Effects of daylength and temperature on growth and yield components of three seed spices

Plants of dill, caraway and coriander were grown in phytotrons at either 18°/12°C or 24°/12°C (day/night temperatures) with 10 h or 16 h photoperiods. In all four combinations the three species reached maturity and producéd seeds. The time to flowering and harvesting was reduced by the long-day treatments, but plant weight and most of the other morphological characteristics measured, except plant height, were reduced as a result of the earlier flowering. Seed yield was highest in caraway in short-days, in dill in long-days and in coriander by the higher temperature treatment. Physiological and practical implications are discussed.