Leaf transpiration plays a role in phosphorus acquisition among a large set of chickpea genotypes

Low availability of inorganic phosphorus (P) is considered a major constraint for crop productivity worldwide. A unique set of 266 chickpea (Cicer arietinum L.) genotypes, originating from 29 countries and with diverse genetic background were used to study P-use efficiency. Plants were grown in pots containing sterilised river sand supplied with P at a rate of 10 μg P g–1 soil as FePO4, a poorly soluble form of P. The results showed large genotypic variation in plant growth, shoot P content, physiological P-use efficiency and P-utilisation efficiency in response to low-P supply. Further investigation of a subset of 100 chickpea genotypes with contrasting growth performance showed significant differences in photosynthetic rate and photosynthetic P-use efficiency. A positive correlation was found between leaf P concentration and transpiration rate of the young fully expanded leaves. For the first time, our study has suggested a role of leaf transpiration in P acquisition, consistent with transpiration-driven mass flow in chickpea grown in low-P sandy soils. The identification of six genotypes with high plant growth, P-acquisition and P-utilisation efficiency suggests that the chickpea reference set can be used in breeding programs to improve both P-acquisition and P-utilisation efficiency under low-P conditions.