Abstract
Plantago ovata was successfully grown in the Ord River Irrigation Area. Optimal sowing rates and layouts found in these trials agreed with Indian experience, suggesting that broadcasting of seed at 8-12 kg ha-1 was optimal. The optimum time of sowing ranged from 7 May in 1985 to 1 June in 1986. Harvest index was dramatically affected by seasonal conditions, with a mean of 19.5% and 1985 and 13.2% in 1986. This harvest index reduction in 1986 was due to the higher vegetative yields as well as lower seed yields. In 1985 the seed yield for crops sown on the optimal date was 1.36 t ha-1. In 1986, yields fell from 1.08 to 0.43 t ha-1 from the optimal to last showing date. Reducing yields from later sowings were principally due to less potential light interception as a result of shorter growth duration. Conversion of available light into biomass was also lower in 1986. The rate of progress towards flowering and maturity could not be explained by the base temperature/base photoperiod model of Hadley et al. (1984)
