Quantitative Classification of Rice (Oryza sativa L.) Root Length and Diameter Using Image Analysis

Abstract

Quantitative study of root morphological characteristics of plants is helpful for understanding the relationships between their morphology and function. However, few studies and little detailed and accurate information of root characteristics were reported in fine-rooted plants like rice (Oryza sativa L.). The aims of this study were to quantitatively classify fine lateral roots (FLRs), thick lateral roots (TLRs), and nodal roots (NRs) and analyze their dynamics of mean diameter (MD), lengths and surface area percentage with growth stages in rice plant. Pot experiments were carried out during three years with three rice cultivars, three nitrogen (N) rates and three water regimes. In cultivar experiment, among the three cultivars, root length of ‘Yangdao 6’ was longest, while the MD of its FLR was the smallest, and the mean diameters for TLR and NR were the largest, the surface area percentage (SAP) of TLRs (SAPT) was the highest, indicating that Yangdao 6 has better nitrogen and water uptake ability. High N rate increased the length of different types of roots and increased the MD of lateral roots, decreased the SAP of FLRs (SAPF) and TLRs, but increased the SAP of NRs (SAPN). Moderate decrease of water supply increased root length and diameter, water stress increased the SAPF and SAPT, but decreased SAPN. The quantitative results indicate that rice plant tends to increase lateral roots to get more surface area for nitrogen and water uptake when available assimilates are limiting under nitrogen and water stress environments.

Vegetal-Derived Biostimulant Enhances Adventitious Rooting in Cuttings of Basil, Tomato, and Chrysanthemum via Brassinosteroid-Mediated Processes

“…Since the complete physical separation of lateral roots from adventitious roots was not possible, particularly in basil and tomato due to fibrous nature of their roots, we performed root diameter class distribution analyses to differentiate these root components by carefully manipulating parameters. This method has been proven to be effective in separating different root types [46], and commonly used in root studies. The results revealed that the roots examined in our study are actually classified into very fine (<0.5) to fine (0.5-2 mm) [47] and we further classified them into multiple categories within the range.…”

Morphological and histological differences among three types of component roots and their differential contribution to water uptake in the rice root system

“…Muller et al (2019) recently pointed out the functional significance of random diversity in LRs. Gu et al (2017) also classified LRs based on their diameter and length, and discussed their possible importance in water and nitrogen uptake by examining their developmental responses to different conditions of soil water and nitrogen application rates. Our studies also showed that L-type LR production and elongation were promoted in response to mild drought stress, which implied the differences in responses to environmental conditions between L-type LR and S-type LR (Bañoc et al, 2000: Kano et al, 2011Suralta et al, 2010Suralta et al, , 2018.…”

Maize lateral root developmental plasticity induced by mild water stress. I: Genotypic variation across a high‐resolution series of water potentials

“…Stimulation of lateral root number has also been seen in a wide variety of crop plants including perennial ryegrass ( Lolium perenne ), rice ( Oryza sativa ), wheat ( Triticum aestivum ), oats ( Avena sativa ), soybean ( Glycine max ), and maize (Banoc, Yamauchi, Kamoshita, Wade, & Pardales, ; Jupp & Newman, ; Read & Bartlett, ; Weaver, ). In addition to enhanced number, the total length of lateral root systems has been shown to increase in some crops in response to water deficit, for example, in maize, wheat, rice, and ryegrass (Gu et al, ; Jupp & Newman, ; Kano, Inukai, Kitano, & Yamauchi, ; Schmidhalter, Evéquoz, Camp, & Studer, ; Weaver, ). In most such studies, the extent to which increases in root length were attributable to increases in root number was not distinguished.…”