Mixture of wheat varieties for dual purpose

Forage and grain production of an early sown, long-cycle wheat variety (ProINTA Super) was compared to that in its association with a short-cycle wheat variety (Buck Pronoto), both varieties exposed to one or two defoliations. The purpose was producing an earlier and greater amount of dry matter in a dual-purpose wheat. Research was conducted in the Asociacion de Cooperatives Argentinas experimental field (38 degrees 36' S, 61 degrees 58' W, 122 masl). 15 km SW from Cabildo (Bs. As), in the semi-arid V South wheat subregion. Experimental plots, 7 rows 4m long each and 0,20 m apart from each other, were seeded on 4 March 2004. Seeding rate used was 300 viable seeds/m(2) for Super, adding 400 viable seeds/m(2) for the association. The first defoliation was made on 30 April and the second one on 2 July, both to a 7 cm stubble height. Grain harvest was made on 17 December in all treatments. ProINTA Super, cultivated either exclusively for grain production (without defoliation), or dual purpose with one defoliation or associated with Buck Pronto, with one or two defoliations, produced equal grain amounts (average 1940 kg/ha). Seeded early either for dual purpose or associated, both varieties with one defoliation, also produced approximately 2400 kg dry matter/ha. However, when seeded early, associated with the other variety, and both exposed to two defoliations, produced 2080 kg of grain/ha and 4060 kg dry matter/ha.