Maize kernels were soaked for 16 h in solutions containing the
growth regulators BAS 106.W at 40 or 80 mg/l, PP333 at 80 or 160
mg/l, or BNO 0184 at 100 or 150 mg/l. The plant growth
regulator (PGR)-treated kernels and water-soaked controls were sown in
planting trays, and seedling transplants were raised in a glasshouse
for 24 days. When they were planted in the field, the PGR-treated
plants were significantly shorter than controls, with average plant
heights (measured from soil level to uppermost leaf collar) of
4·7 cm (BAS 106.W, 40 mg/l), 3·7 cm (BAS 106.W, 80
mg/l), 6·1 cm (PP333, 80 mg/l), 8·0 cm (PP333,
160 mg/l), 6·4 cm (BNO 0184, 100 mg/l), 7·1 cm
(BNO 0184, 150 mg/l) and 11·0 cm (controls). The dwarfing of
PGR-treated transplants was mainly due to shortened leaf insertions of
the lower leaves. Shoot weights were little affected by PGR-treatment,
since decreased plant heights were partly compensated for by thicker
stems and broader leaves. PGR effects on leaf numbers were negligible.
At crop maturity, PGR-treated plants and controls showed similar grain
weights and harvest indices. A partial leaf removal treatment at
planting using untreated seedlings was associated with rapid crop
establishment in the field and like the PGR treatments, it had no
significant effect on final yield. It is suggested that a PGR-treatment
with a short term dwarfing effect would facilitate the production and
handling of maize seedling transplants and may improve establishment
and early growth in the field.