Apart from sowing time and varieties, you can study irrigation, nutrients, microbial treatments, method of planting/sowing, spacing with respect to response on plant growth and development characters.
It depends of the aim and goal of your experiment. The question is what do you want to investigate. The influence of daylight length on some yield components, or what?
However, in fact you can study crop weather relationship even without treatments of sowing windows and different varieties, only on the basis of historical data. Please, see these references under the following links.
1. Article Empiric mathematical model for predicting the content of alp...