How yield relates to ash content, Δ¹³C and Δ¹⁸O in maize grown under different water regimes
Cabrera-Bosquet, Llorenç | Sánchez, Ciro | Araus, José Luis
BACKGROUND AND AIMS: Stable isotopes have proved a valuable phenotyping tool when breeding for yield potential and drought adaptation; however, the cost and technical skills involved in isotope analysis limit its large-scale application in breeding programmes. This is particularly so for Δ¹⁸O despite the potential relevance of this trait in C₄ crops. The accumulation of minerals (measured as ash content) has been proposed as an inexpensive way to evaluate drought adaptation and yield in C₃ cereals, but little is known of the usefulness of this measure in C₄ cereals such as maize (Zea mays). The present study investigates how yield relates to ash content, Δ¹³C and Δ¹⁸O, and evaluates the use of ash content as an alternative or complementary criterion to stable isotopes in assessing yield potential and drought resistance in maize. METHODS: A set of tropical maize hybrids developed by CIMMYT were subjected to different water availabilities, in order to induce water stress during the reproductive stages under field conditions. Ash content and Δ¹³C were determined in leaves and kernels. In addition, Δ¹⁸O was measured in kernels. KEY RESULTS: Water regime significantly affected yield, ash content and stable isotopes. The results revealed a close relationship between ash content in leaves and the traits informing about plant water status. Ash content in kernels appeared to reflect differences in sink-source balance. Genotypic variation in grain yield was mainly explained by the combination of ash content and Δ¹⁸O, whilst Δ¹³C did not explain a significant percentage of such variation. CONCLUSIONS: Ash content in leaves and kernels proved a useful alternative or complementary criterion to Δ¹⁸O in kernels for assessing yield performance in maize grown under drought conditions.
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