Table 1.
(a) Variation in crop photosynthesis rate per unit leaf area collected at saturating light and current atmospheric [CO2] (A sat). All the data were collected at 400 μmol mol−1 [CO2] while in Blum et al. (1990) and Fischer et al. (1998) measurements were taken at 345 μl L−1 [CO2], in Hervé et al. (2001) and Watanabe et al. (1994) measurements were taken at a [CO2] of 350 μmol mol−1 and in Gu et al. (2012) measurements were taken at a [CO2] of 380 μmol mol−1. (b) Variation in stomatal conductance (gs) and mesophyll conductance (gm) in different studies.
| (a) Reference | Crop | Range of A sat (μmol m−2 sec−1) | Intraspecific variation (μmol m−2 sec−1) | Relation with yield |
|---|---|---|---|---|
| Rawson et al. (1983) | Wheat | 20–45 (mg dm−2 h−1) | 12 mg dm−2 h−1 | A sat and yield not correlated. Cumulative CO2 fixation by flag leaf and yield P < 0.001 r 2 = 0.30 |
| Blum (1990) | Wheat | 9.6–16.6 | 7 | High yielding cultivar showed highest A for the flag leaf |
| Watanabe et al. (1994) | Wheat | 25.5–31.5 | 6 | Yield data not present |
| Fischer et al. (1998) | Wheat | 14.8–25.9 | 11.1 | Asat and mean grain yield r 0.72 and 0.91 (P < 0.01) |
| Reynolds et al. (2000) | Wheat | 20.9–27 at booting, 18–23.6 at anthesis, 23–11.8 at grain filling | 11.2 to 5.6 depending on stage | A sat and grain yield P < 0.01, r = 0.73 |
| Chytyk et al. (2011) | Wheat | 27.5–34.5 | 7 | Yield data not present |
| Sadras et al. (2012) | Wheat | 9.3–19.6 | 10.3 | Data not plotted |
| Driever et al. (2014) | Wheat | 30.5–19.1 | 11.4 | Correlation between grain yield and A not significant (P > 0.05) |
| Carmo‐Silva et al. (2017) | Wheat | 21.2–31.1 (pre‐anthesis), 17.1–23.7 (post‐anthesis) | 9.9–6.6 | P < 0.05 (r = 0.27 pre‐anthesis and r = 0.25 post‐anthesis) |
| Pettigrew (2004) | Cotton | 20.3–37.7 | 17.4 | Yield data not present |
| Pater et al. (2017) | Canola | 5.5–22.5 | 17 | Yield data not present |
| Gu et al. (2012) | Rice | 12.8–25.5 | 12.7 | Yield data not present |
| Hervé et al. (2001) | Sunflower | 17.3 ± 10.2 (mean ± SD) | na | Yield data not present |
| (b) Reference | Crop | gs range (mol m−2 sec−1) | gm range (mol m−2 sec−1) | Note |
|---|---|---|---|---|
| Fischer et al. (1998) | Wheat | 0.34–0.57 | – | Field conditions |
| Jahan et al. (2014) | Wheat | – | 0.51–1.05 | Greenhouse conditions |
| González et al. (1999) | Barley | 0.01–0.06 (cm sec−1) | – | Field conditions |
| Barbour et al. (2010) | Barley | 0.25–0.52 | 0.05–0.50 | Greenhouse conditions |
| Pater et al. (2017) | Canola | 0.12–0.63 | – | Large screening in greenhouse and field conditions |
| Hervé et al. (2001) | Sunflower | 1.01 ± 0.08 (mean ± SD) | – | Greenhouse conditions |
| Ouyang et al. (2017) | Rice | 0.15–0.31 | 0.05–0.21 | Pot experiment |