Genetic gains in grain yield and physiological traits of winter wheat in Hebei Province of China, from 1964 to 2007

Abstract

Understanding the key characteristics associated with genetic progress is essential to future wheat breeding strategies. Our objectives were to investigate the genetic progress in grain yield (GY) and key characteristics in wheat (Triticum aestivumL.) cultivars released from 1964 to 2007 in Hebei province, China. Field experiments including 9 milestone cultivars were conducted during three growing seasons (2010–2011, 2011–2012, and 2012–2013) at Shijiazhuang of Hebei. Grain yield is significantly increased by the linear rate of 47.4 kg ha−1 yr−1 or 0.717% (R 2 = 0.909, P < 0.001) and mainly attributed to the increase of harvest index (HI) (r = 0.927, P < 0.01), kernels per spike (Skernel) (r = 0.919, P < 0.01) and thousand kernel weight (TKW) (r = 0.869, P < 0.01). Aboveground biomass (AGBM) has also important contribution to genetic gain in yield before 1997 (r = 0.838, P < 0.05). Although there is decline tendency in spikes m−2 due to decreased maximum tiller numbers (Mtiller) and increased percentage of ear-bearing tiller (ET%) after 70 s, changes of spikes m−2 have no significant effect on yield improvement. Grain yield has positive correlation with kernels m-2 (r = 0.767, P < 0.05) in spite of slower increasing rate of kernels m−2 after 1970s. Genetic gain of GY has close relation with decreased plant height (PH) (r = −0.811, P < 0.01), and PH of stone cultivars after 1970s were 70–80 cm which was optimum for grain yield. Days to heading (DH), days to anthesis (DA) and days to maturity (DM) of stone cultivars have no significant correlation with genetic gain. The significant HI increase mainly results from a significant increase in TKW (r = 0.811, P < 0.01) and Skernel (r = 0.919, P < 0.01). The increased TKW is positively associated with the maximum filling rate (Rmax) (r = 0.720, p < 0.05), average filling rate (Ra) (r = 0.836, p < 0.01), water-soluble carbohydrate (WSC) at anthesis in stem (WSC0) (r = 0.820, p < 0.05), Stem WSC 10 d after anthesis (WSC10) (r = 0.861, p < 0.01) and chlorophyll content (Chl) (r = 0.783, p < 0.05). Thus the physiological traits of Chl of flag leaf, stem WSC and high filling rate can be used to select criterions for further improving yield potential.