INVESTIGADORES
ECHARTE Laura
artículos
Título:
Enhancing the ability of CERES-Maize to compute light capture
Autor/es:
J.I. LIZASO; W.D. BATCHELOR; M.E. WESTGATE; L. ECHARTE
Revista:
AGRICULTURAL SYSTEMS
Referencias:
Año: 2003 vol. 76 p. 293 - 311
ISSN:
0308-521X
Resumen:
Recently it has been proposed to use the relationship between average intercepted photosynthetically
active radiation (IPAR) around silking and total number of seeds per plant as
the basis to improve kernel number prediction in CERES-Maize. However, there has been no
previous evaluation of the accuracy of IPAR predictions in the model. The objectives of this
work were to evaluate CERES-Maize predictions of IPAR around silking by testing their
components incident PAR, light extinction coefficient (k), and leaf area index (LAI), and to
develop alternative methods to simulate PAR and k. Measured IPAR was averaged over a
thermal time window of 250 before to 100 growing degree-days after silking and compared
with model predicted IPAR averaged over the same thermal time window. Independent data
sets were used to develop and test new relationships to predict fraction of PAR to solar
radiation as a function of incident total solar radiation, and canopy extinction coefficient as a
function of the crop phenological age. The new relationships were incorporated into CERESMaize
and the new IPAR predictions were compared with measured values. We found that
the common assumption of predicting PAR as 50% of the solar radiation overestimated PAR
for our conditions in Iowa, where a value of 43% worked better. The extinction coefficient
changed with crop development, reaching a peak of 0.66 at silking, and being lower early and
late in the season. The best IPAR predictions were obtained when the new procedures to
convert solar radiation into PAR and estimate k were coupled with the original leaf area
model of CERES-Maize. # 2003 Elsevier Science Ltd. All rights reservedk), and leaf area index (LAI), and to
develop alternative methods to simulate PAR and k. Measured IPAR was averaged over a
thermal time window of 250 before to 100 growing degree-days after silking and compared
with model predicted IPAR averaged over the same thermal time window. Independent data
sets were used to develop and test new relationships to predict fraction of PAR to solar
radiation as a function of incident total solar radiation, and canopy extinction coefficient as a
function of the crop phenological age. The new relationships were incorporated into CERESMaize
and the new IPAR predictions were compared with measured values. We found that
the common assumption of predicting PAR as 50% of the solar radiation overestimated PAR
for our conditions in Iowa, where a value of 43% worked better. The extinction coefficient
changed with crop development, reaching a peak of 0.66 at silking, and being lower early and
late in the season. The best IPAR predictions were obtained when the new procedures to
convert solar radiation into PAR and estimate k were coupled with the original leaf area
model of CERES-Maize. # 2003 Elsevier Science Ltd. All rights reservedk. Measured IPAR was averaged over a
thermal time window of 250 before to 100 growing degree-days after silking and compared
with model predicted IPAR averaged over the same thermal time window. Independent data
sets were used to develop and test new relationships to predict fraction of PAR to solar
radiation as a function of incident total solar radiation, and canopy extinction coefficient as a
function of the crop phenological age. The new relationships were incorporated into CERESMaize
and the new IPAR predictions were compared with measured values. We found that
the common assumption of predicting PAR as 50% of the solar radiation overestimated PAR
for our conditions in Iowa, where a value of 43% worked better. The extinction coefficient
changed with crop development, reaching a peak of 0.66 at silking, and being lower early and
late in the season. The best IPAR predictions were obtained when the new procedures to
convert solar radiation into PAR and estimate k were coupled with the original leaf area
model of CERES-Maize. # 2003 Elsevier Science Ltd. All rights reservedk were coupled with the original leaf area
model of CERES-Maize. # 2003 Elsevier Science Ltd. All rights reserved# 2003 Elsevier Science Ltd. All rights reserved