SEED YIELD OF TRANSPLANTED GLASSHOUSE-GROWN ONION (ALLIUM CEPA L.) PLANTLETS. I. PRELIMINARY FINDINGS (*)
The results of a two-year study conducted in northern-east Italy's Po valley to test innovative seed-onion management techniques designed to shorten the growth cycle in standard rotations by growing plantlets in glasshouse and protecting them against winter frost are reported and discussed. The cvs. 'Texas Grano,' 'Borettana' and 'Dorata di Parma' were rated at the University of Bologna's Ozzano experimental station in the following tests at densities of 6.6 bulbs/m2 for and 13.3 plantlets/m2: standard bulb-to-seed with autumn planting; transplant of plantlets acclimated in unheated glasshouse, in nursery or in polystyrofoam cellular trays; and transplant of glasshouse-nursed plantlets in the cellular trays vernalized at 5°C for 50–60 days. Standard bulb planting registered the highest seed yields; the glasshouse-grown plantlets in nursery evinced good bolting (80–90%) but only moderate-sized inflorescences (5–6 cm diam.). Thus, in all likelihood, higher planting densities (40–50 plants/m2) should result in yields comparable to those of bulbs. Plantlets grown in cellular trays showed poor aptitude for seed production. Plantlet hardening evinced no effect on seed yield increment. Further testing on long- and short-day cultivars and on higher density planting of glasshouse-grown nursery plantlets is in progress.
Dellacecca, V., Miggiano, A., Lovato, A.F.S. and Galletti, S. (1994). SEED YIELD OF TRANSPLANTED GLASSHOUSE-GROWN ONION (ALLIUM CEPA L.) PLANTLETS. I. PRELIMINARY FINDINGS (*). Acta Hortic. 362, 43-50