Sp. Loss et al., ADAPTATION OF FABA-BEAN (VICIA-FABA L) TO DRYLAND MEDITERRANEAN-TYPE ENVIRONMENTS .2. PHENOLOGY, CANOPY DEVELOPMENT, RADIATION ABSORBTION AND BIOMASS PARTITIONING, Field crops research, 52(1-2), 1997, pp. 29-41
Faba bean (Vicia faba L.) was considered poorly adapted to the low-rai
nfall environments of south western Australia because of its susceptib
ility to moisture and heat stresses. As part of a larger study of the
adaptation of faba bean to short-season Mediterranean-type environment
s, faba bean cv. Fiord was sown at three or four dates ranging from ea
rly May to early July at two sites in 1993 and 1994 to examine its phe
nology, canopy development, and biomass partitioning. Faba bean took f
ull advantage of early sowing by producing greater seed yields because
it flowered earlier, had longer durations of anthesis, produced more
nodes, had greater green area index (GAI), absorbed more photosyntheti
cally active radiation (PAR), greater peak and final biomass, more pod
s in the upper canopy, and larger harvest index (HI) than when plantin
g was delayed. Rate of leaf appearance on the main stem was consistent
ly 0.19 leaves day(-1) across sowing times, sites, and seasons, and th
e final numbers of nodes were 20 to 24 with early sowing. Up to 4 stem
s plant(-1) developed under favorable conditions, but some death occur
red and final stem numbers were 2.5 to 3.0 plant(-1) regardless of sow
ing time. Peak PAR absorbtion was about 75-90% at green area indices o
f 4 to 5 with early sowing. The estimated radiation-use efficiency (RU
E) was 1.85 g MJ(-1) and did not vary with sowing time. Unlike most ot
her crops in this environment, faba bean can be sown in autumn (April)
because of its ability to tolerate mild frosts at flowering and poddi
ng, and because it partitions assimilates into pods and seeds early in
the season before severe drought stress commences in spring. Pod set
in this study was adequate for moderate yields and HI was consistently
high. The ability of faba bean to partition assimilates into seed was
not reduced significantly with late sowings, producing HI of 53 to 62
% in 1993 and 33 to 53% in the dry 1994 season.