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Yarce C.J.,Colombian Sugarcane Research Center Cenicana | Rojas G.,ICESI University
Zuckerindustrie | Year: 2012

About ten years ago, NIR technology was implemented at the Colombian Sugarcane Research Center Cenicaña for the analysis of sugarcane quality, followed by the development of methodologies for the quantification of some elements in soils and sugarcane leaves. Methodologies were based on the presence of high content materials, such nitrogen, potassium, calcium, and magnesium; however, determination of micronutrients which are found in soils and leaves in the range of parts per million has been challenging. Development of a NIR methodology for quantification of macro (N, P, K, Ca, Mg) and micronutrients (Cu, Zn, Mn, Fe) in a single experiment is here reported. Calibration curves were constructed using approximately 500 samples that were previously analyzed by methods of reference such atomic absorption. Statistical analysis of the data showed that there are not significant differences between the methods of reference and NIR, suggesting that NIR is a very fast, economical and convenient methodology for the daily analysis of sugarcane leaves.

Rodriguez L.A.,Colombian Sugarcane Research Center Cenicana | Valencia J.J.,Colombian Sugarcane Research Center Cenicana | Urbano J.A.,Riopaila Castilla S.A. Sugar Mill
Journal of Terramechanics | Year: 2012

Four tire types (A, block-shape tread; B, rib-shape tread; C, low-lug tread; D, high-lug tread) used to harvest and transport sugarcane were compared regarding the compaction induced to the soil. Tires were tested at three inflation pressures (207, 276, 345 kPa) and six loads ranging from 20 to 60 kN/tire. Track impressions were traced, and 576 areas were measured to find equations relating inflation pressure, load, contact surface and pressure. Contact surface increased with increasing load and decreasing inflation pressure; however, the contact pressure presented no defined pattern of variation, with tire types A and B generating lower contact pressure. The vertical stresses under the tires were measured and simulated with sensors and software developed at the Colombian Sugarcane Research Center (Cenicaña). Sensors were placed at 10, 30, 50 and 70 cm depth. Tire types A and B registered vertical stresses below 250 kPa at the surface. These two tires were better options to reduce soil compaction. The equations characterizing the tires were introduced into a program to simulate the vertical stress. Simulated and measured stresses were adjusted in an 87-92% range. Results indicate a good correlation between the tire equations, the vertical stress simulation and the vertical stress measurement.

Vargas G.,Colombian Sugarcane Research Center Cenicana | Vargas G.,Agricultural Research Center Hays | Michaud J.P.,Agricultural Research Center Hays | Nechols J.R.,Kansas State University
Entomologia Experimentalis et Applicata | Year: 2013

Maternal effects can mold progeny phenotypes in various ways and may constitute ecological adaptations. By examining the effect of oviposition sequence on progeny produced by different size classes of female ladybird beetles (produced by controlling larval access to food), we show that maternal signals can change through adult life and alter the developmental programs of progeny, ostensibly to synchronize their life histories with predictable resource dynamics, thus maximizing maternal fitness. We also show that female body size, as determined by larval food supply, interacts with female age to influence progeny fitness. When fed ad libitum as adults, small females reared with limited food access laid fewer, smaller eggs than large females reared with ad libitum food access. Maternal body size interacted with oviposition sequence to influence progeny development, but the latter had greater impact. Eggs laid later by medium and large females hatched faster than those laid earlier, larvae fed longer in the fourth instar, their pupation period was shorter, total developmental time was reduced, and adults emerged with greater mass, most notably daughters. Oviposition sequence effects on progeny from small mothers were non-significant for total developmental time and progeny mass. Only large mothers increased egg size over time and egg mass was not consistently correlated with developmental parameters, indicating that progeny phenotype was impacted by other, more cryptic, maternal signals. Such signals appear costly, as food limitation during development constrained not only fecundity and egg size but also maternal ability to manipulate progeny phenotype. The production of faster-developing offspring that mature to larger sizes late in the oviposition cycle may be adaptive for exploitation of ephemeral aphid outbreaks with predictable dynamics of prey abundance and competition. © 2012 The Netherlands Entomological Society.

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