**3.1.2 Statistical analysis**

As there are inherent relationships among weather factors, relatively high correlations may exist among air temperature, solar radiation, vapor-pressure deficit, and wind speed. Therefore, to evaluate their individual effects as well as the cultivar effects on panicle temperature, we analyzed our data by means of generalized linear models and multiple regression procedures using SPSS (Version 14J for Windows, SPSS Japan Inc., Tokyo, Japan). In this analysis, air temperature, solar radiation, and vapor-pressure deficit values were used in one hour intervals between 6000 and 1200 based on Japan Standard Time. The relative contribution of each weather component to panicle temperature was determined using their standardized partial regression coefficients, and the overall strength of the relationships was quantified using the multiple correlation coefficients.
