Effects of Medium Shape, Fertilization Methods and Plant Density on the Growth of Pansy Grown in Medium Hardened by Heat Fusion Polyester Fiber without Polyethylene Pot

To develop bedding plant production system without polyethylene pots (PP), problems that may be encountered with compacted medium hardened by heat fusion polyester fiber were investigated. Effects of medium shape, fertilization methods and plant density on the growth of pansy in medium without PP were investigated. To improve water usage on compacted medium, a watering space (6×6×depth 3cm) was made on the upper part of the compacted medium (9×9×depth 9cm). In the early stages of the experiment the amount of water supplied per pot (weight after irrigation-weight before irrigation) of medium with water space was 10–25% greater than that of medium without a water space. However, from the mid to late stages of the experiment, the difference gradually declined. The amount of water supplied per pot was similar between with and without water space especially on cloudy or rainy days. The growth of pansies on medium without PP was remarkably greater with water space than without water space. On 10g/liter basal fertilizer treatment, pansies had severe symptoms of fertilizer damage. The growth of pansy on 10g/liter basal fertilizer was inhibited compared to that of 5g/liter basal fertilizer. Spacing treatment was conducted whenever plant density was half. Height of pansy grown with spacing treatment was significantly lower than that without spacing treatment. PP had no effects on growth when pansy was grown without spacing treatment. However, when pansy was grown with spacing treatment, pansy grown without PP had significantly greater growth than with PP. Algal growth on the medium increased with increasing irrigation rate or nutrient rate. Combination of spacing treatment and medium without PP decreased the rate of algal growth on medium.固化培地を利用したポリポットを用いないポットレス栽培において，潅水効率の上昇，施肥の簡易化，藻の発生抑制のため，培地の形状，施肥方法および栽植密度がパンジーの生育に及ぼす影響について検討した．9㎝角のポット型培地に6×6×深さ3㎝のくぼみ（ウォータースペース）を培地上部に作成すると，栽培前期の水供給量（灌水後の重量―灌水前の重量）が約10～25% に多くなった．しかし，栽培中期から後期にかけてはその違いは次第に小さくなり，特に曇雨天時には水供給量に差はみられなくなった．ウォータースペースの有無にかかわらず，ポリポットがあると生育に違いは認めらなかったが，ポットレス区ではウォータースペースによって生育が改善された．元肥量10ｇ/liter 区では生育初期に高濃度障害と思われる症状が見られ，5ｇ/liter 区より生育が抑制された．栽植密度を半分にしたスペーシングによって，草丈はかなり抑制された．スペーシングなしの場合にはポットの有無による差は小さかったが，ポットレス栽培の生育がスペーシング栽培でかなり改善された．ポットレス・スペーシング有・灌水量120ml区の生育が最も旺盛であった．養分量が多いほど灌水量が多いほど，藻の発生が大であったが，スペーシングとポットレスを組み合わせると藻の発生が改善された