In Nayarit, Mexico, it is common to perform leaf analyses in mango for nutrient diagnosis; however, the appropriate period to carry out leaf sampling is unknown, so procedures extrapolated from other producing regions are used, which leads to incorrect diagnoses. The aim of this research was to identify the appropriate leaf sampling period (ALSP) in ‘Ataúlfo’, ‘Kent’ and ‘Tommy Atkins’ mangos grown without irrigation. From 2006 to 2007 we worked with commercial orchards in the north, center and south of Nayarit. In ‘Ataúlfo’ and ‘Kent’ the spring (SpVF) and summer vegetative flushes (SuVF) were considered, and in ‘Tommy Atkins’ the SpVP and autumn one (AVF). Leaf samplings were performed monthly, starting when the leaf reached 5 cm in length and concluding upon its abscission. For each nutrient, a mathematical model was obtained to generate functions that predicted its concentration during the life of the leaf. Subsequently, we calculated the derivatives of each function, which enabled us to identify the period in which the concentration of nutrients presented the least variation and thus define the ALSP. In ‘Ataúlfo’, the ALSP for the SpVF and SuVF was from 9 to 11 and 3.3 to 5.3 months of age, respectively; in ‘Kent’, this period was from 8 to 10.5 (SpVF) and 3.2 to 5.0 (SuVF) months, and in ‘Tommy Atkins’ it corresponded to leaves from 8.7 to 12.2 (SpVF) and 8.6 to 9.4 (AVF) months. The mathematical procedure used was adequate to identify the ALSP in the three mango cultivars.

The cape gooseberry (Physalis peruviana L.) is an exotic fruit with a growing international market. In Mexico, there is little research on its growth and mineral nutrition. Therefore, the objective of this study was to determine the growth dynamics and yield of cape gooseberry cultivation based on three Steiner nutrient solution concentrations (50, 100 and 150 %) under greenhouse conditions. The experiment was established in Cuernavaca, Morelos, Mexico (18º 58’ 51’’ North latitude and 99º 13’ 55’’ West longitude, at 1,866 masl). The accumulated heat units (HU) were determined and the occurrence of the phenological phases was recorded during crop development. Crop growth was assessed through the number of leaves, leaf area and dry matter accumulated per plant. At harvest, the number and weight of fruits (with and without calyx) were recorded. The phenology of cape gooseberry cultivation was favored with the highest concentration of the nutrient solution, requiring 1,370 HU from transplant to ripeness; this represented 15 and 5 days of precocity compared to the other concentrations: 1,527 HU (50 %) and 1,435 HU (100 %), respectively. The highest leaf production, leaf area, dry matter, crop growth rate and fruit weight (with and without calyx) were obtained with the Steiner nutrient solution at 100 and 150 %, so it is suggested to use the 100 % solution.

El índice de madurez del fruto de Vanilla planifolia Jacks. ex Andrews se considera importante para obtener vainilla de calidad. En México, la cosecha se realiza cuando la parte distal del fruto se torna amarilla, pero no hay evidencia de los beneficios de esta práctica. El objetivo de este trabajo fue evaluar la calidad del fruto de vainilla a los 224, 252 y 273 días de edad, y su relación con el perfil de aroma de la vainilla beneficiada. Las flores de Vanilla planifolia se polinizaron manualmente en una plantación comercial y los frutos se cosecharon en cada fecha correspondiente. Las variables evaluadas fueron humedad, materia seca y contenido de azúcares (glucosa, fructosa y sacarosa), y en fruto beneficiado fueron vainillina, ácido p-hidroxibenzoico, ácido vainillínico y p-hidroxibenzaldehído. Los resultados mostraron que el contenido de materia seca y la concentración de azúcares de los frutos verdes de 252 días fueron significativamente menor (14.92 y 10.6 %, respectivamente) que el resto de los tratamientos. Asimismo, en frutos beneficiados de 252 días, el contenido de ácido p-hidroxibenzoico, ácido vainillínico y p-hidroxibenzaldehído fue significativamente menor (103, 855 y 1434 mg∙kg-1 , respectivamente) que los de 224 días de edad (148, 1132 y 2035 mg∙kg-1, respectivamente). Los frutos de 252 días tuvieron una calidad inferior, posiblemente porque su cosecha coincidió con el mes más frío, lo cual pudo afectar la acumulación de materia seca y de compuestos aromáticos

One way to mitigate the negative effects of high temperatures (HT) on crops is the use of plant genetic resources, and Mexico, as a center of domestication of tomato (Solanum lycopersicum L.), has numerous native varieties. The objective of this study was to evaluate the physical and physiological quality of seeds of three native tomato varieties and a commercial one, from fruit produced under HT conditions. The native varieties used were ‘Campeche (C-40)’, ‘Yucatán (Y-25)’ and ‘Malinalco (M-430’), and the commercial one was ‘Moneymaker’ (MM). For the production of the fruit, two greenhouses were used, one ventilated for the control treatment (C) (34.2 ºC) and the other with heating for the HT (38 ºC) treatment. The physical and physiological quality of the seeds of the fourth-cluster fruit of each treatment was evaluated. The values obtained for the weight of 1000 seeds, seed length and width, electrical conductivity (EC) and the rate of radicle emergence after accelerated aging were higher (P ≤ 0.05) in the HT treatment, while the germination (G) percentage was higher (P ≤ 0.05) with the C. The EC correlated inversely with G (r² = -0.7*), which may indicate that HT affects membrane permeability and in turn G.