Question

land Resources distribution and utilization ​

Answer 1

Answer:

Objective statistical methods were used to determine the overall climatic sensitivity of wheat yields in Sonora, Mexico and the Southern United States Great Plains. The major differences between the two cultures can ultimately be ascribed to ‘genetic’ factors. The research was conducted to determine if the high-yielding variety (HYV) package is more sensitive to climatic fluctuation than the more traditional U.S. regime. Improved design Thompson-type models were developed for both areas, and were accepted as valid after tests on independent data. Both models had an rms error of 7% of the mid-1970s yields, when run on data withheld from the original specification. After validification, a series of sub-models were constructed that use successively less of the 1970s and 1960s data. Doing this corresponds to a removal of more and more HYV years from the Sonora model, while a similar period of increase (though non-HYV) is modeled in the U.S.A. The magnitudes of the regression coefficients of the most important climatic determinants of yield were then examined for significant changes. Yield sensitivities were found to increase approximately 300% in the Sonora model, while the results for the U. S. A. are more equivocal. The nature of the two agricultural packages suggest that the differences are ultimately ‘genetically’ related, and stem from changes in cultural practice related to the dwarfing gene. Because of physical limitations on the Sonora irrigation system, it is unlikely there will be an environmental remedy for this problem in the near future.