Biological Systems Engineering
First Advisor
Xin Qiao
Second Advisor
Haishun Yang
Date of this Version
12-2023
Citation
A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science
Major: Agricultural and Biological Systems Engineering
Under the supervision of Professor Xin Qiao
Lincoln, Nebraska, December 2023
Abstract
As the “Cornhusker State”, Maize (Zea mays) is an important crop in Nebraska. However, farmers in the state are challenged by unstable supply of surface water and limited groundwater resources. A better understanding of maize's response to water stress that occurs at different growth stages can help implement the best irrigation practices that conserve water while maintaining yields. In this study, we conducted field experiments at the Panhandle Research, Extension, and Education Center to compare the responses of maize to eight irrigation treatments which included both limited and deficit irrigation regimes during 2022 and 2023 growing seasons. Specifically, maize was stressed at early, middle, and late growth stages, and their responses were recorded. Maize yield ranged from 5.3 to 14.3 Mg/ha in 2022 and 9.0 to 12.0 Mg/ha in 2023. In 2022, an increasing trend in yields with increasing irrigation levels was observed, whereas, in 2023, yields increased up to 66% irrigation level and decreased afterward at 100% irrigation level. Further, late-cutoff treatment produced 3% more maize yield by conserving 11% of water in 2022 and 1.7% more corn yield by conserving 26% of water in 2023 as compared to 100% irrigation treatment. The irrigation water use efficiency (IWUE) decreased as the irrigation level increased and ranged from 3.1 to 1.4 kg m-3 in 2022 and 3.0 to 0.8 kg m-3 in 2023. The actual evapotranspiration (ETa) increased with the irrigation levels and ranged from 179 mm to 609 mm for DAP 29 (days after planting) to DAP 127 in 2022 and 260 mm to 548 mm for DAP 28 to DAP 140 in 2023. Based on our results, we suggest the late-cutoff treatment as the best irrigation management strategy among the strategies evaluated in our research, particularly owing to the variation in climate between the years.
Advisor: Xin Qiao
Comments
Copyright 2023, Swathi Palle