Effects of irrigation levels on growth and chemical constituents in Curcuma alismatifolia

Abstract

The irrigation regime affects plant growth and development, as well as phytochemical content. This research was aimed to investigate the effects of irrigation levels on physiological responses and biochemical changes in Curcuma alismatifolia 'Dang Doi Tung' Plants were grown by using soil, rice husk, and rice husk charcoal (ratio 1:1:1) as the growing media under a plastic greenhouse with averaged 27°C, 80%. RH, and 333.20 µmol m-2 s-1 light intensity. Plants were prepared by daily watering until shoot sprouting (4 weeks after plating; WAP). Then the experiment was started. The experimental design was a completely randomized design with four irrigation levels, i.e., 100% of crop evapotranspiration (ETc), 75, 50, and 25% ETc. The results showed that at the flowering stage (12 WAP), the plant height, number of leaves plant-1, and leaf area of plants irrigated with 100% ETc were higher than other treatments. In addition, the irrigation levels of 100%ETc significantly increased photosynthesis values and chlorophyll contents; while, the low level of irrigation (25% ETc) decreased the chlorophyll content and photosynthetic rate. It was also found that stomatal conductance in the 25% ETc treatment was lower than other treatments. Total phenolic contents were the highest in flowers compared to leaves, rhizomes, and fibrous root parts. Plants irrigated at 100% ETc gave lower total phenolic contents than those at 75, 50, and 25% ETc. There were 23 chemical constituents in fresh rhizomes at harvest stage, and the levels of each constituent varied by irrigation treatments.