EFFECT OF SEED SOURCE AND SEED PHOSPHORUS-CONTENT ON THE GROWTH AND YIELD OF WHEAT IN NORTH-EASTERN VICTORIA

Wheat (Triticum aestivum L.) seed was grown at 2 locations differing i n phosphorus (P) status (low and high) in north-eastern Victoria (36 d egrees S, 146 degrees E), with applied superphosphate (kg P/ha: 0, 12, 24, 100 and 200), to produce seed of different P content. This seed w as used in field and glasshouse experiments in 1993 and 1994 to invest igate the effects of seed source and P content on the growth and yield of wheat. Wheat seed grown at the low P status site was smaller than seed grown at the high P status site, irrespective of the amount of ap plied P. Seed from the low P status site produced less early dry matte r in both field and glasshouse experiments in 1993, but there was no e ffect of seed source on grain yield in either experiment. High seed P content either had no effect or reduced seedling emergence in the fiel d experiments. In the glasshouse, low P content in seed from the low P status site resulted in reduced emergence. Increases in dry matter pr oduction and grain yield with higher seed P content were only observed in the drought season of 1994, Application of P resulted in increased emergence, dry matter production and grain yield at most seed P conte nt levels but there were no significant interactions between seed P co ntent and applied P. Application of N did not affect dry matter produc tion in either year, but increased grain protein in both years and gra in yield in 1993. Seed from low P status environments can affect early seedling growth but in average growing seasons, or in glasshouse cond itions, wheat growth compensates so that differences in grain yield ar e not observed. However, in order to avoid risk of poor early seedling growth and possible yield penalties when the crop is stressed, wheat seed should be collected from adequate soil P status sites.