THE EFFECT OF TEMPERATURE ON SEED SET AND EMBRYO DEVELOPMENT IN RECIPROCAL CROSSES OF WHEAT AND BARLEY

The effect of temperature on seed set and embryo development in recipr ocal crosses of barley and wheat was assessed in crosses involving two spring barley varieties (Betzes, Martonvasari 50) and one wheat varie ty (Chinese Spring). Detached tillers placed in nutrient solution were pollinated in controlled oiled environments at constant day-night tem perature regimes (12, 15, 18 and 21 degrees C) with a light intensity of 30,000 lux and a relative humidity of 80%. When barley was used as the female, lower temperatures (12 and 15 degrees C) produced the maxi mum seed set, whereas for the reciprocal cross, the highest temperatur e (21 degrees C) produced the best seed set in the Chinese Spring x Be tzes combination. Low temperature retarded the embryo development. The highest numbers of hybrid plants were produced at 18 degrees C and 21 degrees C in the barley x wheat cross and in the wheat x barley cross , respectively. Embryos of about 1.5 mm length in the barley x wheat c ross, and of about 1.0 mm length in the wheat x barley cross germinate d successfully The smallest embryo giving rise to hybrid plants was 0. 57 mm in the barley x wheat cross and 0.51 mm in the wheat x barley cr oss.