Effects of climate change and agricultural practices on crop physiology, growth and yield
Due to tremendous increase in human population, high demand of food and fuel keeps increasing. It is important to understand how climate change and agricultural practices would influence plant physiology and crop productions. The overall objective was to determine how precipitation changes, nitrogen applications, tillage, or planting dates and densities would influence leaf photosynthesis, plant biomass, and yield of several food and biofuel crops. Four experimental studies were presented in this dissertation. In the first study, I investigated how switchgrass growing in mescosms was affected by five precipitation/irrigation treatments (i.e. ambient precipitation, -33%, -50%, +33% and +50% of ambient precipitation) in a greenhouse over two years. Results showed the precipitation treatment significantly affected the leaf physiology, soil respiration, plant growth, and above-ground biomass. High precipitation stimulates switchgrass photosynthesis and growth. In the second study, a three-year (2012-2014) field experiment was conducted to investigate the effects of tillage, biochar and different nutrient applications on corn physiology and yield. Results showed different agricultural practices had significant effects on plant leaf physiology, soil respiration and yield. No tillage treatment significantly increased corn yield, probably due to the preservation of soil moisture during drought periods. Different nitrogen applications have limited influences on plant physiology and yield. In the third study, a greenhouse experiment was designed to understand the effects of soil acidity (4.5, 6.5) and fly ash addition (0, 2.5%, and 20%) on leaf photosynthesis and biomass of big bluestem (BB) and eastern gamagrass (GG). Result showed high soil pH (6.5) enhanced leaf physiology and biomass for both grasses, but high fly ash addition only influenced GG’s leaf physiology. In the fourth study, a 3-year field research (2010–2012) was set out to determine whether the growth and yield production of four pigeonpea varieties were influence by planting date and density. There were significant differences in leaf physiology, growth and yield among varieties, between planting dates, and between years. Results indicated variety selection and early planting may improve pigeonpea growth and yield.
"Effects of climate change and agricultural practices on crop physiology, growth and yield"
ETD Collection for Tennessee State University.