ผลของปัจจัยภายนอกต่อการเจริญเติบโตและปริมาณฮอร์โมนของบัวหลวง

Abstract

The study of external factors on growth and development, and phytohormones contents in sacred lotus was conducted into 3 experiments: The first experiment, the study of year-round growth, development, and phytohormone contents in sacred lotus, was conducted by investigating the growth, development, and phytohormone contents of sacred lotus under year-round natural environmental conditions. The experiment was conducted in 12 months of tropical weather as treatments, from May to April. Aboveground growth (leaf number, leaf area, flower stalk length, flowering percentage) and underground growth parameters (internode length, internode number, internode diameters, total stolon length, rhizome enlargement index) were investigated, and two phytohormones, i.e., abscisic acid (ABA) and trans-zeatin-riboside (t-ZR) were analysed in leaf, stolon, node and flower of the plant. The findings revealed that under the high temperatures (32.3 °C) and long-day conditions (13.09 h per day) of May, June, and July, the plant's leaf and flower growth was promoted, ABA concentrations in leaf and flower were decreased, and t-ZR concentration in leaf was increased but decreased in stolon. Under the low temperature (22.9 °C) and short-day conditions (11.17 h per day) from October to February, the growth of lotus leaf and flower was suppressed, while the growth of underground stolon was enhanced, ABA concentrations in all organs were increased, and t-ZR concentration in the leaf was decreased but increased in the stolon. The second experiment, the effects of water temperature on growth, development and phytohormone contents in sacred lotus, was conducted by installing the water-chilling unit into a 125 x 280 x 60 cm of concrete cubic tank with 3 different water temperatures as treatments, i.e., T1: ambient temperature as a control, T2: cooling water temperature 20 °C, and T3: cooling water temperature 15 °C. Aboveground growth (leaf number, leaf area, leaf stalk length, flowering percentage) and underground growth parameters (internode length, internode number, internode diameters, total stolon length, rhizome enlargement index) were collected, and two phytohormones, i.e., abscisic acid (ABA) and trans-zeatin-riboside (t-ZR) were analysed in leaf, stolon and node of the plant. The results showed that both ranges of water-cooling temperatures reduced the plant's leaf growth, flowering percentage, and underground growth. The 15°C water temperature increased ABA concentration in all organs and t-ZR concentration in the plant’s stolon and nodes. The 20 °C water temperature increased concentration of t-ZR in the leaf. Both ranges of water-cooling temperatures decreased the total amount of t-ZR in the plant. The third experiment, the effects of shading and fertilizer rates on growth, development, and photosynthesis in sacred lotus, was conducted with two factors of treatment: the first factor is two levels of shading, i.e., non-shading and 50% shading. The second factor was two levels of fertilizer rates, i.e., 5 g and 10 g per plant for 20-day intervals. Weekly growth parameters and final growth after 7 months were investigated. Stomatal conductance (gs), photosynthetic rate (A), and Photosynthetically Active Radiation (P.A.R.) were measured in each month of the experiment. The results showed that under 50% shading, leaf number and leaf width were reduced, but leaf stalk length was increased, and stomatal conductance, photosynthetic rate, and P.A.R. were found to decrease under the shading conditions. The fertilizer rate of 10 grams for 20-day intervals increased leaf number, leaf width, leaf stalk length, internode diameters, node number, and rhizome enlargement index (REI), while different rates of fertilizer caused stomatal conductance, photosynthetic rate, and P.A.R. to be indifferent. There are interactions between shading factors and fertilizer rate factors in terms of leaf number, flower size, node number and total dry weight. However, it was not found an interaction in photosynthetic rate, stomatal conductance and P.A.R. The interaction between no-shading and 10 g of fertilizer gave the highest leaf number, flower size, node number and total dry weight of lotus plant.