Transplanted maize (Zea mays) for grain production in southern England. III. Effects of plant growth regulator treatments on maize transplant morphology

Abstract

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.