Theses and Dissertations

Date of Award

12-2020

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Dr. Rupesh R. Kariyat

Second Advisor

Dr. Alexis Racelis

Third Advisor

Dr. Mirayda Torres-Avila

Abstract

The role of human disturbance in accelerating weed growth is well understood. While most of these studies have focused on soil mediated disturbance, mowing is also a management practice that could impact weed traits. Using silver leaf nightshade (Solanum elaeagnifolium), a noxious and invasive weed, we asked whether continuous mowing affects growth and plant defense traits. We found that mowed plants produced significantly less fruits, had lower total seed fitness, but had higher seed mass, and germinated significantly faster. When three common herbivores were allowed to feed on the seedlings; tobacco hornworm (Manduca sexta), a generalist Solanaceae caterpillar gained more mass while feeding on seedlings from unmowed plants, while cow pea aphid (Aphis craccivora) a generalist, sustained higher population growth on mowed, suggesting possible negative cross talk between jasmonic acid and salicylic acid defense pathways. Texas Potato Beetle (Leptinotarsa texana), a co-evolved specialist on S. elaeagnifolium did not show any differential feeding effects between the treatments. We also found that specific root length, an indicator of nutrient acquisition and overall foraging efficiency, was significantly higher in seedlings from mowed plants. Taken together, our results show that mowing enhances some growth and defense traits and is possibly producing super weeds

Comments

Copyright 2020 Jesus Chavana. All Rights Reserved.

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