Offsettinq the potentia aadverse ettects ot ow night temperatures with CO_2

摘要

Decreasing the night temperature in greenhouse production can decrease the energy costs. Problems may arise as low night temperature (LNT) is known to increase leaf starch contents and delay plant development. Danish work (European Journal of Horticultural Science) investigated whether increased CO_2 concentrations can decrease the negative effects of LNT using Chrysanthemum 'Coral Charm'. Plants were grown under long day conditions (LD) with a photoperiod of 17 h. Day temperature set point was 22 degG, the night temperature set points were 20 deg c and 12 degc, and set points of CO_2 concentrations were, ambient CO_2 of 400 Ml 1-1 and high CO_2 of 900 Ml 1-1- Plants were harvested after 3, 4 and 7 weeks. Generally, the treatment with high CO_2 increased growth in terms of increased shoot dry matter (DM) and the formation of leaves in plants grown at LNT. LNT at ambient CO_2 concentrations had the opposite effect decreasing shoot DM production, stem length and leaf number. It is suggested to use high CO_2 concentrations in greenhouse production of Chrysanthemum when grown under LNT.