> wheat.reg1 <- lm(wheatyld ~ temp + rain + temprain)
> summary(wheat.reg1)

Call:
lm(formula = wheatyld ~ temp + rain + temprain)

Residuals:
       Min         1Q     Median         3Q        Max 
-1.910e-06 -6.630e-07 -1.993e-07  7.635e-07  2.097e-06 

Coefficients:
              Estimate Std. Error t value Pr(>|t|)    
(Intercept)  8.321e-06  7.053e-07  11.799 6.09e-12 ***
temp        -3.511e-09  2.210e-09  -1.589 0.124259    
rain        -3.387e-06  7.508e-07  -4.511 0.000122 ***
temprain     4.999e-09  2.444e-09   2.045 0.051065 .  
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 

Residual standard error: 1.067e-06 on 26 degrees of freedom
Multiple R-squared: 0.7252,     Adjusted R-squared: 0.6935 
F-statistic: 22.87 on 3 and 26 DF,  p-value: 1.839e-07 

> anova(wheat.reg1)
Analysis of Variance Table

Response: wheatyld
          Df     Sum Sq    Mean Sq F value    Pr(>F)    
temp       1 4.6100e-13 4.6100e-13  0.4042   0.53046    
rain       1 7.2962e-11 7.2962e-11 64.0298 1.761e-08 ***
temprain   1 4.7670e-12 4.7670e-12  4.1834   0.05107 .  
Residuals 26 2.9627e-11 1.1400e-12                      
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 
> 
> e_wheat <- resid(wheat.reg1)
> 
> par(mfrow=c(3,2))
> 
> plot(fitted(wheat.reg1),e_wheat)
> qqnorm(e_wheat)
> qqline(e_wheat)
> plot(rain,e_wheat)
> plot(temp,e_wheat)
> plot(e_wheat,type="l")
> 
> par(mfrow=c(1,1))
> 
> # Conduct Shapiro-Wilk Normality test on residuals
> 
> shapiro.test(e_wheat)

        Shapiro-Wilk normality test

data:  e_wheat 
W = 0.9756, p-value = 0.7001

> 
> # Conduct Breusch-Pagan Test of Homogeneity of Variance
> 
> library(lmtest)
> 
> bptest(wheatyld ~ temp + rain + temprain,studentize=FALSE)

        Breusch-Pagan test

data:  wheatyld ~ temp + rain + temprain 
BP = 3.6023, df = 3, p-value = 0.3077

> 
> # Conduct Durbin-Watson Test of Uncorrelated Errors
> 
> library(car)
> 
> durbinWatsonTest(wheat.reg1)
 lag Autocorrelation D-W Statistic p-value
   1     -0.07753563      1.991958   0.936
 Alternative hypothesis: rho != 0