Peer review

Terminal drought substantially reduces chickpea yields. Reducing water use at vegetative stage by reducing transpiration rate (TR) under high vapor pressure deficit (VPD), i.e. under dry/hot conditions, contributes to drought adaptation. We hypothesized that this trait could relate to differences in the genotype’s dependence on root’s water transport pathways and hydraulics. The transpiration rate response in profligate and conservative chickpea genotypes was evaluated under increasing VPD in the presence/absence of apoplastic & cell‐to‐cell transport inhibitors. Conservative genotypes ICC4958 and ICC8058 restricted TR under high VPD compared to profligate genotypes ICC14799 and ICC867. Profligate genotypes were more effected by aquaporin inhibition of the cell‐to‐cell pathway than conservative genotypes, as measured by root hydraulic conductance and transpiration under high VPD. Aquaporin inhibitor treatment also led to a higher reduction in root hydraulic conductivity in profligate than in conservative genotypes. By contrast, the blockage of the apoplastic pathway in roots decreased TR more in conservative than in profligate genotypes. Interestingly, conservative genotypes had high early vigor whereas profligate genotypes had low early vigor. In conclusion, profligate genotypes depended more on the cell‐to‐cell pathway, which could have explained their higher root hydraulic conductivity, whereas water saving from transpiration restriction showed a higher dependence on the apoplastic pathway. This opens the possibility to do screening for conservative or profligate phenotypes using these inhibitors, itself opening to the search of the genetic basis of these differences.

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