Modeling the response of maize phenology, kernel set, and yield components to heat stress and heat shock with CSM-IXIM

LIZASO, J.; RUIZ RAMOS, M.; RODRIGUEZ, C.; GABALDÓN LEAL, C; OLIVEIRA, J.A.; LORITE, I.J.; RODRIGUEZ, A.; MADDONNI, G.A.; OTEGUI, M.E.

FIELD CROPS RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 214 p. 239 - 252

0378-4290

The available evidence suggests that the current increasing trend in global surface temperatures will continueduring this century, which will be accompanied by a greater frequency of extreme events. The IPCC has projectedthat higher temperatures may outscore the known optimal and maximum temperatures for maize. Thepurpose of this study was to improve the ability of the maize model CSM-IXIM to simulate crop development,growth, and yield under hot conditions, especially with regards to the impact of above-optimal temperaturesaround anthesis. Field and greenhouse experiments that were performed over three years (2014?2016) using thesame short-season hybrid, PR37N01 (FAO 300), provided the data for this work. Maize was sown at a targetpopulation density of 5 plants m−2 on two sowing dates in 2014 and 2015 and on one in 2016 at three locationsin Spain (northern, central, and southern Spain) with a well-defined thermal gradient. The same hybrid was alsosown in two greenhouse chambers with daytime target temperatures of approximately 25 and above 35 °C.During the nighttime, the temperature in both chambers was allowed to equilibrate with the outside temperature.The greenhouse treatments consisted of moving 18 plants at selected phenological stages (V4, V9, anthesis,lag phase, early grain filling) from the cool chamber to the hot chamber over a week and then returning theplants back to the cool chamber. An additional control treatment remained in the cool chamber all season, and in2015 and 2016, one treatment remained permanently in the hot chamber. Two maize models in the DecisionSupport System for Agrotechnology Transfer (DSSAT) V4.6 were compared, namely CERES and IXIM. The IXIMversion included additional components that were previously developed to improve the crop N simulation and toincorporate the anthesis-silking interval (ASI). A new thermal time calculation, a heat stress index, the impact ofpollen-sterilizing temperatures, and the explicit simulation of male and female flowering as affected by the dailyheat conditions were added to IXIM. The phenology simulation in field experiments by IXIM improved substantially.The RMSE for silking and maturity in CERES were 7.9 and 13.7 days, decreasing in IXIM to 2.8 and7.3 days, respectively. Similarly, the estimated kernel numbers, kernel weight, grain yield and final biomasswere always closer to the measurements in IXIM than in CERES. The worst simulations were for kernel weight,and for that reason, the differences in grain yield between the models were small (the RMSE in CERES was1219 kg ha−1 vs. 1082 kg ha−1 in IXIM). The greenhouse results also supported the improved estimations ofcrop development by IXIM (RMSE of 2.6 days) relative to CERES (7.4 days). The impact of the heat treatments ongrain yield was consistently overestimated by CERES, while IXIM captured the general trend. The new IXIMmodel improved the CERES simulations when elevated temperatures were included in the evaluation data.Additional model testing with measurements from a wider latitudinal range and relevant heat conditions arerequired.