Experiments aiming to adapt the perennial balloon flower (Platycodon grandiflorus) as a commercial cut flower crop were conducted for 4 years under various growing conditions: four controlled-temperature rooms at two photoperiods in a phytotron, heated and unheated greenhouses, and a saran net-house (15% shade). Best flower yield was obtained following crown cooling for 12 weeks at 2 to 4 °C. Platycodon is a day-neutral plant, but produce more flowering stems under long days. Flower initiation and development is enhanced with increased growing temperature from 17/12 °C (day/night) to 27/22 °C. At very high temperatures (32/24 °C), however, only a few flowers are formed. Best quality stems were produced at 12 to 14 °C night temperature. At higher night temperatures, flowering stems were thin and weak. Gibberellin treatments to the crowns and the plants did not affect flowering time. Chemical name used: gibberellin (GA3).

1. The trehalase found in an extract prepared from a yeast strain that cannot ferment trehalose was studied and characterized. The enzyme is highly specific for trehalose with K(m) 1.02x10(-2)m, and an optimum pH of 6.9. 2. It is inhibited by glucose and by trehalose 6-phosphate, and does not facilitate any significant transglucosylations. 3. pK values 7.7 and 5.8 were detected for the groups associated with binding of the non-ionized substrate to the enzyme. 4. The trehalase was found to be highly labile and was inhibited by thiol-binding reagents. 5. The possible role of this enzyme in the trehalose-dissimilation patterns in the yeast cell was evaluated.

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Zantedeschia (Fam. Araceae), a genus of 6 or 7 species, are all native to South Africa, They generally grow in wet, marshy land often at the edge of forests. Z. aethiopica is used in Israel for cut flower production, as well as for rhizome propagation. The crop is mainly grown in unheated greenhouses during winter and early spring. Annual production of Z. aethiopica has increased rapidly over the last few years. This paper reports results of a series of studies on the influence of planting depth and density, leaf removal and growth regulator treatments (gibberellic acid (GA) and benzyl adenine (BA)) on flowering and rhizome production. The objective was to define optimum growing procedures for the production of high yields of top quality Z. aethiopica flowers and rhizomes during the December to May winter growing season in Israel. We found that flower yield was high when rhizomes were planted at a depth of 10 cm below the soil surface. Deeper planting (20 cm) yielded highest rhizome weights, whereas planting at 10 cm, yielded the highest number of rhizomes. Changing planting density did not affect the number of flowers produced per plant, but close planting resulted in longer flower stems. Leaf removal increased flower yield. Dipping rhizomes in 350 ppm BA followed by a dip in 350 ppm GA 3 increased flower yield five fold over the control. However, a dip with only BA, yielded the same number of flowers, as the combined treatment. Although many malformed or green flowers developed as a result of GA 3 treatments, combination treatments with BA or BA alone reduced the extent of this problem.

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