Root architecture modifications in pigeonpea for improved water extraction from deep soil layers

Abstract

A growing body of evidence suggests that the next leap in dryland crop productivity will come from below ground rather than above it. This research compared root architecture and deep-water extraction in three pigeonpea (Cajanus cajan) genotypes—ICPL 87119 (standard), ICP 7035 (deep-rooted), and ICPL 332 (compact)—grown in 1.5 m deep rhizotrons at the University of Hohenheim, Stuttgart, Germany, over two seasons (2022-2023). ICP 7035 maintained root length density of 1.3 cm cm⁻³ at 105 cm depth, four-fold higher than ICPL 332 (0.1 cm cm⁻³). Under terminal drought, ICP 7035 extracted 68% more water from the 60-120 cm zone and yielded 34% more grain than the compact type. Steep root angle (≥60°) and aerenchyma formation were identified as the key traits enabling deep-root function.