No abstract

To determine the adequate irrigation conditions in a nutrient-flow wick culture (NFW) system, the water contents of root media were analyzed with different wick lengths (2 and 3 cm), pot sizes (6-, 10-, and 15-cm diameter), and media compositions (mixtures of 5 peatmoss : 5 perlite and 7 peatmoss : 3 perlite). The growth of potted ‘New Alter’ kalanchoe (Kalanchoe blossfeldiana) in the NFW system was also compared with that of plants grown in other irrigation systems, such as nutrient-stagnant wick culture and ebb-and-flow culture. All factors, such as wick length, pot size, and medium composition, influenced the water content of the medium in the NFW system. Pots that included more peatmoss with a shorter wick could easily take up the nutrient solution. The water content of the media increased by more than 8% and 5% in 2- and 3-cm wick lengths within 15 minutes respectively. The fluctuation of water content became greater with a decrease of pot size in the NFW system. Kalanchoe plants grew well in the NFW system with four irrigations for 15 min per day each. The dry weight and leaf area of the plants were higher in the NFW system (4×) and considerably lower in the NFW system with two irrigations for 15 min per day each. Therefore, more precise irrigation is required in the NFW system than in other systems.

Temperature is a principal environmental factor that directly affects the growth and timing of appearance for crop leaves. To estimate the leaf number and leaf area of 'Seoul' pak-choi plants (Brassica campestris ssp. chinensis), we applied the concept of growing degree-days {GDD = (Tavg-Tbase)X days), where Tavg , Tbase, and days were the daily average air temperature, base temperature, and days after transplanting, respectively. Leaves that were beginning to unfold with a leaf area >1 cm 2 were counted every 2