Root scanner

The determination of root architecture parameters followed the method by Tripathi et al. [74 (link)]. Three tomato seedlings with uniform growth were chosen for each treatment, and their roots were gently spread out in a transparent tray using tweezers. The roots of each treated tomato were subjected to scanning using a root scanner from Regent Instruments, Inc. (Quebec City, QC, Canada), and the resulting scanned images were preserved. Subsequently, the root images were subjected to analysis using specialized root analysis software (Win RHIZO Pro LA2400, Regent Instruments Inc., Quebec City, QC, Canada) to extract data on the root length, total root surface area, total root volume, number of lateral roots, number of root tips, and number of crossings.

Roots of 20-d-old plants were scanned using root scanner (Regent Instruments Inc., Québec, QC, Canada) (Figure S1A) and the images were analyzed in WinRhizo Pro software (Regent Instruments, Ville de Québec, QC, Canada) to obtain total root length (cm plant⁻¹), surface area (cm² plant⁻¹), volume (cm³ plant⁻¹) and number of root tips. Root and shoot P concentration (μg g⁻¹ dry weight (DW)) was determined by ascorbic acid method [28 (link)] after digestion of dried tissue with di-acid mixture (HNO₃:HClO₃::9:4). Tissue P content was calculated from P concentration in root or shoot, the sum of which was the total P uptake, expressed as μg P plant⁻¹.