Development of a statistical method based on phenotypic parameters to determine the age of agave salmiana and its correlation with plant composition

ABSTRACT. A statistical model was developed to estimate the age of plants of Agave salmiana salmiana. This species is originally from Mexico and it has been used to produce alcoholic beverages such as mezcal and pulque. Producers do not know the best age to industrially exploit this plant. The content of reducing sugars has been empirically correlated with the age, but to the best of our knowledge, there is no known method to determine the age of plants with ease and high precision. In the present study, phenotypic parameters easily determined by visual inspection or with rudimentary tools were used to develop a statistical model to estimate the age of plants. The parameters selected were the height and diameter of central meristem, the diameter of rosette and the number of leaves. The study was performed in two phases; the first was to develop the model and the second to determine the composition of reducing sugars and agavins and correlate it with age. During the first phase, the phenotypic parameters of 233 plants of 1, 2 and 3 years old were measured and linear models were developed. The height of central meristem is the parameter the most indicated to estimate the age of plants with a determination coefficient of R2= 0.945. This statistical model was used to analyze the variation of reducing sugars and agavins with the age of plants. Four ages of plants were selected (4, 6, 8 and 10 years) from a non-controlled plantation. The wet mass of plants, reducing sugar content and fructan content increased with the age of plants. In the case of reducing sugars, their content was also a function of the section of leaves, being higher in the point of leaves and smaller in the base of leaves.