The effects of leaf removal and of modifying temperature set-points with solar radiation on tomato yields

An experiment was conducted to assess whether the severity of leaf removal or modifying night temperature set-points based upon the amount of solar radiation intercepted the previous day could affect tomato yields. A night temperature set-point of 16degreesC increasing linearly by 3 K for every 1000 klx h (similar to67 mol m(-2) d(-1)) was compared with a 19degreesC set-point which decreased by 5 K for every 1000 klx h. Similar mean diurnal temperatures were achieved in these two regimens and consequently there was little effect on the pattern of yield or cumulative yields for the whole season. When leaves were removed every week up to two trusses above the ripening truss (high leaf removal: HLR), fruits were warmer during the day and cooler at night, and ripened 1.2 d earlier than those on plants where leaves were removed up to two trusses below the ripening truss (low leaf removal: LLR). The leaf removal treatments had a similar pattern of yield and there was no significant difference in the cumulative yields for the season. This was despite the fact that the HLR plants probably had only 50% of the leaf area of LLR plants. This lack of response Was primarily attributed to the poor light penetration in the canopy, which meant that lower leaves contributed little to the net canopy photosynthesis. The effects of leaf removal on fruit quality and water usage are presented and discussed in relation to the best leaf removal strategy to use for commercial tomato production.