Effect of Combination of Overhead Irrigation and Subirrigation on the Growth of Bedding Plants Grown in Polyester Fiber Medium Hardened by Heat Fusion, without use of Polyethylene Pots
The effects of irrigation methods on several bedding plants without polyethylene pots using compacted
polyester fiber medium hardened by heat fusion were investigated. The characteristics of overhead
irrigation with a tray collecting runoff water (combination of overhead irrigation and subirrigation)
were investigated at the same time. Irrigation usage (the amount of water supplied per pot / amount of irrigation water) with a combination of overhead irrigation and subirrigation was improved compared to overhead irrigation alone. The growth of garden type Cyclamen grown under a combination of both overhead irrigation and subirrigation was significantly greater than that grown in either wick irrigation, ebb & flow irrigation or overhead irrigation. Notably, smaller growth was achiered in garden type cyclamen grown with overhead irrigation. The growth of Vinca grown in a combination of overhead irrigation and subirrigation was significantly greater than that grown with overhead irrigation alone. The irrigation amount had no effect on the growth of Vinca regardless of irrigation method. The growth of Petunia was greater with increased amounts of irrigation water. However, the growth of Pansy grown under overhead irrigation was significantly greater than that grown in a combination of overhead
irrigation and subirrigation. These results suggest that a combination of overhead irrigation and subirrigation method in bedding plant production without polyethylene pots is generally suitable since the plants grow without drought stress. However, it may be suggested that the amount of irrigation water should be as low as possible in the winter season or with sensitive species in order to prevent waterlogging injury.熱融着性ポリエステル繊維固化培地を利用したポットレス花壇苗生産における灌水方法として，水受けトレイを用いた頭上灌水（頭上底面灌水）の実用性を検討した．頭上灌水と比較して頭上底面灌水では灌水効率（培地に吸収された灌水量／灌水量）が大幅に改善できた．ガーデンシクラメンの生育は頭上底面灌水区で最もよく，次いでひも灌水，底面灌水の順であり，頭上灌水区で最も生育が抑制された．ニチニチソウでは頭上灌水より頭上底面灌水区で生育が改善されたが，灌水量には差はほとんどみられなかった．ペチュニアでは灌水量が多いほど，専用トレイに溜める水量が多いほど生育が旺盛になった．しかし，パンジーでは頭上底面灌水によって生育が抑制された．ポットレス花壇苗生産では頭上底面灌水が最も適切であったが，蒸発散の少ない冬期や過湿に弱い種においては灌水量をできるだけ少なくすべきと考えられた
