Twenty-two sugarcane genotypes were subjected to either 30 or 50 photo-
inductive days at a constant 12.5 hrs daylength then followed by decreasing
daylength at a rate of 30 secay until reach to 11.5 hrs daylength to investigate their
flowering performance.
Results of individual and combined analysis of variance over two inductive
cycles revealed significant differences among genotypes for duration of pre-flag leaf
stage. duration of flag leaf stage. duration of emergence stage. minimum days to
flower. maximum days to flower. duration of flowering period and percent of total
flowered plants.The difference between inductive cycles was significant for all
characters except for duration of panicle emergence and duration of flowering
period.The genotypes I inductive cycles interactions were significant for all studied
characters.
The twenty-two sugarcane genotypes under study were classified into four
groups. The first included ten genotypes; NCO 310. G 99-165. F146. F161. CP57-
614. EH94-1B1-1. Ph 7115, UP34-3B. CP31-294 and 30 50. that responded to 30
and 60 inductive cycles. therefore the number of inductive cycles required to
complete flower induction of these genotypes probably ranged between 30 and 60
inductive cycles.The second group consisted of two genotypes: EH 94-119-72 and
R00 1. that flowered only under 30 inductive cycles therefore 30 inductive cycles
was the optimum treatment for these two genotypes.The twelve genotypes that
responded and reached to complete flowering under 30 day cycles. could be
considered as easy to flower genotypes.The third group ‘mcluded five genotypes; BO
55. G 95-21.Crystallina. CP 67-412 and G 98-24 that flowered only under 60
inductive cycles which indicate that 60 inductive cycles could be considered the
optimum treatment for these genotypes. The fourth group Included five genotypes; CP
44-101.CP 704517.00 301. GT 54-9 and G 53-33. that did not show any response
neither under 30 nor under 60 inductive cycles which inclcates that these genotypes
are shy to flower or need more inductive cycles to induce flowering. Therefore. the
twenty tivo evaluated sugarcane genotypes varied considerably among themselves in
their response to flowering under the used photoperiod inductive cycles.