PRODUCTION PRACTICES FOR IMPROVED GRAIN-YIELD AND QUALITY OF SOFT WHEATS IN WESTERN-AUSTRALIA

The aim of our experiments was to determine whether the soft-grained, club-head wheats used for the Australian Soft grade (cvv. Tincurrin an d Corrigin), required different management to maximise grain yield and quality than the standard-head wheats used for other grades. Two seri es of field experiments were conducted in the 300-500 mm rainfall zone in the southern wheatbelt of Western Australia between latitudes 32 a nd 34 degrees S from 1989 to 1993. Agronomic variables examined in the experiments included sowing time, nitrogen (N) fertiliser and seed ra te. Grain yield, grain protein concentration, hectolitre weight and sm all grain sievings (below a 2 mm slotted screen) were measured on the grain samples. It was concluded that the optimum time for sowing the s oft wheats, both of which are of mid-season maturity, was May. Small g rain sievings and grain proteins of the soft wheats exceeded the recei val standards for the grade when sown outside this period and were mor e sensitive to earlier or later sowings in this regard than the other wheats. The soft wheats had smaller kernels and were more likely than other cultivars to produce grain samples with high levels of sievings associated with sowing at inappropriate times and the use of N fertili ser. They had consistently 1-1.5% lower grain protein concentrations t han the other cultivars used in the experiments. Hectolitre weights se ldom fell below the receival standard of 74 kg/hL for any of the grain samples. Increasing seed rate did not increase the level of sievings at all sites. Although sievings were affected by sowing time, N fertil iser and cultivar, there were large influences associated with site fa ctors that also caused excessive sievings. Fertile sites where the cro p did not respond to N fertiliser and sites where the crop was infecte d by leaf rust were associated with high levels of sievings. Standard- head wheats were less susceptible to dockages, but lower yielding than the club-head, soft wheats. Seed rates for the soft wheats should be chosen to maximise yield rather than to attempt to avoid price dockage s at receival.