Session: 16-01-01: Poster Session: NSF-Funded Research (Grad & Undergrad)

Paper Number: 99968

99968 - Mechanics of Growth of the Primary Cell Walls of Fast-Growing Plants 

Abstract

Background: The stem of annual plants sustain rapid longitudinal growth in a short period. During this period, primary cell walls (PCWs) maintain internal structure and connectivity while providing the additional function of fluid conduction and thermal management. Identifying the mechanics and microstructural changes within the PCW during rapid growth periods can reveal vital concepts for flexible multifunctional composites. Hence, this study investigates the microstructural and compositional changes in flexible fast-growing plants of sunflower and soybean and correlates them to their mechanical demands at various stages of growth, to identify the underlying mechanics of growth.

Methods and Results: Sunflowers were grown in the greenhouse under controlled environmental conditions such as humidity and temperature and soybean were planted in the growth chamber with variable environmental constraints such as water and nutrition. Section of stems of both sunflower and soybeans were extracted at multiple stages of growth from week 4 (vegetative period) to week 12 (reproductive period) and examined under scanning electron microscopy (SEM). Thus obtained images were analysed using ImageJ software to quantify the morphological changes of growth. Additionally, Raman Spectroscopy was performed over the stem sections focussing on the coiled features within the PCW to reveal its composition at various stages. Further tensile testing was carried out on the stem sections to correlate the morphological and compositional changes to the overall mechanical performance of the stems during their growth stage (i.e. week 4 to week 12).  Key growth features observed include the formation of coils within the cell wall which were prominent in earlier stages of growth resulting in a highly pliant cell wall. Coiling appeared to be the dominant mechanism for the longitudinal growth of plant stems in the early stages, which further fused together in later stages resulting in the formation of pits. Together, the formation of these specialized structures (coils and pits) was designed to accommodate competing demands of strength, flexibility, and conduction of water and nutrients for the growth of the sunflower and soybean. Work is ongoing to correlate these microstructural features with their compositional modifications via Raman spectroscopy studies and the overall mechanical performance via tensile testing under various conditions of growth and environmental stressors. Establishing these relationships will enable an understanding of the mechanics of PCW to enable the design of flexible, lightweight polymer composites for multiple applications.

Keywords: Raman spectroscopy, Scanning electron microscopy, tensile test, primary cell wall, flexible composite, polymer, ImageJ, Coil

 

Presenting Author: Anandu Nair Gopakumar South Dakota State University

Presenting Author Biography: Currently pursuing PhD in Mechanical Engineering at South Dakota State University<br/>Completed Master&#39;s in Materials Engineering from National Institute of Technology Karnataka, India.<br/>Completed Bachelor&#39;s in Polymer Science and Engineering from Cochin University of Science and Technology, India.

Authors:

Anandu Nair Gopakumar South Dakota State University
Debrup Chakraborty South Dakota State University
Anamika Prasad South Dakota State University