Articles
ABOVE-GROUND ASSIMILATE PARTITION IN BELL PEPPER (CAPSICUM ANNUUM L.) FOR PROCESSING UNDER MEDITERRANEAN CONDITIONS
Article number
654_24
Pages
221 – 229
Language
English
Abstract
The aim of this study is to construct a simple empirical model to simulate dry matter (DM) partition of pepper under non-limiting growth conditions.
During three years (20002002) pepper crop was field grown in Southwestern Portugal on a total of nine planting dates.
Every two weeks, DM partition to above-ground plant parts and fruit number were determined, and phenological development stages were daily assessed.
Air temperature was continuously measured above the crop.
Developmental stage is simulated using a normalised scale that divides the current thermal time, above a base temperature of 7°C, by the thermal time at the beginning of flowering (i.e. normalised thermal time, Nτ). Part of the data were 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 Nτ was closely fitted by a piecewise function.
An expolinear relation between fruit DM and total aerial DM was found (r2 = 0.97). In order to set an upper limit for the amount of assimilate that can be allocated to fruits, average fruit weight in relation to Nτ was fitted by a logistic function (r2 = 0.92), and fruit number per plant in relation to Nτ was fitted by an expolinear function (r2 = 0.77). Daily potential fruit growth is calculated by the product of the number of fruits and the average fruit DM increment, where this is obtained by differencing the logistic function.
DM allocated to the various plant components was then simulated and the model validated.
It is possible that the approaches presented in this study hold for the case of water and nutrient limited growth.
The performance of this simple approach was validated, and the associated statistics are reported.
During three years (20002002) pepper crop was field grown in Southwestern Portugal on a total of nine planting dates.
Every two weeks, DM partition to above-ground plant parts and fruit number were determined, and phenological development stages were daily assessed.
Air temperature was continuously measured above the crop.
Developmental stage is simulated using a normalised scale that divides the current thermal time, above a base temperature of 7°C, by the thermal time at the beginning of flowering (i.e. normalised thermal time, Nτ). Part of the data were 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 Nτ was closely fitted by a piecewise function.
An expolinear relation between fruit DM and total aerial DM was found (r2 = 0.97). In order to set an upper limit for the amount of assimilate that can be allocated to fruits, average fruit weight in relation to Nτ was fitted by a logistic function (r2 = 0.92), and fruit number per plant in relation to Nτ was fitted by an expolinear function (r2 = 0.77). Daily potential fruit growth is calculated by the product of the number of fruits and the average fruit DM increment, where this is obtained by differencing the logistic function.
DM allocated to the various plant components was then simulated and the model validated.
It is possible that the approaches presented in this study hold for the case of water and nutrient limited growth.
The performance of this simple approach was validated, and the associated statistics are reported.
Publication
Authors
M.I. Vieira, M.E. Ferreira, J.P. de Melo-Abreu
Keywords
modelling, dry matter distribution, fruit growth
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