A model for potato growth and yield under tropical highland conditions

Abstract

Based on crop and climate data for 1983–1984 in Rwanda at three altitudes ranging from 1350 m to 2350m above sea level, a regression model based on a radiation and temperature dependent conversion coefficient between intercepted solar radiation and dry matter production was developed and validation was carried out in 1984–1985. Total dry matter ( TDM) production in this model depends on the accumulated intercepted photosynthetically active radiation ( IPAR) and a net conversion coefficient ( NCC). ( IPAR) depends on mean daily photosynthetically active radiation ( PAR), on the proportion of ground covered with green leaves ( PGC) and a ground cover conversion ratio ( GCCR) between IPAR and PGC. NCC depends on the PAR dependent gross conversion coefficient ( GCC) via a temperature correction factor ( TCF): TDM = IPAR × NCC IPAR = PGC × GCCR × PAR GCCR = 0.8 for normal crops and GCCR = 1.0 for crops developing abundant foliage NCC = GCC × TCF GCC = 5.59 − 0.21 × PAR TCF = 0.992 − 0.0193 × TEMP Tuber dry matter, in this model, is the product of TDM and the harvest index. The model also includes information on the temperature dependence of tuber dry matter content and the number of tubers per plant.