version ISSN 1668-298X
The utilization of dual purpose wheat crops may contribute to perform a more efficient use of environmental resources. In Balcarce (Buenos Aires, Argentina) a wheat crop (Triticum aestivum, cv. Baguette 20) was seeded at an early date (March 17, 2006) and the forage production was compared with three defoliation frequencies: T1 (three defoliations); T2 (two defoliations) and TG (without defoliations). The aerial biomass, grain yield (kg ha-1) and its components were quantified (g DW m-2) for these three and for a non defoliated treatment seeded at a normal date for grain production (Jun 7, TN). Accumulated forage production by T1 was smaller than for T2 (497 and 392 g m-2, respectively). The defoliations after two nodes (stage Zadoks 32) affected negatively the photosynthetically active radiation intercepted by the crop, diminishing the number of grains m-2 and the weight per grain; in consequence, the production of grain fell 60% with respect to TG and 71% with respect to TN. A quantitative relationship between the decrease of grain yield and the moment of the last cut (i.e., days between the last defoliation and anthesis) was established. With double purpose wheat, it is feasible to obtain a grain production that is not to be expected with other forage winter crops.
Keywords : Wheat; Forage production; Grain yield; Defoliation timing.