Ear photosynthetic anatomy effect on wheat yield and water use efficiency

Abstract

The screening of C 4 property in C 3 crops is an alteration that could improve photosynthetic capacity and efficiency, enhancing potential grain yield, particularly under water stress conditions. The present study aimed to determine how photosynthetic anatomy affects wheat (Triticum aestivum) photosynthetic rate and yield. Gas exchange and anatomical characteristics of the flag leaf and ear were compared in different ploidy wheats (diploid, tetraploid, and hexaploid) under well-watered (WW) and water-stressed (WS) conditions. The photosynthetic rate of the ear (P N _ear) decreased to a lesser extent than that of the flag leaf (P N _leaf) under WS and that the P N _ear of tetraploid wheat decreased the least. Furthermore, the integral water-use efficiency (WUE i ) of tetraploid wheat increased the most among the three wheat species. The anatomical characteristics varied not only between the WW and WS conditions but also between the three wheat species; tetraploid species showed higher stomatal frequency (SF), stomatal area per organ area (SA), vein distance (D V ), and bundle-sheath cell number (N BS ), and lower vein distance in the glume and lemma. Correlation analysis showed that grain yield presented significant positive correlation with the P N _leaf, P N _ear, and WUE i . The P N _leaf was affected by stomatal length (SL), stomatal width, and SA, while the P N _ear was affected by SF, SA, and stomatal size in the ear organs. The WUE i was generally positively correlated with SL, N V , and N BS in the ear organs. The higher vein density and well-developed bundle sheath of tetraploid species may contribute to the higher P N _ear and lower decrease in grain yield.

Rehydration Compensation of Winter Wheat Is Mediated by Hormone Metabolism and De-Peroxidative Activities Under Field Conditions

“…Rehydration at different growth stages can compensate for the decline in biomass caused by crop water deficit, especially after a moderate drought before the booting stage ( Jiang et al, 2020 ). There is an obvious compensatory phenomenon in wheat plant height and leaf area ( Li Y. et al, 2020 ), but there are rare reports of ear development on winter wheat after rehydration. In this work, we monitored the compensatory growth of two winter wheat varieties that have different drought resistance levels after rehydration ( Figure 1 ).…”

Photosynthetic organs contributions to grain yield genetic gains in Chilean winter wheat

“…This loss of assimilates has adverse effects on grain filling when the leaf photosynthesis declines because of senescence and/or stress conditions (e.g., drought, heat, and leaf diseases) (Abbad et al., 2004; Blum, 1998). Contrary to the leaf, the ear photosynthesis is less affected under stress conditions because: (a) it has a better CO 2 diffusive conductance during drought, suggesting efficient assimilation of CO 2 per unit of water transpired (Araus et al., 1993; Bort et al., 1996; Hein et al., 2016); (b) it has a better osmotic adjustment, higher relative water content, delayed senescence, and a greater capacity to transport assimilate (Hein et al., 2016; Morgan, 1980; Tambussi et al., 2007); (c) it has organs enclosing the developing grain (i.e., lemma and palea) which recycle respired CO 2 (Bort et al., 1996; Morgan, 1980; Tambussi et al., 2007); and (d) several reports suggested the ear as an intermediate C3–C4 organ, where some ear parts were reported to have a C4 metabolism (Imaizumi et al., 1990; Jia et al., 2015; Li et al., 2019; Lu & Lu, 2004), and consequently the higher enzymatic activity of the C4 pathway and the higher capacity of photosynthetic carbon assimilate transport could increase the ear drought tolerance (Jia et al., 2015; Li et al., 2019). Thus, selecting high ear photosynthesis is vital for increasing yield potential under stress and favorable conditions (Álvaro et al., 2008; Maydup et al., 2010; Reynolds et al., 2005, 2011; Slafer et al., 1999; Tambussi et al., 2005, 2007).…”