Grain yields of field pea (Pisum sativum L.) in South Australia

The grain yield of field pea (Pisum sativum L.) between 1959-60 and 1991-92 was examined in selected Hundreds in important peagrowing regions of South Australia. Over the 33 years, the rates of increase in grain yield have been substantial, ranging from 20 to 48 kg/ha.year. The rate of increase in the State average for the same period was 22 kg/ha. year. The largest rates of increase have occurred mainly in the Hundreds in the higher rainfall areas. Yields have increased irregularly. During the 1960s grain yields rose relatively slowly, but from the mid 1970s to the mid 1980s, large increases occurred. Since then, yields have increased relatively little or, in some Hundreds, declined. With one exception, grain yield was positively and significantly correlated with seasonal (April-October) rainfall in each Hundred, but there were few significant correlations with rainfall in individual months. Yield was often correlated with winter and autumn rainfall but not with spring rainfall. The efficiencies of seasonal water use in the Hundreds ranged from 2.7 to 4.8 kg/ha.mm; these were lower than the maximum values recorded for other winter grain legumes, suggesting that water use efficiencies can improve substantially.