Influence of 2,3,5‐triiodobenzoic acid (TIBA) On Soybeans Planted in Different Cultural Systems¹

Field studies were conducted over a 2‐year period at Urbana, Ill., with two soybean varieties [ Glycine max (L.) Merr.], to evaluate their response to 2,3,5‐triiodobenzoic acid (TIBA) in various cultural management systems. Soybean yields increased as row spacing decreased from 101.6 to 25.4 cm. Compared to the yield from the 101.6 cm row spacing, the increase was 10, 18, and 20% for 76.2, 50.8, and 25.4 cm row spacings, respectively. The variety ‘Wayne’ outyielded ‘Harosoy 63’ at all row spacings and TIBA treatments. TIBA had little effect on yield at the 101.6, 76.2 and 25.4 cm row spacings, but caused a yield increase of about 6.5% with both varieties at the 50.8 cm row spacing. For both varieties, TIBA treatment significantly reduced height and lodging at all row spacings, increased pod set, and decreased seed weight. Neither TIBA nor row spacing influenced oil or protein composition of the seed.