Effect of Day Length on Growth, Photosynthesis and Food Reserves in <I>Curcuma alismatifolia </I>Gagnep.

Abstract

Effect of day length on growth, development and food reserves in Curcuma alismatifolia Gagnep. was carried out. Rhizomes of plant were grown in black plastic pots using sand: rice husk: rice husk charcoal (1:1:1) as growing media. After shoot emerged, plants were transferred to  growth chamber under light intensity of 60 mmol/m²/s for 7, 10 and 13 hrs, temperature at 27±2 ^oC, relative humidity (RH) 70-80%. The results showed that C. alismatifolia grown under long day (13 hr) had significantly greater result in terms of plant height (130 cm), pseudo-stem diameter (0.82 cm) than those grown under 7 and 10 hr condition. However, number of leaves per plant, number of new rhizomes per cluster, and number of storage roots per rhizome were not different among treatments. Photosynthetic rate of plants grown under long day (13 hrs) was between 50-55 mmol/m²/s at 3 and 4 weeks after planting. It was higher than that of plants grown under 7 and 10 hrs of day length. Photosynthetic rate at 5 weeks after planting was not significantly different among treatments. Moreover, the result showed that chlorophyll fluorescence was also not significantly different among treatments at 3, 4 and 5 weeks after planting. For  food reserves in new rhizomes, it was found that  total non-structural carbohydrate and reducing sugar in new rhizomes and storage roots of plants under  13 hrs of day length were significantly higher than those in the others treatments. Plants grown under short day length (7 hr) reduced in K concentrations in new rhizomes and reduced in P and Ca concentrations in storage roots