A Quantitative Scale of Spike Initial and Pistil Development in Barley and Wheat

Spring barley cv. Koru and spring wheat cv. Highbury were grown in constant controlled conditions of 16 h photoperiod, and temperatures of 10 and 15 °C respectively. A range of spike growth and developmental attributes were closely monitored from seedling emergence to pollination in the most advanced floret. Simple, quantitative scales of development from seedling emergence (0) to pollination (10) are proposed, based on the morphogenesis of the spike initial, then the floret and finally the pistil. These scales allow developmental (ontogenetic) progress to be quantified without involving any attribute of growth or size of the plant or its organs.