Persian lemon in the Mexican counties of Nayarit and Veracruz: Foliar sampling period for nutritional diagnosis

English. ABSTRACT In Mexico, Nayarit and Veracruz stand out as producers of Persian lemon. Nayarit has a larger surface area with high production potential and a 68% expansion of its cultivated area in the last 10 years. Veracruz has larger planted area and production volume. This investigation was conducted aiming to determine the period of nutritional stability in Persian lemon leaves and define the appropriate time to perform foliar sampling for nutritional diagnosis. In 2017, rainfed orchards were selected in both states. Per orchard, 20 trees were selected, 50 shoots were marked per flow (Nayarit winter and summer, Veracruz winter and spring), and sampled monthly. Soil and foliar nutrient analysis was performed (total nitrogen (N-total) (semi-microKjeldahl digestion), nitrates (NO3) (colorimetry), potassium (K) (atomic absorption), phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn), (ICP-Optical Coupled Plasma using an ICAP 7200 spectrophotometer (Thermo Scientific®), and boron (B) (colorimetry) (Genesis 20 spectrophotometer (Thermo Scientific®)). Daily predicted values were calculated and the best functions (highest R2, lowest mean square of the error and value of the Mallows coefficient) were chosen. Mathematical derivatives and criteria were calculated to determine the best period for sampling. For Nayarit, the appropriate period for leaf sampling was the summer flush of July 29 to August 18 and from February 8 to March 19 for the winter flush. In Veracruz, it was from April 10 to May 10 for the winter flush and from September 23 to October 8 for the spring flush.

Spanish; Castilian. RESUMEN En México, destacan Nayarit y Veracruz como productores de limón Persa. Nayarit por mayor superficie con alto potencial productivo y expansión de 68% en su área cultivada en los últimos 10 años. Veracruz por mayor superficie sembrada y volumen de producción. Esta investigación se realizó con el objetivo de determinar el período de estabilidad nutrimental en hojas de limón Persa y definir el período apropiado para muestreo foliar para diagnostico nutrimental. En 2017 se seleccionaron huertos de temporal en ambos estados. Por huerto se eligieron 20 árboles, se marcaron 50 brotes por flujo (Nayarit invierno y verano, Veracruz invierno y primavera), y se muestrearon mensualmente. Se realizó análisis de suelo y nutrimental foliar (nitrógeno total (N-total) (digestión semi-microKjeldahl), nitratos (NO3) (colorimetría), potasio (K) (absorción atómica, fósforo (P), azufre (S), calcio (Ca), magnesio (Mg), cobre (Cu), fierro (Fe), manganeso (Mn) y zinc (Zn), (ICP-Plasma acoplado óptico empleando un espectrofotómetro ICAP 7200 (Thermo Scientific®), boro (B) (colorimetría) (espectrofotómetro Genesis 20 (Thermo Scientific®)). Se calcularon los valores predichos diarios y se eligieron las mejores funciones (mayor R2, menor cuadrado medio del error y valor del coeficiente de Mallows). Se calcularon las derivadas matemáticas y el criterio para determinar el mejor periodo para el muestreo. Para Nayarit, el período apropiado para muestreo foliar fue: verano del 29 de julio al 18 de agosto e invierno del 08 de febrero al 19 de marzo. En Veracruz fue: invierno del 10 de abril al 10 de mayo, primavera del 23 de septiembre al 08 de octubre.