Improved photosynthetic capacity during the mid- and late reproductive stages contributed to increased cotton yield across four breeding eras in Xinjiang, China

Abstract

Photosynthesis is the basis for yield formation, and the improvement of photosynthetic efficiency is one important way to improve crop yield. The objective of this experiment was to compare the photosynthetic characteristics of early-maturing cotton (Gossypium hirsutum L.) cultivars from four breeding eras in the northern half of China’s Xinjiang Region. The four cultivars in this study were as follows: (i) ‘Xinluzao 1’, representing era 1 (1980s); (ii) ‘Xinluzao 7’, representing era 2 (1990s); (iii) ‘Xinluzao 13’, representing era 3 (2000s); and (iv) ‘Xinluzao 45’, representing era 4 (2010s). The results showed that the yield increases can primarily be attributed to (i) increases in boll number and lint percentage between eras 1 and 4 and (ii) increases in photosynthetic rates during eras 3 and 4. Compared with the earlier cultivars, the era 3 and 4 cultivars had greater canopy apparent photosynthetic rates and canopy apparent photosynthetic light use efficiency during the mid- and late reproductive stages. The era 3 and 4 cultivars also maintained high leaf area index and high fractional interception of photosynthetically active radiation until boll opening. Furthermore, the era 4 cultivars had higher leaf photosynthetic rates during the late reproductive stage compared with earlier cultivars. Overall, these results indicated that improvements in photosynthetic capacity, especially during the mid- and late reproductive stages contributed to the yield increases in the era 3 and 4 cultivars.