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

Abstract

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 sterilized river sand supplied with P at a rate of 10 μg P g soil as FePO , a poorly soluble form of P. The results showed large genotypic variation in plant growth, shoot P content, physiological P-use efficiency, and P-utilization 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 6 genotypes with high plant growth, P-acquisition, and P-utilization efficiency suggests that the chickpea reference set can be used in breeding programmes to improve both P-acquisition and P-utilization efficiency under low-P conditions.

The carboxylate‐releasing phosphorus‐mobilizing strategy can be proxied by foliar manganese concentration in a large set of chickpea germplasm under low phosphorus supply

“…Using the leaf transpiration rate data measured on the youngest fully expanded leaves from Pang et al . (), there was a weak correlation between the concentration of Mn in mature leaves and leaf transpiration rate ( r = 0.28, P < 0.01) (Table ; Fig. ).…”

“…For example, our results show a weak but significant correlation between foliar Mn concentration and root size including total root length, root surface area and root hair cylinder volume, but the correlation was much weaker than that with carboxylates. Likewise, a weak but significant correlation between foliar Mn concentration and leaf transpiration also was found in this study, but this correlation was much weaker than the correlation between leaf P concentration and leaf transpiration rate ( r = 0.57, P < 0.001) measured on the same plants of 100 chickpea genotypes (Pang et al ., ). Therefore, although we suggest using Mn as a proxy for belowground carboxylate exudation process, we should not ignore the role of leaf transpiration and root size in Mn accumulation.…”

“…When genotypic effects were significant, the least significant difference at P = 0.05 is presented in figures or figure New Phytologist (2018) v.12.5 (Systat Software Inc., 2011). The data from 100 genotypes on total shoot P content, and leaf transpiration rate of the youngest fully expanded leaves on main stems were obtained for the same plants as those used for this study and have been presented elsewhere (Pang et al, 2018); they were used for the regression analysis in this study. Principal component analysis (PCA) based on the correlation matrix was undertaken using Genstat to examine the relationships among plants.…”

“…In addition to the role of carboxylates in P mobilization and acquisition, Pang et al . () found that leaf transpiration also plays a role in P acquisition in chickpeas grown in low‐P sandy soil with a very low P‐buffering capacity, possibly via transpiration‐driven mass flow. However, the role of leaf transpiration in Mn acquisition is unknown.…”

“…However, for crop species without cluster roots, such as chickpea, the effect of carboxylates recovered in the rhizosheath on Mn mobilization and its accumulation in mature leaves is unknown. In addition to the role of carboxylates in P mobilization and acquisition, Pang et al (2018) found that leaf transpiration also plays a role in P acquisition in chickpeas grown in low-P sandy soil with a very low P-buffering capacity, possibly via transpiration-driven mass flow. However, the role of leaf transpiration in Mn acquisition is unknown.…”