Effects of Low Night Temperature and Short Day Length on Some Phytohormones and Nutrient Status in Curcuma alismatifolia Gagnep.

The effects of low night temperature (LNT) and short day length (SDL) on the plant growth, phytohormone concentration and nutrient status in leaves, rhizomes and storage roots of Curcuma alismatifolia Gagnep. at the flowering stage were studied. In the first experiment, plants were grown under controlled conditions of 30 /24 ° C (day/night temperature: DT/NT) or under low night temperature conditions of 30/18 ° C with 13 h day length and 11 h night length. In the second experiment, plants were grown with either a 13 h long day length or an 11 h short day length under the temperature conditions of 30/24 ° C. The humidity and light levels in both experiments were maintained at 70-80% RH and 270 µmol m -2 s -1 , respectively. The LNT treatment decreased the dry weight of leaves, the number of shoots per a cluster, spike length, flower stalk length and percent flowering, and it delayed the flowering date. The concentrations of ABA and t-ZR were affected differently by distinct environmental condition. LNT treatment did not affected ABA concentration in all the plant parts, but it decreased only t-ZR in rhizomes and storage roots. In contrast, SDL treatment induced only high ABA in leaves and t-ZR in underground organs. The LNT treatment also decreased N and P contents of rhizomes and N and K contents of leaves. The SDL treatment reduced the N, P and K accumulation in all parts, except for the P accumulation in storage roots. The results indicate that hormonal and nutritional changes were at least partially induced by LNT and SDL treatments, leading to different growth and development in this plant.