Opuntia ficus–indica (L.) Mill. yield depends on nutrients and nutrient ratios
Keywords:Nitrogen, Phosphorus, Potassium, Calcium, Magnesium, Stoichiometry.
Opuntia ficus–indica (L.) Mill. is growing in 25 countries to harvest its fruit (cactus pear), young cladodes (stems or ‘nopalitos’) and mature cladodes. Mexico is the only country with commercial production of ‘nopalitos’ of O. ficus–indica (L.) Mill. covering 12,041 ha with annual mean yields, at farm level, ranging from 9.03–99.93 t ha–1, and an overall average of 64.33 t ha–1. This great variability of annual mean yields is associated with a wide range of farming systems that differ in terms of crop management practices such as fertilization, a labor closely related to satisfy the nutritional requirements of cultivated species. Nutrient balance in crop science is an indirect effect of nutrient interactions on biotic or commercial yield. In this regard, a database (n = 360) of yield (biomass) and nutrient concentrations of N, P, K, Ca and Mg from an experiment established at El Orito, Zacatecas, Mexico during April 1999 was used to identify yield dependence on nutrients and nutrient ratios through Pearson correlation coefficients. Yield is significantly (p ? 0.05) dependent on N, Mg, Ca and K concentrations in one–year old cladodes. The K:ln P, ln Ca:ln P, and ln Mg:ln P mass ratios have a positive effect on yield; whereas the ln P:ln N, ln Mg:ln N, and ln N:ln Ca ratios negatively affect the production of biomass.