The effect of low-temperature (LT) storage at 10 °C on dormancy relaxation and budbreak was studied in tubers of colored Zantedeschia. LT storage for 35 or 64 days enhanced budbreak by about 80 days compared to tubers stored at 20 °C. Primary bud elongation did not occur at 10 °C for 143 days, but took place after the tubers were transferred to 20 °C. Prolonged LT storage enhanced the rate of bud elongation at 20 °C. It is proposed that LT storage enhances dormancy relaxation but, at the same time, inhibits bud elongation in nondormant buds. This dual effect can serve growers in programmed production of year-round forcing of colored calla lily flowers.
Vered Naor, Jaime Kigel, and Meira Ziv
Abraham H. Halevy, Menashe Levi, Menashe Cohen, and Vered Naor
Experiments to advance early production of herbaceous peony (Paeonia lactiflora Pall.) flowers were conducted over 8 years in the higher elevation, cooler regions of Israel. Anatomical studies during the summer revealed that flower bud initiation of apical buds in the crowns began at the end of July and continued also in lateral buds from mid-August until the plants became dormant in mid-November. Container-grown plants of various cultivars were moved to cold rooms maintained for 10 to 13 weeks at 2 °C, from mid-August to mid-October, then drenched with 250 mL of various concentrations of GA3 and transferred to a greenhouse. The optimal GA3 concentration for flower production was 100 mg·L-1. Plants treated in this way flowered 2-3 months before the natural flowering period. Field-grown plants in uncovered greenhouse structures were exposed to natural winter cold temperatures (0-10 °C), until they had received various chill units according to a “dynamic model” (for details see Erez et al., 1988). The crowns were then drenched with various amounts and concentrations of GA3, and the greenhouses were covered with plastic sheets. The optimal chill units for most cultivars was 40 and the optimal GA3 drench treatment was 250 mL of 100 mg·L-1. Covered and GA3-treated field-grown plants flowered ≈1 month earlier than untreated plants grown in the open field. The GA3 treatment also greatly increased the number of produced flowers.