No specific treatments are carried out for seeds of cultivated spinach. For the wild species S. turkestanica, the seed clusters are first broken, followed by rinsing of the seeds in running tap water for 3 days. Seeds are then sown in trays with soil, which are placed in the dark at 4°C for 3-5 days. Subsequently, the trays are placed at 15-20°C in a greenhouse for 2 weeks, or under cold/warm uncontrolled but frost-free conditions (short day). Depending on the germination result, the temperature treatments are repeated 1-2 times. For the wild species S. tetrandra, the seed clusters are first rinsed in 50°C water for 30 minutes, followed by cooling down in tap water for 10 minutes, sterilization in 4% chloride solution for 24 hours and 3 times rinsing in sterile water. The seed clusters are then dissected into separate seeds and incubated in 4°C water for 5 days (these steps can also be reversed). The seeds are germinated in vitro at 15°C or sown directly in soil, after which plants are raised under short day conditions.
No specific vernalization treatments are applied to induce flowering.
In the beginning of January, seeds are sown in trays filled with soil. The trays are placed at ±18°C in a greenhouse. Dehydration of the trays is prevented. Excess water is also prevented to avoid damage by fungi. When the cotyledons have developed well, the seedlings are transplanted to small pots, which are placed at 10-14°C in a greenhouse. The pots are regularly watered to avoid dehydration. For wild species, the regeneration protocol starts at the end of December because of the preceding dormancy breaking treatments. Wild Spinacia species are very sensitive to day length. Too much light should be avoided during growing in order to prevent shooting during the seedling stage.
Seedlings are transplanted to pots of ±5 liter at the end of January, and kept at 14°C in the greenhouse during the winter. In the beginning of March, the plants of the different accessions are transferred to separate isolation chambers with a temperature of 10-18°C. After inflorescences have started to develop, plants are staked to prevent lodging.
Pest and disease control
Protective measure are applied when aphids (Aphis fabae, Myzus persicae) or spider mites are observed.
Manual seed harvesting takes place from May until mid-June. A single harvest per accession is carried out when the majority of plants has produced ripe seeds. Flower stalks with ripe seeds are collected in cotton bags, which are hang to dry in the greenhouse for a few days before the start of seed drying procedures.