Evaluating Leaf Wax and Bulk Leaf Carbon Isotope Surrogates for Water Use Efficiency and Grain Yield in Winter Wheat
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© Crop Science Society of America. Bulk leaf carbon isotopic composition (δ 13 C bulk ) has been widely used to investigate leaf level water use efficiency (WUE l ) in efforts to boost grain yield relative to crop water use. Although widely used for isotopic analyses, the bulk leaf represents a complex mixture of compounds. Single-compound isotopic analyses carry diagnostic advantages over bulk analyses in a range of applications and may also serve as surrogates for WUE l and grain yield in crops. This study tests whether compound-specific carbon and hydrogen isotopes of leaf wax n-alkanes (δ 13 C alk and δD alk ) and n-alcohols (δ 13 C alc ) could be used as surrogates for WUE l and grain yield using conventional δ 13 C bulk as a reference. Ten winter wheat (Triticum aestivum L.) cultivars were planted under two irrigation treatments (full and deficit irrigation) at Uvalde (wet location) and Amarillo (dry location), TX, during two growing seasons. There were significant relationships between δ 13 C alk or δD alk and δ 13 C bulk , indicating they can all serve as surrogates for WUE l in most cases. Compared with δ 13 C bulk , we found stronger relationships between δ 13 C alk at Uvalde or δD alk under deficit irrigation at Amarillo and grain yield. The δ 13 C alk also had higher broad-sense heritability than δ 13 C bulk , indicating larger cultivar effects in δ 13 C alk than in δ 13 C bulk . In contrast, the δ 13 C alc was not consistently related with δ 13 C bulk or grain yield. Our study introduces the idea that δ 13 C alk and δD alk may supplement conventional δ 13 C bulk with potential to assist in the breeding process when selecting for high-WUE and high-yielding cultivars.
author list (cited authors)
Liu, X., Feakins, S. J., Dong, X., Xue, Q., Han, J., Marek, T., ... Ibrahim, A.