Simulation the Effect of Climate Change on Growth Period and Yield of three Hybrids of Maize (Zea mays) under Low Irrigation Conditions (Case study: Moghan Plain)

According to the present state of climate science, the increase in greenhouse gas concentrations will result in changes of the climate parameters; particularly, an increase of the global temperature and changes in precipitation are expected. These changes in climate, which are likely to occur during future decades, may have significant consequences (positive or negative) on the development, growth, and crops yield. Climate change and its impacts on water recourses is known as one of the most important challenges which human would be faced with it in future century. Future climate change in each region can be predicted through the models of the Globa Circulation Model (GCM). It is also possible to investigate the effect of climate change on the yield and the water requirement of plants using performance predictive models as Aquacrop model. The main objective of this study is to assess the effect of climate change on the future climate of Moghan plain and also, simulation three corn hybrids parameters such as grain yield, biomass yield and growth period of corn, under different irrigation treatments.

In this study, AquaCrop model was used to simulate grain yield and biomass of different maize hybrids under the future climate in different irrigation treatments. For this purpose, rainfall data, minimum temperature, maximum temperature and sunshine model of the LARS-WG fine-scale model with using six general circulation models (ADCM3, HadCM3, IPCM4, GFCM2, NCCCSM INCM3), for which three scenarios the fourth report of the Climate Change Board (A1B, A2, and B1) was predicted and reviewed for the Moghan region during 1970-2010, 2011-2030 and 2046-2065. AquaCrop model was calibrated and validated by field data (2015 and 2016 year), corn plants collected in the area. Then, the grain and biomass yield values in the upcoming periods for different irrigation treatments (I1 = normal irrigation, I2 = irrigation cut off at vegetative growth stage, I3 = irrigation cut during flowering stage and I4 = irrigation cut off at the seed filling stage) different maize hybrids (C1 = SC704, C2 = SC703 and C3 = SC705).

According to the results, in the statistical period of 2011-2030 compared base periods (1970-1999), the average monthly temperature was 1.41, 1.35, and 1.66 ° C, respectively for scenarios A1B, A2, and B1. Also, the average monthly rainfall will be reduced to of 6, 11 and 15 mm, respectively, for scenarios A1B, A2 and B1, and during 2046-2065 periods, compared to period of 1979-2010. Furthermore, the monthly average of the temperature will be increased to 2.9, 2.69 and 2.32 ° C respectively, for scenarios A1B, A2 and B1. During this period, the amount of rain reduction was estimated at 18, 15 and 14 millimeters, respectively, in scenarios A1B, A2, and B1. The results of simulation of grain yield and total biomass of maize cultivars under the influence of irrigation administrations using AquaCrop model showed that the root mean square variables of seed and dry matter yield errors in years 2015 and 2016 were 413 and 891 kg.ha-1. The root mean square mean of normalized error of seed and dry matter yield was 11 and 10%, respectively. Also, with using future meteorological data under different scenarios was observed that growth period, grain yield and biomass yield during 2011-2030 and 2046-2065 periods for three scenarios A2, B1 A1B were decreased. Among the cultivars studied, Hybrid SC704 corn had more growth and yield than other corn hybrids, and this figure could be recommended for future climate change for Moghan area.

Future meteorological data under different scenarios of climate change will decrease growth period, grain yield and biomass yield during 2011-2030 for scenarios A1B, A2 and B1, respectively, 7 %, 16 % and 9%, and during period 2045-2065 for scenarios A1B, A2 and B1, respectively, 13 %, 14 % and 12 percent. Among the cultivars studied, the growth period of SC 704 hybrid was higher for all three scenarios than other hybrids and it has more growth and yield, therefore can recommended to change future climate for Moghan region.