Heat before flowering decreases albinism in strawberries

In some summers in Ontario, strawberry fruits of some cultivars do not develop colour properly, and show 'albino fruits'. So, to study the effect of heat on albinism fruit in cultivated strawberry plants, cold-stored plants of 'Seascape' and 'Honeoye' were potted and grown in growth chambers at either 30/18°C, or 18/6°C with 12-h photoperiod. Plant growth was separated onto three growth stages: planting to first open terminal flower (first flower), first flower to white fruit, and white fruit to harvest. Plants were moved between the growth chambers at the beginning of each growth stage, so that all eight combinations of temperature and growth stages were tested. When the terminal fruit was ripe, it was scored: red or albino. Fruits of plants grown at 18/6°C between white fruit and harvest had less albino fruit than those grown at 30/18°C. For the plants at the growth stage between first flowers to white fruit, the proportion of albino fruits was similar for both temperature regimes. Whereas those grown at 18/6°C from planting to first flower had more albino fruit than those grown at 30/18°C, when grown at 30/18°C from white fruit to harvest. This indicates that warm weather during flower development will condition the plant to protect fruit from discoloration. It is suggested that heat-shock proteins produced before flowering protect the fruit when they ripen in heat.