Abstract
Both increased harvest index (HI) and increased dry matter (DM) are beneficial to yield; however, little is known about the priority of each under different yield levels. This paper aims to determine whether HI or DM is more important and identify the physiological attributes that act as indicators of increased yield. Two field experiments involving different cultivation patterns and water-nitrogen modes, respectively, were carried out from 2013 to 2016 in Huang-Huai Plain, China. Plant DM, leaf area index (LAI), and radiation interception (RI) were measured. Increased yield under low yield levels <7500 kg ha-1 was attributed to an increase in both total DM and HI, while increases under higher yield levels >7500 kg ha-1 were largely dependent on an increase in HI. Under high yield levels, HI showed a significant negative correlation with total DM and a parabolic relationship with net accumulation of DM during filling. Higher net accumulation of DM during filling helped slow down the decrease in HI, thereby maintaining a high value. Moreover, net DM accumulation during filling was positively correlated with yield, while post-anthesis accumulation showed a significant linear relationship with leaf area potential (LAP, R2 = 0.404–0.526) and radiation interception potential (RIP, R2 = 0.452–0.576) during grain filling. These findings suggest that the increase in LAP and RIP caused an increase in net DM accumulation after anthesis. Under DM levels >13,000 kg ha-1 at anthesis, maintaining higher LAI and RI in lower layers during grain formation contributed to higher yield. Furthermore, the ratio of upper- to lower-layer RI showed a second-order curve with yield during filling, with an increase in the optimal range with grain development. Pre-anthesis translocation amount, translocation ratios and contribution ratios also showed second-order curves under high yield levels, with optimal values of 3000–4500 kg ha-1, 25–35, and 30–50%, respectively. These results confirm the importance of HI in improving the yield, thereby providing a theoretical basis for wheat production in the Huang-Huai Plain.
Highlights
With the increasing world population, which is estimated to reach 9.4 billion by 2050 (Foulkes et al, 2009), global agriculture in the 21st century is facing a significant increase in crop production
GN, and dry matter (DM) showed the same trend between locations: Shangshui > Wenxian > Kaifeng, while the thousand grain weight (TGW), harvest index (HI), and total DM revealed variations
Our results are consistent with these findings, whereby high-efficiency cultivation (HH), super high-yielding cultivation (SH), and optimized cultivation compared with FP (OFP) treatment resulted in a higher DMAM than farming practices (FP), thereby increasing the HI
Summary
With the increasing world population, which is estimated to reach 9.4 billion by 2050 (Foulkes et al, 2009), global agriculture in the 21st century is facing a significant increase in crop production. Since the HI of modern cultivars is already high, it has been suggested that further improvements in yield will rely more on increases in total DM (Aranjuelo et al, 2013; Parry and Hawkesford, 2010; Parry et al, 2010). That further increases in wheat yield are largely dependent on increases in HI, rather than increases in DM (Aranjuelo et al, 2013; Fan et al, 2017). Increased food production remains a priority for future world populations In wheat production, both a high HI and DM are beneficial to increased yield; the contribution of each differs in different regions. Understanding the respective relationships between yield, DM, and HI in modern cultivars is necessary, under different yield levels, as is confirming the respective importance of DM and HI in terms of sustainable high yield
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