TOMATO

PH: 5.5-6.5
Plant spacing: 40-60 cm (3-5 plants/m2)
Germination time and temperature: 4-6 days; 20-30 °C
Growth time: 50-70 days till first harvest; fruiting 90-120 days up to 8-10 months (indeterminate varieties)
Optimal temperatures: 13-16 °C night, 22-26 °C day
Light exposure: full sun
Plant height and width: 60-180 cm; 60-80 cm
Recommended aquaponic method: media beds and DWC

 

Growing tomatoes in aquaponic units: Tomatoes are an excellent summer fruiting vegetable to grow using all methods of aquaponics, although physical support is necessary. Given the high nutrient demand of tomatoes, especially potassium, the number of plants per unit should be planned according to the fish biomass, in order to avoid nutrient deficiencies.

A higher nitrogen concentration is preferable during early stages to favour plants' vegetative growth; however, potassium should be present from the flowering stage to favour fruit settings and growth.
Growing conditions: Tomatoes prefer warm temperatures with full sun exposure. Below 8-10 °C the plants stop growing, and night temperatures of 13-14 °C encourage fruit set. Temperatures above 40 °C cause floral abortion and poor fruit setting. There are two major types of tomato plants: determinate (seasonal production) and indeterminate (continuous production of floral branches). In the first type, plants can be left to grow as bushes by leaving 3-4 main branches and removing all the auxiliary suckers to divert nutrients to fruits. Both determinate and indeterminate varieties should be grown with a single stem (double in case of high plant vigour) by removing all the auxiliary suckers. However, in determinate varieties, the apical tip of the single stem has to be cut as soon as the plant reaches 7-8 floral branches in order to favour fruiting. Tomato rely on supports that can be either made of stakes (bush plants) or bound to vertical plastic/nylon strings that are attached to iron wires pulled horizontally above the plant units.

Tomatoes have a moderate tolerance to salinity, which makes them suitable for areas where pure freshwater is not available. Higher salinity at fruiting stage improves quality of the products.
Planting instructions: Set stakes or plant support structures before transplanting to prevent root damage. Transplant the seedlings into units 3-6 weeks after germination when the seedling is 10-15 cm and when night-time temperatures are constantly above 10 °C. In transplanting the seedlings, avoid waterlogged conditions around the plant collar to reduce any risks of diseases. Once the tomato plants are about 60 cm tall, start to determine the growing method (bush or single stem) by pruning the unnecessary upper branches. Remove the leaves from the bottom 30 cm of the main stem to favour a better air circulation and reduce fungal incidence. Prune all the auxiliary suckers to favour fruit growth. Remove the leaves covering each fruit branch soon before ripening to favour nutrition flow to the fruits and to accelerate maturation.
Harvesting: For best flavour, harvest tomatoes when they are firm and fully coloured. Fruits will continue to ripen if picked half ripe and brought indoors. Fruits can be easily maintained for 2-4 weeks at 5-7 °C under 85-90 percent relative humidity.