Characteristics of canopy structure and contributions of non-leaf organs to yield in winter wheat under different irrigated conditions

Abstract

Non-leaf green organs of wheat plants may have significant photosynthetic potential and contribute to grain yield when the plants are subjected to stress at late growth stages. Canopy structure, change of green non-leaf organ area (e.g., ear, peduncle, sheath), the proportion of green non-leaf organs area to total green area and the contribution proportion from different organs’ photosynthate to grain yield in winter wheat ( Triticum aestivum L.) were studied at Wuqiao Experiment Station of China Agricultural University, Hebei, China, in 2001–2002 and 2002–2003 using two winter wheat cultivars, Shijiazhuang8 (SJZ-8) and Lumai21 (LM-21). Four irrigation treatments used were W0 (no water applied during spring), W1 (750 m 3 ha −1 water applied at elongation), W2 (1500 m 3 ha −1 applied 50% at elongation and 50% at anthesis) and W4 (3000 m 3 ha −1 applied 25% at upstanding, booting, anthesis and grain filling), respectively. Results showed that the area of top three leaf blades decreased and the proportion of green non-leaf organ area to the total green area at anthesis increased with the decreasing of water supply. Root weight increased in the 0–100 cm soil layer and decreased in the 100–200 cm layer when water supply increased, suggesting reducing irrigation enhanced root weight in deep soil layer. The photosynthetic contribution of non-leaf organs above flag leaf node to grain yield increased with decreasing water supply, and was significantly higher than that of the flag leaf blade contribution. Winter wheat grain yield increased, but water use efficiency (WUE) decreased, with increase in water supply. Higher light transmission ratio in the canopy after anthesis was achieved with smaller size and high quality top leaf blades, higher grain-leaf ratio and larger proportion of green non-leaf area, which lead to higher canopy photosynthetic rate and WUE after anthesis. Irrigation of 1500 m 3 ha −1 applied in two parts, 750 m 3 ha −1 applied at elongation and another 750 m 3 ha −1 applied at anthesis, was the best irrigation scheme for efficient water use and for high yield in winter wheat.