Effects of water and nutrient stresses on reduction of vegetative growth in chrysanthemum grown under restricted root zone volume

Two experiments were conducted to test the effects of reducing water and nu trient stresses on vegetative growth of chrysanthemum cv. Pinky in restrict ed root zone volume (10 similar to 1000 ml). In Exp. 1, plants were grown u sing continuous flowing hydroponic system (CFHS). In Exp. 2, plants grown o n a substrate were supplied nutrient solution via a drip system (SDS) 1, 3, 8 or 13 times per day until leaching occurred. In CFHS, stem length and node number were unaffected by root zone volume 25 days after planting (DAP). Total leaf area, shoot and root dry weights dec reased with a decrease in root zone volume; there were small differences am ong the plants grown in different containers, e.g. shoot dry weight of plan ts grown in 10 ml containers was about 80% of that in 1000 ml containers. S hoot to root ratio slightly increased with a decrease in root zone volume. In SDS, reduction in stem elongation was observed 14 DAP in plants grown in 30 ml containers fertigated only once a day. However, there was little dif ference in stem lengths among the plants grown in different containers 28 D AP when fertigated 8 times per day. Shoot growth 35 DAP was reduced with a decrease in root zone volume, however in plants grown in 30 ml or 100 ml co ntainers, reduction of shoot growth markedly decreased with an increase in fertigation frequency. Root zone volume had a little effect on shoot growth if plants were fertigated 8 or 13 times. Irrespective of fertigation frequ ency, root dry weight increased with an increase in root zone volume. Shoot to root ratio was unaffected by root zone volume in plants fertigated 1 or 3 times but the ratio in plants treated 8 or 13 times increased with decre ase in root zone volume. Thus, limiting of water and nutrients is the main factor in growth suppress ion caused by root zone restriction. Hence, vegetative growth of chrysanthe mum plants in small container (less than or equal to 100 ml), e.g. cell or pot transplants production, can be sustained by the application of water an d nutrients 8 times per day.