Effect of time of sowing on flowering in faba bean (Vicia faba)

Abstract

Sequential sowings of faba bean (Vicia faba) were conducted to examine the effect of sowing date and a vernalisation treatment on the phenology of a range of faba bean accessions. There was very little difference between accessions in the rate of germination. Delayed sowing increased the time to establishment, but the thermal time from sowing to emergence did not vary greatly. On average 208¦C.day was required for emergence and the base temperature for germination was near 0¦C for all accessions. The shortest time from emergence to first flower averaged over all sowing dates was 43 days for Accession 286 (range 29-52 days), and the longest was 73 days for Accession 863 (50-96 days). The greatest response to vernalisation occurred when the seed was sown in early autumn (April). When sown in late winter (August), however, there was little response to vernalisation despite the plants being exposed to higher mean temperatures. In that case, long and lengthening days partly overcame the vernalisation requirement of some cultivars. For the range of sowing dates normally expected in dryland crops in southern Australia, there was little effect of vernalisation on the time to flowering and the major controls of development were through responses to temperature and daylength. The range of maturity types in the current breeding program appears sufficient to extend the range of environments in which faba bean is grown.