The research aims to study the negative and positive effects of climate change (maximum temperatures, minimum temperatures, relative humidity, rainfall rate) on the productivity of wheat and maize crops in old and new lands in Egypt's desert governorates. As it became clear from estimating the stepwise regression model using the random model method, the results showed that increasing the maximum temperature in the month of December alone leads to an increase in wheat productivity in the desert governorates of Egypt in the ancient lands by a statistically significant amount of about 0.08 tons/acre, which represents about 2.88%. Of the average wheat productivity across Egypt's desert governorates, which amounts to about 2.825 tons/acre, the minimum temperature in the months of November and March alone leads to an increase in wheat productivity in Egypt's desert governorates in the old lands by a statistically significant amount of about 0.08 tons/acre and 0.07 tons/acre on The arrangement represents about 2.88%, 2.48% of the average wheat productivity across Egypt's desert governorates, which amounts to about 2.825 tons/acre, and the humidity in the month of March alone leads to an increase in wheat productivity in Egypt's desert governorates in the old lands by a statistically significant amount of about 0.03 tons/acre. Which represents about 1.06% of the average wheat productivity across Egypt's governorates, which amounts to about 2.825 tons/acre.
While increasing the maximum temperature in the month of February alone leads to a decrease in wheat productivity in the desert governorates of Egypt in the ancient lands by a statistically significant amount of about 0.5 tons/acre, which represents about 17.7% of the average wheat productivity in the desert governorates of Egypt, the minimum temperature In the months of December and January alone, it leads to an increase in wheat productivity in Egypt's desert governorates in the ancient lands by a statistically significant amount of about 0.03 tons/acre and 0.11 tons/acre, respectively, which represents about 1.06%, 3.89% of the average wheat productivity across Egypt's desert governorates. Humidity in the months of November and May alone leads to a decrease in wheat productivity in Egypt's desert governorates in the ancient lands by a statistically significant amount of about 0.02 tons/acre and 0.02 tons/acre, respectively, which represents about 0.71%, 0.71% of the average wheat productivity across Egypt's desert governorates. The annual average rainfall of one degree for each of them leads to a decrease in wheat productivity in Egypt's desert governorates in the ancient lands by a statistically significant amount of about 0.06 tons/acre, respectively, which represents about 2.12% of the average wheat productivity across Egypt's desert governorates.
As was shown from the results, increasing the maximum temperature, the minimum temperature in June and August in July, and the relative humidity in August for each of them by one degree leads to an increase in the productivity of Levantine maize in the desert governorates of Egypt in the new lands by a statistically significant amount of about 0.21 tons/acre, 0.19. tons/, 0.20 tons/acre, and 0.05 tons/acre, respectively, representing about 7.16%, 6.48%, 6.82%, and 1.70% of the average productivity of Levantine maize at the level of Egypt's desert governorates, amounting to about 2.934 tons/acre, while increasing both The maximum temperature in July, Xi7, by one degree leads to an increase in the productivity of Levantine maize in the desert governorates of Egypt in the new lands by a statistically significant amount of about 0.18 tons/acre, which represents about 6.13% of the average productivity of Levantine maize across Egypt's governorates.