Effects of gibberellic acid and cycocel on colouring and sizing of lemon

The effects of autumn applications of GA₃ and CCC on colouring and sizing of ‘Lisbon’ lemon (Citrus limon (L.) Burm. f.) were investigated over a period of 6 years. The implications of regulating the colour and size of lemon on extending its harvest were also assessed.A combination of GA₃ at 10 p.p.m. and CCC at 1000 p.p.m. delayed colouring and arrested growth of lemons, thus extending harvest into late spring by increasing the supply of small-sized premium quality fruit. The effects on colouring could be ascribed to the inhibition of carotenogenesis and the decline in the rate of chlorophyll losses which, although primarily GA₃ effects, were enhanced by CCC. Fruit circumference was reduced and juice content was probably less in the early developmental stages.