Some water use responses of barley, lupin and rapeseed

Abstract

Barley, lupin and rapeseed were sown in the field on five occasions at Woogenellup, Western Australia. Dry matter accumulation, water use and meteorological data were measured for each crop and sowing time. Potential evapotranspiration functions were calculated for each crop, showing that barley required less water per unit of dry matter when water was not limiting than either of the other crops. Actual evapotranspiration functions were also calculated and showed only small differences between the relative water use of the species when soil water was limiting. The water use, yield and maturity characteristics of the three crops were used to estimate the likely range of sowing times for three locations in the Albany region based on average cumulative rainfall. Barley was found to have the highest water use efficiency (kg grain mm-1 of water used) of the three crops, especially under drier conditions, and was most suitable for late sowing. The yield and water use efficiency of lupin decreased with later sowing and rapeseed was the least efficient species in terms of water use. The results are also discussed in terms of dryland cropping strategies, water use in relation to dryland salt accumulation, and adaptive characteristics of the three crops.