Table 1.
Arabidopsis and crop root phenotypic responses to salinity.
| Species | Root Phenotype | NaCl concentration (mM) | Growth media | References |
|---|---|---|---|---|
| Arabidopsis | Primary root length decreased, and lateral root growth promoted | 50 | Agar | Zolla et al. (2010) |
| Redistribution of biomass from main root to lateral roots | 75 – 125 | Agar | Julkowska et al. (2017) | |
| Halotropism – root bending away from salt | 50 – 250 | Agar | Galvan-Ampudia et al. (2013) | |
| Barley | Reduction in number and length of seminal roots, reduced elongation rate | 100 – 150 | Agar | Shelden et al. (2013) |
| Increased cortical cell length | 100 | Agar | Shelden et al. (2016) | |
| Apoplastic barriers in endodermis; suberin deposition in cortical cells in elongation zone | 100 | Agar | Ho et al. (2020) | |
| Reduced root hair density and root length | 1 – 100 | Hydroponics | Shabala et al. (2003) | |
| Cotton | Primary root growth reduced above 75 mM, elongation rate decreased and shortened growth zone | 1–150 | Germination paper rolls | Zhong and Lauchli (1993) |
| Length and weight enhanced of primary root, thinner roots | 25 – 100 | Hydroponics | Kurth et al. (1986) | |
| Maize | Elongation rate reduced in the primary root and cell division inhibited | 80 | Hydroponics | Bernstein and Kafkafi (2002) |
| Changes in RSA, reduced root growth | 100 | Soil - CT Scanning | Subramanian et al. (2015) | |
| Root biomass reduced; salt tolerance positively correlated with primary root depth | 50 – 100 | Semi-hydroponics | Wang et al. (2020) | |
| Rice | Formation of apoplastic barriers | 100 – 200 | Hydroponics | Krishnamurthy et al. (2011) |
| Lateral root density reduced in tolerant genotype | 50 – 250 | Hydroponics | Ijaz et al. (2019) | |
| Root biomass decreased, root: shoot biomass increased | 50 – 150 | Filter paper | Lin and Kao (1999) | |
| Shallow root growth angle | EC = 9 dS/m * | Field (saline paddies) | Kitomi et al. (2020) | |
| Rye | Cell division decreased and cell death increased | 250 | Hydroponics | Ogawa et al. (2006) |
| Cell division increased | 50 – 100 | Hydroponics | Ogawa et al. (2006) | |
| Sorghum | Halotropism – root bending away from salt | 300 500 |
Agar Soil |
Galvan-Ampudia et al. (2013) |
| Root: shoot biomass increased | - 0.8 MPa * | Hydroponics | Weimberg et al. (1984) | |
| Tomato | Main root length decreased on agar and in pouches (not rhizotrons) | 120 | Rhizotrons, Pouches, Agar, Pots | Gandullo et al. (2021) |
| Halotropism – root bending away from salt | 300 500 |
Agar Soil |
Galvan-Ampudia et al. (2013) | |
| Wheat (Durum) | Seminal root growth inhibited | 50 – 200 | PVC tubes & filter paper | Rahnama et al. (2011) |
| Reduction in biomass, root: shoot biomass increased | 1 – 150 | Pots (sand/ perlite) | Husain et al. (2004) | |
| Wheat (Bread) | Seminal root growth decreased, lateral root growth enhanced, seminal root angle decreased | 50 – 200 | PVC tubes & filter paper | Rahnama et al. (2019) |
| Narrower seminal root angle | ESP = 17 % * | Clear pot method | Anzooman et al. (2019) | |
| Reduced root hair density and length | 100 | Hydroponics | Robin et al. (2016) | |
| Root biomass increased | EC < 9 ds/m * | Soil | Nuttall et al. (2006) |
* Electrical Conductivity (EC): 1 dS/m = 10 mM NaCl (Munns et al, 2020a); Osmotic Potential (MPa): - 0.1 MPa approximates 23 mM NaCl (Weimberg et al., 1984); Exchangeable Sodium Percentage (ESP) > 17 % = strongly sodic soil.