Photosynthetic characteristics and nitrogen distribution of large-spike wheat in Northwest China

Abstract

The leaf photosynthesis and nitrogen (N) translocation in three large-spike lines and control cultivar (Xi'nong 979) of winter wheat (Triticum aestivum L.) were studied in 2010–2011 and 2011–2012. The objectives of this study were to investigate the differences in the physiological characteristics of large-spike lines and control cultivar and identify the limiting factors that play a role in improving the yield of breeding materials. The average yield, grain number per spike, kernel weight per spike, and 1000-kernel weight of the large-spike lines were 16.0, 26.8, 42.6, and 15.4%, respectively, significantly higher than those of control. The average photosynthetic rates (Pn) were not significant between the large-spike lines and control cultivar during the active growth period. The average PSII maximum energy conversion efficiency (Fv/Fm), PSII actual quantum efficiency (ΦPS??), photochemical quenching coefficient (qP), PSII reaction center activity (Fv‘/Fv‘) and water-use efficiency (WUE) of the large-spike lines were 1.0, 5.1, 3.6, 0.8, and 43.4%, respectively, higher than those of the control during the active growth stages. The N distribution proportions in different tissues were ranked in the order of grains<culms+sheathes<ra-chis+glumes<flag leaves<penultimate leaves<remain leaves. This study suggested that utilization of the large-spike wheat might be a promising approach to obtain higher grain yield in Northwest China.

Keywords

• wheat
• nitrogen distribution
• large-spike lines
• photosynthetic characteristics
• yield