Doctoral Dissertations

Date of Award

5-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Plant Sciences

Major Professor

Avat Shekoofa

Committee Members

Heather Kelly, Larry Steckel, Aaron Smith, Matthew Wiggins

Abstract

Triazole fungicide has the ability to protect crops from varying water stresses. Xyway LFR@FMC is a triazole, at-plant fungicide and has been observed to improve plant performance under limited water conditions. A greenhouse study was conducted to assess the potential of Xyway LFR@FMC in altering the ability of corn plants to control transpiration rates under water deficit-stress (DS) conditions. Greenhouse grown plants were treated with Xyway LFR@FMC at 0.56, 0.77, 1.11,1.26 L ha-1. Plants treated with 1.11 L ha-1 reduced the amount of water loss in response to DS and had the highest fraction of transpirable soil water (FTSW) thresholds. There was an increase in shoot hydraulic conductance (Kshoot) and plants had higher leaf water potential (LWP) by 1.11 L ha-1 under DS conditions. Therefore, in 2022 and 2023, a field study was initiated to assess the Xyway LFR@FMC contribution to plant growth and yield improvement under different water regimes. Xyway LFR@FMC at 1.11 L ha-1 and no fungicide/check were the main plots. Within each main plot there were three water regimes, high (HI) and low (LO) number of irrigation events and rainfed (RF). Plants treated with Xyway LFR@FMC had significantly higher plant height, stem diameter, LWP, and yield compared to no- fungicide under all three water regimes in 2022. Due to a favorable growing condition in 2023 i.e., less disease pressure, frequent rainfall, and lower vapor pressure deficit (VPD, kPa) rates there was no significant separation for yield among the water regimes. But the yield was significantly higher across multiple years for the fungicide treated plots compared to no-fungicide. The results indicate that Xyway LFR@FMC has the potential to improve plant growth and protect yield under varying water regimes. But environmental conditions and assessment of disease levels should be used as a guide to determine the fungicide application’s benefit. Furthermore, the fungicide treated RF plants had almost $122.56 average net return rate per hectare in 2022 compared to RF plants without fungicide. This indicates that the application of Xyway LFR@FMC at planting is one possible way to protect the corn yield under a limited water scenario (i.e., RF).

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