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Agronomy, Volume 4, Issue 1 (March 2014) – 11 articles , Pages 1-177

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301 KiB  
Article
The Effect of Mean Daily Temperature and Relative Humidity on Pollen, Fruit Set and Yield of Tomato Grown in Commercial Protected Cultivation
by Danny Harel, Hadar Fadida, Alik Slepoy, Shelly Gantz and Kobi Shilo
Agronomy 2014, 4(1), 167-177; https://doi.org/10.3390/agronomy4010167 - 21 Mar 2014
Cited by 63 | Viewed by 10050
Abstract
The research trial was carried out in the Mediterranean region where high summer temperatures have been proved to have a detrimental effect on the delicate tomato fruitset process. The flower to fruit set process was simultaneously monitored in fogged and unfogged shelters during [...] Read more.
The research trial was carried out in the Mediterranean region where high summer temperatures have been proved to have a detrimental effect on the delicate tomato fruitset process. The flower to fruit set process was simultaneously monitored in fogged and unfogged shelters during the three-month Mediterranean summer season. Comparisons of pollen quality, fruit set rates and fruit yield revealed that mean daily temperatures of 25–26 °C are the upper limit for proper fruit set and fruit yield for tomatoes grown in protected cultivation during the hot Mediterranean summer period. A moderate reduction of 1–1.5 °C in mean daily temperatures together with the increased RH (relative humidity) from 50% to 70% during day time improved the pollen grain’s viability. Suggestions concerning more efficient controls on the fogging system considering those findings are discussed. Full article
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283 KiB  
Editorial
Acknowledgement to Reviewers of Agronomy in 2013
by Agronomy Editorial Office
Agronomy 2014, 4(1), 165-166; https://doi.org/10.3390/agronomy4010165 - 28 Feb 2014
Cited by 3 | Viewed by 4001
Abstract
The editors of Agronomy would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2013. [...] Full article
1259 KiB  
Article
Effects of Field Plot Size on Variation in White Flower Anther Injury by Tarnished Plant Bug for Host Plant Resistance Evaluations in Arkansas Cotton
by Jeffrey Willers, Tina Gray Teague, George Milliken and Fred Bourland
Agronomy 2014, 4(1), 144-164; https://doi.org/10.3390/agronomy4010144 - 27 Feb 2014
Cited by 3 | Viewed by 6618
Abstract
Field trials conducted in 2008 and 2009 investigated whether plot size affects incidence of white flower anther injury by tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)) in host plant resistance (HPR) evaluations. The three cotton lines evaluated in the trial included [...] Read more.
Field trials conducted in 2008 and 2009 investigated whether plot size affects incidence of white flower anther injury by tarnished plant bug (Lygus lineolaris (Palisot de Beauvois)) in host plant resistance (HPR) evaluations. The three cotton lines evaluated in the trial included a susceptible frego bract line (RBCDHGPIQH-197) and 2 standards, SureGrow (SG) 105 and Deltapine (DP) 393. Samplers monitored white flower anther injury between single row mini-plots embedded within multiple row max-plots. A sub-section of the max-plots was sprayed with insecticides to evaluate these tactics on altering the incidence of white flower anther injury. Plant bug numbers were very low in 2008, while infestation levels were higher in 2009. Significantly higher numbers of flowers with anther injury were observed in both years in the susceptible frego bract line compared to SG 105 and DP 393 lines. In both years, anther injury levels were similar in the max- and mini-plots, with lower levels observed in max-sprayed plots. The white flower monitoring procedure is a consistent indicator of adult plant bug preferences and is not influenced by plot size or interspersions of cultivar lines among plots. Full article
(This article belongs to the Special Issue New Phenotyping Platforms for Field Trials)
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688 KiB  
Article
Comparative Evaluation of Common Savannah Grass on a Range of Soils Subjected to Different Stresses II: Root Zone Physical Condition
by Raymond Springer, Gaius Eudoxie and Gregory Gouveia
Agronomy 2014, 4(1), 124-143; https://doi.org/10.3390/agronomy4010124 - 19 Feb 2014
Cited by 6 | Viewed by 6237
Abstract
The root zone physical condition influences root development and function, which affects turfgrass growth, quality and performance. The temporal variability of root zone properties was investigated in a factorial experiment combining sand layering compaction and moisture stress on the performance of Savannahgrass (SG) [...] Read more.
The root zone physical condition influences root development and function, which affects turfgrass growth, quality and performance. The temporal variability of root zone properties was investigated in a factorial experiment combining sand layering compaction and moisture stress on the performance of Savannahgrass (SG) (Axonopus compressus), Bermudagrass (BG) (Cynodon dactylon (L.) Pers.) (cv. Tifway 419) and Zoysiagrass (ZG) (Zoysia spp.) grown in four contrasting soils. Four stresses—drought (D), waterlogging (WL), high compaction (HC) and low compaction (LC)—were applied either with or without a surface sand layer. Root zone properties, including root weight (RW), bulk density (BD), surface hardness (SH), redox potential (Eh) and non-capillary pore space (NCPS), were monitored over a four-month growth period. Surface hardness values were greater for the high compaction effort in treatments without sand, but were highest under drought. Sand addition resulted in lower SH for all grass × soil combinations. The soil texture influenced root zone BD for all turfgrasses, with the clay soils recording significantly lower bulk densities (<1.00 g/cm3) than those with coarser fractions. Compaction had a minimal influence on BD, the effect being further modified by grass type. Low BD was associated with high RW. RW was also significantly higher in the sand-amended treatments. Waterlogging reduced Eh for all soils, with higher values recorded in the sand treatments. The redox potential was lowest in River Estate soil and in pots planted with ZG. Across turfgrasses, Princes Town and Talparo soils had significantly lower NCPS for the sand treatment. NCPS was highest for ZG across stress treatments, but values were similar to SG under compaction treatments. Sand layering improved the root zone aeration status, particularly with SG, resulting in a better physical condition. Full article
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2371 KiB  
Article
Elements of an Integrated Phenotyping System for Monitoring Crop Status at Canopy Level
by Donald Rundquist, Anatoly Gitelson, Bryan Leavitt, Arthur Zygielbaum, Richard Perk and Galina Keydan
Agronomy 2014, 4(1), 108-123; https://doi.org/10.3390/agronomy4010108 - 17 Feb 2014
Cited by 28 | Viewed by 7037
Abstract
Great care is needed to obtain spectral data appropriate for phenotyping in a scientifically rigorous manner. This paper discusses the procedures and considerations necessary and also suggests important pre-processing and analytical steps leading to real-time, non-destructive assessment of crop biophysical characteristics. The system [...] Read more.
Great care is needed to obtain spectral data appropriate for phenotyping in a scientifically rigorous manner. This paper discusses the procedures and considerations necessary and also suggests important pre-processing and analytical steps leading to real-time, non-destructive assessment of crop biophysical characteristics. The system has three major components: (1) data-collection platforms (with a focus on backpack and tractor-mounted units) including specific instruments and their configurations; (2) data-collection and display software; and (3) standard products depicting crop-biophysical characteristics derived using a suite of models to transform the spectral data into accurate, reliable biophysical characteristics of crops, such as fraction of green vegetation, absorbed photosynthetically active radiation, leaf area index, biomass, chlorophyll content and gross primary production. This system streamlines systematic data acquisition, facilitates research, and provides useful products for agriculture. Full article
(This article belongs to the Special Issue New Phenotyping Platforms for Field Trials)
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880 KiB  
Article
Yield Response of Native Warm-Season Forage Grasses to Harvest Intervals and Durations in Mixed Stands
by Vitalis W. Temu, Brian J. Rude and Brian S. Baldwin
Agronomy 2014, 4(1), 90-107; https://doi.org/10.3390/agronomy4010090 - 17 Feb 2014
Cited by 22 | Viewed by 6833
Abstract
Tolerance to frequent defoliations is critical for native warm-season grasses managed for forage and wildlife habitat. Yield response of big bluestem (Andropogon gerardii), indiangrass (Sorghastrum nutans), and little bluestem (Schizachyrium scoparium) to treatments (30-, 40-, 60-, 90- [...] Read more.
Tolerance to frequent defoliations is critical for native warm-season grasses managed for forage and wildlife habitat. Yield response of big bluestem (Andropogon gerardii), indiangrass (Sorghastrum nutans), and little bluestem (Schizachyrium scoparium) to treatments (30-, 40-, 60-, 90- or 120-d harvest intervals) and durations were assessed on early-succession mixed stands. Over three years, phased harvestings were initiated in May, on sets of randomized plots, in five replications to produce one-, two-, and three-year old stands, by the third year. Each plot had marked indiangrass and big bluestem plants which were hand-clipped on harvest-days before whole-plot harvesting. Species yields were greater in first- than second-year plots but not affected by treatments. June–September yields in 2008 were greatest for the 30-d, and more in the first- (8472 kg ha−1) than second-year (7627 kg ha−1) plots. In 2009, yields were also greater in first- than second-year plots but without treatment effects. Recovery yields showed no treatment effect, but were about 67% less for second- compared to first-year plots and much less than plots never harvested before. Data suggest that harvesting similar mixed native warm-season grass stands at 30- to 40-d intervals may provide good hay yields without compromising post-season stand recovery for multiple uses. Full article
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1008 KiB  
Article
Biological Control of the Weed Hemp Sesbania (Sesbania exaltata) in Rice (Oryza sativa) by the Fungus Myrothecium verrucaria
by Clyde D. Boyette, Robert E. Hoagland and Kenneth C. Stetina
Agronomy 2014, 4(1), 74-89; https://doi.org/10.3390/agronomy4010074 - 27 Jan 2014
Cited by 24 | Viewed by 9450
Abstract
In greenhouse and field experiments, a mycelial formulation of the fungus Myrothecium verrucaria (IMI 361690) containing 0.20% Silwet L-77 surfactant exhibited high bioherbicidal efficacy against the problematic weed hemp sesbania. Infection and mortality levels of 100% of hemp sesbania seedlings occurred within 48 [...] Read more.
In greenhouse and field experiments, a mycelial formulation of the fungus Myrothecium verrucaria (IMI 361690) containing 0.20% Silwet L-77 surfactant exhibited high bioherbicidal efficacy against the problematic weed hemp sesbania. Infection and mortality levels of 100% of hemp sesbania seedlings occurred within 48 h after fungal application in the greenhouse. In rice field tests conducted over a three year period, M. verrucaria at an inoculum concentration of 50 g L−1 (dry mycelium equivalent) controlled 95% of ≤20 cm tall hemp sesbania plants. M. verrucaria also controlled larger plants (≥60 cm tall) using this high inoculum concentration. This level of weed control, as well as rice yields from plots where weeds were effectively controlled, were similar to those which occurred with the herbicide acifluorfen. These results suggest that a mycelial formulation of M. verrucaria has potential as a bioherbicide for controlling hemp sesbania in rice. Full article
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1367 KiB  
Article
Short-Term Effect of Feedstock and Pyrolysis Temperature on Biochar Characteristics, Soil and Crop Response in Temperate Soils
by Victoria Nelissen, Greet Ruysschaert, Dorette Müller-Stöver, Samuel Bodé, Jason Cook, Frederik Ronsse, Simon Shackley, Pascal Boeckx and Henrik Hauggaard-Nielsen
Agronomy 2014, 4(1), 52-73; https://doi.org/10.3390/agronomy4010052 - 22 Jan 2014
Cited by 43 | Viewed by 8597
Abstract
At present, there is limited understanding of how biochar application to soil could be beneficial to crop growth in temperate regions and which biochar types are most suitable. Biochar’s (two feedstocks: willow, pine; three pyrolysis temperatures: 450 °C, 550 °C, 650 °C) effect [...] Read more.
At present, there is limited understanding of how biochar application to soil could be beneficial to crop growth in temperate regions and which biochar types are most suitable. Biochar’s (two feedstocks: willow, pine; three pyrolysis temperatures: 450 °C, 550 °C, 650 °C) effect on nitrogen (N) availability, N use efficiency and crop yield was studied in northwestern European soils using a combined approach of process-based and agronomic experiments. Biochar labile carbon (C) fractions were determined and a phytotoxicity test, sorption experiment, N incubation experiment and two pot trials were conducted. Generally, biochar caused decreased soil NO3 availability and N use efficiency, and reduced biomass yields compared to a control soil. Soil NO3 concentrations were more reduced in the willow compared to the pine biochar treatments and the reduction increased with increasing pyrolysis temperatures, which was also reflected in the biomass yields. Woody biochar types can cause short-term reductions in biomass production due to reduced N availability. This effect is biochar feedstock and pyrolysis temperature dependent. Reduced mineral N availability was not caused by labile biochar C nor electrostatic NH4+/NO3 sorption. Hence, the addition of fresh biochar might in some cases require increased fertilizer N application to avoid short-term crop growth retardation. Full article
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1065 KiB  
Article
No Effect Level of Co-Composted Biochar on Plant Growth and Soil Properties in a Greenhouse Experiment
by Hardy Schulz, Gerald Dunst and Bruno Glaser
Agronomy 2014, 4(1), 34-51; https://doi.org/10.3390/agronomy4010034 - 22 Jan 2014
Cited by 56 | Viewed by 9926
Abstract
It is claimed that the addition of biochar to soil improves C sequestration, soil fertility and plant growth, especially when combined with organic fertilizers such as compost. However, little is known about agricultural effects of small amounts of composted biochar. This greenhouse study [...] Read more.
It is claimed that the addition of biochar to soil improves C sequestration, soil fertility and plant growth, especially when combined with organic fertilizers such as compost. However, little is known about agricultural effects of small amounts of composted biochar. This greenhouse study was carried out to examine effects of co-composted biochar on oat (Avena sativa L.) yield in both sandy and loamy soil. The aim of this study was to test whether biochar effects can be observed at very low biochar concentrations. To test a variety of application amounts below 3 Mg biochar ha−1, we co-composted five different biochar concentrations (0, 3, 5, 10 kg Mg−1 compost). The biochar-containing compost was applied at five application rates (10, 50, 100, 150, 250 Mg ha−1 20 cm−1). Effects of compost addition on plant growth, Total Organic Carbon, Ntot, pH and soluble nutrients outweighed the effects of the minimal biochar amounts in the composted substrates so that a no effect level of biochar of at least 3 Mg ha−1 could be estimated. Full article
(This article belongs to the Special Issue Biochar as Option for Sustainable Resource Management)
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753 KiB  
Article
A Draft Genome Sequence for Ensete ventricosum, the Drought-Tolerant “Tree Against Hunger”
by James Harrison, Karen A. Moore, Konrad Paszkiewicz, Thomas Jones, Murray R. Grant, Daniel Ambacheew, Sadik Muzemil and David J. Studholme
Agronomy 2014, 4(1), 13-33; https://doi.org/10.3390/agronomy4010013 - 17 Jan 2014
Cited by 18 | Viewed by 12533
Abstract
We present a draft genome sequence for enset (Ensete ventricosum) available via the Sequence Read Archive (accession number SRX202265) and GenBank (accession number AMZH01. Enset feeds 15 million people in Ethiopia, but is arguably the least studied African crop. Our sequence [...] Read more.
We present a draft genome sequence for enset (Ensete ventricosum) available via the Sequence Read Archive (accession number SRX202265) and GenBank (accession number AMZH01. Enset feeds 15 million people in Ethiopia, but is arguably the least studied African crop. Our sequence data suggest a genome size of approximately 547 megabases, similar to the 523-megabase genome of the closely related banana (Musa acuminata). At least 1.8% of the annotated M. acuminata genes are not conserved in E. ventricosum. Furthermore, enset contains genes not present in banana, including reverse transcriptases and virus-like sequences as well as a homolog of the RPP8-like resistance gene. We hope that availability of genome-wide sequence data will stimulate and accelerate research on this important but neglected crop. Full article
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1703 KiB  
Article
Eco-Friendly Nets and Floating Row Covers Reduce Pest Infestation and Improve Tomato (Solanum lycopersicum L.) Yields for Smallholder Farmers in Kenya
by Elisha O. Gogo, Mwanarusi Saidi, Francis M. Itulya, Thibaud Martin and Mathieu Ngouajio
Agronomy 2014, 4(1), 1-12; https://doi.org/10.3390/agronomy4010001 - 09 Jan 2014
Cited by 52 | Viewed by 8136
Abstract
Tomato (Solanum lycopersicum L.) is an important vegetable for supplying vitamins, minerals and fiber in human diets worldwide. Successful open field production of tomato in the tropics is limited by insect pests among other constraints. Two trials were conducted at the Horticulture [...] Read more.
Tomato (Solanum lycopersicum L.) is an important vegetable for supplying vitamins, minerals and fiber in human diets worldwide. Successful open field production of tomato in the tropics is limited by insect pests among other constraints. Two trials were conducted at the Horticulture Research and Teaching Field, Egerton University, Kenya with the objective of evaluating the effects of agricultural nets (agronets) herein called eco-friendly nets (EFNs) and floating row covers (FRCs) on pest population and yield of tomatoes. A randomized complete block design with five replications was used. Tomato plants were protected with either fine mesh EFN (0.4-mm pore diameter), large mesh EFN (0.9-mm pore diameter) or FRC. The EFN and FRC were maintained permanently closed or opened thrice a week from 9 am to 3 pm. Two control treatments were used: open unsprayed (untreated control) or open and sprayed with alpha-cypermethrin based insecticide (treated control). The use of EFN and FRC helped to manage pests with the lowest pest population obtained under FRC maintained permanently covered and the highest population recorded in the untreated control. Covering tomato plants with EFN or FRC also resulted in more marketable fruit and lower yield losses compared with the unprotected systems. The EFN and FRC offer great potential as part of integrated systems for pest management and yield improvement in tomato production in regions with a tropical climate. Full article
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