Root systems of oilseed and pulse crops-morphology, distribution and growth patterns

• Main Author: Liu, Liping
• Other Authors: Van Rees, Ken C. J.
• Format: Others
• Language: en
• Published: University of Saskatchewan 2009
• Subjects: Rooting Patterns; Pulses; Oilseeds
• Online Access: http://library.usask.ca/theses/available/etd-06292009-152839/

This study determined the key characteristics of temporal patterns of root growth during the crop development period, as well as the vertical patterns of root distribution in the soil profile for important oilseed and pulse crops grown on the semiarid Canadian Prairie. Rooting characteristics greatly influence the nutrient acquisition and water-use patterns for any plants. However, crop root systems have not been studied intensively due to time, labor and costs constraints. In the literature, root studies mostly focus on cereal crops and very limited information is available for oilseeds and pulses even though these broadleaf crops are critical in the diversification of cropping systems. Thus the objectives of this study were to 1) examine the root morphological characteristics, root distribution patterns in the soil profile, and the fine root distributions of oilseeds and pulses in comparison with wheat; 2) to determine the rhizospheric properties of pulse crops. In 2006 and 2007, canola (<i>Brassica napus</i> L.), flax (<i>Linum usitatissimum</i> L.), mustard (<i>Brassica juncea</i> L.), chickpea (<i>Cicer arietinum </i> L.), field pea (<i>Pisum sativum</i>L., lentil (<i>Lens culinaris</i>), and spring wheat (<i>Triticum aestivum</i> L.) were grown under low- (natural rainfall) and high-water (rainfall+irrigation) conditions in southwest Saskatchewan. Roots were sampled at the seedling, early-flower, late-flower, late-pod, and physiological maturity growth stages, and root parameters determined using image analysis. The growth of roots progressed markedly from seedling to late-flowering and then declined to maturity. Root growth of pulse crops was not significantly affected by water conditions, but canola had 70% greater root length, 67% more root surface area, and 79% more root tips under high-water than under low-water conditions. At the late-flower stage, over 70% of the roots in oilseeds and pulses were distributed within the 0-60 cm soil profile and the largest proportion (around 50%) were found in the top 20-cm of the soil depth. About 85% of the roots in oilseeds and pulses were classified as extra fine (diameter <0.4mm). The rhizosphere fungi were significantly different among tested pulses and also pulse rhizosphere fungi were significantly affected by soil depth but not by water conditions. Inoculation of <i>Penicillium bilaiae</i> (product -JumpStart®) to the pulse crops increased the amount of the fungi in their rhizospheres by as much as 42% compared to the pulses not inoculated. Results from this study are novel and provide the baseline for model-related studies on water use and nutrient uptake by root systems of oilseed and pulse crops in semiarid environments.