Adaptation of faba bean (Vicia faba L.) to dryland Mediterranean-type environments .3. Water use and water-use efficiency

As part of a larger study examining the adaptation of faba bean (Vicia faba L.) to short-season Mediterranean-type environments, faba bean cv. Fiord was sown at four dates ranging from early May to early July at five sites in 1993 and six sites in 1994 in southwestern Australia. Evapotranspiration (ET), i.e. crop water use was measured at two sites using a neutron moisture meter and estimated at other sites from daily rainfall measurements to examine the water use and water-use efficiency (WUE). ET from sowing to maturity decreased significantly with delayed sowing; however, all soil moisture was depleted at crop maturity in all treatments. When soil evaporation (Es) before the late sowings was taken into account, ET of the various sowing times did not differ. As has been shown in other crops in similar environments, the pattern of water use is an important parameter determining seed yield in faba bean and there was a significant correlation (P < 0.01) between post-anthesis ET and seed yield (r(2) = 0.70). The ratios of pre-anthesis to post-anthesis ET of early sown faba bean were less than 1.3 and much less than ratios reported for other crops in short-season Mediterranean-type environments. The estimated WUE for both dry matter production and seed yield from early sown faba bean (up to 36 and 14 kg ha(-1) mm(-1) respectively) were comparable to those reported for cereals and greater than those for other grain legumes in similar environments. The estimated value of Es (110 mm) and maximum achievable transpiration efficiency (TE, 20 kg ha(-1) mm(-1)) commonly used for cereals grown in southern Australia also appeared to be valid for faba bean. (C) 1997 Elsevier Science B.V.