It may surprise you but the tomato color was not always red. The first tomato varieties that were cultivated were yellow or orange. It is only through breeding that red color became a standard for tomato.
Eighty five to ninety percent of the red color in ripe tomato is due to the presence of Lycopene. The skin of the tomato has the highest content of lycopene of all the tomato parts.
When it comes to fresh vegetable and fruits, color is one of the best indicators of quality along with texture, size and flavor. Color and color uniformity contributes directly to quality and marketability.
Freedom of tomatoes from physiological disorders is very important not only from an appearance point of view but because other attributes may be affected as well, such attributes include nutritional status and shelf life.
Color disorder may appear in different ways
The tops of fruit do not ripen properly. The flesh on the fruit shoulders remains green (green shoulder) or turns yellow. Yellow-eye is used to describe this disorder when only a ring of tissue around the stem scar is affected.
Internal White Tissue
Although the exterior of the tomato may appear red, fruit with this disorder exhibit areas of hard, white tissue on the shoulders and/or in the core.
The tomato fruit appears mottled green, yellow, and red. The flesh develops large patches of hard, grey to yellowish tissue that do not ripen. When the fruit is cut open, brown strands of vascular tissue may be seen.
Since color is one of the key factors growers invest enormous efforts to avoid color disorders.
We decide to turn to Rafi Hetzroni, One of Hazera’s top sells man for the Israeli market and ask him to share with us his knowledge and experience and maybe some tips which help you
Rafi: The factors that influence color in tomato are genetics and environmental.
The grower can, by awareness, help the plant to maximize its full red color potential.
Nitrogen and Potassium
According to Rafi the grower needs to maintain Nitrogen & Potassium ratio in the soil. Especially in cold winters. In cold winters the Nitrogen in the soil doesn’t dismantle well or at all and when the weather turning warmer it dismantles instantly and the plant receive higher level of Nitrogen than Potassium. Therefore it is important to reduce the Nitrogen fertilization levels and on the other hand a grower can increase the potassium fertilization (although it is rather better to avoid it in order to prevent soil salting.
What about radiation?
Rafi: indeed, another facture that influence tomato color homogeneity is exposure to sun radiation. Full foliage contributes to the fruit color because of its Photosynthesis and the coverage it supply to the fruit from the solar radiation. Thus, going out from the winter it is important to avoid exposing the fruit to direct radiation and to be careful not to take out leaves which will reveal the fruit (especially while picking).
Foliage removal needs to be done with caution. In greenhouse, for instance, removing the foliage near the fruit will cause reduce in nutrition.
If the growing is done in open field, stacked, it is important that the line will faced from the north to the south in order to avoid direct solar radiation
Not only radiation impacts the fruit color but temperature as well. Since the Bio – synthetic path of Lycopen is affected by temperature the grower should balance it.
In the summer, especially, in net houses or greenhouses it is important to make sure that the temperature won’t reach high level. It is recommended to wash the nets, shadowing or whitening. If it is possible, choose higher net or green houses.
The right time for picking
In order not to defect the full color potential of the fruit it is important not to pick it before the color turning point, when the blossom end turn its color to pink.
Are there diseases or pests which harm the tomato color?
Rafi: The tomato spotted wilt virus attacks and causes disease in a wide range of plant species, but tomatoes seem to be a favorite host. Tomato spotted wilt virus infected tomato causing irregular yellow blotches. Affected fruit are worthless, since they fail to ripen properly and are unfit for fresh consumption or processing.
Here comes the genetics to the grower help since he can choose plant which is resistant to TSWV, or he might choose disinfest the pests.
Acarine harm the fruit as well by stinging the fruit causing it scars which looks as small color spots. Once again the grower needs to use disinfestations.
Rafi emphasize that it is important to choose the variety carefully. To pay attention to its genetic characteristics – Resistances, foliage, fruit setting in hot conditions, high vigor and of course the basic color genetic of the plant and later on to support his growing by agro technical elements.
For further information Hazera team is always at your service helping you to make the most of your TOMATO Plant
Meirav Ron and Matti Sarfati