Monitoring Russian Thistle (Salsola iberica) Root Growth Using a Scanner-Based, Portable Mesorhizotron¹

Abstract

A mesorhizotron and scanning system was modified to study the development of Russian thistle root systems during the 1996 and 1997 growing seasons at Lind, WA. Our imaging equipment combined the full profile images afforded by conventional rhizotrons with the portability of cylinder-based minirhizotron systems at a fraction of the cost of either system. Root development of Russian thistle in early spring was rapid and extensive compared with shoot growth. In 1996, 30 d after planting (DAP) Russian thistle roots were at least five times as long as the corresponding plant's shoots. During the next 20 d, shoots grew a maximum of 20 cm, whereas roots grew a maximum of 120-cm deep. Maximum root elongation rate reached 2 to 3 mm/cm2/d at the 70- to 120-cm depths 30 to 50 DAP in 1996 and 55 to 70 DAP in 1997. More than one (multiaxial grouping) Russian thistle root was often observed growing through the same soil channels. After the rapid early season growth, roots began to shrink or die back until shoots were clipped to simulate wheat harvest. Within 7 d after harvest, roots regenerated in old root channels. Our mesorhizotron system is a promising inexpensive tool for monitoring root morphological development of Russian thistle under field conditions.

Development of Dryland Oilseed Production Systems in Northwestern Region of the USA

“…Early planted winter wheat generally has a dense canopy that is actively growing by the time R. thistle begins to establish in the spring such that winter wheat is able to reduce R. thistle emergence, seedling survivability, and seed production [153]. Spring cereals compete poorly with R. thistle because they have less early root growth [102] and slower canopy closure than winter wheat and the weed will continuously germinate and emerge between early April and late June [153]. Spring wheat yield losses from R. thistle can range from 11 to 55 % depending on weed density and precipitation [155].…”

Then and Now: 125 Years of Dryland Wheat Farming in the Inland Pacific Northwest

“…Since its introduction to the area in the early 1900s, Russian thistle ( Salsola iberica ) has been the most troublesome broadleaf weed in the low‐precipitation region. Russian thistle seed germinates and emerges during the spring and summer in repeated flushes after rainfall events of 10 mm or more and quickly sends a taproot deep into the soil profile (Pan et al, 2001). Repeated harrowing (Fig.…”

Efficacy of 2,4-D Choline as Influenced by Weed Size in the Texas High Plains

“…It also has become one of the most economically damaging glyphosate-resistant weed species in the United States [3]. Russianthistle, a C4 summer annual broadleaf weed that is prevalent in the western United States, is extremely competitive due in part to its aggressive root system [4,5]. Early seedling emergence, tolerance to drought, heat, and salinity, hermaphroditic flowers that are out-crossed and selffertile, and wind-mediated pollen dispersal also contribute to its competitiveness [6][7][8].…”