scholarly journals Estudio fitosociológico y evaluación del banco de malezas del suelo en tres fincas maiceras del Estado Portuguesa, Venezuela

2021 ◽  
Vol 34 (1) ◽  
pp. 27-38
Author(s):  
Sandra Torres ◽  
Aída Ortiz

Los estudios fitosociológicos (EF) y bancos de semillas de malezas del suelo (BSMS) son una herramienta para el manejo de las malezas. El objetivo de esta investigación fue realizar un EF y evaluar el BSMS en tres fincas maiceras del estado Portuguesa, Venezuela, determinándose el índice de valor de importancia (IVI) y plántulas por superficie. Se encontraron diferencias entre la composición florística entre fincas y estudios realizados, detectándose un mayor número de especies en el EF. Las especies con mayor IVI en la finca 1 fueron Ludwigia decurrens Walter, Eclipta prostrata (L.) L., Euphorbia heterophylla L. y Amaranthus dubius Mart. ex Thell., mientras que en el BSMS las de más altas densidades fueron Torenia crustacea (L.) Cham. & Schltd., L. decurrens y Cyperus esculentus L., con 1809,95; 434,39 y 253,39 plántulas∙m-2, respectivamente. En la finca 2, Rottboellia cochinchinensis (Lour.) W.D. Clayton, E. prostrata, Eleusine indica (L.) Gaertn y Helianthus annuus L. tuvieron los más altos IVI, y en el BSMS las especies T. crustaceae, Ammannia latifolia L. y L. decurrens las densidades más altas (389,14; 181,00 y 126,70 plántulas∙m-2, respectivamente). En la finca 3, las malezas con mayores IVI fueron Murdannia nudiflora (L.) Brenan, Cyperus rotundus L. y E. indica, y el BSMS estuvo conformado principalmente por C. rotundus y E. indica con 687,78 y 171,95 plántulas∙m-2, respectivamente. En total, en los dos estudios se registraron 32 especies de malezas en 21 familias botánicas.

2018 ◽  
Vol 53 (3) ◽  
pp. 485-498
Author(s):  
G.P. Kononenko ◽  
◽  
M.I. Ustyuzhanina ◽  
A.A. Burkin ◽  
◽  
...  

2014 ◽  
Vol 2014 (2) ◽  
pp. 83-91
Author(s):  
Alfredo Garcia-Perez ◽  
◽  
Mark Harrison ◽  
Bill Grant ◽  
◽  
...  

Helia ◽  
2000 ◽  
Vol 23 (33) ◽  
pp. 97-104
Author(s):  
F.M. Khalifa ◽  
A.A. Schneiter ◽  
E.I. El Tayeb

SUMMARY Seed germination of six sunflower (Helianthus annuus L.) hybrids was investigated across a range of eleven constant temperatures between 5°C and 45°C. Large temperature differences in germination rate 1/t (d-1), cardinal temperature (°C) and thermal time θ (°cd) were observed among hybrids. Base temperatures (Tb) varied between 3.3°C and 6.7°C whereas maximum germination temperatures (Tm) varied between 41.7°C and 48.9°C. Final germination fraction was attained at 15°C - 25°C whereas the maximum rate of germination was attained at 30.4°C - 35.6°C. The maximum germination rate of hybrid USDA 894, the cultivar with the slowest germination rate, was only 50% of that of hybrid EX 47. The low Tb and high Tm of sunflower appear to be one of the factors which explain the successful adaptation of sunflower to a wide range of temperature. These findings are discussed in relation to the origin of the crop and its wide adaptations in diverse habitats and climatic zones.


Helia ◽  
2001 ◽  
Vol 24 (35) ◽  
pp. 101-110 ◽  
Author(s):  
S. Sridhara ◽  
T.G. Prasad

SUMMARYA field experiment was conducted at Gandhi Krishi Vignana Kendra, University of Agricultural Sciences, Bangalore to study the effect of irrigation regimens on the biomass accumulation, canopy development, light interception and radiation use efficiency of sunflower. The treatments includes irrigating the plants at 0.4, 0.6, 0.8 and 1.0 cumulative pan evaporation. The results indicated that the aboveground biomass, canopy development, radiation interception and radiation use efficiency were influenced favorably by the irrigation regimens. Irrespective of the irrigation regimen, the radiation use efficiency of sunflower increased from 15 DAS to 75 DAS and then tended to decline. The decrease in RUE after anthesis is coupled with decrease in leaf nitrogen content. In general the RUE of sunflower ranged from 0.49 g MJ-1 to 1.84 g MJ-1 at different growth stages. The light transmission within the canopy increased exponentially with plant height and the canopy extension coefficient is found to be 0.8.


Helia ◽  
2020 ◽  
Vol 43 (73) ◽  
pp. 185-189
Author(s):  
Michail Christov ◽  
Miroslava Hristova-Cherbadzhi

AbstractNew traits that are useful for the cultivated sunflower can be received by applying classical breeding methods. A new form sunflower that is resistant to herbicides Pulsar and Express was obtained by hybridization between the sunflower mutant M-95-674 and the line HA 425. Test results from the period 2017–2019 confirm the resistance to both herbicides. This resistance can be transferred into other classical selected lines.


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