Scoring Photoperiod Sensitivity in Barley 1

Photoperiod response in barley ( Hordeum vulgare L.) was studied in short and long‐day environments using selected barley lines and advanced generation populations. In a short‐day environment, days to flowering in selected barley lines ranged from 51 to 140; in a long,lay environment, from 37 to 48 days. In the same short‐day environment, days to node at ground level (NGL) ranged from 28 to 70 and in the long‐day environment from 20 to 30 days. The relative differences among lines were similar whether response was measured by days to NGL or by days to flowering. Also, data from four barley populations indicated that the NGL stage of growth provides a reliable guide to photoperiod sensitivity. Because of certain advantages, espedally saving of time and space in growth chamber experiments, we recommend that days to NGL be considered as an alternative to scoring of flowering as a measure of photoperiod response in barley.