I am a firm believer in Analysis of Covariance which is basically regression anlysis with continuous and dummy variables. Statistical significant of regression coefficients are hypothesis test on the factors. But why do I favor this approach? Because differences in variables, other than the major one you are testing, can be better detected (meaning a sharper analysis can be performed). Parsimony in variables, is however, important due to confounding and the actual accuracy for which regression coefficients can be estimated. You may wish to build a simulation model using a hypothetical distribution of reputed effects for the variable of interest and ACTUAL DISTRIBUTIONS FOR ALL OTHER VARIABLES IN THE REGRESSION MODEL. This will test and give guidance on the issues of variables construction, number of variables including interaction terms, and assuming a positive effect for the variable of interest, how good is your model design (statistically speaking since you know apriori the strenght of variable of interest hypothetically) in actually uncovering the effect.
Talk to some experts in the field to discuss why yield results vary (as a potential variable of interest). For example, sunlight may vary from plot to plot, so create a dummy variable to measure the differences in access to light(or water or wind or nitrogen delivery). Whatever factors you are using MUST be determined in advance (by a prior experiment, for example) and supported by expert opinion.
As a final word, which you may of aware of, Analysis of Variance models (ANOVA) can all be transformed into equivalent regression model forms. This is important because if some of the underlying assumptions are invalid (for example, normally distributed error terms), use the regression literature to suggest fixes (for normality issues, Box-Cox Analysis of Transformation) and even Robust Regression models (like Least-Absolute Deviations, Median Regression, etc). Also, from the perspective of Bayesian Regression Analysis, the results go from yes/no in ANOVA to a whole distribution of possible results.
Don't be surprised however if this suggestion is resisted by your professor as he may be poorly schooled in regression analysis (and how to fix assumption violations), spreadsheet based skills needed in constructing random variables for your simulation model, and anything about Robust Regression Analysis. By the way, if the simple ANOVA model has good attributes (or weak), your simulation exercise we confirm (or warn you).