Inheritance of the light intensity response in spring cultivars of common wheat

The effects of low/high light intensities and day length on ear emergence time in climatic chambers were studied in 12 common wheat (Triticum aestivum L.) cultivars of different ecogeographical origin. Low light intensity (LI) affected the time to ear emergence in all the wheat cultivars of both the photoperiod sensitive and insensitive genotypes, increasing the number of days to ear emergence (DEE). Based on the increase in DEE, we chose samples with different light intensity responses among the cultivars and analyzed their F2 hybrids to see if they were segregating. Taken together, the data for the F2 plants and test cross showed that the strong response to light intensity is a recessive trait and that the parental cultivars differ by the two genes controlling the LI response in common wheat. Besides heading time, low LI increased the number of days to tillering in all the cultivars except Pitic 62, but short day affected the period to tillering less than low LI. The symbol Rli (the response to light intensity) is suggested to designate the genetic control of the response to LI in wheat. Thus, the response to LI may influence the adaptability to changing environmental conditions and yield of wheat cultivars.