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Villavicencio, Colombia

The diagnosis and recommendation integrated system (DRIS) is an efficient method for evaluating the nutritional status of crops and was initially developed for rubber. In Colombia, the size of the rubber crop has grown significantly during the last decade, but recommendations do not yet exist for crop nutrition management at a local level. The aim of the present study wasto determine preliminary DRIS norms for rubber clone RRIM 600 under the conditions found on the Eastern Plains of Colombia. To this end, 78 leaf samples were collected, 19 of which were classified as high-yield, showing production above 2,690 kg ha-1, while the remaining 59 samples were classified as low-yield. The highest variance ratio and the value of R were used as criteria for selecting DRIS norms and were found to present differences, only coinciding for 32 of the studied ratios. The calculation of the DRIS indexes was carried outusing the determined norms; and K was found to be the element that most strongly limited production and showed the greatest probability of exhibiting a response upon exogenous application. Additionally, small quantities of Cu and S can generate imbalances that influence the yield of this clone.

Sugar production in sweet sorghums is affected by the environment. Therefore, in this study on the effects of the genotype x environment interaction on sugar accumulation, plant traits associated with the sugar content in the stem were evaluated in ten sorghum genotypes grown in six contrasting environments. The results indicated that the stem dry weight, juice sugar concentration (ºBrix), stem sugar content and juice volume were controlled by the genetic constitution of the genotype, with a large environmental contribution to their expression. The results allowed for the identification of the sweet sorghum genotypes that have a high potential for the biofuel agroindustry due to their high sugar contents in the environmental conditions of Palmira, Espinal, Cerete and Codazzi. Humid tropical environments such as Gaitan and Villavicencio were less favorable for the competitive production of sweet sorghums for bioethanol due to their low levels of solar radiation and soil fertility. © 2014, Universidad Nacional de Colombia1. All rights reserved.

Te Citrus leprosis virus CiLV-C is a quarantine disease of economic importance. Over the past 15 years, this disease has spread to several countries of Central and South America. Colombia has about 45,000 hectares of citrus planted with an annual production of 750,000 tonnes. Te CiLV-C has only been detected in the departments of Meta, Casanare and recently Tolima. Meta has 4,300 hectares representing 10% of the national cultivated area, and Casanare, where CiLV-C appeared in 2004, has no more than 500 ha planted with citrus. Te presence of the citrus leprosis virus in Colombia could afect the international market for citrus, other crops and ornamental plants with the United States and other countries without the disease. Te false spider mite Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) is the main vector of the CiLV-C. Disease management is based on control programs of the vector and diminishing host plants. Chemical mite control is expensive, wasteful and generates resistance to diferent acaricides. Tis paper provides basic information on CiLV-C and its vector, advances in diagnosis and methods to control the disease and prevention of its spread.

Chaparro-Zambrano H.N.,La Libertad Research Center | Velazquez H.A.,La Libertad Research Center | Orduz-Rodriguez J.O.,La Libertad Research Center
Agronomia Colombiana | Year: 2015

‘Valencia’ sweet orange is widely cultivated in Colombian tropical lowlands, with low yields and a lack of technology. As a result, nine rootstocks commonly used in tropical zones: ‘C-35’, ‘Carrizo’, ‘Swingle’ citrumelo or CPB 4475, ‘Cleopatra’, ‘Sunki × English’, ‘Volkamer’, ‘Webberi’ and ‘Yuma’ were evaluated. The plants were established in 2001 and were evaluated for vegetative growth, fruit yield and quality for 10 years (2004-2013). The obtained results indicated that ‘Sunki × English’ and ‘Volkamer’ were the best rootstocks for fruit yield and the worst was ‘Yuma’. Furthermore, all of the rootstocks, except ‘Yuma’, stabilized their height in the last year. In terms of volume, ‘Amblycarpa’ and ‘Cleopatra’ were the bigger plants and ‘Yuma’ was the smallest. In addition, for yield efficiency, ‘Yuma’ had the best rootstocks, followed by ‘Sunki × English’. All of the rootstocks showed a similar fruit quality, except for ‘Sunki × English’, which obtained the highest total soluble solids/total titratable acids ratio. © 2015, Universidad Nacional de Colombia1. All Rights Reserved.

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