Tesis
Desenvolvimento do arroz e do arroz vermelho: modelagem e resposta à mudança climática
Fecha
2008-02-28Registro en:
LAGO, Isabel. Rice and red rice development: modeling and response to climate change. 2008. 94 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Santa Maria, Santa Maria, 2008.
Autor
Lago, Isabel
Institución
Resumen
Increases of 1.1 to 6.4°C in temperature are projected by the end of the XXI century in
several locations, including Brazil. Among processes that may be affected by increasing
temperatures is the duration of the developmental cycle of crops. Simulation models are tools
that allow to describe the possible interactions that take place in agroecoystems and their
response to climate change scenarios. The objectives of this dissertation were (i) to simulate
the development of irrigated rice and red rice comparing a linear (thermal time model) with a
non-linear (WE model) model, and (ii) to investigate the response of the development of rice
and red rice to climate change scenarios in Santa Maria, RS, Brazil, considering symmetric
and asymmetric increases in minimum and maximum daily air temperatures. Data from a
four-year experiment conducted during the 2003-2004 (five sowing dates), 2004-2005 (five
sowing dates), 2005-2006 (three sowing dates), and 2006-2007 (two sowing dates) growing
seasons in Santa Maria, RS, Brazil were used. Plants were grown in 12 liter pots during the
four years, and in a paddy rice field during the 2006-2007 growing season. Nine cultivated
rice genotypes (IRGA 421, IRGA 416, IRGA 417, IRGA 420, BRS 7 TAIM, BR-IRGA 409,
EPAGRI 109, an Hybrid, and EEA 406), and two red rice biotypes (awned blackhull-
ABHRR, and awned yellowhull-AYHRR) were used. Developmental data available and used
in this study were dates of emergence (EM), panicle differentiation (R1), anthesis (R4), and
all grains with brown hulls (R9) recorded in five plants per replication in each sowing date.
Data collected in the 2004-2005 and 2005-2006 growing season were used to estimate the
coefficients of the two models and data collected in the 2003-2004 and 2006-2007 growing
season were used as an independent data set for models evaluation. A one hundred years
climate scenarios of 0°C, +1°C, +2°C, +3°C, +4°C, and +5°C, with symmetric and
asymmetric increases in minimum and maximum daily air temperatures were created with the
LARS-WG Weather Generator using a 1969-2003 database. Date of developmental stages in
each climate scenario was calculated with the non-linear model (WE model). The root mean
square error (RMSE) for all developmental stages varied from 4.9 to 10.5 days with the
thermal time model and from 4.3 to 10.9 days with the WE model. The WE model gave better
predictions in six out of eleven genotypes, with better predictions for early (R1) than for later
(R4 and R9) developmental stages. The duration of the EM-R1 phase in general decreased
whereas the duration of the R1-R4 and R4-R9 phases most often increased as temperature
increased in the climate change scenarios. The simulated rice development response to
elevated temperature was not the same when the increase in minimum and maximum
temperature was symmetric or asymmetric. Current rice genotypes may be less competitive
with red rice in future climates.