Field Crop 2024, Vol.7, No.2, 45-57 http://cropscipublisher.com/index.php/fc 47 optimized sowing dates, reducing the risk of water deficits and stabilizing yields across different rainfall gradients (Figure 1) (Otegui et al., 2021). Furthermore, empirical analysis in the United States has indicated that GM technology reduces the adverse effects of maize-maize rotation on yield, thereby offering good prospects for future productivity improvements (Chavas et al., 2014). Figure 1 (A) Schematic representation of leaf area index (LAI) evolution (in green) for early- and late-sown maize crops in a representative location (Pergamino) of the Central humid region of Argentina. Mean historic values of incident solar radiation (Solar Rad) and air temperature (Temp) are shown in red and blue, respectively. (B) Water balance evolution for the same region, based on the difference between rainfall and potential evapotranspiration (PET) (Adopted from Otegui et al., 2021) Image caption: Lines are representative of the median (50%) and the 25% and 75% percentiles. Vertical dashed arrows correspond to the estimated silking date of each crop in (A). (C-E) Water stress index for crop growth under dryland farming, obtained with the CERES-Maize model for a historic series of 41 climate records for Pergamino (1978-1979 to 2018-2019). Data represent the extreme phases of the ENSO phenomenon (La Niña and El Niño, with 14 years each) as well as mean values across all seasons. Vertical arrows indicate the median for silking (black) and physiological maturity (gray), together with the corresponding number of days after sowing. Horizontal arrows indicate the vegetative (green) and reproductive (orange) periods. (C) Sowing on 20 September with soil at field capacity up to 1.8 m depth. (D) Sowing on 10 Dec with soil as in (C). (E) Sowing on 20 December with the uppermost 60 cm soil layer at field capacity and the rest at 30% of plant-available soil water (Adopted from Otegui et al., 2021) 3.2 Reduction in pesticide use The adoption of GM maize has led to a substantial reduction in pesticide use, contributing to more sustainable agricultural practices. On average, GM technology has reduced chemical pesticide use by 37% (Klümper and Qaim, 2014). Specifically, the introduction of Bt maize, which expresses insecticidal proteins from Bacillus thuringiensis, has significantly decreased the need for insecticides. This reduction in pesticide use has been particularly notable in the United States, where the use of insecticides on maize has declined substantially since the introduction of GM crops (Coupe and Capel, 2016). Additionally, the global adoption of GM crops has been estimated to reduce pesticide use by millions of kilograms annually, with significant environmental benefits such as reduced diesel consumption and lower carbon dioxide emissions (Phipps and Park, 2002).
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