Effects of Night Cooling on Flowering and Quality of Potted Marguerite Lines in High Temperature Period

The relationship between the cooling period and its starting time in night cooling at 21 °C was investigated during summer using ‘Sunday Ripple’ and ‘Furenka’, which are the primary cultivars grown in Shizuoka Prefecture. The 7M-C and 8E-C tended to require fewer days from pinching to flower budding and pinching to the third flower and exhibited a lower number of leaves than 7M-N and 8E-N. The number of days required for emergence of the third flower was reduced by 4-7 days for ‘Sunday Ripple’ and 17-32 days for ‘Furenka’. The 7M-C, 7M-FC, 7M-SC, and 7M-N were divided and verified. As a result, the number of days from pinching to flower budding and days from pinching to third flower of 7M-FC was equivalent to those of 7M-C and tended to be shorter than those of 7M-N. By contrast, the flowering of 8L-C exhibited no difference between treatments with and without cooling. As a result, it was confirmed that a reduction in the days required for pinching to flower budding and pinching to third flower in 7M-C, 8E-C, and 7M-FC. The number of first branches, flower budding branches, and flower buds were used as indicators of pot plant quality. No difference was observed between treatments with and without night cooling, and the pot plant quality was identical. The cooling degree hour values in 8E-C and 7M-FC were ～30 % lower than those in 7M-C. This study demonstrated that night cooling in the potted Marguerite lines in 8E-C and 7M-FC reduced the number of days required for flowering while retaining the quality. Furthermore, it was shown that 8E-C and 7M-FC were able to reduced cooling costs compared with 7M-C.