José Dimas López-Martínez

Compositional Nutrient Diagnosis in Maize Grown in a Calcareous Soil

ABSTRACT Preliminary compositional nutrient diagnosis (CND) norms for maize (Zea mays L.) were developed from a small database as means and standard deviations of row-centered log ratios V X of five nutrients [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] and a filling value R, which comprised all nutrients not chemically analyzed and quantified in 72 leaves of hybrid ‘Pioneer 3044.’ Norms were derived from maize grain yields higher than 7.7 t ha−1. Principal-component analysis performed using CND nutrient indexes allowed us to identify an antagonism between N and Mg explained by the calcareous nature of the soil and the relevant N fertilization with ammonium (NH4 +), and a positive interaction between P and K, and P-Ca and K-Ca antagonisms. Maize plants tended to take up lower amounts of N and K and higher amount of Mg in our calcareous soil than the concentrations of these nutrients reported to be optimum.

Measurement of Capsaicinoids in Chiltepin Hot Pepper: A Comparison Study between Spectrophotometric Method and High Performance Liquid Chromatography Analysis

Direct spectrophotometric determination of capsaicinoids content in Chiltepin pepper was investigated as a possible alternative to HPLC analysis. Capsaicinoids were extracted from Chiltepin in red ripe and green fruit with acetonitrile and evaluated quantitatively using the HPLC method with capsaicin and dihydrocapsaicin standards. Three samples of different treatment were analyzed for their capsaicinoids content successfully by these methods. HPLC-DAD revealed that capsaicin, dihydrocapsaicin, and nordihydrocapsaicin comprised up to 98% of total capsaicinoids detected. The absorbance of the diluted samples was read on a spectrophotometer at 215–300 nm and monitored at 280 nm. We report herein the comparison between traditional UV assays and HPLC-DAD methods for the determination of the molar absorptivity coefficient of capsaicin ( and  M−1 cm−1) and dihydrocapsaicin ( and  M−1 cm−1), respectively. Statistical comparisons were performed using the regression analyses (ordinary linear regression and Deming regression) and Bland-Altman analysis. Comparative data for pungency was determined spectrophotometrically and by HPLC on samples ranging from 29.55 to 129 mg/g with a correlation of 0.91. These results indicate that the two methods significantly agree. The described spectrophotometric method can be routinely used for total capsaicinoids analysis and quality control in agricultural and pharmaceutical analysis.

Impacto del estiércol bovino en el suelo y producción de forraje de maíz

La demanda de forrajes en la Comarca Lagunera ha obligado a que el maiz sea permanente en el padron de cultivos, para sostener la produccion de forraje es necesario manejar adecuadamente el suelo. El objetivo de este estudio fue determinar el impacto de la aplicacion de estiercol bovino en el pH, conductividad electrica (CE), materia organica (MO), nitratos (NO3) y amonio (NH4) de un suelo arcilloso y su efecto en la produccion de forraje de maiz. El trabajo se realizo en la Facultad de Agricultura y Zootecnia-UJED, en 1998 a 2007. Los tratamientos de estudio fueron 40, 80, 120 y 160 Mg ha-1 de estiercol bovino lechero, testigo absoluto y tratamiento quimico 100-150 (kg ha-1; N-P), bajo un diseno bloques al azar, tres repeticiones. La variable medida en planta fue forraje verde. Los tratamientos de 160 y 120 Mg ha-1 de estiercol incrementaron 189 y 180% la MO del suelo, (4 y 3.8%). Para nitratos, los mejores tratamientos fueron 120 y 160 Mg ha-1 de estiercol, con valores finales de 22.25 y 21.33 mg kg-1. La CE se incremento arriba de 4 dSm-1 en cinco anos en los tratamientos de estiercol; no aplicando estiercol en el sexto ano bajaron estos valores hasta niveles normales para el desarrollo y produccion de maiz con rendimientos arriba de la media regional (45 Mg ha-1) en los tratamientos de estiercol. La aplicacion del estiercol con monitoreo regular del suelo es una buena alternativa para el productor lechero, manteniendo buenos rendimientos de forraje y calidad del suelo