Division of Horticulture, I.A.R.I., New Delhi-110 012.
The effect of GA (100 and 200 ppm), thiourea (100 and 200 ppm) and kinetin (10 and 20 ppm) on germination of freshly extracted and stored seeds was investigated in four citrus species-amilbed, Kama khatta, trifoliate orange and Florida rough lemon. The germination of fresh seeds was enhanced in amilbed, trifoliate orange, Florida rough lemon by GA, in Karna Khatta and Florida rough lemon by thiourea and in Florida rough lemon by kinetin. No germination was recorded in seeds stored for six weeks with or without treatments containing plant growth regulators in any of the four species. In freshly extracted seeds, level of ±-amylase, total phenolic and inhibitory substances were not found to be related to the germination in the four citrus species studied. But it appears that high accumulation of phenolic substances is connected with the inhibition of germination in seeds stored for six weeks.
