Relationship between root vigour, photosynthesis and biomass in soybean cultivars during 87 years of genetic improvement in the northern China

Abstract

In the last century, world soybean yield has been constantly enhancing at a remarkable rate. Factors limiting the soybean yield may be multiple. It is widely acknowledged that changes of root metabolism can influence aboveground characteristics, such as the seed yield and photosynthesis. In this study, we considered root bleeding sap mass (BSM) and root activity (RA) as indicators of the root growth vigour. We used 27 soybean cultivars, spanning from 1923 to 2009, to evaluate the contribution of root characteristic improvement to efficient photosynthesis and dry matter production. The BSM, RA, net photosynthetic rate (P N ), and organ biomass were measured at different growth stages, such as the fourth leaf node, flowering, podding, and seed filling stage. Our results showed that the soybean cultivars increased their biomass and P N thanks to genetic improvement. At the same time, BSM and RA also increased in dependence on a year of cultivar release. However, both P N and biomass were positively correlated with root characteristics only at the podding stage. Our data revealed that the improved root characteristic may have contributed to enhanced photosynthesis, biomass, and yield of soybean cultivars during last 87 years of genetic improvement. We suggest that BSM and RA could be used as important indexes for further practice in soybean production improvement.

Agronomic traits of soybean cultivars released in different decades after grafting record‐yield cultivar as rootstock

“…The betterment of root functions could contribute to the enhanced photosynthesis of soybean (Cui et al. ). High photosynthetic capacity would result in greater efficiency at producing carbon resources (Boerma and Ashley , Morrison et al.…”

“…In this study, plants grafted onto L14 or Z35 rootstocks resulted in a higher grain yield than that of their non-grafts or self-grafts, which was attributed to the increase of 100-seed mass. The betterment of root functions could contribute to the enhanced photosynthesis of soybean (Cui et al 2016). High photosynthetic capacity would result in greater efficiency at producing carbon resources (Boerma andAshley 1988, Morrison et al 1999).…”

“…, Cui et al. ). But the breeders have seldom considered selection for root traits during the improvement in soybean on account of the difficulty in observing and measuring roots in situ .…”

“…Apart from the factors of environment or agronomic practices, however, it also seems that the root functions per se of cultivars may be the key limited factors for yield gain. Roots mediate uptakes of water and ions, and respond to external signals, which had significant relationships with the agronomic and yield traits (Pantalone et al 1996, Cui et al 2016. But the breeders have seldom considered selection for root traits during the improvement in soybean on account of the difficulty in observing and measuring roots in situ.…”

Photosynthesis in reciprocal grafts of drought-tolerant and drought-sensitive cultivars of soybean under water stress

“…The xylem sap is resulting from root pressure and might mediate exchanges between shoots and roots (Li et al 2009). The root bleeding sap mass (RBSM) was used as an indicator of the root growth vigor in previous study and had positive relationship with PN in soybean (Cui et al 2016). However, it remained to be clarified whether a relatively high photosynthesis of drought-resistant soybean under water stress is typical only for leaves or for the root system or for the whole plant.…”