II. 11. Day-length sensitivity in spring barley.
S.O. Fejer and George Fedak. Ottawa Research Station, Ottawa, Ontario, Canada.
Some years ago we noticed that a number of barley introductions from the Middle East remained in the vegetative stage in our California winter nursery where all our other barley material consistently produced high kernel yields. We ran a test in our Ottawa phytotron under 12 and 16 hour day-lengths and found that while some very early cultivars such as Mari and Gateway had spike emergence dates 30-40 days from sowing under both day-lengths, many of the introductions needed twice the time under the shorter days, and some did not show any spike emergence even after more than 100 days under short days, and were very late (70-80 days) under long days. Three of the latter introductions were intercrossed in a diallel fashion with Olli, representing extreme day-length insensitivity, Mari, reported in the literature to belong in the same category, and Conquest, an average cultivar. The F1, tested under long days, surprisingly showed relative earliness in the crosses between the "sensitive" introductions (33 days), compared to the group between "insensitive" cultivars (43 days), with some very early segregates in crosses between groups (26 days), with an average of 30 days which could be ascribed to heterosis. However, one F1 between "sensitives" (not in the diallel, discontinued) stayed vegetative in 80 days. In the F2, with a limited number of lines in the growth rooms, values for "sensitives" were 29 days (with lines as early as 25 days), for "insensitives" 38 days, and for hybrids 28 days with some record early ones of 22 days. At the same time the latest lines (65 days) also occurred in the hybrids and 3 of them (outside the diallel) remained vegetative in 80 days. In the GCA values of both generations, the late values for cultivars were clearly separated from the earlier "sensitive" introductions. Thus there must be separate genetic control of day-length sensitivity and earliness in this material. Further work with F3 lines is in progress to elucidate the situation and get an idea about the number of genes involved.