Restricting the above ground sink corrects the root/shoot ratio and substantially boosts the yield potential per panicle in field‐grown rice (Oryza sativa L.)

Abstract

Rice has shallow, weak roots, but it is unknown how much increase in yield potential could be achieved if the root/shoot ratio is corrected. Removing all tillers except the main one, in a japonica (Sakha 101) and an indica (IR64) rice cultivar, instantly increased the root/shoot ratio from 0.21 to 1.16 in Sakha 101 and from 0.16 to 1.46 in IR64. Over 30 days after detillering, the root/shoot ratios of the detillered plants decreased to 0.49 in Sakha 101 and 0.46 in IR64 but remained significantly higher than in the controls. The detillered plants showed two- or fourfold increase in the main tiller fresh weight, as a consequence of more positive midday leaf relative water content (RWC), and consistently higher rates of stomatal conductance and photosynthesis, but not transpiration, compared with the controls. The enhanced photosynthesis in Sakha 101 after detillering resulted from both improved water status and higher Rubisco contents whereas in IR64, increasing the Rubisco content did not contribute to improving photosynthesis. Detillering did not increase the carbohydrate contents of leaves but prevented starch depletion at the end of grain filling. The leaf protein content during vegetative and reproductive stages, the grain filling rate, the number of filled grains per panicle were greatly improved, bringing about 38.3 and 35.9% increase in the harvested grain dry weight per panicle in Sakha 101 and IR64, respectively. We provide evidence that improving the root performance by increasing the root/shoot ratio would eliminate the current limitations to photosynthesis and growth in rice.

Novel QTL Associated with Shoot Branching Identified in Doubled Haploid Rice (Oryza sativa L.) under Low Nitrogen Cultivation

“…The additive effect (−1.1) suggests that the allele from Milyang352 (P2, japonica ) contributed to the observed phenotypic variance explained (PVE, 11.98%) ( Table 2 , Figure 4 D). Biomass dry weight is affected by many factors, including the acquisition of mineral nutrients and crop productivity [ 51 ]. It was also proposed that there is an interdependent relationship between the shoot and roots [ 52 , 53 ].…”

A critical role of stable grain filling rate in maximizing rice yield revealed by whole plant carbon nitrogen interaction modeling

“…In another case, based on the correlation between grain filling parameters and yield components in 15 different genotypes, it was concluded that the grain filling rate was much more important than the grain filling duration (Jones, Peterson, & Geng, 1979); however, observations from six field-grown tropical irrigated rice, in another study, demonstrated that the grain filling duration, instead of the grain filling rate, was significantly positively correlated with the grain yield (W. Yang, Peng, Dionisio-Sese, Laza, & Visperas, 2008). Other debates on gaining higher yield during grain filling include whether plants should have higher or lower root:shoot ratio (Ma, Li, Xu, & Huang, 2010; Nada & Abogadallah, 2016), more or less leaf nitrogen remobilization (Lee et al, 2020; Shin et al, 2020; Q. Wang et al, 2018; J.…”