Morphological Trait Difference, Growth and Ecophysiological Performance of Mikania micrantha Grown Under Contrasting Light and Nutrient Regimes

Abstract

Mikania micrantha , a world’s worse weed, is rapidly expanding throughout the subtropical and tropical parts of Asian countries. Abundant growth and development of Mikaniavines make them dominant over introduced habitat and causes significant damage to native floras, faunas and entire ecosystems. To investigate the role of environmental resources associated with its rapid growth and development, Mikania seedlings were grown at green house chamber by manipulating two levels of light and nutrient for 110 days. Total thirteen harvests had performedthroughout the study period on the weekly basis. Specific leaf area, leaf area ratio, leaf weight ratio, root weight ratio, relative growth rate, net assimilation rate and total biomass of seedlings grown under light and nutrient treatments were measured in each harvest. Photosynthetic performance of mature and fully grown Mikania seedlings was measured at 9th and 11th harvests. Mikania seedlings grown under full sun light and nutrient rich soil had allocated greater amount of total leaf area and total chlorophyll content capturedthe higher intensities of solar irradiances to attain maximum photosynthetic rate. Due to opportunistic capture and utilization of more resources for their physiological process and morphological allocation patternthe seedlings grown under full sun light with nutrient rich soil achievedcomparatively higher degree of net assimilation rate (NAR)and relative growth (RGR) than the seedlings grown at resource limited treatments. The seedlings grown under full sun light andnutrient rich soil had attained maximum biomass performance indicating the interaction effect between full light and high soil nutrient resources. Mikaniaseedlings grown under resource limited treatments had observed poor growth performance however these seedlings modified their morphological allocations such as higher specific leaf area and leaf area ratio to assimilatemore resources from the existing environment. The abilities of Mikania to tolerate adverse environmental conditions and efficiently utilize higher intensities of sun light and soil nutrient to increase overall performance and greater proportion of biomass allocation on aboveground parts make them to grow dominantly over the introduced habitat.