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Bernal E. Valverde

Bernal E. Valverde
Research and Development in Tropical Agriculture / Investigación y Desarrollo en Agricultura Tropical

PhD

About

54
Publications
20,532
Reads
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1,009
Citations
Additional affiliations
January 2012 - present
Nanjing Agricultural University
Position
  • Guest Professor
November 2009 - present
University of Copenhagen
Position
  • Honorary Adjunct Professor
November 2006 - November 2009
University of Copenhagen
Position
  • Visiting Scientist

Publications

Publications (54)
Article
Full-text available
2-Amino-3-methylhexanoic acid (AMHA) was synthetized as a non-natural amino acid more than 70 years ago; however, its possible function as an inducer of plant resistance has not been reported. Plant resistance inducers, also known as plant elicitors, are becoming a novel and important development direction in crop protection and pest management. We...
Article
Full-text available
Introduction Computer-aided design has become an important tool to develop novel pesticides based on natural lead compounds. Tenuazonic acid (TeA), a typical representative of the natural tetramic acid family, was patented as a potential bioherbicide. However, its herbicidal efficacy is still not up to the ideal standard of commercial products. Ob...
Article
Full-text available
BACKGROUND Tea, one of the most important commercial crops on earth, is strongly affected by weeds on productivity and quality. Bioherbicides are shedding new light on weed control in tea gardens in an economical and safe manner. RESULTS A pathogenic strain SYNJC-2-2 was isolated from diseased leaves of a noxious weed, goosegrass (Eleusine indica)...
Article
Bromacil was introduced at the beginning of the 1960s for PRE and early POST control of grasses and broadleaf weeds, particularly in citrus (Rutaceae spp.) orchards and pineapple [ Ananas comosus (L.) Merr.] plantations as well as in noncultivated areas. Both the acidic form of bromacil and its lithium salt are highly soluble in water; the herbicid...
Article
Full-text available
Pollen-mediated herbicide-resistance transgene flow occurs bidirectionally between transgenic cultivated rice and weedy rice. The potential risk of weedy traits introgressing into hybrid rice is underestimated and poorly understood. Two of each glufosinate-resistant transgenic rice varieties and hybrid rice (F1) and their succeeding generations (F2...
Article
The effects of four phytotoxins usnic acid (UA), salicylic acid (SA), cinnamic acid (CA) and benzoic acid (BA) on photosynthesis of Chlamydomonas reinhardtii were studied in vivo to identify and localise their initial action sites on two photosystems. Our experimental evidence shows that the four phytotoxins have multiple targets in chloroplasts, w...
Article
A toxin-deficient mutant strain, HP001 mutant of Alternaria alternata, whose mycelium is unable to infect its host, produces little tenuazonic acid (TeA) toxin. How TeA plays a role in initiating host infection by A. alternata remains unclear. In this research we use Imaging-PAM based on chlorophyll fluorescence parameters and transmission electron...
Chapter
Full-text available
Rice is an economically important crop in the USA and Brazil, whereas it is a staple food in parts of Central and South Americas. Rice production practices vary greatly across the region due in part to different agroclimatic conditions. The majority of rice grown in the USA is irrigated, while rainfed rice is common in South America. Nevertheless,...
Article
Full-text available
Background: Weedy rice, as one of the worst paddy field weeds worldwide, bears vigorous seedlings and dominantly competes with cultivated rice causing serious crop yield losses. To elucidate the causes of its stronger seedling vigor endowing its dominant competition with cultivated rice, comparative studies on seedling growth characteristics were...
Article
Full-text available
In perennial crops like coffee, glyphosate drift exposure can occur multiple times during its commercial life span. Due to limited glyphosate degradation in higher plants, a potential accumulation of glyphosate could lead to increased biological effects with increased exposure frequency. In this study, we investigated glyphosate translocation over...
Article
Full-text available
Main conclusion: A combination of unique EPSPS structure and increased gene copy number and expression contribute to natural glyphosate tolerance in three lilyturf species. A few plants are naturally tolerant to glyphosate, the most widely used non-selective herbicide worldwide. Here, the basis for natural tolerance to glyphosate in three lilyturf...
Article
Full-text available
The aim of the presented study was to develop a bioassay for rapid diagnosis of herbicide dose-response and resistance in Echinochloa. Pre-germinated seeds of Echinochloa spp. were incubated in growth pouches (18 cm-16.5 cm) containing herbicide solutions in a range of concentrations. Shoot and root lengths were measured after 6 d of incubation. Do...
Article
Glyphosate is a commonly applied herbicide in coffee plantations. Because of its non-selective mode of action it can damage the crop exposed through spray drift. Therefore, it is of interest to study glyphosate fate in coffee plants. The aim of this study was to develop an analytical method for accurate and precise quantification of glyphosate and...
Article
Full-text available
Weedy rice infests paddy fields worldwide at an alarmingly increasing rate. There is substantial evidence indicating that many weedy rice forms originated from or are closely related to cultivated rice. There is suspicion that the outbreak of weedy rice in China may be related to widely grown hybrid rice due to its heterosis and the diversity of it...
Article
Full-text available
Cold tolerance adaption is a crucial determinant for the establishment and expansion of invasive alien plants into new cold environments; however, its evolutionary mechanism is poorly understood. Crofton weed (Ageratina adenophora), a highly invasive alien plant, is continuously spreading across subtropical areas in China, northeastward from the fi...
Article
Introduction Broad-Leaved Weed Species Resistant to Glyphosate Grass Weed Species Resistant to Glyphosate Other GR Grass Weeds Perspectives References
Article
Full-text available
El arroz maleza (AM), Oryza sativa L. reduce drásticamente tanto el rendimiento paddy como la calidad molinera del arroz. Así mismo, su presencia desvaloriza el precio de las fincas. Este estudio tuvo por objetivo caracterizar algunas poblaciones de AM en el Distrito de Riego del Río Zulia, Departamento Norte de Santander, Colombia. El experimento...
Article
Striga is an obligate parasitic weed that attacks cereal crops in sub-Saharan Africa. In Western Kenya, it has been identified by farmers as their major pest problem in maize. A new technology, consisting of coating seed of imidazolinone resistant (IR) maize varieties with the imidazolinone herbicide, imazapyr, has proven to be very effective in co...
Article
Twenty-one grass weeds have evolved resistance to herbicides in Latin America, particularly in rice, soybean, wheat, and orchards. Junglerice, the most widespread and economically important rice weed, evolved resistance to propanil, acetylcoenzyme A carboxylase (ACCase)-inhibitor herbicides, quinclorac, and imazapyr in Central America, Colombia, an...
Article
Transgenic herbicide-resistant rice is needed to control weeds that have evolved herbicide resistance, as well as for the weedy (feral, red) rice problem, which has been exacerbated by shifting to direct seeding throughout the world-firstly in Europe and the Americas, and now in Asia, as well as in parts of Africa. Transplanting had been the major...
Article
Herbicide-resistant crops (HRCs), particularly glyphosate-resistant soybean, are increasingly important in Latin America. Prior to commercial release of these crops, their short- and long-term risks should be thoroughly assessed. A risk assessment should include the identification and characterization of potential hazards and an estimation of the l...
Article
Rapid detection methods were developed for discriminating between resistant (R) and susceptible (S) biotypes of Echinochloa colona to either propanil or fenoxaprop-P at all growth stages. In the pregerminated seed assay for fenoxaprop-P, seeds were placed on 1.0% agar containing a range of concentrations of herbicides and kept under humid condition...
Article
A population model of itchgrass was developed for a typical corn–based cropping system in the Pacific coastal region of Costa Rica. Field experiments were conducted to quantify density-dependent seedling mortality and fecundity. Additional information required for the model was obtained from the literature. Effect of control methods on itchgrass de...
Article
Field experiments were conducted at four locations in the Central Pacific region of Costa Rica between 1994 and 1996 to determine suitable tactics for integrated control of propanil-resistant junglerice in rain-fed rice. Stubble incorporation within 3 mo after rice harvest did not affect the density of junglerice that emerged with the crop at the b...
Conference Paper
Full-text available
En este capítulo introductorio se presentan conceptos fundamentales acerca del empleo de bioanálisis y describe en detalle el cómo realizarlos para determinar la respuesta a herbicidas solos o en interacción con otros productos utilizando plantas enteras. En lo posible, procuro incluir elementos prácticos, muchos de mi propia experiencia, de la rea...
Article
Full-text available
Whole-plant greenhouse bioassays and absorption, translocation, and metabolism experiments were conducted to investigate the resistance and cross resistance patterns and resistance mechanism of itchgrass (Rottboellia cochinchinensis) biotypes from Bolivia to herbicides that inhibit the enzyme acetyl coenzyme-A carboxylase. Varying levels of resista...
Article
Full-text available
Bernal Valverde from the Royal Veterinary and Agricultural Univeristy (Denmark) and member of our International Advisory Board, reports on the XV Congress on the Latin American Weed Science Society.
Article
Genetically modified, herbicide-resistant crop (HRC) cultivars, which allow for simplified weed control decisions compared with conventional cultivars, have considerable potential in Latin America. The number of herbicide applications can be reduced in HRCs, and otherwise difficult-to-control species, including red rice in rice or herbicide-resista...
Chapter
Rice is the most important food crop in the world. Globally, it provides 23 and 16% of human per capita energy and protein, respectively. ¹ About 153 million ha of rice was planted in 1999 for a total estimated production of 589 million t. ² However, by the year 2025, rice production must increase by 40% over current levels if the growing demands f...
Article
Rice cultivars resistant to broad-spectrum herbicides have been developed and their commercial release is imminent, especially for imidazolinone and glufosinate resistant varieties in the USA and Latin America. Glyphosate-resistant rice should follow within a few years. Rice growers throughout the world could benefit from the introduction of herbic...
Article
Pre-emergence activity of pendimethalin on propanil-resistant jungle rice (Echinochloa colona) was demonstrated in glasshouse trials. Both susceptible and resistant populations, collected from Costa Rica, were controlled by 1·25 kg ha-1, the usual application rate used in the field where Rottboellia cochinchinensis is also a problem. When applied p...
Conference Paper
Full-text available
The integrated pest management (IPM) is an important component of the agricultural sustainable production system. CATIE have developed IPM activities in Central America since 1984, especially in pest of coffee, corn, plantains and tomato. The strategic inputs for sustainability studied during 1996 were as follows: biology and phenology of the white...
Article
The effect of the mono-oxygenase inhibitors tridiphane, piperonyl butoxide and prochloraz on propanil uptake, metabolism and phytotoxicity was measured in a resistant (R) biotype of Echinochloa colona. The uptake of propanil was not significantly affected by any of the three mono-oxygenase inhibitors. The first metabolite of propanil metabolism, 3,...
Article
Uptake and metabolism of propanil were measured in both susceptible (S) and resistant (R) biotypes of Jungle-rice, Echinochloa colona (L.) link at different growth stages. Results showed that there was no significant difference in uptake between S and R biotypes of E. colona at any given growth stage, but that uptake was significantly reduced at ol...
Article
Aryl acylamidase (aryl-acylamine amidohydrolase, EC 3.5.1.13) activity has been measured in crude extracts from leaves of propanil-susceptible (S) and propanil-resistant (R) biotypes of the grass weed. Echinochloa colona (L.) Link from Columbia. Both specific and total amidase activity increased with plant age up to 15 days (four-leaf stage), then...
Article
Primary root cells from five dinitroaniline-resistant (R) and three susceptible (S) goosegrass biotypes from North Carolina and South Carolina were observed by transmission electron microscopy to determine whether resistance was associated with changes in cell wall formation. Cell wall malformations were found in some cells from two of the R-biotyp...
Article
Dinitroaniline herbicides are absorbed readily by roots and emerging shoots, but shoot exposure is more phytotoxic. Translocation within the plant varies by specific herbicide but commonly is minor. Dinitroaniline herbicides injure plants by binding to tubulin, a dimer protein in the ceil that polymerizes to form microtubules (MTs). MTs form the ma...

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