Agronomy and Horticulture Department

 

Date of this Version

9-2012

Comments

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 Agronomy, Under the Supervision of Professors P. Stephen Baenziger and Harkamal Walia, Lincoln, Nebraska, September, 2012.

Copyright (c) 2012 Sumardi Bin Abdul Hamid.

Abstract

In Nebraska, about 75% of the wheat production is in the western half of the state, and about 92% of the winter wheat acreage is in dryland production, where productivity is limited by low and/or uncertain rainfall. We have investigated the effects of water stress on few established winter wheat (Triticum aestivumL.) cultivars, which are known for their superior adaptation to either rainfed or irrigated wheat production systems in western Nebraska. We also began a study to investigate the variation in the root system architecture to confer drought tolerance in winter wheat. The objectives of this study were to investigate the effects of water stress on root and shoot growth of winter wheat cultivars, and also to characterize the root system architecture (RSA) traits of winter wheat cultivars in order to evaluate their drought tolerance under limiting water conditions. The root length, root dry matter, root-to-shoot length ratio and root-to-shoot mass ratio of the three cultivars were significantly greater in the water stress than well-watered conditions. Results from the water stress experiment showed that Goodstreak is a drought tolerant cultivar due to its longest root length and high root dry matter. Based on the RSA phenotyping of the 3-week old water-stressed plants, Goodstreak had the highest total root length, total root length density, projected area of roots and network root length distribution. Under water stress conditions, Harry demonstrated a shallow root system with low root and shoot dry matters but displayed the highest root-to-shoot length ratio. It appeared that Harry utilized less water and invested less energy into dry matter under water stress. Our findings support the fact that Wesley performed well in irrigated wheat production systems in Nebraska because of its high shoot and root biomasses. This study leads us to suggest that Wesley is a drought sensitive cultivar because it uses the available soil moisture at ‘uneconomical’ and ‘unsustainable’ rate compared to Harry and Goodstreak.

Advisors: P. Stephen Baenziger and Harkamal Walia