Adaptation of faba bean (Vicia faba L) to dryland Mediterranean-type environments. I. Seed yield and yield components

Faba bean (Vicia faba L.) was thought unsuitable for commercial dryland production in short-season Mediterranean-type environments because of its susceptibility to moisture and high temperature stresses. Faba bean cv. Fiord was sown at four dates ranging from early May to early July at 7 sites in 1993 and 5 sites in 1994 in south western Australia. In 1993, seed yields varied from 2.0 to 4.2 t ha(-1) when sown in early May. The following year was one of the driest in decades at most sites, and yields varied from 0.8 to 1.8 t ha(-1) when sown in mid to late May. In both years, yields declined with delayed sowing at a rate of 13.5 to 56.0 kg ha(-1) day(-1) depending on the site and season. Faba beans produced their first flowers earlier than other grain legumes and cereals in this environment (63 to 90 days after sowing), tolerated mild spring frosts, and had consistently high harvest indices (37-62%). Seed number per pod was relatively consistent across times of sowing, while mean seed weight decreased with delayed sowing in dry environments. Seed yield was most strongly correlated with number of pods m(-2). This study demonstrates that faba bean can produce impressive biomass and seed yield in a range of dryland Mediterranean-type environments. This is the first study to demonstrate that given a suitable cultivar, faba bean is adapted to dryland Mediterranean-type environments with 300 to 400 mm yr(-1) average rainfall; however, early sowing is critical for high seed yields. (C) 1997 Elsevier Science B.V.