************** just tipped GPP, page-93

a) applying the bs in lab conditions (it didn't look like it was in a cold room) compared to applying outdoors in winter are likely to result in different take up rates of the bs. Which if it rains shortly after application could result in it being washed off. Alternatively, is it degraded by sunlight?
b) is the equipment capable of applying at the rate of 10lt/ha? That's a very low rate. With about 1,000,000 seeds/ha that's one hundredth of a millilitre per plant, some will be lost to the soil and it will have to be a fine spray so wind would be a problem.
c) a full cycle, ~120 days, in the field in winter is most likely to give different results to a lab test after 79 days.
d) variability. In the lab water and light are controlled. What happens if there's no rain, and thus very little growth, for a month after application? Does the effect of the bs wear off if the plant can't benefit from it immediately? Or no sun?
e) how critical is the window for application? If you miss it by a month because of weather or ground conditions, does that affect the yield?

Yes, a lot of ifs and maybes, but that's why you do field trials.