Effects of Changes of Nutrient Solution Concentration According to Growth Stage on Growth and Flowering of Cut Chrysanthemum Grown Hydroponically in Perlite

국화의 펄라이트 양액재배시 생육단계에 따른 양액농도의 변화가 생육과 개화에 미치는 영향

This study was carried out to investigate the effects of changes of ionic strength according to growth stage on growth and flowering of Dendranthema grandiflorum (Ramat.) Kitamura 'Seiun' grown hydroponically in perlite. The stage I, II, and III covered early vegetative growth (27-40 days after planting), latter vegetative growth (41-54 days), and reproductive growth (55-80 days), respectively. The 2 strength (1S and 2S) of nutrient solution were treated in stage I, whereas 3 strengths (1S, 1-2S, and 2S) were treated in stage II. Then, total 9 treatments in stage III were designated by 3 treatments (tap water, 1S, and 2S) for each 3 strengths in stage II. Each nutrient solution was applied 8 times per day. At vegetative growth stage (54 days after planting), stem length was highest when irrigated 8 times a day with 1S nutrient solution. Both photosynthesis and transpiration rate were higher in 1S than those in other treatments (1-2S, 2S), whereas leaf chlorophyll content was highest in 2S treatment. Ion content of plant treated with 2S was higher than other treatments. Growth (plant height, leaf area, stem length), fresh weight, and dry weight of each plant organ after flower bud formation were better in tap water treatment (1-1-0) than other 1S treatments (1-1-1, 1-1-2). Regarding the number of days to flowering, tap water treatment was the most effective. Thus, after flower bud formation supplying tap water or lower concentration of nutrient solution than those used during the vegetative growth stage was economical in saving chemical fertilizers, shortening the number of days to flowering, reducing salt accumulation in media, saving efforts of leaching, and reducing ground water contamination.

국화의 생육단계별 적정 양액농도를 구명하기 위해 국화의 생육단계를 영양생장기 2단계와 생식생장기 1단계, 즉 3단계로 나누어 양액농도를 처리한 결과, 영양 생장기에서는 1배액에서 초장이 가장 길었고, 광합성과 증산량도 가장 높았다. 그러나 엽내 엽록소 농도는 양액의 농도가 높을수록 컸다. 화아형성이후, 생육 (초장, 엽면적, 경경)과 각 기관별 생체중, 건물중에서도 1배액처리구가 좋았으며, 특히 화아형성이후 수돗물 관수에 의해서도 1배액과 비슷하거나 오히려 더 좋게 나타났다. 그리고 수돗물 관주처리에서 개화소요일수가 짧았다. 이와 같은 결과는 양액의 관주 농도가 높을수록 배지내 염류집적으로 식물체가 스트레스를 받은 것으로 사료된다. 국화의 생육단계별로, 초기 활착기까지는 1/2배액으로 한 후 생육이 왕성한 영양생장기에는 1배액으로, 화아형성 이후에는 양액의 농도를 줄이는 것이 국화 양액재배시 비료염의 절약, 개화소요일수 단축, 배지내 비료염 축적의 감소, 지하수 오염의 감소 등 경제적이고 환경친화적인 방법이라고 사료된다.