Global efficiency and evapotranspiration: main variables to size irrigation canals
La eficiencia global y la evapotranspiración: variables que determinan la capacidad de canales de riego
Available online: 2012-06-15 / pages 5-11
Capacity of irrigation networks is vital to satisfy peak crop´s water demands and to improve resource use efficiency. The methods to size canal capacity depend on mainly two variables: one agronomic - crop evapotranspiration - and the other hydraulic –system´s global efficiency. However, there is not an integral procedure to estimate the agronomic variable in large irrigation areas with a diversified crop pattern, different planting dates, and several crop seasons. In this paper, a methodology is presented to estimate the integrated evapotranspiration for large irrigation areas that is used to estimate irrigation canal capacity in conjunction with the global efficiency variable. This methodology was applied to the “Santa Rosa” Water Irrigation Association in the 075 Irrigation District located in the state of Sinaloa, Mexico. With the proposed methodology, a value of 4.08 mm·dia-1 was estimated for the integrated evapotranspiration at Water Irrigation Association level. Using a design global efficiency of 49 %, the canal capacity was calculated to be 21.70 m³·seg-1. Considering estimated design discharge and efficiencies used, the results are comprehensive giving flexibility for water distribution. It is concluded that the proposed methodology fulfills its established objective and can be applicable to other cases.
Theoretical model for predicting the cutting place in order to optimize the extraction of the coconut pulp
Modelo teórico para predecir el lugar del corte y optimizar la extracción de la pulpa en coco
Federico F. Hahn-Schlam;
Available online: 2012-06-15 / pages 13-17
Coconut is an important crop produced in Mexican coastal regions. Coconut is sold as fresh water and dried pulp is used to produce vegetable oil. An industrial plant for fresh water extraction lets pulp as residue, which should be also sold. Workers have a great ability to extract coconut pulp after the shells are sun-dried for half a day. A machine for on-line pulp extraction has to be designed, requiring that coconut is sliced in two identical shell pieces for both: transversal and longitudinal cuts. A vision system acquired images from the sliced coconuts obtaining its circularity and Feret diameter. Coconuts cut transversally used a model that measured coconut length with a linear differential transformer; 93 % of the tests presented two identical shells. A simulation was carried out for positioning a round extractor for separating the pulp from the shell. When the centroide was used as the control coordinate pulp losses were over 35 %; a model for positioning the extractor decreased pulp losses to less than 16 %.
Agronomic behavior of creole chili (Capsicum annuum L.) in fertirrigation with plastic mulch and row cover in xalostoc, morelos
Comportamiento agronómico del chile criollo (Capsicum annuum L.) en fertirrigación con acolchado plástico y cubierta flotante en Xalostoc, Morelos
Alejandro Javier Bustos-Rangel;
Miguel Ángel Jaime Hernández
Available online: 2012-06-15 / pages 19-24
A study at the IPRO-UAEM fields in Xalostoc, Morelos, spring-summer 2011, was conducted with the purpose of evaluating the agronomic response of creole chili using plastic mulch, floating row cover, and fertirrigation. The fertilization dose was 220-100-150 per ha of NPK. Black plastic mulch, (T1), silver plastic mulch (T2), black plastic mulch and floating row cover (CFP), (T3), silver plastic mulch and floating row cover (CFP), (T4) and control (T5) were the treatments evaluated, distributed in a randomized complete block design with five treatments and four replicates. The experimental unit consisted of four rows at the spacing of 1 m x 6 m length (24 m2), 30 cm distance between plants, two plants per shrub. Plant height at 30 and 60 days after transplanting (ddt), stem diameter (dt), number of fruits (nf) and fruit diameter (df) were the variables evaluated. The Tukey test α = 0.5 % was used for means comparison. Analysis of variance for plant height showed no significant statistical differences among treatments at 30 and 60 days after transplanting (ddt). Analysis of variances for stem diameter showed significant statistical differences among treatments at 60 days after transplanting, values ranged from 3.57 to 4.82 cm with an average of 3.91 cm. The variable number of fruits showed significant difference among treatments at 30 days; values ranged from 2.10 to 9.31 cm, with an average of 4.89 cm. Analysis of variance for fruit diameter showed significant differences among treatments; values ranged from 1.30 to 1.57 cm, with an average of 1.39 cm.
Evaluation of red pitahaya fruits (Hylocereus undatus) under axial compression load
Evaluación de frutos de pitahaya roja (Hylocereus undatus) sometidos a carga de compresión axial
Missael Bonifacio Romero-Escobedo;
Carlos Alberto Villaseñor-Perea
Available online: 2012-06-16 / pages 25-30
Pitahaya fruits (Hylocereus undatus) were evaluated in commercial maturity harvested in San Gabriel Chilac, Puebla. Compression loads and defor¬mation of fruits were determined until its elastic limit (CLE) and bioyield point (CPB). Then were evaluated the physicochemical and physiological variables at room temperature (20 °C ± 2) for 10 days. The results were: average weight at harvest was 419.4 ± 86.8 g, sphericity of 81.4 ± 4.8 %, surface area of 26,022 mm2, density of 0.93 g•cm-3, a compressive load to elastic limit 0.085 kN (deformation of 0.12 mm•min-1), load to the bioyield point of 0.153 kN (deformation of 0.21 mm•min-1). The concept of threshold load from the mechanical viewpoint doesn´t match the physiological response of pitahaya fruit. We recommended storage pitahaya fruits with a stacking load below the elastic limit load.
Operating rules for the reservoir system of the irrigation district 005 Delicias, Chihuahua, Mexico
Reglas de operación para el sistema de presas del distrito de riego 005 Delicias, Chihuahua, México
Available online: 2012-06-15 / pages 31-39
Water extraction policies and operating rules for La Boquilla and Francisco I. Madero reservoirs system are analyzed and validated. Both reservoirs constitute the main water supply sources for the Irrigation District 005 Delicias, Chihuahua, Mexico. Statistical correlation, linear programming and simulation models of the reservoir operation are applied to define policies and to validate operating rules. The water extraction statistical analysis reveals that, in fact, a rational management system policy, according to the water storage volume at the beginning of the agricultural year, is not being applied; thus the proposed rules are aimed at overcoming this deficiency. Reservoir operation simulation models are applied to validate the rules. The models results show that water use efficiency increases apart from keeping steady water storage levels. Thereby, it is feasible to irrigate each year the same land surface area, decrease spills and prevent water shortage, which enables a steady economy in the region.
Physical, geometrical and mechanical characterization of huitlacoche (Ustilago maydis (D.C.) Corda)
Caracterización física, geométrica y mecánica de huitlacoche (Ustilago maydis (D.C.) Corda)
Carlos Alberto Villaseñor-Perea;
Available online: 2012-06-15 / pages 41-45
Physical, geometrical and mechanical properties of huitlacoche cobs were assessed. The average values of weight, geometric mean diameter, sphe¬ricity, the external surface area and volume of huitlacoche were: 259.7 g, 78.4 mm, 65.5 %, 196.03 cm2 and 266.9 cm3, respectively. The color of the peridium is located in the gray scale (L * = 40.4, hue = 86.9, chroma = 5.0). The peridium breaking to the puncture strength was 1.4 N, and the breaking strength of the huitlacoche cob by compression was 377 N with a deformation of 2.9 mm•mm-1.