Propagation
Capers can be grown easily from fresh seeds gathered from ripe fruit and planted into well-drained seed-raising mix. Seedlings will appear in two to four weeks. Old, stored seeds enter a state of dormancy and require cold stratification to germinate. The seed of the genus Capparis is bitegmic. The testa is 0.2–0.3 mm thick, with all its cell walls somewhat lignified, some of them with distinct thickening; its tegmen consists of an outer fibrous, lignified layer four to ten cells thick, with a lignified endotegmen composed of contiguous cuboid cells, with strongly thickened radial walls. Only the mesophyll between exo- and endotegmen is unlignified. Caper seed germination shows a dependence on the integrity of the covering structures. The viable embryos germinate within three to four days after partial removal of the lignified seed coats. The seed coats and the mucilage surrounding the seeds may be ecological adaptations to avoid water loss and conserve seed viability during the dry season.
Use of stem cuttings avoids high variability in terms of production and quality. Nevertheless, plants grown from cuttings are more susceptible to drought during the first years after planting. The caper bush is a difficult-to-root woody species, and successful propagation requires careful consideration of biotypes and seasonal and environmental parameters. Rooting percentages up to 55 are possible when using one-year-old wood, depending on cutting harvest time and substrate used. Propagation from stem cuttings is the standard method for growing ‘Mallorquina’ and ‘Italiana’ in Spain, and ‘Nocella’ in Salina. Hardwood cuttings vary in length from 15 to 50 cm and diameter of the cuttings may range from 1.0 to 2.5 cm. Another possibility is to collect stems during February through the beginning of March, treat them with captan or captafol and stratify them outdoors or in a chamber at 3–4°C, covered with sand or plastic. Moisture content and drainage should be carefully monitored and maintained until planting. Using semi-hardwood cuttings, collected and planted during August and September, low survival rates (under 30%) have been achieved. Softwood cuttings are prepared in April from 25- to 30-day shoots. Each cutting should contain at least two nodes and be six to 10 cm long. Basal or subterminal cuttings are more successful than terminal ones. Then, cuttings are planted in a greenhouse under a mist system with bottom heat; 150 to 200 cuttings/m2 may be planted.
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