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Agronomy, Volume 2, Issue 4 (December 2012), Pages 240-383

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Research

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Open AccessArticle Allelopathy—A Tool to Improve the Weed Competitive Ability of Wheat with Herbicide-Resistant Black-Grass (Alopecurus myosuroides Huds.)
Agronomy 2012, 2(4), 284-294; doi:10.3390/agronomy2040284
Received: 4 September 2012 / Revised: 9 October 2012 / Accepted: 12 October 2012 / Published: 18 October 2012
Cited by 1 | PDF Full-text (1610 KB) | HTML Full-text | XML Full-text
Abstract
Controlling black-grass in winter wheat production in northern Europe is an increasing problem because of more frequent winter crops and development of herbicide resistance in weeds. Alternative weed management strategies are needed, e.g., use of more competitive cultivars. Factors that increase cultivar [...] Read more.
Controlling black-grass in winter wheat production in northern Europe is an increasing problem because of more frequent winter crops and development of herbicide resistance in weeds. Alternative weed management strategies are needed, e.g., use of more competitive cultivars. Factors that increase cultivar competitiveness include early vigor and straw length, but also allelopathy. Therefore, the allelopathic properties of wheat cultivars included in the Swedish national list or in the release pipeline were investigated using a bioassay with herbicide-resistant and herbicide-sensitive black-grass as receiver plants. Wheat-rye translocation lines were also included in this screening to identify possible sources of high allelopathic activity. The bioassay results were followed up in two-year field trials. The results revealed large variations in allelopathic activity between cultivars. Most cultivars showed interference with both herbicide-sensitive and herbicide-resistant black-grass, although the allelopathic effect was lower on the herbicide-resistant biotype. Cultivars with high allelopathic activity gave only half the black-grass biomass of low allelopathic cultivars. Dinaro, a triticale (wheat-rye hybrid) cultivar and the new wheat cultivar Nimbus showed the highest allelopathy and inhibition of black-grass growth. Only a few wheat lines with rye chromatin, all or part of a rye chromosome, showed high allelopathy. Use of cultivars with high allelopathic activity can thus be important in integrated weed management of black-grass. Full article
(This article belongs to the Special Issue Weed Management and Herbicide Resistance)
Open AccessArticle Integrated Palmer Amaranth Management in Glufosinate-Resistant Cotton: I. Soil-Inversion, High-Residue Cover Crops and Herbicide Regimes
Agronomy 2012, 2(4), 295-311; doi:10.3390/agronomy2040295
Received: 29 August 2012 / Revised: 23 October 2012 / Accepted: 24 October 2012 / Published: 5 November 2012
Cited by 6 | PDF Full-text (238 KB) | HTML Full-text | XML Full-text
Abstract
A three year field experiment was conducted to evaluate the role of soil-inversion, cover crops and herbicide regimes for Palmer amaranth between-row (BR) and within-row (WR) management in glufosinate-resistant cotton. The main plots were two soil-inversion treatments: fall inversion tillage (IT) and [...] Read more.
A three year field experiment was conducted to evaluate the role of soil-inversion, cover crops and herbicide regimes for Palmer amaranth between-row (BR) and within-row (WR) management in glufosinate-resistant cotton. The main plots were two soil-inversion treatments: fall inversion tillage (IT) and non-inversion tillage (NIT). The subplots were three cover crop treatments: crimson clover, cereal rye and winter fallow; and sub subplots were four herbicide regimes: preemergence (PRE) alone, postemergence (POST) alone, PRE + POST and a no herbicide check (None). The PRE herbicide regime consisted of a single application of pendimethalin at 0.84 kg ae ha−1 plus fomesafen at 0.28 kg ai ha1. The POST herbicide regime consisted of a single application of glufosinate at 0.60 kg ai ha−1 plus S-metolachlor at 0.54 kg ai ha−1 and the PRE + POST regime combined the prior two components. At 2 weeks after planting (WAP) cotton, Palmer amaranth densities, both BR and WR, were reduced ≥90% following all cover crop treatments in the IT. In the NIT, crimson clover reduced Palmer amaranth densities >65% and 50% compared to winter fallow and cereal rye covers, respectively. At 6 WAP, the PRE and PRE + POST herbicide regimes in both IT and NIT reduced BR and WR Palmer amaranth densities >96% over the three years. Additionally, the BR density was reduced ≥59% in no-herbicide (None) following either cereal rye or crimson clover when compared to no-herbicide in the winter fallow. In IT, PRE, POST and PRE + POST herbicide regimes controlled Palmer amaranth >95% 6 WAP. In NIT, Palmer amaranth was controlled ≥79% in PRE and ≥95% in PRE + POST herbicide regimes over three years. POST herbicide regime following NIT was not very consistent. Averaged across three years, Palmer amaranth controlled ≥94% in PRE and PRE + POST herbicide regimes regardless of cover crop. Herbicide regime effect on cotton yield was highly significant; the maximum cotton yield was produced by the PRE + POST herbicide regime. Averaged over three years, the PRE, POST and PRE + POST cotton yields were about three times higher than no herbicide regime. In a conservation tillage production system, a PRE + glufosinate POST herbicide based regime coupled with a cereal rye cover crop may effectively control Palmer amaranth and maximize cotton yields. Full article
(This article belongs to the Special Issue Weed Management and Herbicide Resistance)
Open AccessCommunication Improved Sustainability through Novel Water Management Strategies for Strawberry Transplant Establishment in Florida, United States
Agronomy 2012, 2(4), 312-320; doi:10.3390/agronomy2040312
Received: 3 October 2012 / Revised: 15 November 2012 / Accepted: 22 November 2012 / Published: 6 December 2012
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Abstract
Establishing bare-root transplants in Florida, United States, is an inefficient water-consuming activity. Between 3500 and 5500 m3/ha are applied with sprinkler irrigation to lower temperatures around the transplant crown and aid early root development, but more than 97% of the [...] Read more.
Establishing bare-root transplants in Florida, United States, is an inefficient water-consuming activity. Between 3500 and 5500 m3/ha are applied with sprinkler irrigation to lower temperatures around the transplant crown and aid early root development, but more than 97% of the water volume runs off the polyethylene-covered beds. Research has been conducted to evaluate the feasibility of producing containerized (plug) short-day cultivar transplants under Florida conditions, the effect of continuous and intermittent low-volume sprinklers on transplant establishment and the use of kaolin clay to reduce stress on young transplants. Research results demonstrated that growers may have alternatives to reduce water use and pumping costs during strawberry transplant establishment by the following: (a) plug transplants can be produced from mother plants from Florida’s subtropical weather without chilling conditioning and still be competitive in the winter market; (b) using continuous and intermittent low-volume sprinkler irrigation saves between 16% and 33% of the water volumes for strawberry establishment; and (c) using kaolin clay showed to be a low-cost (US$63/ha plus application costs) investment to reduce irrigation volumes by at least 30%. Full article
(This article belongs to the Special Issue Sustainable Crop Production)
Open AccessArticle Multiple Resistance of Horseweed to Glyphosate and Paraquat and Its Control with Paraquat and Metribuzin Combinations
Agronomy 2012, 2(4), 358-370; doi:10.3390/agronomy2040358
Received: 2 November 2012 / Revised: 23 November 2012 / Accepted: 12 December 2012 / Published: 19 December 2012
Cited by 3 | PDF Full-text (215 KB) | HTML Full-text | XML Full-text
Abstract
Greenhouse and field studies were conducted in 2007 and 2008 to investigate possible multiple-resistance of horseweed to paraquat and glyphosate, and to evaluate the effect of the addition of metribuzin to paraquat on control of paraquat-resistant horseweed. Results indicated that the GR [...] Read more.
Greenhouse and field studies were conducted in 2007 and 2008 to investigate possible multiple-resistance of horseweed to paraquat and glyphosate, and to evaluate the effect of the addition of metribuzin to paraquat on control of paraquat-resistant horseweed. Results indicated that the GR50 (herbicide dose required to cause a 50% reduction in plant growth) value for the susceptible population S102 was 0.066 kg ae/ha glyphosate, and for the resistant population MDOT was 0.78 kg/ha glyphosate. The level of glyphosate resistance for MDOT was 12-fold compared with S102. The GR50 value for the susceptible population S102 was 0.078 kg ai/ha paraquat, and for the resistant population MDOT was 0.67 kg/ha paraquat. The level of paraquat resistance for MDOT was 9-fold compared to S102, suggesting multiple-resistance to glyphosate and paraquat in the MDOT population. In field studies the addition of metribuzin to paraquat improved horseweed control. Full article
(This article belongs to the Special Issue Weed Management and Herbicide Resistance)
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Open AccessArticle Monitoring and Management of Imidazolinone-Resistant Red Rice (Oryza sativa L., var. sylvatica) in Clearfield® Italian Paddy Rice
Agronomy 2012, 2(4), 371-383; doi:10.3390/agronomy2040371
Received: 1 November 2012 / Revised: 10 December 2012 / Accepted: 12 December 2012 / Published: 19 December 2012
Cited by 7 | PDF Full-text (242 KB) | HTML Full-text | XML Full-text
Abstract
The introduction in Italy of Clearfield® rice cultivars carrying imidazolinone-resistant traits provides an efficient option to control red rice, a conspecific weed of cultivated rice. However, despite the promulgation of specific guidelines for Clearfield® technology management, imazamox red rice survivors [...] Read more.
The introduction in Italy of Clearfield® rice cultivars carrying imidazolinone-resistant traits provides an efficient option to control red rice, a conspecific weed of cultivated rice. However, despite the promulgation of specific guidelines for Clearfield® technology management, imazamox red rice survivors have been reported by farmers. Forty-two fields were monitored in 2010 and 2011 throughout the Piedmont and Lombardy regions and field cases were recorded of herbicides use and agronomic practices. Whole-plant sensitivity to imazamox was assessed and the resistance mechanism was determined by molecular analysis. Twenty-six red rice populations out of 42 were imazamox-resistant and plants of all the resistant populations possess a Ser to Asn substitution at locus 653 of the ALS gene determining the target-site resistance. Farmers frequently grow Clearfield® varieties for more than two consecutive years so increasing the selection pressure exerted by imazamox and favoring the evolution of resistant red rice. To maintain the sustainability of this new technology, a proper management based on crop rotation, utilization of certified seeds and strict control of red rice escapes has to be implemented. More generally, all stakeholders must increase their awareness that the selection pressure exerted by ALS inhibitors in rice cropping system should be reduced. Full article
(This article belongs to the Special Issue Weed Management and Herbicide Resistance)
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Review

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Open AccessReview Increasing Food Production in Africa by Boosting the Productivity of Understudied Crops
Agronomy 2012, 2(4), 240-283; doi:10.3390/agronomy2040240
Received: 28 July 2012 / Revised: 10 September 2012 / Accepted: 18 September 2012 / Published: 16 October 2012
Cited by 7 | PDF Full-text (554 KB) | HTML Full-text | XML Full-text
Abstract
The Green Revolution has enabled Asian countries to boost their crop production enormously. However, Africa has not benefitted from this agricultural revolution since it did not consider local, but important crops grown in the continent. In addition to their versatile adaptation to [...] Read more.
The Green Revolution has enabled Asian countries to boost their crop production enormously. However, Africa has not benefitted from this agricultural revolution since it did not consider local, but important crops grown in the continent. In addition to their versatile adaptation to extreme environmental conditions, African indigenous crops provide income for subsistence farmers and serve as staple food for the vast majority of low-income consumers. These crops, which are composed of cereals, legumes, vegetables and root crops, are commonly known as underutilized or orphan crops. Recently, some of these under-researched crops have received the attention of the national and international research community, and modern improvement techniques including diverse genetic and genomic tools have been applied in order to boost their productivity. The major bottlenecks affecting the productivity of these crops are unimproved genetic traits such as low yield and poor nutritional status and environmental factors such as drought, weeds and pests. Hence, an agricultural revolution is needed to increase food production of these under-researched crops in order to feed the ever-increasing population in Africa. Here, we present both the benefits and drawbacks of major African crops, the efforts being made to improve them, and suggestions for some future directions. Full article
(This article belongs to the Special Issue Sustainable Crop Production)
Open AccessReview Micro-Level Management of Agricultural Inputs: Emerging Approaches
Agronomy 2012, 2(4), 321-357; doi:10.3390/agronomy2040321
Received: 19 October 2012 / Revised: 8 December 2012 / Accepted: 10 December 2012 / Published: 18 December 2012
Cited by 4 | PDF Full-text (436 KB) | HTML Full-text | XML Full-text
Abstract
Through the development of superior plant varieties that benefit from high agrochemical inputs and irrigation, the agricultural Green Revolution has doubled crop yields, yet introduced unintended impacts on environment. An expected 50% growth in world population during the 21st century demands novel [...] Read more.
Through the development of superior plant varieties that benefit from high agrochemical inputs and irrigation, the agricultural Green Revolution has doubled crop yields, yet introduced unintended impacts on environment. An expected 50% growth in world population during the 21st century demands novel integration of advanced technologies and low-input production systems based on soil and plant biology, targeting precision delivery of inputs synchronized with growth stages of crop plants. Further, successful systems will integrate subsurface water, air and nutrient delivery, real-time soil parameter data and computer-based decision-making to mitigate plant stress and actively manipulate microbial rhizosphere communities that stimulate productivity. Such an approach will ensure food security and mitigate impacts of climate change. Full article
(This article belongs to the Special Issue Sustainable Crop Production)

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