Fig. 4. Seasonal progress of silk emergence for the plant population and individual apical ears. (a,c) Pioneer 3978 (P3978); (b,d) Pioneer 3925 (P3925). (a,b) Cumulative percentage of plant population at silking (solid lines) and cumulative number of silks exserted on the apical ear (broken lines). (c,d) Daily percentage of plant population that has started silking (solid lines) and daily number of silks exserted from the apical ear (broken lines).