Improving the yield and cut flower quality of autumn flowering Alstroemeria by a soil cooling system

Effects of temperature treatments and soil-cooling methods were evaluated t o improve the cut flower yield and quality of autumn flowering Alstroemeria . 1. 'Regina' and 'Carmen' (syn. 'Cana') plants, kept at a minimum of 10 degr ees C in winter, continually produced flowering shoots if they were planted by 21 May and 20 June, respectively, provided the chilled soil temperature at night was maintained at 14 degrees C. These critical dates correspond w ith the time when it became nearly impossible to keep 'Regina' and 'Carmen' , respectively, below 15 degrees C: and 17 degrees C, which are the critica l and threshold temperatures for flowering. Cut flower yield and quality ob tained by this method were poor. 2. Potted 'Regina' plants which were previously exposed to chilling at 2 de grees C for 10 weeks and then transplanted in a chilled soil bed on 10 June produced flowering shoots in autumn. The plants raised at a minimum of 20 degrees C prior to the chilling treatment produced more vegetative shoots a fter transplanting as compared to the plants raised at a minimum of 10 degr ees C. The former produced a greater number of flowering shoots and high-qu ality cut flowers in early autumn. 3. 'Carmen' plants grown in a chilled soil bed, kept below 17 degrees C for only 6 hr at night produced more vegetative shoots and high-quality cut fl owers in autumn as compared to the plants grown in a bed cooled continuousl y. 4. Keeping the soil at 20 degrees C for 8 similar to 20 weeks prior to cool ing to 17 degrees C on 12 June produced an abundance of vegetative shoots i n summer and autumn and improved the cut flower yield and quality of autumn -flowering two-year-old 'Carmen' plants.