus Rotundus ◽  
Control Treatment ◽  
Root Weight ◽  
Allelopathic Potential ◽  
Germination Speed ◽  
Allelopathic Effects

POTENCIAL ALELOPÁTICO DE EXTRATOS DE Cyperus rotundus L. NA GERMINAÇÃO E ESTABELECIMENTO DE PLÂNTULAS DE FEIJÃO-CAUPI Este trabalho investigou os efeitos alelopáticos de extratos de Cyperus rotundus L. na germinação de sementes e crescimento inicial das plântulas de Vigna unguiculata L. Walp. Extratos alcoólicos nas concentrações 0; 1,5%; 3,0%; 4,5%; 6,0%; 7,5% e 9,0%, obtidos a partir da trituração de folhas de C. rotundus L. foram utilizados para umedecimento das folhas de papel toalha “germitest”. Os dados foram submetidos a análise de variância pelo F e as médias comparadas pelos testes de Tukey e Kruscal-Wallis, ambos a 5% de probabilidade. A primeira contagem de germinação, índice de velocidade de germinação, comprimento de raiz, comprimento da parte aérea e massa seca da raiz do feijão-caupi foram analisados de forma paramétrica, sendo constatado que apenas houve significância na variável primeira contagem e uma redução na germinação em relação ao tratamento controle em torno de 10%. Nas condições em que essa pesquisa foi realizada, os extratos alcoólicos de C. rotundus L. não afetam a germinação de sementes e crescimento inicial das plântulas de feijão-caupi.Palavras-chave: tiririca, alelopatia, interferência, plantas daninhas. ABSTRACT:This study aimed to investigate the allelopathic effects of Cyperus rotundus L. extracts on seed germination and early development of seedlings of Vigna unguiculata L. Walp. Alcoholic extracts at concentrations of 0, 1.5%, 3%, 4.5%, 6.0%, 7.5%, and 9.0% were obtained by crushing C. rotundus L. leaves used to moisten the “germitest” paper sheets. The data were subjected to analysis of variance and also both Tukey and Kruscal-Wallis tests were carried out at 5% for the data means. The first germination count, germination speed index, root length, shoot length, and dry root weight of cowpea were parametrically analyzed. The only variable with significance was first germination count. The germination reducted in relation to the control treatment around 10%. Thus, in the conditions used in this research, alcoholic extracts of C. rotundus L. did not affect either seed germination or early growth of cowpea seedlings.Keywords: nut grass, allelopathy, interference, weeds. DOI:

scholarly journals Evaluation of Allelopathic Effects of Nigella sativa L. against Rigid Ryegrass

2019 ◽  
Vol 76 (1) ◽  
pp. 135
Author(s):  
Ioannis ROUSSIS ◽  
Ilias TRAVLOS ◽  
Ioanna KAKABOUKI ◽  
Spyridoula CHAVALINA ◽  
Varvara KOUNELI ◽  
...  
Keyword(s):  
Nigella Sativa ◽  
Seedling Emergence ◽  
Tiller Number ◽  
Plant Residues ◽  
Lolium Rigidum ◽  
Allelopathic Potential ◽  
Future Studies ◽  
Emergence Rate ◽  
Allelopathic Effects ◽  
Rigid Ryegrass

A pot experiment was conducted to evaluate the allelopathic potential of Nigella sativa L. on seedling emergence and first growth of the serious weed rigid ryegrass (Lolium rigidum L.). The results revealed significant weed suppressive effects of N. sativa residues incorporated into the soil. The lowest seedling emergence rate (38%) was observed in pots treated with 20 g leaf residues. Regarding height, the lowest value (26.7 cm) was found in 20 g root residues. The highest quantity of shoot residues reduced leaf number, tiller number, fresh and dry aerial biomass up to 58, 51, 64 and 59%, respectively. It can be concluded that the effect of incorporation of plant residues depended on the type and amount of residue. N. sativa could be utilized as an allelopathic crop to control weeds and future studies should focus on isolating and identifying allelochemicals in roots, shoots and leaves of this species.

Factors influencing young children’s ability to discriminate unfamiliar faces by age

2000 ◽  
Vol 24 (4) ◽  
pp. 480-491 ◽  
Author(s):  
P. A. George ◽  
G. J. Hole ◽  
M. Scaife
Keyword(s):  
Discrimination Performance ◽  
Image Features ◽  
Age Discrimination ◽  
Face Features ◽  
Factors Influencing ◽  
The Face ◽  
Gaussian Blurring ◽  
High Degree ◽  
Unfamiliar Faces

Three experiments examined young children’s ability to discriminate between pairs of unfamiliar faces which differed in age. Apre-test found that 99% of 6-year-olds, but only 36%of 4-year-olds, could reliably decide which of two faces was the oldest. Experiment 1 attempted to identify the nature of the information used for age-processing faces. Face-pairs were presented in four different versions: Original (unmodified image); Features-only (containing only the internal face features); Skin-blur (in which the skin regions of the face were subjected to Gaussian blurring); or Overall-blur (in which the entire image was blurred). The last three versions selectively reduced specific cues to age. No significant differences in age-discrimination performance were found between these different versions, suggesting that, as with adults, children are capable of adaptively using a variety of cues in order to discriminate between faces on the basis of age. Experiments 2 and 3 investigated in more detail a phenomenon suggested by Experiment 1: That children found it easier to discriminate between faces by age that were similar in age to themselves, than between adult faces. The results suggest that children as young as 6 years can use age to discriminate between faces of all ages with a relatively high degree of accuracy, but experience most difficulty with adult faces.

Determination of allelopathic potential of a weed Pluchea lanceolata through a multifaceted approach

1996 ◽  
Vol 74 (9) ◽  
pp. 1445-1450 ◽  
Author(s):  
Inderjit Inderjit ◽  
Surinder Kaur ◽  
K. M. M. Dakshini
Keyword(s):  
Soil Nutrients ◽  
Phenolic Content ◽  
Agricultural Practices ◽  
Allelopathic Potential ◽  
Multifaceted Approach ◽  
Pluchea Lanceolata ◽  
Allelopathic Effects ◽  
Growth Experiments ◽  
Biotic Characteristics

The allelopathic potential of soils from four sites infested with the weed Pluchea lanceolate (DC.) C.B. Clarke (Asteraceae) was investigated. All sites had similar precipitation, similar crops, and weeds in addition to P. lanceolata. The objectives of this study were threefold: first, variations in the allelopathic effects of P. lanceolata infested soils on growth of three crops; second, soil phenolic content as a result of P. lanceolata infestation; and third, if the chemical characteristics and mycoflora of soils and biotic characteristics of P. lanceolata are responsible for the differences in allelopathic potential. Allelopathic effects of P. lanceolata infested soils were assessed on seedling growth of onion, cucumber, and turnip. Qualitative variation in the soil phenolic content from the four P. lanceolata infested sites was observed. No significant differences in soil mycoflora, soil nutrients, and P. lanceolata biotic characteristics were observed. Growth experiments showed mat crops demonstrated variation in allelopathic response to the soils from the four P. lanceolata infested sites. The present study indicates mat in natural field conditions, allelopathic potential of P. lanceolata varies because of agricultural practices specific to each site. Keywords: allelopathy, Asteraceae, interference, phenolics, soil nutrients, weed.

scholarly journals Allelopathic Potential of Ethanolic Extract and Phytochemical Analysis of Paspalum maritimum Trind

2019 ◽  
Vol 37 ◽  
Author(s):  
J.C. PEREIRA ◽  
C.L.A. PAULINO ◽  
L. ENDRES ◽  
A.E.G. SANTANA ◽  
F.R.S. PEREIRA ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Condensed Tannins ◽  
Ethanolic Extract ◽  
Phytochemical Analysis ◽  
Allelopathic Effect ◽  
Active Fraction ◽  
Allelopathic Potential ◽  
Plant Parts ◽  
Allelopathic Effects ◽  
Donor Species

ABSTRACT: Allelopathy is defined as the ability of certain plants and microorganisms to interfere with the metabolism of other species through substances released into the environment, being an alternative to control weeds and diseases. In this context, this study aimed to evaluate the allelopathic potential and identify groups of secondary metabolites of Paspalum maritimum Trind. The species Lactuca sativa, Digitaria insularis, Emilia coccinea, and Portulaca oleracea were used as recipient plants. The ethanolic extract was obtained from shoot and root of donor species to evaluate the allelopathic potential. Potentially allelopathic effects were evaluated by means of germination tests, germination speed index, and initial seedling growth. A phytochemical analysis of the extract was also performed to identify the secondary metabolites. The ethanolic extract from both plant parts had an allelopathic effect on recipient species. The presence of condensed tannins, chalcones and aurones, flavonones, steroids, and saponins were detected in the most active fraction of the shoot of P. maritimum.

Factors influencing the quality of objective-prism spectra

1966 ◽  
Vol 24 ◽  
pp. 55-56
Author(s):  
R. H. Hardie
Keyword(s):  
Image Quality ◽  
Spectral Features ◽  
The Past ◽  
Factors Influencing ◽  
Objective Prism ◽  
High Degree ◽  
Relevant Factors

The definition and clarity of spectral features in objective-prism spectra are determined largely by the telescope's image quality and the seeing conditions. Over the past 3 years, a systematic attempt has been carried out to identify and minimize all relevant factors which would tend to limit the image quality of spectra taken with the Seyfert 24-inch telescope in the Baker Corrector-Reflector arrangement. Both the inherent image quality and the seeing conditions have been brought up to a high degree of perfection.

scholarly journals Assessment of intraspecific genetic variation between three morphotypes of Cissus quadrangularis using CCMP markers

2015 ◽  
Vol 24 (2) ◽  
pp. 205-212
Author(s):  
Ritesh Kaur ◽  
CP Malik
Keyword(s):  
Genetic Variation ◽  
Sequence Analysis ◽  
Chloroplast Genome ◽  
Intraspecific Variation ◽  
Microsatellite Primers ◽  
Genome Sequences ◽  
Chloroplast Microsatellite ◽  
Cissus Quadrangularis ◽  
High Degree ◽  
Degree Of Similarity

The objective of the current study was to assess and establish intraspecific variation between three morphotypes of Cissus quadrangularis using ten Consensus Chloroplast Microsatellite Primers. Significant level of genetic variation was detected between the three morphotypes. Sequence analysis of the CCMP PCR fragment showed the high degree of similarity to the chloroplast genome sequences of other Vitaceae members indicating that these regions are highly conserved.Plant Tissue Cult. & Biotech. 24(2): 205-212, 2014 (December)

scholarly journals Recent Advances in Saffron Soil Remediation: Activated Carbon and Zeolites Effects on Allelopathic Potential

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1714
Author(s):  
Mahdieh Kheirabadi ◽  
Majid Azizi ◽  
Seyedeh Faezeh Taghizadeh ◽  
Yoshiharu Fujii
Keyword(s):  
Activated Carbon ◽  
Aqueous Extract ◽  
Crocus Sativus ◽  
Carotenoid Content ◽  
Adsorptive Capacity ◽  
Allelopathic Effect ◽  
Allelopathic Potential ◽  
Methanolic Extracts ◽  
Lettuce Growth ◽  
Allelopathic Effects

Saffron (Crocus sativus L.) is a highly valuable plant. Iran provides nearly 90% of the world’s total saffron and is the biggest global producer. The allelopathic effects of saffron corm (SC) and saffron field soil (SFS) have been hypothesized to play an important role in replanting. Recently, adsorbent materials have been used to neutralize the effects of allelochemicals. These materials, including activated carbon and zeolite, have large surface areas, pore volumes, as well as tremendous adsorptive capacity and complex chemical and physical properties. In this study, three independent experiments were conducted. In the first test, the allelopathic effects of aqueous and methanolic extracts of SC remnant and 9-year-old SFS as well as filtered aqueous extract of soil were investigated. In the second assay, the effects of SC remnants and SFS with different ages (i.e., 4, 6, and 9 years old) in combination with adsorbents were examined on the germination and growth of lettuce (Lactuca sativa L.) seedlings by the sandwich method. In the third experiment, we examined the effects of SC remnants combined with adsorbents on lettuce growth parameters. Our results showed that the allelopathic effects of aqueous and methanolic extracts of SC remnant were significantly superior to those of 9-year-old SFS. The aqueous extract of SC remnant reduced the root length of lettuce by 50%. The use of activated carbon and zeolites significantly decreased the observed allelopathic effect. Moreover, lettuce growth in rhizosphere soil was significantly inhibited by SC remnant and SFS extracts. The allelopathic effects of SC remnants caused a growth imbalance between the shoot and roots. Based on biochemical analyses, using the adsorbents increased the carotenoid content and chlorophyll index of lettuce by 23.33% and 5.25%, respectively. Adsorbents may play a role in treating soils contaminated by allelochemicals.

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