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Search Results: 1 - 10 of 130898 matches for " William T. Molin "
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Morphological Characterization of Amaranthus palmeri x A. spinosus Hybrids  [PDF]
William T. Molin, Vijay K. Nandula
American Journal of Plant Sciences (AJPS) , 2017, DOI: 10.4236/ajps.2017.86103
Abstract: The growth of clones of seven Amaranthus palmeri x A. spinosus hybrids was compared to type specimens of A. palmeri and A. spinosus
Soybean Seed Nutrition as Affected by Cotton, Wheat, and Fallow Rotation  [PDF]
Nacer Bellaloui, Salliana R. Stetina, William T. Molin
Food and Nutrition Sciences (FNS) , 2014, DOI: 10.4236/fns.2014.516173
Abstract:

Limited information is available on the effects of crop rotation on seed nutrition. Therefore, the objective of the current research was to determine whether crop rotations are beneficial to soybean seed nutrition for the first two complete rotation cycles in an experiment conducted from 2007 through 2012. The first complete rotation cycle (experiment one) was conducted in 2009, then repeated in 2010, and the second complete rotation cycle (experiment two) was conducted in 2011, and then repeated in 2012. The rotation sequences were: wheat-late cotton-fallow-soybean (WCFS), fallow-cotton-wheat-soybean (FCWS), and fallow-cotton-fallow-soybean (FCFS). The results showed that WCFS and FCFS resulted in higher seed oil, palmitic and stearic acids, glucose, sucrose, fructose, Fe, P, and B. No consistent effects on seed protein, oleic acid, linoleic acid, linolenic acid, raffinose, stachyose, and Mn contents were observed. These changes were accompanied by higher P, K, B, Fe in soil and N, K, and B in leaves, indicating that soil and leaf nutrients may result in continuous supply and mobility of nutrients from leaves to seed during seed fill. Our research demonstrated that crop rotation management can result in seed nutrient changes, affecting seed quality.

Influence of Water Quality, Formulation, Adjuvant, Rainfastness, and Nozzle Type on Efficacy of Fomesafen on Palmer Amaranth (Amaranthus palmeri) Control  [PDF]
Vijay K. Nandula, William T. Molin, Jason A. Bond
American Journal of Plant Sciences (AJPS) , 2018, DOI: 10.4236/ajps.2018.98120
Abstract: Protoporphyrinogen oxidase (PPO) inhibitors are one of the few remaining postemergence herbicide options for controlling Palmer amaranth in soybean growing areas of Mississippi, USA. Most Palmer amaranth populations in Mississippi are resistant to both glyphosate and acetolactate synthase inhibitors. Resistance to PPO inhibiting herbicides in Palmer amaranth has very recently been reported in Arkansas, Tennessee, and isolated pockets of Mississippi. A significant proportion of reports of PPO inhibitor failures in Mississippi are not considered to be resistance-related at this time. Therefore, the objective of this research was to evaluate factors affecting the efficacy of fomesafen on Palmer amaranth including: quality of spray carrier (water), formulations, adjuvant, rainfastness, and nozzle type. All water samples and formulation combinations provided >95% control of Palmer amaranth 3 WAT. Some combinations of water samples and formulations did not result in complete control of the treated plants, with one or two individuals surviving 3 WAT. Formulation 1 provided 99% control compared to 95% from formulation 2. Irrespective of combinations of herbicide, adjuvant and height, control of Palmer amaranth was ≥91%. Formulation 1 provided 94% control compared to 88% from formulation 2. The adjuvant x height interaction was significant, owing to a 10% reduction in control of larger plants (86%) compared to smaller plants (96%) in presence of COC. COC provided better control (93%) than NIS (88%). Simulated rainfall applied ≥60 min after herbicide application did not adversely affect efficacy on Palmer amaranth when formulation 1 was applied in combination with NIS, with control ranging from 94% to 100%. Formulation 1 with COC provided ≥93% control at all rainfall application times, except 30 min after herbicide treatment, which resulted in 79% control. Formulation 2 provided better control with COC (79% to 100%) than NIS (71% to 90%), in general, across the rainfall treatments applied at various times following herbicide application. All nozzle and weed height combinations resulted in 89% or better control of Palmer amaranth. In summary, water quality, formulation, adjuvant, rainfastness, or nozzle type did not affect the activity of fomesafen under optimal application conditions in the greenhouse.
Corn Yield Response to Reduced Water Use at Different Growth Stages  [PDF]
Hirut Kebede, Ruixiu Sui, Daniel K. Fisher, Krishna N. Reddy, Nacer Bellaloui, William T. Molin
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.513139
Abstract:
To develop an efficient water use strategy for crop irrigation, we need to know how much water can be reduced without decreasing yield. A study was designed to determine corn growth stages at which water could be reduced without affecting grain yield, and at what soil moisture level water deficit stress begins in the plants in a silt loam soil. An experiment was conducted in a randomized complete block with a 3 × 4 factorial design in four replications, where treatments consisted of three soil moisture levels [100%, 75%, and 50% of field capacity (FC) of a silt loam soil by weight] and four growth stages [fourteen leaf stage (V14), silking (R1), milk (R3), and dent (R5) stages] in a greenhouse. Growth stages at the reproductive and grain fill stages of corn were selected because this study was intended for the Mississippi Delta, where there is frequent drought during these growth stages making irrigation necessary for corn production, whereas there is usually adequate rainfall during the vegetative growth stages. Results from this study showed that reducing soil moisture from 100% FC (fully irrigated) to 75% FC of a silt loam soil starting at the R1 growth stage in corn did not reduce yield significantly compared to yield from the 100% FC, while saving a significant amount of water. Physiological investigations at the three soil moisture treatments showed that a mild moisture deficit stress might have started at the 75% FC treatment. With further investigation, if savings in water at 75% FC result in a significant reduction in energy cost, it may be profitable to reduce soil moisture to 75% FC in a silt loam soil.
Glyphosate Resistance in Giant Ragweed (Ambrosia trifida L.) from Mississippi Is Partly Due to Reduced Translocation  [PDF]
Vijay K. Nandula, Alice A. Wright, Christopher R. Van Horn, William T. Molin, Phil Westra, Krishna N. Reddy
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.613211
Abstract: A giant ragweed population from a glyphosate-resistant (GR) soybean field in Mississippi, USA was suspected to be resistant to glyphosate. Greenhouse and laboratory studies were conducted to confirm and quantify the magnitude of glyphosate resistance in a resistant biotype selected from this population and to elucidate possible physiological and molecular mechanisms of glyphosate resistance. Glyphosate dose response studies indicated that ED50 (effective dose required to reduce plant growth by 50%) values for glyphosate-resistant (GR-MS) and glyphosate-susceptible (GS-MS) biotypes, based on percent injury, were 0.52 and 0.34 kg ae/ha glyphosate, respectively, indicating a 1.5-fold level of resistance in GR-MS. The absorption pattern of 14C-glyphosate in the two giant ragweed biotypes was similar throughout the measured time course of 168 h after treatment (HAT). The amount of 14C-glyphosate that translocated out of treated leaves of the GR-MS and GS-MS plants was similar up to 24 HAT. However, the GS-MS biotype translocated more (71% and 76% of absorbed at 48 and 96 HAT, respectively) 14C-glyphosate than the GR-MS biotype (44% and 66% of absorbed at 48 and 96 HAT, respectively) out of the treated leaf. No target site mutation was identified at the Pro106 location of the EPSPS gene of the GR-MS biotype. The mechanism of resistance to glyphosate in giant ragweed from Mississippi, at least, is due to reduced glyphosate translocation.
Glyphosate-Resistant Goosegrass from Mississippi
William T. Molin,Alice A. Wright,Vijay K. Nandula
Agronomy , 2013, DOI: 10.3390/agronomy3020474
Abstract: A suspected glyphosate-resistant goosegrass [ Eleusine indica (L.) Gaertn.] population, found in Washington County, Mississippi, was studied to determine the level of resistance and whether the resistance was due to a point mutation, as was previously identified in a Malaysian population. Whole plant dose response assays indicated a two- to four-fold increase in resistance to glyphosate. Leaf disc bioassays based on a glyphosate-dependent increase in shikimate levels indicated a five- to eight-fold increase in resistance. Sequence comparisons of messenger RNA for epsps, the gene encoding the enzyme 5-enolpyruvylshikimate-3-phosphate synthase, from resistant and sensitive goosegrass, revealed a cytosine to thymine nucleotide change at position 319 in the resistant accessions. This single nucleotide polymorphism causes a proline to serine amino acid substitution at position 106 in 5-enolpyruvylshikimate-3-phosphate synthase. A real-time polymerase chain reaction assay using DNA probes specific for the nucleotide change at position 319 was developed to detect this polymorphism. Goosegrass from 42 locations were screened, and the results indicated that glyphosate-resistant goosegrass remained localized to where it was discovered. Pendimethalin, s-metolachlor, clethodim, paraquat and fluazifop controlled resistant goosegrass 93% to 100%, indicating that several control options for glyphosate-resistant goosegrass are available.
Early Detection of Soybean Plant Injury from Glyphosate by Measuring Chlorophyll Reflectance and Fluorescence
Yanbo Huang,Steven J. Thomson,William T. Molin,Krishna N. Reddy
Journal of Agricultural Science , 2012, DOI: 10.5539/jas.v4n5p117
Abstract: Early detection of crop injury from off-target drift of herbicide is critical in crop production. Subtle changes in canopy reflectance could present useful information to detect the onset of crop stress. This study was conducted in a greenhouse to evaluate a portable spectroradiometer and a portable chlorophyll fluorometer for the detection of crop injury caused by glyphosate spray. Non-glyphosate resistant soybean (Glycine max L. Merr.) plants were sprayed with glyphosate using a pneumatic track sprayer in a spray chamber. Four plants received a rate of 0.86 kg ae/ha glyphosate and four plants received 0.086 kg ae/ha. Additional four non-sprayed plants were used as controls. After the glyphosate spray, the chlorophyll reflectance of the plants was measured with the spectroradiometer at 4, 24, 48, and 72 hours to determine the plant response to herbicide. Simultaneously, fluorescence induction kinetics of the crop under stress was measured with the portable chlorophyll fluorometer. Results of the statistical mean separation indicated that the plant chlorophyll reflectance measurement could be used to differentiate crop stress from glyphosate at 24 hours after spray among treatments and to identify the effect of herbicide at 24 hours after spray in each treatment. Moreover, linear discriminant analysis with the reflectance data showed that the crop stress of the soybean plants from glyphosate could be identified at 24 hours or more post application. Results of the statistical mean separation also indicated that use of plant chlorophyll fluorescence measurement could not differentiate crop stress until 48 hours after spray among treatments while it could identify the effect of herbicide 24 hours after spray in each treatment. These findings demonstrate that chlorophyll reflectance and fluorescence measurements both could be used for early detection of crop stress.
Identification of Genetic Elements Associated with EPSPS Gene Amplification
Todd A. Gaines, Alice A. Wright, William T. Molin, Lothar Lorentz, Chance W. Riggins, Patrick J. Tranel, Roland Beffa, Philip Westra, Stephen B. Powles
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065819
Abstract: Weed populations can have high genetic plasticity and rapid responses to environmental selection pressures. For example, 100-fold amplification of the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene evolved in the weed species Amaranthus palmeri to confer resistance to glyphosate, the world’s most important herbicide. However, the gene amplification mechanism is unknown. We sequenced the EPSPS gene and genomic regions flanking EPSPS loci in A. palmeri, and searched for mobile genetic elements or repetitive sequences. The EPSPS gene was 10,229 bp, containing 8 exons and 7 introns. The gene amplification likely proceeded through a DNA-mediated mechanism, as introns exist in the amplified gene copies and the entire amplified sequence is at least 30 kb in length. Our data support the presence of two EPSPS loci in susceptible (S) A. palmeri, and that only one of these was amplified in glyphosate-resistant (R) A. palmeri. The EPSPS gene amplification event likely occurred recently, as no sequence polymorphisms were found within introns of amplified EPSPS copies from R individuals. Sequences with homology to miniature inverted-repeat transposable elements (MITEs) were identified next to EPSPS gene copies only in R individuals. Additionally, a putative Activator (Ac) transposase and a repetitive sequence region were associated with amplified EPSPS genes. The mechanism controlling this DNA-mediated amplification remains unknown. Further investigation is necessary to determine if the gene amplification may have proceeded via DNA transposon-mediated replication, and/or unequal recombination between different genomic regions resulting in replication of the EPSPS gene.
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Molin,T 顾聚兴
红外 , 1995,
Abstract: 简化了的软件和廉价的硬件引发人们对新应用的兴趣。
Estudos com penetrometria: novos equipamentos e amostragem correta
Molin, José P.;Dias, Carlos T. dos S.;Carbonera, Lucelha;
Revista Brasileira de Engenharia Agrícola e Ambiental , 2012, DOI: 10.1590/S1415-43662012000500015
Abstract: abstract the most commonly used indicator for soil compaction diagnose is the cone index (ci) obtained from penetrometers. several models are available in the market with different operating principles and comparability of results among them is not sufficiently known. this study aimed to compare three cone penetrometers with different operation principles and to establish an optimal number of replications for each sampling point. the equipment used were an impact penetrometer, an electronic penetrometer manually operated and an electronic penetrometer hydraulically operated, in three environments. the equipment, in general, did not produce comparable ci values in magnitude and in tendency. however it is not clear whether these differences are relevant for diagnosis of soil compaction. it is possible yet, to affirm that after 15 replications, the sampling errors of ci values did not decrease significantly, ranging between 5 to 20% for the three penetrometers in each plot.
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