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EFFECT OF TEMPERATURE ON FLOWERING OF NERINE BOWDENII W. WATTS
Subsequently leaves die off.
The bulbs are then lifted and stored at 2°C for 100 – 120 days.
During a growth period the apex first initiates 6 – 10 leaves (which emerge after replanting) and then develops into an inflorescence primordium.
A new apex is formed in the axil of the last initiated full leaf (sympodial axis). During the next growth period flower buds are formed by the inflorescence primordium, which will reach anthesis at the end of the next growth cycle.
Thus, there are two growth cycles between initiation of an inflorescence primordium and anthesis.
If bulbs were grown at 9 to 25°C flowering was not affected by temperature.
In the next year, however, flowering of bulbs previously grown at 21 or 25°C was reduced.
Analysis of bulbs during growth showed that at 17°C the bud was 12 mm long, while at 25°C it was 8 mm.
At 17°C most of the individual flowers had all floral organs, including distinct pistil primordia.
At 25°C stamen primordia were rarely visible while no pistil primordia were found.
Lack of pistil primordia of flowers initiated in a previous season, when bulbs were grown at 25°C instead of 17°C, may have been the cause of flower bud abortion observed in the next growing season.
It is supposed that in Nerine bowdenii the absence of pistil primordia might result in reduced sink activity of a developing flower, thus causing flower bud abortion.