1. Speed of growth & development By André Kool, GreenQ 10 February 2010

2. Speed of growth “Speed” Flower-Harvest approximately 6-10 weeks Lightlevel/plantload determines 24 Hr-average. 24 Hr-average determines speed. Important for speed is optimal day-climate  Cold heads and a death climate cannot be compensated by a warmer night

3. Speed of growth Higher 24 Hr-averages with relative warm nights will result in: 1.slightly faster from flower to harvest (less then a week) 2.Higher risk of weak heads and trusses (quality problems in hot summers) 3.Smaller fruits (but kg’s not compensated by more trusses and fruits) 4.Higher risk of unbalanced growth (too vegetative) because of weak trusses & small fruits 5.Higher risk of hollow fruits

4. Speed of truss formation and balance Relation between speed of truss formation & temperature

5. Truss / week 24-hour-average in °C 016 17 18 19 20 21 1.2 1.1 1.0 0.9 0.8 Speed of truss-formation

6. Speed of truss formation and balance T higher =more trusses=more generative plant ? No, because truss & flower get weak when you grow to fast and too small fruits will not restrain (control) vegetative growth!! Lightlevel/plantload/stem densitytemperature speed

7. Speed of truss-formation Speed depends on 24 Hr-average (see graph) However it’s not only 24 Hr-average: Experiments at Naaldwijk Station showed already in 80’s D 20.8- N 16.3- 24 Hr average 18.4  0.86 Truss/week D 18.3- N 18.4- 24 Hr average 18.4  0.83 Truss/week

8. Speed of truss-formation Other research did also find a 3-5% slower truss formation at relative high night- and low day-temperatures. In growing practise we see similar effects with regard to ripening of fruits: “Speed” is more determined by…… day temperature

9. Speeding up fruitripening? Pulling leafs: more exposure to radiation of heating pipes / sun light Short leafs  long leafs (see pulling leafs) Relative high day & low night temperature High night=dangerous  high risk of “hollow fruits” and hardly faster fruitripening

10. Hollow fruits: a risk of warmer nights

11. Fast harvest: choice of cultivar Big size beef tomatoes  first harvest when truss 8-10 is flowering. Small size (cherrie, cocktail) tomatoes  first harvest when truss 6-8 is flowering “Smaller size tomatoes are more early”

12. Questions?

13. Thanks for your attention! www.greenq.nl