Full explanation
Tillering drivers: (1) day length (short — suppresses, long — stimulates); (2) temperature (optimum +10–15°C); (3) N supply (high N at BBCH 20–25 → maximum tillering); (4) water (drought at tillering — major loss of productive tillers); (5) variety (intensive, low-VRN — weak tillering, require dense sowing; extensive — strong tillering, allows thinner sowing). Winter wheat in Ukraine: autumn tillering produces 3–5 shoots before winter entry; spring adds 1–3, of which 60–80% become productive. Shoot count: productive-stem density at BBCH 30–32 is a direct yield predictor. Standard: 600–900 productive stems/m² for 6–8 t/ha wheat; <500 signals insufficient tillering, may require earlier and higher first N topdressing.