Above-ground assimilate partition in bell pepper (Capsicum annuum L.) for processing under Mediterranean conditions.

摘要

A study was conducted to develop a simple empirical model to simulate dry matter (DM) partitioning of pepper (C. annuum) under non-limiting growth conditions. Pepper crop was field-grown in southwestern Portugal during 2000-02, with 3 planting dates (second fortnight of April and first and second fortnight of May) per year. Every 2 weeks, DM partitioning to aboveground plant parts and fruit number were determined, and phenological development stages were daily assessed. Air temperature was continuously measured above the crop. Developmental stage was simulated using a normalized scale that divides the current thermal time, above a base temperature of 7 degrees C, by the thermal time at the beginning of flowering (i.e. normalized thermal time, N tau ). A part of the data was used to derive empirical relations and the remaining data were latter used in the validation process. The relation between the fraction of vegetative DM in leaves (and stems) in relation to N tau was closely fitted by a piecewise function. An expolinear relation between fruit DM and total aerial DM was found (r2=0.97). To set an upper limit for the amount of assimilate that can be allocated to fruits, average fruit weight in relation to N tau was fitted by a logistic function (r2=0.92), and fruit number per plant in relation to N tau was fitted by an expolinear function (r2=0.77). Daily potential fruit growth was calculated by the product of the number of fruits and average fruit DM increment, where this was obtained by differentiating the logistic function. DM allocated to the various plant components was then simulated and the model validated. It is possible that the approaches presented hold for the case of water- and nutrient-limited growth. The associated statistics are reported.