Modeling sugar content of pineapple under agro-climatic conditions on Reunion Island

A process-based model simulating the change in total soluble solids (TSS (%)) in fruit flesh was developed to describe the effect of climatic conditions on the sugar content of 'Queen Victoria' pineapple at harvest on Reunion Island. Sugar content varies throughout fruit development according to three processes (the supply of carbohydrates to the fruit, fruit metabolism, and dilution) which are affected by environmental factors, mainly temperature, rainfall and fertilization. The ecophysiological model of soluble sugar accumulation was linked to SIMPIÑA, a crop model that accurately predicts the daily increases in flesh dry and fresh weight. When the process-based model and crop model were linked, the dry and fresh matter of the pineapple flesh, as affected by climatic conditions, could be used as inputs to predict the TSS (%) at harvest. The relative rate of transformation of carbon as sugars in the fruit flesh for the synthesis of compounds other than sugars was estimated during fruit growth. TSS (%) were compared for harvested fruit grown under eight agro-climatic conditions. In the flesh of fruit harvested close to maturity, i.e., at 1400 degree-days after flowering, TSS (%) were significantly related (r2 = 0.55, P < 0.001) to total soluble sugar content. The variability of TSS (%) between the eight agro-climatic groups ranged from 16.9 for pineapples grown in dry locations irrigated, under N-deficit conditions to 19.4 for pineapples grown in dry locations, without irrigation and without N deficiency. The variability of TSS (%) was substantial within each of the eight agro-climatic groups: standard deviations ranged from 0.9 to 1.5 for pineapples grown in dry locations, irrigated, without N deficiency and in dry locations, without irrigation and without N deficiency, respectively. For data from 14 experiments conducted under different climatic conditions, N fertilization, and irrigation conditions, the model predicted the TSS (%) at harvest with an RRMSE of 0.04