Results
Growth response to early sowing under field
conditions
To study the impact of sowing date on sunflower development\sout, we
performed two field experiments with different sowing dates in 2021 and
2022. The pattern of plant and canopy growth differed between ES and
normal sowing (Fig. 2). Although the growth rate of the canopy cover did
not differ with ES (Fig. 2E), the latent phase was ca. 25 days longer
(60 d, vs. 35 d with normal sowing). This was consistent with lower
vigor (i.e., plant emergence) in the cold treatment (Fig. 2A) and the
observation that the number of days required for leaves to fully develop
was nearly twice as long with ES (45 d) than with normal sowing (25 d)
(Figure 2D). Once emerged, plants grew significantly slower with ES (1.4
cm/d) (Fig. 2C) than with normal sowing (2.2 cm/d) (Fig. 2F).